Abstract: A print head, formed with spaced linear subheads of jet nozzles, prints all of the lines or image element rows on a print medium such as a sheet of paper by scanning along the face of the sheet. The head is advanced between scans by an equivalent number of lines generally equal to the number of nozzles in the head, whereby all print lines are addressed only once. Apparatus for printing includes the use of pointers in registers to keep track of head structure and location on a print medium for calculating print addresses. A partial page memory is used which wraps around to the beginning from the end. An edge sequence control logic circuit modifies the print data so that nozzles not over the image area do not print. A positive printer carriage position encoder uses an index marker located in the middle of a strip of incremental markers. Sensing of the index marker resets an up/down counter with a value that gives a positive value for all count conditions.

Abstract: A method for examining a propagative medium, such as a signal transmission cable, that requires the acquisition and examination of a minimum number of data points to determine the presence of an anomaly in the medium. When an anomaly is detected, its characteristics, such as loation, type and amount of loss are determined. The characteristics are then displayed. If the anomaly is a reflectionless loss, the region containing the anomaly is examined repetitively to determine its location and to improve the accuracy of its location measurement. With each successive level of examination, additional samples are collected within the region. The new samples are combined with the existing samples to reduce random noise in the data. Through this method the location of the anomaly is re-determined with greater accuracy.

Abstract: A drop-on-demand ink jet print head (9) has an ink pressure chamber (22) coupled to a source of ink (11) and an ink drop ejecting orifice (103) with an ink drop ejection orifice outlet (14). An acoustic driver (36), in response to a driver signal (100), produces a pressure wave in the ink and causes the ink to pass outwardly through the ink drop ejecting orifice (103) and the ink jet ejection orifice outlet (14) of the ink jet print head (9). In accordance with the present invention, controlling the operation of the ink jet print head (9) with a particular drive signal reduces print quality degradation resulting from rectified diffusion, which is the growth of air bubbles dissolved in the ink from the repeated application of pressure pulses to the ink residing within the ink pressure chamber (22) of the ink jet print head (9), such pressure pulses causing the application of pressures below ambient pressure.

Abstract: An integrated circuit device having improved substrate capacitance isolation for use in a ultra low capacitance probe or an input to an oscilloscope or the like has an electrically conductive layer formed directly underneath an input node on the integrated circuit. The electrically conductive layer has a geometry substantially equal to the input node and is driven by a voltage output from a high impedance unity gain circuit. In one embodiment, the electrically conductive layer is formed in the first metal layer of the integrated circuit while an alternate embodiment an emitter region of a semiconductor device in the high impedance circuit is used as the electrically conductive layer.

Abstract: An improved optical filter for use in an optical measurement instrument has a corrective optical glass filter with a negative deviation in the range of 470 nm added to the optical filter to offset a positive deviation in the range of 470 nm in an amber or blue glass filter used in the optical filter. The improved optical filter in interposed between a photoelectric element in the optical measurement instrument and the source of electromagnetic radiation. The photoelectric device converts the electromagnetic radiation to an electrical signal which is processed and displayed. In one embodiment of the invention the optical filter has a spectral response matching that of the average human eye and in a further embodiment the optical filter has an approximate equal response over a spectral range from ultraviolet to infrared.

Abstract: An analog-to-digital converter comparator circuit includes a pair of differential amplifiers having their outputs normally intercoupled in a subtractive sense. At a sampling strobe time, the output of one differential amplifier is reversed such that outputs of the two differential amplifiers are additive. The period of time during which the output signals add can be made as short as desired, for example by successively operating differential coupling circuits at the amplifier outputs through an intervening delay line. A very small aperture time is secured which is substantially shorter than the time constant of subsequent circuitry. A latch circuit receives the output of the comparator for assuming one of two different states in accordance with the comparator sampled output.

Abstract: An instrument for depicting change in the value of a first variable as a function of a second variable comprises a display device for displaying a set of n measured values distributed along a display axis, and a sampler for acquiring a set of N (greater than n) samples of the first variable and storing values of those N samples in ordered fashion relative to a first storage domain that maps to the second variable. A set of n display samples is selected from the set of N stored samples and the values of that set of n display samples are provided to the display device. When the set of n display samples is a set of samples that are at a predetermined spacing in the first storage domain and/or occupy a selected interval of the first storage domain, a set of N1 (greater than n) samples of the first variable are acquired and their values are stored in ordered fashion relative to a second storage domain that maps to the interval of the first storage domain.

Abstract: A laser objective lens shield for preventing ejecta from a target object from impacting the objective lens has an inner and an outer conical structure that nest concentrically together. The inner conical structure has a plurality of orifices that are orthogonal to the conical axis, which is aligned with the lasing axis, and the outer conical structure has a fluid port by which a pressurized fluid hose may be coupled to the shield. Both conical structures have an exhaust aperture opposite the orifices and port, respectively. When the conical structures are nested together the edge around the exhaust apertures is sealed by suitable means, such as foam tape, so that a plenum chamber is formed between the orifices and the fluid port. Pressurized air introduced at the fluid port becomes a laminar air flow from the orifices orthogonal to the lasing axis to deflect ejecta away from the laser objective lens out the exhaust aperture.

Abstract: A direct digital synthesizer (DDS) for generating an output periodic waveform from a stored digital waveform has a linear feedback shift register coonfigured as a counter. The linear feedback shift register is clocked by the internal reference clock of the DDS, and a predetermined output of the linear feedback shift register is detected to provide a control signal. The control signal causes the frequency or phase of the output waveform to be changed according to control parameters input to a control logic circuit. The control logic circuit preloads the new parameter vlaues into appropriate frequency/phase registers which are switched to the input of the accumulator in the DDS on the next cycle of the reference clock when the control signal is detected.

Abstract: An analog acquisition system includes an array of analog capture cells for capturing and storing a signal on an analog bus. Each capture cell in the array may be sequentially selected for sampling the signal at successive sample times. Timing for selecting a row of the analog memory array is provided by a slow shift register and timing for selecting a capture cell within the row of the analog memory array is provided by a fast tapped delay line. Additional circuitry is provided for controlling the delay of the tapped delay line such that total delay is equal to the time the slow shift register takes to transfer from one row to the next.

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 method and apparatus for tiling a display area defined by lines joining vertices with a surface normal vector associated with each vertex whereby the display area is subdivided into sub-display areas by calculating additional vertices and surface normal vectors by interpolation and rendering a given sub-display area by calculating intensity values at its vertices and tiling its area by linear interpolation of the calculated vertex intensity values.

Abstract: A measurement probe has a probe tip coaxially disposed within one end of a elongate cylindrical outer conductor with the probe tip extending beyond the end of the outer conductor. A body of insulating material surrounds the outer conductor and a portion of the probe tip to provide electrical isolation between the probe tip and the outer conductor. A notch is formed in the insulating material distant from the probe tip to expose the outer conductor for providing an electrical connection between an outer conductor of a removable adapter and the elongate cylindrical outer conductor of the measurement probe. The measurement probe meets all safety standards for use as a floating measurement probe as well as being adaptable for providing a coaxial signal path having a common voltage ground.

Abstract: Computer-controlled test and measurement systems, including resources having multiple states and resources having multiple inputs, are modeled as data flow diagrams of topologically interconnected resources. A set of "tasks" are defined for changing the states of multiple-state resources and causing software resources to produce output data. Methods and apparatus, including internal and external task ordering rules, are provided to automatically interleave such tasks and implement input-ordering restrictions. Thereby, a sequence of tasks is produced to control the systems so as to assure valid data collection and protect physical resources from abuse. Data structures are illustrated for implementing the invention in an object-oriented programming environment.

Abstract: A determination as to whether the linear change in a dependent variable Y=(Dy/Dx)*X resulting from an ith step change of magnitude dx in an independent variable X would be better approximated by a change m*dy or a change (m+1)*dy in the dependent variable, is made by(a) setting m equal to floor (Dy/abs(Dx)), setting r equal to (Dy/abs(Dx))-m, setting DirX equal to Dx/abs)Dx), and setting Er equal to r-0.5; and(b) for each value of i in the range from 1 to (Dx/dx)-1, determining whether Er is less than 0 and, if so, setting Er equal to Er+r, X equal to X+DirX*dx and y equal to Y+m*dy, and otherwise setting Er equal to Er+r-1, X equal to X+DirX*dx and Y equal to Y+(m+1)*dy.

Abstract: A projection lens assembly (10) projects onto a display screen (38) electrons emitted from an output side (86) of an electron multiplier such as, for example, a microchannel plate (70). The projection lens assembly includes a dome-shaped mesh element (16) that is concave as viewed from the display screen. The mesh element is positioned between the microchannel plate and a filter element (20) having a beam-limiting aperture (22). The mesh element is of an aspherical shape that allows the projection lens assembly to project the electrons toward the display screen with substantially no spherical aberration, thereby forming near the beam-limiting aperture an electron beam crossover of small diameter. The beam-limiting aperture is formed with a relatively small diameter that allows the filter element to block electrons of energies outside a preselected range of energy values, thereby reducing chromatic aberration in the image formed on the display screen.

Abstract: A system is disclosed which reduces significantly the time for processing multi-bit two-color data for display. The system generates multi-bit two-color data by expanding single-bit monochromatic data, and provides three types of output data: a first expanded multi-bit color data, a second expanded multi-bit color data, and a third unchanged multi-bit data, the unchanged data being combinable with other data for producing data overlays.The system comprises a data expansion circuit for maintaining selected data unchanged and for expanding selected single-bit data to multi-bit two-color data, a memory for storing multi-bit data, and a data compression circuit for compressing selected multi-bit data to single-bit data.

Abstract: A system for expanding a waveform in a measurement test instrument has a display area containing a waveform representative of data acquired by a measurement test instrument and an active movable cursor intersecting the waveform. The system has first and second viewports with the first viewport displaying the waveform in the display area and the second viewport displaying a portion of the waveform from the first view port in an expanded form when the second viewport is in the display area. The second viewport has a center point and dimensions defined in the first viewport with the center point being defined by the intersection of the active movable cursor with the waveform and the dimensions being defined with respect with the center point. The second viewport is movable within the first viewport as a function of movement of the cursor.

Abstract: The present invention provides a method of using long digital filters in the presence of round-off errors by prescaling each filter coefficient by a scaling factor. The prescaled coefficients are used to weight input data samples. The resulting weighted data values are then divided by the appropriate scaling factor and combined to produce an output data sample.

Abstract: A pair of waveforms in quadrature relation, or otherwise phase related, are generated from a single direct digital synthesizer employing a single wave lookup table memory. Successive addresses are applied to the memory representing the desired phase difference between the two waveforms plus a fractional part of the increment desired between successive samples along the waveforms. Samples are selected for reconstructing the two respective waveforms by dividing down the sampling clock and providing timing signals therefrom coincident with the correct samples.