Abstract: A light shutter system (10) incorporates a liquid crystal cell (12) operating as a variable optical retarder to selectively produce opaque and transmissive optical states corresponding to the respective first and second amounts of optical retardation of the variable optical retarder. The cell switches between a residual amount of retardation and an increased amount that equals the sum of half-wave retardation and the amount of residual retardation to provide a shutter system whose system retardation switches between zero retardation and half-wave retardation and thereby produces opaque and transmissive states with an optimal contrast ratio. The cell is positioned between a linear polarizing filter (14) and an elliptical analyzer (16), the latter including a linear polarizing filter (20) and an optical retarder (18) of fixed value.

Abstract: An input signal is sampled by alternately coupling the input signal and a reference level to a sample storage element, whereby the magnitude of the signal stored by the storage element immediately following application of the input signal to the storage element is a function of the input signal magnitude and the magnitude of the signal stored by the storage element immediately preceding coupling of the input signal to the storage element is a function of the reference level.

Abstract: A high performance graphics display system for use as an engineering workstation includes a compact method of generating vectors and transmitting addresses for same from a picture processor to frame buffer control circuitry for writing or reading pixel values along the vector in the frame buffer. The system uses a multiplexed address/data bus. Off-screen memory in communication with the picture processor is used to store pixel data read along vectors in the frame buffer preceding writing a vector so that the original data can be restored when the written vector is moved or removed. Vectors are encoded by the picture processor as a first word containing the address of the beginning point of the vector and major axis and X and Y direction bits to indicate the vector's direction. A second word includes a minor axis bit, indicating whether the next pixel to be written or read is on or off the major axis, in the direction indicated for such axis in the first word.

Abstract: An address generator that provides equivalent time sampling for a time domain reflectometer generates read and write addesses for simultaneous application to an aquisition memory over an address bus. For each iteration of a repetitive input signal an excitation pulse is delayed by an amount, dt, that is an integer submultiple of a sampling period, T. Read addresses for each iteration of the repetitive input signal start from an initial address and increment by T/dt for each data sample. Corresponding write addresses are generated from the read addresses one sample time later so that the address on the address bus has a read address that is one address ahead of the write address. The acquisition memory reads out data from the read address for accumulation with corresponding sampled data while accumulated data is being input to the write address.

Abstract: An ink jet print head cleaning and maintenance system has a purge chamber for applying a vacuum to a nozzle orifice surface. A specialized baffle diverts ink entering the purge chamber away a vent port through which the vacuum is drawn. An elongated wipe engages and wipes the orifice surface and is preferably moved at an extremely slow rate across the surface to enhance the wiping operation. An air knife directs a narrow stream of air across a portion of the nozzle orifice surface with air from the air stream being scanned across the surface for cleaning purposes. A specialized drip edge is positioned beneath the orifice surface for directing drops of ink away from the ink jet print head, the drops of ink being generated during the cleaning procedures. A mechanically simple cam mechanism coupled to a rotatable drum of the printer may be used to shift the maintenance system against the nozzle orifice surface for cleaning purposes.

Abstract: A twist lock probe tip has a flexible body of an insulative material with an electrical conductor embedded within the flexible body or coated on one side of a flat flexible body. The flexible body has a notch for exposing the embedded electrical conductor and/or for engaging a lead of an electrical component. The flexible body is inserted between the leads of the electrical component and twisted by means of an attached knob or wing lever so that the notches engage adjacent leads and the conductor contacts the desired lead.

Abstract: A method and apparatus are disclosed for representing and displaying the true (actual) color of an image in an index color system. The user specifies the number of color levels necessary to represent the range of displayable colors, and specifies the color (the red, green, blue primary color values) desired for an image. From the specified number, the apparatus calculates RGB (red, green, blue) color values, and stores them in memory in a manner suitable for referencing by an index type address. From the specified color, the apparatus calculates an index suitable for referencing the desired RGB color values from the stored color values. The apparatus comprises a keyboard and a port to a host computer for inputting index color data and true color data, a processing means coupled to the keyboard and/or host computer for producing index-type data from true color data, a memory means for storing the input data and data produced by the processing means, and a display means for displaying stored data.

Abstract: Vectorscope automatic burst positioning for properly aligning a vectorscope display uses a microprocessor (22) to control a phase shifter (14) according to the amplitudes of the chrominance components demodulated from an input color video signal during the burst interval. The demodulated chrominance components are sampled and digitized (18), and the digitized values are tested to determine whether they fall within a predetermined window. The microprocessor applies a statistical approach over a range of phase values to compute a final phase control signal value for the phase shifter that properly aligns the vectorscope display.

Abstract: A sync vector generator for a composite vectorscope generates a gate from the horizontal sync pulses of a video input signal as a function of a reference signal selected from either the video input signal or an external reference signal. The gate width is equal to an integer multiple of cycles of the subcarrier frequency for the video input signal. A high-Q resonant tank circuit tuned to the subcarrier frequency is activated by the gate to produce a burst signal having a frequency equal to the subcarrier frequency and having a number of cycles equal to the integer multiple. The burst signal is input together with quadrature subcarrier frequency components to the demodulators of a conventional vectorscope to produce an output display that is a measure of horizontal sync jitter and instantaneous SC/H phase.

Abstract: A drop-on-demand ink jet has an ink chamber coupled to a source of ink, and an ink drop orifice with an outlet. An acoustic driver produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop orifice and outlet. The driver is driven with bipolar drive pulses having a refill pulse component and an eject pulse component of a polarity which is opposite to the refull pulse component. The refill and eject pulse components are separated by a wait period. The drive pulses may be adjusted to minimize their energy content at a frequency corresponding to the dominant acoustic resonance frequency of the ink jet. This will accelerate drop breakoff, optimize drop shape and minimize drop speed variations over the range of drop printing rates. The ink jet printer of the present invention may be used to print with a wide variety of inks, including phase change inks to achieve high print quality at high print rates.

Abstract: The present invention (50) corrects duty-cycle errors generated by imperfections in encoder scales and encoder detectors. A preferred embodiment of the invention operates by detecting successive transparent-to-opaque transitions of the encoder scale (20), calculating the distance between the transitions, dividing that distance by two, and generating a synthetic encoder pluse that is timed to represent a position 50 percent of the distance between the transparent-to-opaque transitions.

Abstract: A pinch clip lid for a non-hermetic package containing an electronic component having an exposed face has a step lid that includes means for centering the lid on the package. Attached to opposing sides of the lid are side bars that have a lower portion that extends slightly inwardly to grip the package when the lid is mounted on the package, and that have an upper portion contiguous with the lower portion so that when the top portions are pinched, the lower portions release the grip on the package so that the lid may be removed from or placed on the package.

Abstract: A circuit for software performance analysis implements a balanced binary tree in hardware. This circuit consists of a number of "levels", each containing two (sets of) latches, a RAM, and a digital comparator. One of the latches, the data latch, is used to hold the data element being evaluated. The other latch, the results latch, stores partial results based on the comparisons performed on higher levels. The RAM is addressed by the contents of the results latch on the preceding level in combination with the output of the comparator on that same preceding level. The output of the RAM is compared by the digital comparator with the contents of the data latch, to produce an additional bit of results information for the next level. On each level, the RAM is preprogrammed with twice as many midpoint addresses as is the RAM on the preceding level. The outcome of the comparison done on any particular level is used, along with the results from preceding levels, as an address to access a RAM on the next level.

Abstract: A test fixture for a high pin count surface mounted IC device has a test head assembly connected to an adapter having electrically conductive elements that couple the output of the IC device to test points on the test head assembly. The test points are coupled to conductive pads on the test head assembly via conductive runs. The test head assembly conductive pads mate with conductive pad formed in the electrically conductive elements of the adapter. The conductive elements engage leads on the IC device providing conductive paths between the IC leads an the test points on the test head assembly. The test fixture is secured to the IC device by friction forces between the periphery of the IC device and the inner surface of the adapter. The test fixture or the adapter is usable as a low profile chip carrier by inverting the fixture or adapter and as a circuit board interconnect.

Abstract: A micromechanical sensor comprises a support, a micromechanical element that is movable relative to the support under the application of a stimulus, and a transducer. The transducer comprises a first component carried by the micromechanical element and movable therewith, and a second component stationary relative to the support. One of the first and second transducer components is a member for establishing a magnetic field and the other of the first and second transducer components is a SQUID positioned in the magnetic field for detecting variation in the magnetic field due to relative movement of the micromechanical element and the support.

Abstract: A television signal generator which is fully digital has digital data stored in PROMs, one PROM for each component of the desired encoded television signal corresponding to luminance data and chrominance data. A system clock allows a signal address generator to fetch data from the PROMs. The chrominance data from the PROMs is mixed with appropriate digital representations of a sinusoidal function and a phase offset and is added to the luminance data. The combined digital signal is converted to analog, filtered and output as the desired encoded television signal.

Abstract: An adapter for coupling electrical signal to and from an integrated circuit device mounted on a circuit board has a frame composed of individual side sections with each side section having ribs formed therein for providing detented cantilever engagement of the side sections to the sides of the IC device. Electrically conductive elements fit in between the ribs and engage the leads on the IC. The electrically conductive elements are connected to conductive pads formed on a substrate that is secured with the frame. A securing means that includes pins are used for securing the side sections together.

Abstract: A low jitter clock phase adjust system divides an input clock signal into three clock signals having precisely equal phase differences from each other. The three clock signals are converted into current vectors and input to a trio of two-quadrature multipliers. The current vectors are multiplied by separate control signals generated from an input phase control signal. The separate control signals are generated such that only one of the separate control signals varies at a time. The result is a phase response output that is a linear function of the input phase control signal and that provides a phase adjustment range from -60.degree. to 360.degree..

Abstract: A sampling phase detector for a phase locked loop system receives a gate signal derived from the output of a voltage controlled oscillator to enable the phase detector. A reference signal is applied to the phase detector to charge one of two capacitors during the gate period, the capacitor being charged being determined by the state of the reference signal. At the end of the gate period the difference in charge between the two capacitors is transferred to the output of the phase detector as a control voltage signal to correct the output of the voltage controlled oscillator to be in phase wiht the reference signal.