Tektronix, Inc.

Xerox Corporation

Guenther W Wimmer

David Lyell Knierim

Jeffrey J Anderson

Hue Phuoc Le

Ted E Deur

David B Kreitlow

Richard S Meissner

Monte J Rhoads

Douglas B Bingham

A circuit for controlling a piezoelectric transducer includes an N-channel FET having a gate electrode, a drain electrode coupled to a high voltage signal source Vpp, wherein Vpp is a positive going pulse train, and a source electrode coupled to an output Vcntrl for controlling the transducer and a charging circuit, responsive to a low voltage input signal Vpp_sel, for charging the FET gate to a bias voltage greater than the FET's threshold voltage while Vpp is near zero volts and for maintaining the bias voltage on the FET gate while Vpp ramps up to a value greater than the bias voltage and until Vpp_sel is removed. The control circuit reduces switching time and reduces current spikes in the power supplies to the chip.

High voltage level translator

A flexible bar connected to an actuator is suspended within an ink reservoir. The bar is preferably mounted in a cantilever or free-standing mode and vibrates in response to signals from the actuator. When the actuator signals are discontinued the bar continues to vibrate and causes the actuator to generate signals that are analyzed to determine the level of ink in the reservoir.

Ink level sensor

A fluid pressure regulator comprises a housing defining a cylindrical chamber, an inlet opening for introducing fluid under pressure into the chamber, an outlet opening for allowing fluid to leave the chamber at a regulated pressure, and a bleed orifice in communication with a space at constant pressure. The outlet opening and the inlet opening are in open communication. A ferromagnetic piston member is fitted in the chamber and is slidable within a range of positions such that the bleed orifice is partially covered by the piston. The ferromagnetic piston member is biased at a substantially constant force when it is that range of positions.

Fluid pressure regulator

A device for generating a digitizing pulse for sampling an analog video signal includes a phaes-locked-loop (PLL) circuit and a phase offset circuit. The PLL circuit generates a correction pulse required to bring an output signal of digitizing pulses in phase with a reference horizontal sync signal. The phase offset circuit includes a digital memory which stores a digital number representative of a fraction of a pixel pulse that is desired as phase offset of the digitizing pulse. This fraction is converted into an offset current pulse having a duration equal to the duration of a pixel pulse and an amplitude that is the fraction of a maximum amplitude. The offset current is added to the PLL correction current for generating an output signal of digitizing pulses having the desired phase offset relative to the pixel pulses.

Phase-offset signal generator

An ink jet head 10 has an ink chamber 14 which receives ink from an ink inlet passageway 38. Pressure pulses applied to the ink chamber cause the ejection of ink drops from an ink drop forming orifice 23 and toward printing medium. A purging outlet 41 communicates with the ink chamber through a purging passageway 40. During purging, ink flows in a vortical path through the ink chamber 14 from the ink inlet passageway 38 to the purging outlet passageway 40. This sweeps air bubbles and contaminants from the ink chamber walls and removes them from the ink chamber. Ink pressure within the ink chamber 14 may be elevated to increase the flow of ink during purging. Also, a negative pressure may be applied to the purging outlet during purging. Variable frequency pressure pulses may also be applied to the ink chamber to assist the purging process.

Method and apparatus for purging an ink jet head

A vacuum media capturing and retention system for a drum type printer or recorder is disclosed. The apparatus includes a vacuum drum with two regions of vacuum passages, one for capturing the leading edge of the media and the second for retaining the trailing edge of the media. When the leading edge of the media is initially captured the vacuum level in the drum is at one level. After the leading edge of the media is captured the vacuum level is dropped to a lower level until the trailing edge of the media is captured. Following the capture of the media trailing edge, the vacuum level within the drum is again increased to retain the media thereto during the copying or recording operation of the overall device.

Air density adaptive vacuum controller

An apparatus for generating a trigger signal having pulses synchronized with selectable angular displacement of a rotating object. The apparatus comprises a position encoder to monitor the rotation of the rotating object and to produce M output signal pulses during each revolution of the object, a frequency multiplier coupled to generate an output signal having a frequency N times the frequency of the position encoder output signal, and a frequency divider coupled to generate a pulsed trigger signal of frequency 1/Mth of the frequency of the frequency multiplier output signal, N being a selected integer and M normally being fixed by the physical contruction. The trigger signal comprises N pulses per revolution of the object and the angular displacement of the rotating object associated with each pulse of the trigger signal is selected by appropriate adjustment of N.

Phase locked synchronizer for printer timing control

The invention consists of a transformer coupled low voltage power amplifiers which provides the moderate voltage (200-500 V.sub.p-p) excitation potentials required by PZT ink jet or similar device elements. Transformer coupling is viable in that ink jet drive requirements are 'return to zero' (no net DC component). Product safety aspects are enhanced since high voltage power supplies are not required, furthermore significant reductions in cost of implementation are realized due to the absence of high voltage power supplies and by allowing the use of monolithic power amplifiers. Savings in power may also be realized by matching the transformer to the ink jet PZT element as components of a resonant network.

Low voltage transformer coupled ink jet driver

A system for controlling the amplitude of a drive signal applied to a stepping motor in a manner minimizing the effects of resonance on the resultant angular velocity of the motor shaft. Means are provided for comparing a desired motor drive frequency against one or more known resonant frequencies and, responsive to such comparison, for producing a motor drive signal at an amplitude predetermined to minimize oscillatory fluctuations in the motor shaft velocity.

System and method of minimizing velocity fluctuations in a synchronous

A parameter entry device for electronic instruments that also displays the current user definable system parameters is described. This device allows the user to change those parameters without using conventional rotary switches, internal straps, jumpers, etc.

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Portland, OR, United States of America

Guenther W Wimmer