Opinion ID: 428566
Heading Depth: 2
Heading Rank: 5

Heading: The DIJIT Printer

Text: 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.