Recorders – Markers and/or driving means therefor – With ink supply to marker
Patent
1980-08-08
1983-05-24
Miller, Jr., George H.
Recorders
Markers and/or driving means therefor
With ink supply to marker
346 75, G01D 1518
Patent
active
043853048
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention relates to an improved stacked drop generator apparatus for ink jet printing.
2. Description of the Prior Art
Prior art generators for ink jet printing were bulky in size compared to the drop size produced. Consequently, the number of drop generators per printed character was physically limited. However, instead of decreasing the drop generator size to achieve closer spacing between ink drops, prior ink jet printers reduced the space between drops by increasing the size of the drop. As a result of the larger drop size, character definition and print quality are lessened.
Many ink jet printers have failed to successfully address the problem of fluid dribbling from the exit port once the jet has been energized to expel ink. The fluid, under static pressure in the ink reservoir and awaiting expulsion, was under no restraining force to inhibit leakage out the exit port.
The present invention promotes printed character definition and quality by utilizing the small size of the drop generator. More generators may be stacked to print each character. This feature permits a smaller drop size, better defined characters, and improved printing quality. In addition, the invention uses a deformable device to generate a pressure wave pulse through the printing fluid or ink. This wave expels a drop of fluid from a fluid filled cavity through an exit port. A reverse deformation of the device is then induced to withdraw the fluid at the exit port back into the fluid cavity. Consequently, an ink drop is generated and expelled on demand and ink dribbling from the exit port between drop generations is inhibited.
BRIEF SUMMARY OF THE INVENTION
A stackable drop generator for ink jet printing includes a stackable housing of electrically nonconductive material having a cavity containing fluid, an ink trough alignable with each housing for supplying the cavity with fluid, and holes which, when aligned, receive fastening devices for stacking multiple drop generators. In one form of the invention a piezoelectric ceramic driver is used to produce a pressure wave on the fluid and is located in the cavity of the housing. The driver is bidirectionally deformable in response to changing polarities of electrical pulses received from electrodes. These electrodes also have an ink trough and holes for receiving fastening devices which are alignable with the corresponding ink trough and holes in the housing when multiple drop generators are stacked. An end plate, having an ink supply well, is engageable with one end of a drop generator to store a volume of fluid. This fluid is fed to the ink trough of each housing in a stack of drop generators to flood each fluid cavity. An end plate without an ink well engages the opposite end of, and prevents fluid leakage from the drop generator.
In another form of the invention a bimorph driver is used to produce a pressure wave on the fluid. The bimorph is positioned outside the fluid cavity of the housing and acts on a diaphram wall of the housing.
To permit one electrode to transmit electrical pulses to two adjacent drivers, each driver is alternately poled with respect to its adjacent driver in an adjacent drop generator. Upon application of an electrical pulse to a driver, a positive or negative deformation of the driver is produced depending on the polarity of the pulse, and a corresponding pressure wave acts on the fluid of the cavity. In response to a positive driver deformation, a fluid drop of ink is expelled from the housing through a nozzle. This nozzle is integral with the housing and has an intake end in the cavity and forms an exit port from the housing for the ink drop. A negative driver deformation imparts a low pressure wave which withdraws the fluid into the cavity from the exit port of the nozzle to prevent dribbling of the fluid out of the nozzle. In addition to this negative deformation, the nozzle is composed of a nonwetting material, which inhibits fluid dribbling from the exit port.
BRIEF DESCRIPTIO
REFERENCES:
patent: 3211088 (1965-10-01), Naiman
patent: 3946398 (1976-03-01), Kyser et al.
Burroughs Corporation
Chung Edmund M.
Miller Jr. George H.
Peterson Kevin R.
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