Hydrodynamically damped pressure pulse droplet ejector

DETAILED DESCRIPTION What is claimed is: 1.
A pulsed pressure drop ejecting apparatus wherein a transducer (1) is utilized to compress liquid (13) in a channel (15) to express a droplet from an orifice (23) upon application of a signal to the transducer (1), the improvement comprising the addition of at least one energy dissipative element (25, 27) in the channel (15) so as to achieve simultaneous acoustic impedance matching and near critical hydraulic damping.
2.
The apparatus of claim 1 wherein the energy dissipative element is a screen having holes with a diameter of from about 1 .
mu.
m to about 15 .
mu.
m, and the holes having a length of from about 1 .
mu.
m to about 50 .
mu.
m.




Description:
The invention relates to a pulsed liquid droplet ejecting apparatus wherein one or more energy dissipative elements are placed in the liquid channel to damp hydraulic and acoustic meniscus transients.
The invention can be utilized in any pressure pulse drop ejector apparatus; however, the greatest benefits are realized when the dissipative elements of this invention are utilized in an ink jet recorder system.
Accordingly, the present invention will be described in connection with an ink jet recording system.
A sufficient pressure pulse addressed to a surface tension constrained liquid in a capillary orifice will cause a minute drop of the liquid to be expressed from that orifice.
If the liquid is replenished from a reservoir, the procedure can be repeated at a rate dependent only on the time required for replenishment.
Devices based on the above phenomenon are referred to as pressure pulse drop ejectors.
Pressure pulse drop ejectors are used as drop-on-demand ink jet marking devices.
Other terms for these devices in the literature are impulse jets, asynchronous jets and negative pressure jets.
Advantages of using pressure pulse drop ejectors as marking devices are their mechanical simplicity, quiet operation and ability to put visible ink marks onto plain paper in accordance with a programmed input bit stream