Opinion ID: 428566
Heading Depth: 1
Heading Rank: 1

Heading: the patents in issue and the accused device

Text: 8 Many large and small steps of discovery in physics and electricity from the Nineteenth Century forward have led to the modern practice of ink jet printing. These steps include Michael Faraday's experiments in 1831 in electromagnetic induction and Lord Rayleigh's discovery in 1897 that a stream of liquid droplets issuing from a nozzel can be made uniform in size and spacing by applying cyclic energy or vibrations to the droplets as they form at the nozzle orifice. 9 C.R. Winston was the first person to incorporate these longstanding discoveries into a commercially successful ink jet printer. His device, patented in 1962 (U.S. Patent No. 3,060,429) and marketed as the Teletype Inktronic, recorded information by forming a single-file train of ink droplets that were imprinted with a uniform electrical charge. The droplets were directed between a pair of deflection plates which received variable electrical signals from an input source. The interaction of the constant charge placed on the droplet with the variable charge placed on the deflection plates caused the droplets to be deflected, the magnitude and direction of deflection depending on the charge placed on the deflection plates. After leaving the deflection field, the droplets travelled along their programed trajectories to a recording medium, usually paper, that passed under the nozzle and deflecting apparatus. 10 Although the Winston device was able to print alphanumeric characters, it could operate only at relatively slow speeds, since only one droplet could be present in the deflection field at a time. If a trailing droplet entered the deflection field before the leading droplet exited, the trailing droplet would be deflected along the identical trajectory as the leading droplet, since all droplets received identical charges and their trajectories were determined by the charge placed on the deflection plates when the droplets were present in the deflection field.
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.
15 Upon hearing of Sweet's work in late 1962, Arling D. Brown and Arthur M. Lewis of Brush Instruments added a character or function generator to Sweet's droplet-printing device thereby enabling the device to print alphanumeric characters. Attached as Appendix B is one of the illustrative embodiments included in the Lewis-Brown patent. Character generators are devices which are able to store letters and numerals and to send to the charging electrodes voltage signals corresponding to the letters and numerals. Messages, consisting of a predetermined sequence of letters and numerals, are sent to the character generator which translates the message to a series of voltage signals and then relays the translated message to the charging electrodes which then charge the appropriate droplets to the appropriate level thereby causing the message to be printed. 16 The first Lewis-Brown application was filed on September 25, 1964. 7 Two further applications were filed during 1965; both contained essentially the same disclosures as the initial application. After a brief prosecution, the Lewis-Brown patent issued on January 10, 1967, and A.B. Dick became the exclusive licensee under it. 17 After the Lewis-Brown patent issued, Sweet, whose application was pending, copied claims from the Lewis-Brown patent in order to provoke an interference proceeding between himself and Lewis and Brown. After a lengthy interference process, the Patent Office Board of Interferences resolved the question of priority of invention in favor of the Lewis-Brown patent, holding that the Sweet patent application did not disclose a character generator and therefore Sweet could not claim it in hindsight in combination with the droplet-printing apparatus which his application did disclose. 8
18 In May, 1963, during the course of Sweet's work on the original Sweet device, Dr. Cumming, Sweet's supervisor, directed Sweet's attention to a recording system that used a dense array of wire styluses situated above and across a specially treated paper. Trial Transcript at 100. When electrical potential was applied to an individual stylus in the array, current passed from the stylus to the specially treated paper, which produced marks that combined to form the desired character. Dr. Cumming realized that the wire styluses could be replaced with ink jets, such as those used in the original Sweet device, thereby dramatically improving the speed of the system. 19 After several brainstorming sessions, Sweet and Cumming proposed that Stanford's research laboratory develop this idea, but the research proposal was rejected. Undaunted, Sweet approached Honeywell with the idea, since Honeywell had helped Sweet in his initial patent application. On March 25, 1964, Honeywell, acting on behalf of Sweet and Cumming, filed a patent application that disclosed a device utilizing the multiple jet configuration. The original Sweet-Cumming application disclosed only a facsimile recorder, but an amendment was later filed that disclosed a character generator which enabled the Sweet-Cumming device to print characters. The Sweet-Cumming patent, No. 3,373,437, was issued on March 12, 1968. Attached as Appendix C is an illustration of the Sweet-Cumming invention. 20 The invention disclosed in the Sweet-Cumming patent is described in the patent as an improvement over the recording system disclosed and claimed in the Sweet patent. More specifically, the Sweet-Cumming device is described as utilizing the principles of the Sweet patent but being particularly adapted for presenting a display image as distinguished from a line trace. 21 The record is silent as to why Sweet and Cumming elected to file an entirely separate patent application that expressly claimed the ability to print predetermined characters with ink droplets. The trial court did not expressly draw any inference from this fact, although it did note that the Sweet-Cumming patent acknowledges an indebtedness to Sweet's prior work. 521 F.Supp. at 177. 22 Neither Sweet nor Cumming ever actually built a machine based on the techniques and apparatus disclosed in the Sweet-Cumming patent. Shortly after the patent issued, Sweet assigned his interest to A.B. Dick while Cumming assigned his interest to Mead.
23 In 1967 Mead began in earnest a research and development effort which culminated in the Mead DIJIT printer, the accused device. Attached as Appendix D is an illustration of the DIJIT. While the DIJIT printer embodies virtually all of the principles and techniques disclosed in the Sweet-Cumming patent, Mead's research was independent of the research conducted by Sweet and Cumming. 9 Shortly after the Sweet-Cumming patent issued, Mead purchased Cumming's interest: the DIJIT can thus be thought of as an application of the Sweet-Cumming patent. 10 24 The DIJIT printer contains a row of orifices situated above and across the recording medium so that the recording medium travels underneath the orifice array in a direction perpendicular to the array. A continuous stream or jet of ink issues from each orifice simultaneously and each jet is broken into evenly sized and spaced droplets by a process similar to that used in the Sweet and Lewis-Brown devices. Unlike the other devices, though, all of the droplets that print in the DIJIT are essentially undeflected: images are formed by deflecting into a collector or interceptor selected droplets from selected orifices and permitting the remaining droplets to fall undeflected onto the recording medium. Droplet interception is controlled by a computer which can be programmed to send instructions appropriate for printing alphanumeric characters as well as facsimile reproductions of video signals. 25 The process by which droplets are deflected in the DIJIT is similar to that used in the Sweet and Lewis-Brown devices: each droplet passes near a charging electrode and then through a deflection field. The interaction of the charge placed on the droplet with the electrostatic field causes the droplet to change its course. 26 However, since the sole purpose of deflection in the DIJIT is to prevent selected droplets from reaching the recording medium, all deflected droplets receive a virtually identical charge. Thus, only two charge levels are necessary in the DIJIT: one charge level (one hundred volts) deflects the droplets to the catcher while the other charge level (zero volts) permits the droplets to travel undeflected to the recording medium. Deflection is used in the Sweet and Lewis-Brown devices to direct droplets to various locations on the recording medium as well as to direct droplets to a collector. To accomplish this result, multiple charge levels are used in those devices. 27 Moreover, deflection in the DIJIT is longitudinal with respect to the movement of the recording medium, that is, the ink droplets are deflected in the same direction that the recording medium travels. Longitudinal deflection is used since all deflected droplets are intended to be intercepted and the interceptor or collector is situated across the recording medium, parallel to the orifice array. As noted earlier, the District Court concluded that the Sweet device discloses only transverse deflection.