Random artificially perturbed liquid apparatus and method

• US 4,725,852 A
• Filed: 01/27/1987
• Issued: 02/16/1988
• Est. Priority Date: 05/09/1985
• Status: Expired due to Fees

• Current Assignee: Burlington Industries LLC
• Original Assignee: Burlington Industries LLC
• Inventors: Gamblin, Rodger L., Burchett, Roger C.
• Primary Examiner(s): Hartary, Joseph W.
• Application Number:
  US07/007,400
• Time in Patent Office: 385 Days
• Field of Search: 346/75, 346/1.1, 331/78, 364/717
• US Class Current: 347/75
• CPC Class Codes: B41J 2/025 by vibration
• CPC Class Codes: B41J 2/115 synchronising the droplet separation and charging time
• CPC Class Codes: G01D 15/16 Recording elements transferring recording material, e.g. ink, to the recording surface printing recording elements G01D15/20

Abstract

A frequency-stabilized oscillator is frequency modulated by band-limited random varying signals used to drive a suitable transducer randomly to and artificially perturb fluid jets in an electrostatic fluid jet applicator. Such random artificial pertubation is desirable (especially with longer cross-machine orifice plates) so as to obscure printing irregularities caused by standing wave or other phenomena. However, such random variations are best made with respect to a highly stabilized center frequency.

Claims

1. An electrostatic fluid jet applicator of the type which utilizes random artificial perturbation of the fluid and including structure for producing such random perturbation which comprises:

an electrically driven transducer coupled to said fluid;

a source of randomly varying signals; and

a frequency-stabilized oscillator connected so as to be frequency modulated by said randomly varying signals and to provide a corresponding randomly varying output connected to drive said transducer.

2. An electrostatic fluid jet applicator as in claim 1 wherein said source of randomly varying signals comprises:

a band-limited source of controlled amplitude noise signals.

3. An electrostatic fluid jet applicator as in claim 2 wherein said band-limited source comprises:

a reverse-biased diode having noise signals thereacross;

a high-gain bandpass amplifier connected to amplify said noise signals;

an active low-pass filter (LPF) connected to receive the amplified noise signals from said amplifier and to supply LPF noise signals; and

a variable and controllable attenuator connected to receive said LPF noise signals and to supply said randomly varying signals at a controlled amplitude.

4. An electrostatic fluid jet applicator as in claim 3 wherein said variable and controllable attenuator comprises:

a digital-to-analog converter having a reference input connected to receive said LPF noise signals.

5. An electrostatic fluid jet applicator as in claim 1 wherein said frequency-stabilized oscillator comprises:

a PLL oscillator having a phase detector for comparing the phase of a supplied frequency stable reference signal with that of a feedback signal, a VCO controlled by the phase detector to produce an output PLL signal, a programmable counter for dividing the frequency of the output PLL signal and supplying the feedback signal, and a low-pass loop filter connected between the phase-detector and VCO and connected to receive said randomly varying signals.

6. An electrostatic fluid jet applicator as in claim 1 further comprising:

a post-scaler frequency divider connected to receive the output of the frequency-modulated frequency-stabilized oscillator and to provide a lower divided frequency signal for use in driving the transducer.

7. An electrostatic fluid jet applicator as in claim 5 further comprising:

a post-scaler frequency divider connected to receive the output of the frequency-modulated frequency-stabilized oscillator and to provide a lower divided frequency signal for use in driving the transducer.

8. An electrostatic fluid jet applicator as in claim 5 wherein said programmable counter is periodically reset to a supplied starting multi-bit content so as to determine its effective modulus and wherein at least one predetermined bit of such supplied content is monitored and used to turn on and off said random artificial perturbation.

9. An electrostatic fluid-jet applicator as in claim 1 further comprising:

a variable and controllable attenuator connected to receive said randomly varying output and to provide such output at a controlled amplitude for use in driving said transducer.

10. An electrostatic fluid jet applicator as in claim 9 wherein said attenuator comprises:

a digital-to-analog converter having a reference input connected to receive said randomly varying output.

11. An electrostatic fluid jet applicator for applying fluid droplets to the surface of a relatively moving substrate, said applicator being of the type which includes random artificial perturbation means acoustically coupled to the fluid for artificially stimulating the formation of said droplets at a rate which is controllably varied, said random artificial perturbation means comprising:

an electro-acoustic transducer;

a band-limited source of randomly varying signals; and

a phase locked loop (PLL) oscillator circuit having (1) a reference input supplied by a frequency-stable oscillator, (2) phase detector output and VCO input terminals with a low-pass loop filter connected thereto and also connected to receive said randomly varying signals and (3) a PLL output terminal supplying the output of the PLL oscillator adapted for use in driving said electro-acoustic transducer.

12. An electrostatic fluid jet applicator as in claim 11 wherein said band-limited source of randomly varying signals comprises:

a reverse-biased p-n junction connected to supply noise signals to the input of a cascaded chain of tuned amplifiers having a predetermined bandwidth of less than 100 Hz;

an active low-pass filter connected to receive and process the output of said tuned amplifiers; and

a digitally controlled variable attenuator connected to receive and process the output of said low-pass filter and to provide said randomly varying signals.

13. An electrostatic fluid jet applicator as in claim 11 wherein:

said frequency-stable oscillator includes a crystal-controlled oscillator.

14. An electrostatic fluid jet applicator as in claim 11 wherein said loop filter comprises an RC filter connected to the VCO input terminals via a further resistor and wherein said randomly varying signals are connected to a node joining said further resistor to said RC filter.

15. An electrostatic fluid jet applicator as in claim 11 wherein said PLL oscillator circuit includes a feedback counter having a counting modulus which is controlled by a multi-bit input digital signal and wherein at least one bit of such digital signal is connected to provide on/off control of the random perturbation process.

16. An electrostatic fluid jet applicator as in claim 11 further comprising:

a post-scaler frequency divider connected to frequency divide the output of said PLL oscillator circuit;

an active low-pass filter connected to receive and process the output of said frequency divider; and

a digitally controlled variable attenuator connected to receive and process the output of the low-pass filter and to provide said randomly varying output at a predetermined amplitude.

17. An electrostatic fluid jet application method of the type which utilizes random artificial perturbation of the fluid and including structure for producing such random perturbation which comprises:

electrically driving a transducer coupled to said fluid;

providing a source of randomly varying signals; and

frequency modulating a frequency-stabilized oscillator by said randomly varying signals and providing a corresponding randomly varying output connected to drive said transducer.

18. An electrostatic fluid jet application method as in claim 17 wherein said source of randomly varying signals comprises:

a band-limited source of controlled amplitude noise signals.

19. An electrostatic fluid jet application method as in claim 17 wherein said frequency modulating step comprises:

comparing the phase of a supplied frequency stable reference signal with that of a feedback signal, producing from a VCO an output PLL signal;

dividing the frequency of the output PLL signal to supply the feedback signal;

low-pass filtering signals passing between the phase-detector and VCO, and

injecting said randomly varying signals into the low-pass filtering process to modulate said VCO.

20. An electrostatic fluid jet application method as in claim 17 further comprising:

post-scaler frequency dividing the output of the frequency-modulated frequency-stabilized oscillator to provide a lower divided frequency signal for use in driving the transducer.

21. An electrostatic fluid jet application method as in claim 20 wherein a programmable counter in the PLL is periodically reset to a supplied starting multi-bit content so as to determine its effective modulus and wherein at least one predetermined bit of such supplied content is monitored and used to turn on and off said random artificial perturbation.