Incremental printing of symbolic information – Ink jet – Ejector mechanism
Patent
1997-11-28
2000-11-28
Le, N.
Incremental printing of symbolic information
Ink jet
Ejector mechanism
347 48, 347 68, B41J 202
Patent
active
061525561
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a droplet generator for a continuous stream ink jet print head. U.S. Pat. No. 4,746,929 discloses a droplet generator for a continuous stream ink jet print head wherein a piezoelectric transducer located at one end of an ink filled tube causes waves to travel through the ink along the tube to an absorber at the other end of the tube. The purpose of the absorber is to suppress reflection at the other end of the tube and hence inhibit the formation of standing waves along the tube. A line of nozzle orifices in the tube runs the length of the tube parallel to the direction of travel of waves along the tube. Each orifice communicates with a respective orifice in a plate bonded to, and also running the length of, the tube. The orifices pass ink from the tube to form jets. Suppression of reflection at the end of the tube opposite the piezoelectric transducer is so that the amplitude of the wave travelling along the tube is the same at all points along the length of the tube. Reflection would cause interference with the wave coming from the transducer which would set up standing waves, and thus result in the amplitude not being as aforesaid. By having the amplitude the same at all points along the tube it is ensured that the jets emanating from the nozzle orifices of the tube break up into droplets at the same distance from the tube.
The absorber of the droplet generator of U.S. Pat. No. 4,746,929 must be chemically resistant to the ink, must have an impedance close to that of the ink in order to minimise reflection, and must have a high attenuation coefficient such that once acoustic energy has entered the absorber it does not re-emerge following reflection therewithin. Thus, the absorber is required to have properties which are ink type and frequency specific.
EP-A-449929 discloses a droplet generator for a continuous stream ink jet print head wherein a piezoelectric load rod at one side of an ink filled cavity establishes a standing wave within the cavity at resonance thereof. The nozzle orifices are located on the opposite side of the cavity to the load rod. As with the droplet generator of U.S. Pat. No. 4,746,929 the object is that the amplitude of vibration of the ink is the same across the nozzle orifices.
In EP-A-449929 to achieve resonance for a given ink type the dimension of the cavity from the load rod side to the nozzle orifice side must have a precise value. Thus, the droplet generator of EP-A-449929 is sensitive to structure and assembly, e.g. the tightness of the bolts which secure the cavity assembly together.
According to the present invention there is provided a droplet generator for a continuous stream ink jet print head comprising: a cavity for containing the ink; nozzle orifices in a wall of said cavity for passing the ink from the cavity to form jets; and first and second actuator means for establishing in combined operation a travelling wave which travels from said first actuator means through said ink to said second actuator means and passes in a direction substantially parallel to said wall containing the nozzle orifices.
The invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which:
FIG. 1 is a plan view of a first droplet generator in accordance with the present invention;
FIG. 2 is a front view of the generator of FIG. 1;
FIG. 3 is a side view of the generator of FIG. 1;
FIG. 4 illustrates a phase shifter circuit for use with the generator of FIG. 1; and
FIG. 5 illustrates a second droplet generator in accordance with the present invention.
Referring to FIGS. 1 to 3, a housing 1 contains an elongate square cross-section cavity 3 for containing the ink. Housing 1 includes an ink inlet connection 5, an ink bleed connection 7, and a plate 9 containing a line of nozzle orifices 17 for passing the ink from cavity 3 to form jets. Transmitting and receiving piezoelectric transducers 11, 13 are mounted, by means of nodal clamps 15, at either end of cavity 3.
In operation transmitting transducer 11 is excited t
REFERENCES:
patent: 3739393 (1973-06-01), Lyon et al.
patent: 4104645 (1978-08-01), Fischbeck
patent: 4291316 (1981-09-01), Kakeno et al.
patent: 4746929 (1988-05-01), Lin et al.
patent: 5229793 (1993-07-01), Hadimioglu et al.
patent: 5305016 (1994-04-01), Quate
Electronics and communications in Japan, Part:II, vol. 72, No. 7, Scripta Technica, Inc., pp. 78-86, Jul. 1989.
Martin Graham Dagnall
Pannu Sukbir Singh
Sherman Nigel Edward
Hsieh Shih-Wen
Le N.
Marconi Data Systems Inc.
LandOfFree
Droplet generator for a continuous stream ink jet print 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 Droplet generator for a continuous stream ink jet print head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Droplet generator for a continuous stream ink jet print head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1717704