Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1996-08-20
2001-12-11
Fuller, Benjamin R. (Department: 2855)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S088000, C347S061000, C347S056000
Reexamination Certificate
active
06328421
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for projecting fluid drops, and more particularly to an ink jet recording head for causing minute fluid drops to fly to a recording medium to record visual images. The invention relates to an apparatus for projecting fluid drops, and more particularly to an apparatus for causing electroconductive materials, which are solid at normal temperature and melted by heating, in a state of fluid drops to a circuit substrate or the like and forming bumps thereon for connection to LSIs or the like.
DESCRIPTION OF THE PRIOR ART
Fluid drop projecting apparatuses according to the prior art for use in ink jet printers among others include one disclosed in the U.S. Pat. No. 3,946,398 in which, as illustrated in
FIG. 13A
, a piezo element
12
is oscillated to expand the volume of an ink chamber
30
thereby to suck a fluid
14
, such as ink, from an ink tank (not shown) and, afterwards, as illustrated in
FIG. 13B
, the volume of the ink chamber
30
is compressed to apply pressure to the fluid
14
thereby to cause fluid drops
20
to fly from a nozzle
31
onto a recording medium. They also include another described in the Japanese Patent Publication No. 61(1986)-59911 in which a heating element is built into an ink chamber, bubbles are instantaneously generated by thermal energy in ink, and the ink is projected by the expansive force of the bubbles. According to the prior art, many fluid drop projecting apparatuses utilizing the principle of pumping have been proposed.
Known fluid drop projecting apparatuses which fly a mist of ink include ones disclosed in the Gazettes of the Japanese Patents Laid-open No. 4(1992)-14455, 4(1992)-299148 and 5(1993)-38810. The one according to the Patent Laid-open No. 4(1992)-14455, illustrated in
FIGS. 14A and 14B
, uses as a driver a propagation plate
32
at one end of whose propagation face
33
a plurality of pairs of comb-shaped electrodes IDT
34
are formed; a high-frequency A.C. voltage 35 of about 20 MHz is applied to the driver to excite the surface of the propagation face
33
and thereby to generate a surface elastic wave A. The surface elastic wave A thereby generated travels in the direction of the arrow in the diagram and, when it reaches a part where the propagation face
33
is in contact with ink
14
, leaks therefrom to the ink
14
to become a longitudinal elastic wave (acoustic wave), which excites a surface
37
of the ink exposed in a slit
36
to fly a mist of fluid drops
20
.
In the apparatus described in the Patent Laid-open No. 4(1992)-299148, as shown in
FIG. 15
, a gap is formed between a slit member
38
and a resonator
39
to compose an ink chamber
30
. The ink chamber
30
is filled with ink
14
by capillary action; resonant vibration is applied to the resonator
39
in the thickness direction; the energy of vibration is propagated to the ink eventually to form a random surface wave on an ink interface
41
at an ink outlet
40
, so that the interference of the surface wave causes particles of ink to be projected in a mist form according to the vibrating frequency of the resonator.
According to the Patent Laid-open No. 1993-38810, as illustrated in
FIG. 16
, a pair of electrodes
43
are formed on the upper and lower faces of a piezoelectric substrate
42
, to which a nozzle plate
45
is joined via a gap supporter
44
, and the gap is filled with ink
14
by capillary force. When a voltage displaced by a resonant frequency, which is determined by the thickness of the piezoelectric substrate
42
, is applied to an intersection area
46
formed by the electrodes
43
, the piezoelectric substrate
42
resonates to generate an ultrasonic wave in the ink
14
. The ultrasonic wave travels through the ink
14
to generate a surface wave on a surface
37
of ink filling a nozzle
31
immediately above the intersection area
46
. When the amplitude of this surface wave surpasses a certain level, ink drops
20
are projected in a mist form from the nozzle
31
.
According to any one of the above-cited Patents Laid-open Nos. 1992-14455, 1992-299148 and 1993-38810, though differing in means to generate a surface wave on the ink surface, a surface wave is generated at random on the free surface of fluid by the same principle as that of mist projection by ultrasonic humidifiers, and the interference of the surface wave causes the fluid to be projected in a mist form from an indefinite large number of projection points.
A fluid drop projecting apparatus utilizing the sound pressure of acoustic streaming is disclosed in the Gazette of the Japanese Patent Laid-open No. 63(1988)-162253. According to the invention described in this patent, as shown in
FIG. 17
, an ultrasonic acoustic wave is generated by the vibration of a piezoelectric transducer
47
and converged by a spherical acoustic lens
48
on one point on the free surface
15
of fluid
14
, so that radiation pressure generated when the acoustic wave hits the free surface
15
of the fluid
14
works to separate fluid drops
20
from the free surface of the fluid and project them.
Ink jet and various other types of printers are increasingly required to be capable of providing pictorial color image outputs. Meeting this requirement needs a recording characteristic of continuous and smooth shade gradation from the high light to the shadow. In order to achieve such a gradation recording characteristic by an ink jet method, it is necessary either to modulate the gradation by varying the volume of an ink drop from pixel to pixel or to compose each pixel of a plurality of ink drops each of which is smaller than a pixel and to vary the number of ink drops. By either method, in order to realize smooth shading gradation with no tone jump, a technique to form fluid drops sufficiently smaller than pixels is indispensable. However, with any of the above-described fluid drop projecting apparatuses, it is difficult to form so fine fluid drops for the following reasons.
With the fluid drop projecting apparatuses described in the U.S. Pat. No. 3,946,398 and the Gazette of the Japanese Patent Publication No. 1986-59911, illustrated in
FIGS. 13A
,
13
B, the minimum diameter of fluid drops that can be projected is about equal to the nozzle bore because both project fluid drops by utilizing the principle of pumping, and it is extremely difficult to project fluid drops having a diameter equal to, say, {fraction (1/10)} of the nozzle bore. Therefore, in order to enable any such fluid drop projecting apparatus to project very fine fluid drops, the nozzle bore should be reduced to about the desired diameter of fluid drops. However, such a small nozzle bore would make the nozzle more susceptible to choking and accordingly less reliable. Therefore, it is extremely difficult to form fluid drops as fine as a few &mgr;m to 20 &mgr;m in diameter. Moreover, the smaller nozzle bore means the need for more precise machining with the consequence that, where minute fluid drops have to be projected from an apparatus based on the principle of pumping, a problem arises not only with reliability but also with productivity.
Next, the fluid drop projecting apparatuses described in the Gazettes of the Japanese Patents Laid-open Nos. 1992-14455, 1992-299148 and 1993-38810, which generate a surface wave on the free surface of fluid and project fluid drops in a mist form, can project a mist of fluid drops as fine as a few &mgr;m in diameter. They further can control the number of fluid drops reaching the recording medium by varying the duration of projection. However, with these fluid drop projecting apparatuses, as a result of using the interference of the surface wave generated at random on the free surface of fluid, fluid drops are projected in a mist form from an indefinite large number of projection points, inviting fluctuations in the diameter of fluid drops projected, and moreover the direction and speed of projection also vary from drop to drop. This entails a problem in drop-by-drop controllability, which has to be precise for ink jet
Kojima Ryuichi
Otsuka Yasuhiro
Takizawa Fuminori
Dickens C.
Fuller Benjamin R.
NEC Corporation
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Fluid drop projecting head using taper-shaped chamber for... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fluid drop projecting head using taper-shaped chamber for..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fluid drop projecting head using taper-shaped chamber for... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2595235