Droplet ejecting head, method for driving the same, and droplet ejecting apparatus
First Claim
1. A method for driving a droplet ejecting head including:
- a nozzle having a straight portion formed into a substantially straight shape with a small taper angle;
a pressure generating chamber communicating with the nozzle; and
an electromechanical transducer, the method comprising the steps of;
applying a driving voltage to the electromechanical transducer;
deforming the electromechanical transducer;
producing pressure change in the pressure generating chamber filled with liquid; and
ejecting a droplet from the nozzle, wherein a voltage waveform of the driving voltage includes;
a first voltage change process for expanding volume of the pressure generating chamber to retract a meniscus in the nozzle toward the pressure generating chamber; and
a second voltage change process for compressing the volume of the pressure generating chamber to eject the droplet; and
wherein voltage change quantity and voltage change time of the first voltage change process are set so that retraction quantity D of the meniscus at a time when the second voltage change process is applied satisfies;
0.8·
ln≦
D≦
1.5·
ln where ln designates length of the straight portion.
2 Assignments
0 Petitions
Accused Products
Abstract
A nozzle for ejecting a droplet has a straight portion having a substantially straight shape. A driving waveform to be applied to a piezoelectric actuator includes a first voltage change process for expanding volume of a pressure generating chamber to retract a meniscus of the nozzle portion toward the pressure generating chamber and a second voltage change process for compressing the volume of the pressure generating chamber to eject a droplet. Voltage change quantity and voltage change time of the first voltage change process are set so that meniscus retraction quantity D when the second voltage change process is applied satisfies 0.8·ln≦D≦1.5·ln (ln designates length of the straight portion of the nozzle). Consequently, when the second voltage change process is applied, strong liquid surface interference can be produced in the nozzle central portion. Therefore, a droplet having an extremely small droplet volume can be ejected.
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Citations
17 Claims
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1. A method for driving a droplet ejecting head including:
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a nozzle having a straight portion formed into a substantially straight shape with a small taper angle;
a pressure generating chamber communicating with the nozzle; and
an electromechanical transducer, the method comprising the steps of;
applying a driving voltage to the electromechanical transducer;
deforming the electromechanical transducer;
producing pressure change in the pressure generating chamber filled with liquid; and
ejecting a droplet from the nozzle, wherein a voltage waveform of the driving voltage includes;
a first voltage change process for expanding volume of the pressure generating chamber to retract a meniscus in the nozzle toward the pressure generating chamber; and
a second voltage change process for compressing the volume of the pressure generating chamber to eject the droplet; and
wherein voltage change quantity and voltage change time of the first voltage change process are set so that retraction quantity D of the meniscus at a time when the second voltage change process is applied satisfies;
0.8·
ln≦
D≦
1.5·
lnwhere ln designates length of the straight portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16)
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14. A droplet ejecting head comprising:
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a nozzle having a straight portion formed into a substantially straight shape with a small taper angle;
a pressure generating chamber communicating with the nozzle; and
an electromechanical transducer, wherein a driving voltage is applied to the electromechanical transducer to generate pressure change in the pressure generating chamber and to eject a droplet from the nozzle;
wherein the driving voltage includes;
a first voltage change process for expanding volume of the pressure generating chamber to retract a meniscus in the nozzle toward the pressure generating chamber; and
a second voltage change process for compressing the volume of the pressure generating chamber to eject the droplet;
wherein length ln of the straight portion is set to satisfy;
D/1.5≦
ln≦
D/0.8where D designates a retraction quantity of the meniscus at a time when the second voltage change process is applied; and
wherein the nozzle has a taper portion connected to the straight portion. - View Dependent Claims (15, 17)
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Specification