METHOD AND APPARATUS FOR DIRECTING THE FLOW OF LIQUID DROPLETS IN A STREAM AND INSTRUMENTS INCORPORATING THE SAME

• US 3,717,875 A
• Filed: 05/04/1971
• Issued: 02/20/1973
• Est. Priority Date: 05/04/1971
• Status: Expired due to Term

• Current Assignee: Carl Hellmuth Hertz, Genio R. Arciprete, Jell Ake Gosta Mansson, John L. Rothery, Walter J. Cairns
• Original Assignee: Carl Hellmuth Hertz, Genio R. Arciprete, Jell Ake Gosta Mansson, John L. Rothery, Walter J. Cairns
• Inventors: Hertz, Carl Hellmuth, Rothery, John L., Arciprete, Genio R., Cairns, Walter J., Mansson, Jell Ake Gosta
• Primary Examiner(s): Hartary, Joseph W.
• Application Number:
  US05/140,145
• Time in Patent Office: 658 Days
• Field of Search: 346/75,1 239/4,102
• US Class Current: 347/73
• CPC Class Codes: B41J 2/025 by vibration

Abstract

Method and apparatus for effecting the divergence of liquid droplets formed from a liquid stream ejected under pressure through a small-diameter nozzle. By imparting to the stream periodic mechanical oscillations within a predetermined frequency range, the droplets are caused to split into two or more separate and distinct streams which diverge angularly from the normal axis of the droplet stream. Those droplets in the stream travelling along the normal axis are separated from those travelling in the diverged streams thus providing a means for accurately measuring extremely small quantities of liquid delivered to a desired collection point. The method and apparatus are particularly suited for ink jet recording as well as for metering out small amounts of a liquid.

Claims

1. A method for effecting the divergence of liquid droplets formed from a liquid stream ejected under pressure through an aperture, characterized by the step of imparting to said stream prior to droplet formation periodic mechanical oscillations of a frequency and an amplitude which cause said droplets to diverge angularly into at least two separate and distinct streams from the normal axis of said stream, said mechanical oscillations serving as the only force applied to said stream in effecting said divergence.

2. A method in accordance with claim 1 wherein said periodic oscillations are imparted to said stream prior to its ejection through said aperture.

3. A method in accordance with claim 1 wherein said aperture ranges in diameter between about 5 and 1,000 microns and said frequencies range between 100Hz and 106Hz.

4. A method in accordance with claim 1 wherein said oscillations are essentially transverse to the normal axis of said stream.

5. A method in accordance with claim 1 wherein said oscillations are essentially longitudinal along the normal axis of said stream.

6. A method in accordance with claim 1 wherein said oscillations are transverse to and longitudinal along the normal axis of said stream.

7. A method for accurately metering an amount of a liquid, comprising the steps of a. ejecting a liquid to be metered through an aperture under pressure thereby to form the liquid into a stream which breaks up to form individual droplets;

b. imparting periodic mechanical oscillations to said stream prior to droplet formation, the frequency and amplitude of said oscillations being selectively varied between that which will cause divergence of said droplets into at least two separate and distinct streams angularly displaced from the normal axis of said stream and that which will permit said droplets to travel along said normal stream axis; and

c. separating the liquid thus caused to diverge from said stream axis from that permitted to travel as droplets along said stream axis.

8. A method in accordance with claim 7 wherein said separating comprises directing said liquid caused to diverge from said normal stream axis against porous surface means for removal thereby and directing said droplets traveling along said axis to a receptor.

9. A method in accordance with claim 8 including the step of interposing an apertured interceptor between said aperture through which said liquid is ejected and said receptor.

10. A method in accordance with claim 7 wherein said separating comprises collecting said liquid caused to diverge from said normal stream axis by gravitational force and directing said droplets traveling along said axis to a receptor.

11. A method in accordance with claim 7 including the step of providing an electrical field at or near the point of droplet formation, said field being of a strength and polarity relative to the polarity of said liquid in said stream to enhance but not cause said divergence of said droplets.

12. A method of recording with liquid ink, comprising the steps of a. ejecting liquid ink under pressure through an aperture thereby to form said liquid ink into a stream which breaks up to form individual droplets traveling along the axis of said stream;

b. imparting periodic mechanical oscillations through a transducer to said stream prior to droplet formation;

c. selectively varying the frequency of said periodic oscillations between that band of frequency at which said droplets will be caused to diverge angularly from travel along said axis into at least two separate and distinct streams and another frequency outside said band which perMits said droplets to travel along said axis;

d. intercepting that portion of said ink thus caused to diverge from travel along said axis; and

e. directing said droplets traveling along said axis onto the surface of a record member.

13. A method in accordance with claim 12 including the step of varying the amplitude of said oscillations simultaneously with varying said frequency.

14. A method in accordance with claim 12 including the step of moving said record member relative to said axis.

15. A method in accordance with claim 12 wherein said step of selectively varying the frequency of said periodic oscillications comprises transmitting variable signals to said transducer.

16. A method in accordance with claim 15 wherein said signals are transmitted in the form of pulses and including the step of varying the duration of said pulses.

17. A method in accordance with claim 12 including the step of periodically oscillating said liquid ink stream through a predetermined excursion and at essentially right angles to said axis.

18. A method in accordance with claim 12 including the step of adjusting the pressure under which said liquid ink is ejected and the amplitude of said periodic oscillations to obtain a predetermined pattern of droplet divergence.

19. A method in accordance with claim 12 wherein said periodic oscillations are essentially transverse to said axis.

20. A method in accordance with claim 12 wherein said periodic oscillations are essentially longitudinal along said axis.

21. A method in accordance with claim 12 wherein said periodic oscillations are transverse to and longitudinal along said axis.

22. A method in accordance with claim 12 wherein said periodic oscillations are imparted to said stream prior to its ejection through said aperture.

23. A method of recording with liquid ink, comprising the steps of a. ejecting liquid ink under pressure through a plurality of apertures thereby to form said liquid into a plurality of separate streams each of which breaks up to form individual droplets traveling along the axes of said streams;

b. imparting periodic mechanical oscillations through a plurality of transducers to said streams prior to droplet formation;

c. selectively varying the frequency of said periodic oscillations between that band of frequency at which said droplets in each of said streams will be caused to diverge angularly from travel along said axes into at least two separate and distinct streams and another frequency outside said band which permits said droplets to travel along said axes;

d. intercepting that portion of said ink thus caused to diverge from travel along said axes; and

e. directing said droplets traveling along said axes onto the surface of a record member.

24. A method in accordance with claim 23 including the step of varying the amplitude of said oscillations.

25. A method in accordance with claim 23 including the step of periodically oscillating at least selected ones of said liquid ink streams through predetermined excursions and at essentially right angles to said axes.

26. A method in accordance with claim 23 wherein each of said streams is individually controlled by a separate transducer associated therewith.

27. An apparatus for accurately metering an amount of liquid consisting essentially of a. a reservoir of liquid;

b. liquid delivery means terminating in an aperture of a size such that liquid forced therethrough will form a stream which breaks into droplets traveling along an axis;

c. pump means adapted to transfer said liquid under pressure from said reservoir through said liquid delivery means thereby to form said stream;

d. transducer means with associated driving means adapted to impart periodic mechanical oscillations to said stream over at least two different frequency ranges, one of said frequency ranges being that which will cause said droplets to travel in at least two different paths which diverge from said axis whereBy said transducer means serves as the sole means for controlling the direction of droplet travel;

e. first means adapted to receive that portion of said liquid travelling in said paths diverging from said axis; and

f. second means to receive that portion of said liquid travelling along said axis.

28. An apparatus in accordance with claim 27 wherein said driving means is also adapted to control the amplitude of said oscillations.

29. An apparatus in accordance with claim 27 wherein said liquid delivery means is a capillary and said transducer means is mechanically connected thereto.

30. An apparatus in accordance with claim 27 wherein said transducer means comprises a piezoelectric crystal.

31. An apparatus in accordance with claim 27 wherein said transducer means comprises magnetostrictive means.

32. An apparatus in accordance with claim 27 wherein said driving means is adapted to receive and be actuated by electrical signals.

33. An ink jet recording apparatus, comprising in combination a. a reservoir of liquid ink;

b. liquid ink feed line means terminating in a nozzle;

c. pump means adapted to transfer said liquid ink under pressure from said reservoir through said feed line means and said nozzle at a pressure sufficient to form a liquid ink stream which breaks up into droplets traveling along an axis;

d. transducer means adapted to impart periodic mechanical oscillations to said stream;

e. transducer driving means;

f. means to control said transducer driving means thereby to cause said transducer means to operate over at least two different frequency ranges, one of said frequency ranges being that which will cause said droplets to travel in paths divergent from said axis, whereby said transducer means serves as the sole means for controlling the direction of droplet travel;

g. ink receptor means; and

h. interceptor means positioned between said nozzle and said ink receptor means and adapted to intercept that portion of said ink travelling in said divergent paths while permitting that portion of said ink travelling along said axis to reach said ink receptor means.

34. An apparatus in accordance with claim 33 wherein said means to control said transducer driving means comprises pulsed electrical signal generating means.

35. An apparatus in accordance with claim 33 including means to move said ink receptor means relative to said axis.

36. An apparatus in accordance with claim 33 including means to move said liquid ink feed line through predetermined excursions substantially at right angles to said axis.

37. An apparatus in accordance with claim 33 wherein said interceptor means comprises porous surface means and means for withdrawing ink from said porous surface means.

38. An apparatus in accordance with claim 33 wherein said means to control said transducer driving means includes means to also control the amplitude of said oscillations.

39. An apparatus in accordance with claim 33 including means to provide at or near the point of droplet formation an electrical field of a polarity opposite to the polarity of said liquid in said stream, said electrical field being of a strength which will supplement the action of said oscillations in effecting the divergence of said droplets without serving as the sole force for effecting said divergence.

40. An ink jet recording apparatus, comprising in combination a. liquid ink reservoir means;

b. a plurality of liquid ink feed lines terminating in nozzles, said feed lines being maintained in a regular spaced relationship with each other;

c. pump means adapted to transfer said liquid ink under pressure from said reservoir means through said nozzles at a pressure sufficient to form a plurality of liquid ink streams each of which breaks up into a stream of droplets travelling along its axis;

d. transducer means adapted to impart periodic mechanical oscillation to said ink streams;

e. transducer driving and control means adapted to cause said transducer means to operate over at least two different frequency ranges, one of said frequency ranges being that which will cause said droplets to travel in paths divergent from said stream axes, whereby said transducer means serve as the sole means for controlling the direction of droplet travel in each stream;

f. ink receptor means; and

g. interceptor means positioned between said nozzles and said ink receptor means and adapted to intercept that portion of said ink travelling in said divergent paths while permitting that portion of said ink travelling along said axes to reach said ink receptor means.