Opinion ID: 428566
Heading Depth: 2
Heading Rank: 2

Heading: The Sweet Patent

Text: 11 In 1961 Richard G. Sweet, then an electrical engineer conducting research at Stanford University, received as a gift an aquarium equipped with a device that sent bubbles through the water to provide oxygen to the inhabitants of the aquarium. Sweet's scientific curiosity got the best of him, and he set out to determine how oxygen was transferred from the bubbles to the water. The pursuit of this inquiry led eventually to U.S. Patent No. 3,596,275, the Sweet patent, by all accounts a monumental step in the march toward commercial application of ink jet printing concepts. 12 The apparatus disclosed in Sweet's patent controlled the trajectory of the ink droplets by maintaining a constant voltage on the deflection plates and placing a variable voltage on the droplets, the opposite of the system used by Winston. Attached as Appendix A is one of the illustrative embodiments included in the Sweet patent. This arrangement permitted Sweet's device to operate much faster than Winston's; several droplets, each encoded with its own signal charge, could be present in the constantly-charged deflection field at the same time. Indeed, the operational speed of Sweet's device was limited only by the rate at which the droplets could be formed. Sweet found that he could generate as many as 120,000 droplets per second, resulting in a recording speed hundreds of times faster than the Winston device could achieve. 13 The parties have paid particular attention to the direction of deflection disclosed in the Sweet patent. 5 Claim 1 of the patent teaches that charged droplets are deflected laterally while claim 33 discloses an apparatus for causing charged droplets to follow trajectories that are a function of the amount of charge on said droplets. 6 The District Court concluded that these claims are ambiguous in that the terms laterally and trajectories are meaningless without a reference plane. 521 F.Supp. at 174. The District Court resolved this perceived ambiguity by examining the illustrative embodiments, specifications, and the prosecution history of the patent and, on the basis of this examination, concluded that the claims disclose only deflection in a direction transverse to the movement of the recording medium relative to the nozzle. Id. 14 Appellants vigorously dispute this conclusion. They argue that the term laterally in claim 1 means laterally to the initial droplet direction and that the term trajectories in claim 33 does not address the direction of deflection.