PULSED DROPLET EJECTING SYSTEM

• US 3,683,212 A
• Filed: 09/09/1970
• Issued: 08/08/1972
• Est. Priority Date: 09/09/1970
• Status: Expired due to Term

• Current Assignee: Steven I. Zoltan
• Original Assignee: Steven I. Zoltan
• Inventors: Steven, I. Zoltan
• Primary Examiner(s): J. D. Miller
• Assistant Examiner(s): Mark O. Budd
• Application Number:
  US05/070,838
• Time in Patent Office: 699 Days
• Field of Search: 310/8-8.3,8.5,8.6,8.7,9.1,9.4,9.6 259/1R,DIG.41,DIG.44 417/322 346/75,140
• US Class Current: 310/328
• CPC Class Codes: B41J 2/04541 Specific driving circuit
• CPC Class Codes: B41J 2/04581 controlling heads based on piezoelectric elements
• CPC Class Codes: H04R 17/08 signals being recorded or played back by vibration of a stylus in two orthogonal directions simultaneously
• CPC Class Codes: Y10S 261/48 Sonic vibrators

Abstract

An electro-acoustic transducer is coupled to liquid in a conduit which terminates in a small orifice. Preferably, the acoustic impedance of the supply portion of the conduit is large compared with the acoustic impedance of the orifice. The liquid is under small or zero static pressure. Surface tension at the orifice prevents liquid flow when the transducer is not actuated. An electrical pulse with short rise time causes sudden volume change at the transducer, thereby creating an acoustic pressure pulse having sufficient amplitude to overcome the surface tension at the orifice and eject a small quantity of liquid therefrom. The expelled liquid is replaced by forward flow of liquid in the conduit under the influence of capillary forces in the orifice.

Claims

1. A system adapted upon pulsing to expel a small quantity or a succession of small quantities of liquid in controlled manner, comprising:

a reservoir containing said liquid;

a conduit connected to said reservoir and communicating with the liquid therein and filled with said liquid under low or zero static pressure, said conduit having an exit orifice which is sufficiently small that surface tension in the absence of pulsing prevents said liquid from flowing therefrom;

a tubular transducer of given diameter surrounding said conduit in stress transmitting engagement therewith and thereby coupled to the liquid therein adjacent said orifice, said transducer being adapted to contract radially to displace a small quantity of said liquid overcoming said surface tension to expel a small quantity of said liquid through said orifice and to expand to said given diameter prior to a subsequent contraction;

electrical circuit means connected to said transducer for applying thereto an electrical pulse of a given polarity and with short rise time to cause said transducer to contract rapidly, and upon decay of said pulse to allow said transducer to expand;

said conduit during operation of said system at all times being open from said reservoir to said orifice whereby the liquid within said transducer is replaced by liquid from said reservoir to make up for said expelled liquid upon said termination of said pulse.

2. A system as described in claim 1 in which the transducer is a piezoelectric transducer.

3. A system as described in claim 1 in which the transducer comprises a tubular piezoelectric member which changes internal volume in response to an electrical signal, said tubular member surrounding said second portion of said conduit in stress transmitting engagement therewith.

4. A system as described in claim 1 in which the transducer is an electrostrictive transducer.

5. A system as described in claim 1 in which the tRansducer is a magnetostrictive transducer.

6. A system as described in claim 1 wherein said means for applying an electrical pulse includes means for adjusting the energy of said pulse according to the quantity of liquid that is desired to be expelled during said pulse.