Systems and methods for controlling operation of micro-valves for use in jetting assemblies
A marking system includes a valve body including an orifice plate including multiple orifices and multiple micro-valves. Each micro-valve includes an actuating beam movable from a closed position in which a corresponding one of the orifices is sealed by a portion of the actuating beam such that the micro-valve is closed, into a peak position in response to application of a control signal. A controller is configured to generate a control signal for each of the actuating beams, each control signal including a drive pulse having a predetermined voltage such that the actuating beam moves from the closed position into the peak position in which the corresponding orifice is open and returns to the closed position in a characteristic period, wherein the drive pulse has a duration that substantially corresponds to the characteristic period such that the actuating beam is in the closed position after the drive pulse is complete.
1. A system of micro-valves comprising:
a valve body comprising:
an orifice plate including one or more orifices extending therethrough;
at least one micro-valve, wherein each of the at least one micro-valve comprises:
an actuating beam movable from a closed position in which a corresponding one of the one or more orifices is sealed by a portion of the actuating beam such that the micro-valve is closed, wherein the actuating beam is movable from the closed position into a position away from the corresponding one of the one or more orifices in response to application of a plurality of drive pulses, wherein a frequency of the plurality of drive pulses, a diameter of the one or more orifices, and a characteristic period of the actuating beam are configured to allow a volume of fluid to enter the one or more orifices and form a droplet on an exterior surface of the orifice plate.
2. The system of claim 1 , wherein each drive pulse has a duration that substantially corresponds to the characteristic period such that the actuating beam is in the closed position after the drive pulse is complete.
3. The system of claim 1 , wherein each of the plurality of drive pulses comprises a drive pulse ON time in which the actuating beam moves into the away position, and a drive pulse OFF time in which the actuating beam remains in the closed position.
4. The system of claim 3 , wherein the drive pulse OFF time is at least 15% of a drive pulse duration.
5. The system of claim 3 , further comprising a controller configured to apply a bias voltage to the actuating beam, wherein the drive pulse is part of a drive waveform, wherein the drive waveform comprises a voltage upswing portion in which the drive pulse increases from the bias voltage to a predetermined voltage, a driving portion in which the predetermined voltage is applied for the drive pulse ON time, and a voltage downswing portion in which the control signal decreases from the predetermined voltage to the bias voltage.
6. The system of claim 5 , wherein the bias voltage reduces stress on the actuating beam without moving the actuating beam into the away position away from the orifice.
7. The system of claim 6 , wherein the bias voltage includes one of a positive bias voltage or a negative bias voltage.
8. The system of claim 3 , further comprising a controller configured to apply a bias voltage to the actuating beam, wherein the drive pulse is part of a drive waveform, wherein the drive waveform comprises a biasing portion in which the drive pulse increases from zero volts to the bias voltage, a voltage upswing portion in which the control signal increases from the bias voltage to a predetermined voltage, a driving portion in which the predetermined voltage is applied for the drive pulse ON time, and a voltage downswing portion in which the control signal decreases from the predetermined voltage to zero volts.
9. The system of claim 1 , wherein a drive frequency of the drive pulse is less than a natural oscillation frequency of the actuating beam.
10. The system of claim 9 , wherein the natural frequency is in a range of 1 KHz and 30 KHz.
11. The system of claim 1 , further comprising a controller configured to apply a bias voltage to the actuating beam when the drive pulse is not applied to the actuating beam.
12. The system of claim 1 , wherein the valve body further comprises a fluid manifold coupled to each of the plurality of micro-valves to define a reservoir configured to contain a pressurized fluid to be dispensed when the actuating beams depart from the closed positions.
13. The system of claim 1 , wherein at least one of the actuating beams forms an acoustic sensor, the acoustic sensor configured to move in response to movement of any one of the other actuating beam and generate an electrical signal corresponding to the movement of the other actuating beam.
14. The system of claim 13 , further comprising a controller configured to measure the electrical signal from the acoustic sensor and determine if the other actuating beam is moving correctly based on the electrical signal.
15. The system of claim 14 , wherein the controller is configured to provide a fault indication if the electrical signal departs from a baseline, the fault indication indicative of the other actuating beam not moving correctly.
16. The system of claim 1 , wherein the droplet has a mass between 200 and 300 nanograms.
17. The system of claim 1 , wherein each actuating beam comprises a sealing member aligned to contact a valve seat disposed at the corresponding one of the one or more orifices.
18. The system of claim 17 , wherein a distance between sealing member and the valve seat in the away position is at least 10 microns.