Abstract: A plasma addressed liquid crystal display system (10) includes improved electrode structures (90, 100, 130) that are nonuniform parallel to their surfaces and may also be nonuniform perpendicular to their major surfaces. The nonuniformities include surface nonuniformities (92, 94), bulk nonuniformities (108, 110, 112, 112), and geometric nonuniformities (132, 134). Electrodes having such nonuniformities provide localized sites of preferential and nonpreferential surface and bulk properties of the electrodes, which, in turn, provide improved and locally tailored plasma discharge characteristics. PALC displays having the nonuniform electrodes have improved quality because of reduced firing voltages in one plasma channel region compared to another, reduced sputtering damage, reduced total current between electrodes, decreased discharge initiation time, and decreased ionized gas decay time.

Abstract: A process motor (82) provides bidirectional motive force to a printer (50) drive train (80) that selectively engages with multiple self-homing printing functions. A print head (52) is tiltable to a maintenance position and a transfer roller (64) is loadable against a transfer drum (54) by respective missing tooth gear (96, 160) latching mechanisms. A print media pick roller (122) and transfer drum maintaining devices (70, 72) are actuated by spring-wrap clutches (114, 236) that are protected from reverse rotation by a one-way clutch (106). Print media transport rollers (140, 142) are selectively engaged with the one-way clutch by an electro-mechanical clutch (128). A picked and transported print medium (56) receives an ink image from the transfer drum and is stripped therefrom by stripper fingers (66) and directed into media exit rollers (212, 220) for delivery to a media output tray (68).

Abstract: A ferroelectric relaxor ceramic actuator material, such as lead magnesium niobate ("PMN"), has high electromechanical conversion efficiency, exhibits wide operating and manufacturing temperature ranges, does not require permanent polarization, and provides useful mechanical activity with reduced electrical drive voltages. A PMN actuator (66) may be bonded to an actuator diaphragm (64) with a high temperature soldering or brazing process. PMN material also has a diffuse Curie point range in which the dielectric constant (40), "d" coefficient (32), and dielectric loss (42) characteristics all rise to a peak and then fall as the temperature increases. A phase-change ink-jet print head (50) employs a PMN actuator that is compounded with lead titanate ("PT") to increase the temperature (T.sub.M) at which the peak dielectric constant occurs.

Abstract: An electrical signal jitter and wander measurement system (30) operates in real time and digitally controls bandwidths over which the measurements are performed. A digital phase-lock loop ("PLL") (34) includes a phase detector (44), low pass filters (48, 56), an analog-to-digital converter ("ADC") (54), a digital signal processor ("DSP") (32), a direct digital synthesizer ("DDS") (38), and a tracking oscillator (39). The phase detector receives an input signal that is compared with a signal derived from the DDS. The phase detector signal contains wander and jitter data that are filtered and digitized by the ADC. The DSP receives the data and performs a proportional integral control function to lock the PLL by digitally controlling the DDS frequency. The DDS generates a clock signal at a precise rate determined by the phase accumulation registers. The tracking oscillator locks to multiples of the DDS frequency to increase the resolution of the phase measurement.

Abstract: An ink-jet apparatus (10) and method provides high-resolution, high-speed printing by providing a transducer drive waveform (160) having a spectral energy distribution (170) that concentrates energy (172) around a frequency associated with a dominant (Helmholtz) ink drop ejection mode and that suppresses energy (174) at resonant frequencies associated with ink inlet (18) and ink outlet structures (24, 26, 28, 14) of the ink-jet head. Spectral energy distribution principles used to shape the transducer drive waveform can be used to enhance the jetting performance of many conventional ink-jet heads.

Abstract: A current probe (10) measures a signal current flowing in a conductor (12), which produces a signal flux (14) proportional to the signal current. The probe includes a pair of probe arms (16, 18) that straddle the conductor, a flux shunt (20), a pair of flux diverting arms (22, 24), and a flux link (26). A Hall-effect device (28) senses the amount of flux flowing in the flux shunt. A major portion of the signal flux flows in a preferential path (30) through the flux shunt while a minor portion flows in a flux diverting path (32). The ratio of the amount of the signal flux flowing in the preferential flux path to the diverting path depends on the reluctance in each path, which is determined by air gaps (27, 34). The Hall-effect device drives a current source (40) that provides a diverter current through a pair of flux diverting coils (42, 44) that are wound around flux diverting arms (22, 24) of the current probe.

Abstract: An ink jet (10, 200) provides high-resolution gray scale printing or switchable resolution printing by providing PZT drive waveforms (100, 110, 120, 360, 370), each having a spectral energy distribution that excites a modal resonance of ink in an ink jet print head orifice (14, 208). By selecting the particular drive waveform with selectable energy inputs that concentrates spectral energy at frequencies associated with a desired oscillation mode and that suppresses energy at the other oscillation modes, an ink drop (170, 180, 190, 210) is ejected that has a diameter proportional to a center excursion size of the selected meniscus surface oscillation mode. The center excursion size of high order oscillation modes is substantially smaller than the orifice diameter, thereby causing ejection of ink drops smaller than the orifice diameter. Conventional orifice manufacturing techniques may be used because a specific orifice diameter is not required.

Abstract: A compact ink jet print head has cross-sectionally tapered ink manifolds (16) for supplying ink to ink supply channels (18) leading to the acoustically driven ink pressure chambers (22). An array of closely spaced nozzles (14) which are supplied with ink from the densely packed ink pressure chambers by way of offset channels (71). The tapered manifolds, ink supply channels, pressure chambers, and offset channels are designed to provide uniform operating characteristics among the ink jet nozzles of the array. To enhance the packing density of the pressure chambers, the ink supply channels leading to the pressure chambers and offset channels are positioned in planes between the pressure chambers and nozzles. The tapered ink supply manifolds enhance purging of contaminants or bubbles from the print head by providing uniform ink flow rates (97, 97') along the entire length of the manifolds.

Abstract: A spectrum analyzer (10, 70) employs a method of reducing the amplitude of harmonic and spurious signals (102, 104, 112) introduced into a frequency-domain output spectrum by, for example, nonlinearities in a mixer (12, 78) or an ADC (20, 92). The method employs acquiring and digitizing a normal time-domain data record of an input signal, transforming the time-domain data record to a normal frequency-domain record (30), and storing the normal record. Next, a local oscillator (14, 76) driving the mixer is frequency shifted, and an additional time-domain data record is acquired, digitized, transformed, and stored to produce a shifted frequency-domain data record (40). Then, the shifted data record is mathematically realigned (50) with the normal data record and the normal and realigned data records are combined to produce a frequency-domain data record (60) having reduced harmonic and spurious signal amplitudes.

Abstract: Improved color ink-jet printing is accomplished by an ink-jet nozzle array configuration (32, 110) which has an odd number of nozzles (34) that are uniformly spaced apart by two line widths (2 V) such that naturally interlaced printing is accomplished when a print head (54) employing the nozzle array configuration is moved in uniformly stepped intervals. A color ink-jet print head employing the array configuration further employs multiple horizontally spaced apart instances (30) of the array in which each array ejects a particular color of ink, and the nozzles of each array are aligned in the direction of scanning to eject ink toward a common band of lines.

Abstract: A print head (216) tilt angle positioner (258) includes a scroll cam (344), a tilt arm (332), a flexure (334), a tilt angle adjuster (336), and a biasing spring (338). The tilt arm and the print head are attached to a shaft (220) that rotates the tilt arm and the print head together between printing, maintenance, and shipping tilt angle positions to control the distance of the print head from the image receiving drum.

Abstract: A liquid crystal cell (60) for an optical display system has a first transparent electrode structure (62) including plural separate display electrodes (72A-72E) spaced apart from and generally parallel to a second electrode structure (64) including a common electrode (106) opposing the display electrodes across a thin layer (76) of liquid crystal material captured between the two electrode structures. Each display electrode has left (92A-92E) and right (94A-94E) ends having respective electrical contact areas (96A-96E, 98A-98E). The left and right ends of each display electrode are electrically driven with a drive signal (V.sub.DRIVE (A-E)). The common electrode has top (116) and bottom (118) ends located adjacent respective top (108) and bottom (110) side margins of the second electrode structure and having top center (120) and bottom center (122) locations with respective top and bottom electrical contact areas (124, 126).

Abstract: A split-path isolation amplifier (10) employs a transformer (30) in a high path (26) and a single-input, dual-output closed-loop optocoupler (66) in a low path (24) to achieve a flat, wide frequency response without need for frequency compensation adjustments. In a low path frequency region (106), the optocoupler provides all or most of the signal to the output. The isolation amplifier employs a substantially overlapped crossover frequency region (104) in which the high path signal is applied to a primary winding (28) of the transformer, and the low path signal is applied differentially to secondary windings (40, 42) of the transformer. At frequencies below the crossover frequency range, the signal from the optocoupler dominates as the signal coupled from the primary winding rolls off. At frequencies above the crossover frequency range, the signal coupled from the primary winding dominates as the signal from the optocoupler rolls off.

Abstract: A phase-change ink transfer printing process and apparatus (10) applies a thin layer of a liquid forming an intermediate transfer surface (12) to a heated receiving surface, such as a drum (14). Then an ink-jet printhead (11) deposits a molten ink image (26) onto the heated drum where it cools to the drum temperature and solidifies. After the image is deposited, a print medium (21) is heated by a preheater (27) to a predetermined temperature and fed into a nip (22) formed between the heated drum and an elastomeric transfer roller (23) that is biased toward the drum to form a nip pressure that is about twice the yield strength of the ink image. As the drum turns, the heated print medium is pulled through the nip to transfer and fuse the ink image to the print medium. When in the nip, heat from the drum and print medium combine to heat the ink in accordance with a process window (90), making the ink sufficiently soft and tacky to adhere to the print medium but not to the drum.

Abstract: An ink jet (10) apparatus and method provides high-resolution gray scale printing by providing multiple PZT drive waveforms (100, 110, 120), each having a spectral energy distribution that excites a different modal resonance of ink in an ink jet print head orifice (14). By selecting the particular drive waveform that concentrates spectral energy at frequencies associated with a desired oscillation mode and that suppresses energy at the other oscillation modes, an ink drop (170, 180, 190) is ejected that has a diameter proportional to a center excursion size of the selected meniscus surface oscillation mode. The center excursion size of high order oscillation modes is substantially smaller than the orifice diameter, thereby causing ejection of ink drops smaller than the orifice diameter. Conventional orifice manufacturing techniques may be used because a specific orifice diameter is not required.

Abstract: A spectrum analyzer (50) has a tunable trigger acquisition system (52) that includes a selectable trigger acquisition bandwidth. Sufficiently wide signal acquisition bandwidth is obtained by tapping into a high-frequency IF amplifier (54) signal and down-converting it to a moderate IF frequency for trigger extraction. A down-conversion local oscillator (62) is phase-lock-loop (64) tunable over a range of the high IF frequencies to allow extracting a time and frequency selectable trigger from the desired carrier signal frequency even if the spectrum analyzer is substantially offset in frequency from the desired carrier. The moderate frequency IF amplifier (66) includes a switchable bandpass filter (68) that provides adequate selectivity to detect triggers from a variety of signal types while rejecting unwanted signals such as adjacent channel CATV carriers that are often detectable when the measurement frequency is offset toward the channel edges.

Abstract: A thermal transfer color printer (100) utilizes a single print head (102) positioned outside a carousel (104) of monochrome ink ribbons (106) each stretched between a pair of spaced-apart spools (108, 110) mounted around the periphery of the carousel. A spool spacing (112) provides sufficient clearance for the thermal print head to be positioned between to spools to contact the ribbon. A media drum (116) is positioned coaxially within the carousel. The carousel has a media opening (122) through which a print medium (118) enters and exits a medium clamp (144) attached to the media drum. To print a particular color, the carousel is rotated such that the media opening is adjacent to a media supply, and a print medium is guided from the media supply into the medium clamp. The media drum is rotated to close the medium clamp and position a leading edge (138) of the print medium adjacent to the print head.

Abstract: A print head (216) positioner (260) includes a stepper motor (264) that is coupled by a substantially friction- and backlash-free taut metal band (266) to a lever arm (268) that imparts precise lateral motion to a positioning shaft (220) that is rigidly attached to the print head assembly. Each step of the stepper motor is translated by the lever arm into one pixel (0.085 millimeter) of lateral movement of the shaft. The exact amount of translation per step of the stepper motor is adjustable by an eccentrically mounted ball (272) that is minutely positionable (274) on the lever arm. The ball couples angular motion of the lever arm to lateral motion of the shaft such that adjusting the ball position on the lever arm provides a-variable scale factor adjustment that compensates for tolerance buildups and exact inter-nozzle spacing on the print head. The shaft is biased toward the ball by a spring (284).

Abstract: A video monitor color control system including means for calibrating the intensity response of CRT phosphor sets to each of a plurality of electron gun control levels. Provided is a processor (24) that generates a sequence of discrete DAC signals, each DAC signal identifying an electron gun and a DAC value for driving the electron gun at a selected control level. Also provided is a monitor driver (22) connected to the processor (24) and to the monitor (20) and controllable in response to a DAC signal for driving the electron gun identified by the DAC signal at the control level identified by the DAC signal. The driven electron gun excites the associated phosphor set. A sensor (28) is provided for detecting the luminous intensity level of the phosphor excited by the electron gun, and for converting the detected intensity into a representative signal.

Abstract: A plasma addressing structure having data storage elements (16) uses an ionizable gas to store data in and read data out of the storage elements. The storage elements are defined by the overlapping areas of multiple column electrodes (18) extending in a common direction on a first substrate (22) and multiple channels (20) extending in a common direction on a second substrate (24). A layer of pliant dielectric material (26) separates the first and the second substrates, which are positioned face to face and spaced apart with the direction of the channels transverse to that of the column electrodes. Each of the channels is filled with an ionizable gas and includes two electrodes (46 and 48) electrically isolated from each other. The ionizable gas functions as an electrical switch. The storage element includes a layer (32) of liquid crystal material and receives incident image-carrying light.