High frequency printing mechanism
First Claim
1. A device for producing ink droplets on demand and ejecting such droplets toward a print medium, said device comprising:
- a cantilevered beam having a base end and a free end, the free end having a lower moment of inertia than the base end, said free end having an aperture therein;
a mechanical oscillator attached to the base end of said beam for imparting oscillating motion thereto at a selected frequency and selected amplitude; and
an ink supply in fluid communication with the free end of said beam, said ink being ejected through said aperture in said free end toward said print medium upon said oscillating motion exceeding a predetermined threshold amplitude.
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Accused Products
Abstract
The present invention provides an ink-jet ejection device which is capable of ejection or ink (including hot melt ink) jet frequencies greater than 50,000 Hz. A cantilevered beam of selected shape is mounted at its base to a piezoelectric element which oscillates the base. The beam is shaped so that its moment of inertia is reduced toward its free end. The element is activated by an oscillating electrical signal the frequency of which is equal to or close to a natural frequency of oscillation of the beam. In the preferred embodiment herein a third or higher modal frequency is utilized. Because of the structural configuration of the cantilevered beam and the selected frequency of oscillation thereof, the tip of the beam oscillates over an amplitude which is significantly greater than the oscillation amplitude of the base. The beam is highly damped and made of low density material so that the tip amplitude is extremely responsive to variations in the base amplitude. The tip of the beam is provided with an aperture which is preferably tapered in cross-section. One opening of the tapered aperture is in fluid communication with a reservoir of ink and the other opening of the aperture is positioned at an appropriate distance from a recording medium such as paper towards which individual droplets of ink from the reservoir are to be propelled. When the tip amplitude is above a predetermined threshold the solid-fluid interaction between the tapered aperture and the ink causes a drop of ink to accelerate through the aperture and be ejected upon each excursion of the tip of the beam toward the printing media.
214 Citations
21 Claims
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1. A device for producing ink droplets on demand and ejecting such droplets toward a print medium, said device comprising:
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a cantilevered beam having a base end and a free end, the free end having a lower moment of inertia than the base end, said free end having an aperture therein; a mechanical oscillator attached to the base end of said beam for imparting oscillating motion thereto at a selected frequency and selected amplitude; and an ink supply in fluid communication with the free end of said beam, said ink being ejected through said aperture in said free end toward said print medium upon said oscillating motion exceeding a predetermined threshold amplitude. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. In an ink-jet printing system, an ink-droplet ejection device comprising:
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a vibrating surface having an aperture therein; an oscillator affixed to said vibratory surface for imparting mechanical oscillations thereto in response to an electrical signal; and a source of ink for supplying ink droplets to said vibratory surface at the aperture. - View Dependent Claims (11, 12)
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13. A printing device comprising:
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an oscillator; a vibratory element having a portion affixed to said oscillator and a portion that is free to oscillate in response to the oscillator, the free portion of said element having an aperture therein; and a supply of printing fluid in contact with the free portion of said vibratory element at said aperture, said writing fluid being ejected through said aperture when the vibratory element is oscillated at a selected frequency and a selected amplitude. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method for ejecting ink droplets in an ink jet printing system, the method comprising the steps of:
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a. providing a vibratory surface with an aperture therein; b. oscillating said vibratory surface at a natural oscillating frequency; and c. supplying ink to said aperture. - View Dependent Claims (20)
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21. A device for ejecting fluid droplets comprising:
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a vibratory surface having a tapered aperture, said aperture having first and second openings wherein said first opening is larger than said second opening, said first opening being in surface tension contact with said fluid; and means for vibrating said surface at a selected frequency.
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Specification