Vutek, Incorporated

Peter L Duffield

Arthur L Cleary

Reproducing a predetermined pattern on a medium, by for example, an apparatus that includes in combination a source of colored ink, a primary source of compressed air, a spray head including a housing having an inner ink chamber in flow communication with the source of ink, an outer air chamber in flow communication with the source of air and surrounding the inner ink chamber, a spray nozzle having an outside diameter and an internal longitudinal bore connected to the inner ink chamber and extending forward of the housing. A spray shield has an outer surface adjacent the medium and an inner surface positioned adjacent to and spaced from the housing and has a transverse opening therethrough in alignment with the nozzle. An auxiliary air supply has a pressure significantly less than the pressure of the air from the primary source of compressed air. The auxiliary air supply is in flow communication with the space between the shield and the housing thereby to force clean air through the space and out through the spray shield opening.

Spray head for a computer-controlled automatic image reproduction system

An automatic system for the spray painting of color images in which accurate color reproduction is achieved by a separate look-up table generated for each jet and stored in the computer memory. During the reproduction of an image, the computer uses the look-up tables to determine the pulse width of an air modulation stream to reproduce the precise color density called for by the input data. Because slight variations in the characteristics of two jets spraying the same color would produce objectionable lining in the image, a separate look-up table is provided for each jet. A color test image is generated for a selected jet by successively varying the width of the pulse modulation from the minimum to the maximum. For example, while the jet is making a single scan across the medium, the pulse width modulation of the air stream is varied in 256 separate steps to produce a test image that varies from the lightest to the darkest density of the particular color being sprayed. This pattern is scanned by a densitometer that delivers its output to the computer. The position of the densitometer along the color test image is correlated with the modulation pulse width that produced that particular color density and this information is stored in a look-up table for use during the generation of a reproduced image. A dark current is measured by the densitometer and subtracted from the calibration readings so that the calibration is independent of ambient illumination.

Spray-painting system with automatic color calibration

A system for reproducing color images by electronically scanning an original to control the paint-spraying of a larger duplicate image. Multiple ink spray heads scan the width of the recording medium while being controlled by width-modulation of constant air pressure supplied to the heads. Ink is contained in multiple reservoirs that are each connected to one of the spray heads by a conduit extending substantially perpendicular to the direction of travel of the spray heads. Each ink reservoir contains a sub-reservoir with a bottom surface above the level of the bottom surface of the primary reservoir. Sloping deflector plates cause ink to flow from the primary reservoir into the sub-reservoir during acceleration or deceleration of the reservoirs. The height of the ink in the reservoir is such that a meniscus of ink is maintained on the tip of the spray jet during periods when ink is not being sprayed. A fill cap in each reservoir extends into the interior of the reservoir to limit the height of the ink in the reservoir and avoid spillage. The fill cap area is preferably one inch or more in diameter to permit visual observation of the ink during filling.

Multi-color recorder with plural ink jets and reservoirs co-mounted on a

A system for copying images onto a long sheet of paper or vinyl while. A flow of constant-pressure air is pulse-width modulated in accordance with the control signals and passed over an ink meniscus maintained on the end of a small nozzle. The pulse-modulated air flowing across the meniscus causes the ink to be sprayed onto the recording medium. The dot size on the image remains constant and the pulse width within each pixel is varied to produce the desired density of color. Pressure surges in the ink supply system, produced for example by vibration or acceleration of the ink, are suppressed by a second meniscus in the ink-supply system, formed by a gas bubble or interface near the nozzle meniscus. The second meniscus should have a surface area at least as large as that of the jet meniscus. At the end of each pixel, the ink flow is interrupted for a period of about 100 microseconds to restore system equilibrium. A second and continuous air flow around the air nozzle supplies air to the turbulent flow across the ink jet and reduces recirculation of atomized ink and minimizes contamination of the nozzle and adjacent surfaces. The supply roll is mounted at each end on independently movable arms.

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Meredith, NH, United States of America

Peter L Duffield