Showing papers by "Hewlett-Packard published in 1973"

Method and apparatus for refreshing semiconductor memories in multi-port and multi-module memory system

Abstract: A multi-module, multi-port memory system includes modules having semiconductor memory circuits which require periodic refreshing to retain the contents stored therein. Priority circuits resolve conflicts between the multi-port access of the memory modules and the refreshing requirements of semiconductor memory circuits within the modules. The modules of the preferred embodiment are arranged in a polymorphous array of selectably expendable rows and columns. Modules utilizing different memory technologies may be combined within the address space of the array without interfering with independent multi-port access by various computer processors and other memory using devices.

Electroluminescent semiconductor display apparatus and method of fabricating the same

Abstract: This electroluminescent semiconductor display apparatus utilizes a light-emitting semiconductor device surrounded by a molded white plastic body and transparent material containing scattering centers for diffusing the light emitted from the semiconductor over a large area. The light-emitting device is placed on a base material and a white plastic body is positioned about the device to provide a corridor for light from the device to the upper surface of the body. This pathway is filled with transparent material containing scattering centers, e.g., a mixture of epoxy and glass powder. Light emitted from the device passes up through the corridor diffusely reflecting from the sides of the body and being scattered by the diffusion centers in the transparent material. Thus, at the upper surface of the body, the corridor appears as an essentially uniformly illuminated surface. In the above described manner, a very intense, nearly point source of light emitted from an electroluminescent semiconductor device is diffused to less intense, more uniform illumination over a much larger surface of a display apparatus, thereby obviating the need for large-area light-emitting devices.

MOS threshold shifting by ion implantation

Abstract: In this paper, the theoretical description of threshold shifting of MOS devices by implantation of an impurity beneath the control electrode is presented. Experimental measurements are presented which verify the theoretical predictions. In particular, MOS capacitors and transistors were used to experimentally verify the theory ( n -type Si substrates to verify the case of p -channel devices). Implanted layers sufficient to compensate the background substrate doping were used. This layer creates a buried conducting channel beneath the gate that is isolated from the substrate by the p-n junction. Modulation of this conduction region by the surface depletion region was found to be responsible for the transistor action. For n -type substrates ( p -channel devices) ion energies of 33 and 53 keV were selected for use with gate oxides of ≈ 0·1 μm. Boron doses ranged from 5×10 10 to 2×10 12 atoms/cm 2 . Threshold shifts from 0·2 to 5 V were observed. Device performance was not degraded by the implantation. Annealing temperatures as low as 500°C were found to be sufficient to anneal the damage caused by the implantation. Changes in the characteristic C vs V curves of the devices were predicted and experimentally observed. A method of picking the approximate turn-off voltage of the devices from the C vs V curves is pointed out.

Spectrum shaping with parity sequences

Abstract: A method is disclosed for shaping a Fourier transform spectrum of an array of input data. The method may be used to produce a Fourier spectrum in which the moduli of the Fourier coefficients are all equal to one predetermined constant. This makes possible hologram synthesis with phase only transmittance and is an improvement over kinoforms where amplitude information must be discarded. The present method rests on the introduction of an auxiliary parity array of data which is interlaced with the true data array to be stored, the parity array being chosen so that a Fourier spectrum of the combined data and parity arrays has a level spectrum. In an image reconstructed from the hologram, optical detectors may be positioned to detect only the reconstructed data points. Other spectrum shaping is also possible including phase quantization.

Method for manufacturing thin film circuits

Abstract: A thin film capacitor and resistor is disclosed, each capacitor being formed by a structure including a metallic film on an insulating substrate, the metallic film having an oxidized surface formed by anodizing, an oxide layer on the oxidized surface of the metallic film, and a pair of spaced-apart conductor layers over the oxide layer, each resistor being formed by a resistive film on the substrate and a pair of spaced-apart conductor layers connecting with the ends of the resistive film. In the manufacture of the circuit, a predeposited substrate is produced that may be utilized by circuit designers in the subsequent fabrication of custom microcircuits. A heat treating technique is employed in trimming the resistors of the circuit.

Detector indicating availability and position of tape

Abstract: A tape detector operates inside an information recording and retrieving system structure. In the detector, a lense-equipped light source located inside a housing produces three beams of light which, after crossing above, below, and through an ordinary commercial recording tape, pass through an optical prism where they are deflected back toward the light source housing. On their return, the light beams again cross above, below, and through the tape and then converge on the surfaces of three photodetectors arranged in a vertical line in the same housing as and adjacent to the light source. Signals from the photodetectors indicate the following: the upper photodetectors signal whether the tape is available for recording, the middle one signals a particular position of the tape such as the beginning or the end of the tape, and the lower one signals the presence or absence of a tape cartridge within the system structure.

Calculator with key code association and display features

Abstract: A programmable calculator is provided with an indexing scheme for directly associating displayed key codes with the physical position of non-numeric or the identity of digit keys contained on the keyboard. Individual keys are represented by a two-digit number wherein the most significant digit is the number of the row in which the key is located and the least significant digit is the number of the column which the key occupies along that row. For digit keys the first digit of the key code is zero and the second digit of the key code is the assigned value of the key. The calculator also includes provision for displaying the key code of the last key actuated.

Surface effects of GaAs0·6P0·4 light emitting diodes

Abstract: Gallium arsenide phosphide light emitting diodes have shown a considerable perimeter to area effect, having decreased brightness for a fixed current at a large perimeter to area ratio. In this work the cause of this effect is investigated using electroluminescent data, d.c. electrical characteristics, junction capacitance data, scanning electron microscope measurements, and pulsed MOS capacitance measurements. Investigation of the current voltage characteristics as a function of temperature ruled out tunneling as a probable mechanism. Experiments using various dielectrics in which the diode was measured with the dielectric, then remeasured after the dielectric was removed, indicated that the effect was persistent and not modified by these treatments. Scanning electron microscope measurements in the specimen current mode and pulse MOS capacitance measurements showed that the surface recombination velocity was of the order of 10 6 cm/sec. This value was consistent with the observed perimeter to area effect on the current-voltage and brightness characteristics, indicating that these perimeter effects are dominated by the high surface recombination velocity. Increasing doping of the n -type material resulted in a decrease in the minority carrier lifetime but did not affect the surface recombination velocity.

Frequency stabilized gas laser

Abstract: A rod made of an insulating material having a thermal coefficient of expansion in the range from +1 to -1 part in 107 per degree centigrade is mounted between a pair of mirrors and hermetically sealed either within a glass or a stainless steel enclosure containing a gas discharge medium. The stainless steel enclosure may be clamped to and fixedly spaced from the rod by projections formed on the enclosure and symmetrically disposed around the rod toward the ends of the rod. The mirrors and an annular piezoelectric disc positioned within the enclosure between one of the mirrors and one end of the rod are axially mechanically biased against the ends of the rod either by a spring loading structure or by a gas pressure differential. An anode and an annular cathode electrically insulated from one another for operation at different potentials are mounted toward the opposite ends of the rod. A discharge path communicating with the gas discharge medium and including a portion of a bore axially extending through the rod is provided in the rod between and in communication with the anode and the cathode to provide a gas discharge for excitation of the gas discharge medium to produce a laser beam. This discharge path may be placed in a magnetic field having a component in the direction of the laser beam to Zeeman split the atomic transition line at which the laser action occurs so that the laser oscillates at two different frequencies and thereby produces an output beam with two components of different frequency and polarization. In response to a portion of the laser beam a feedback control circuit changes the thickness of the piezoelectric disc to maintain the spacing between the mirrors as required, for example, to stablize the frequency, or frequencies, of oscillation of the laser at or in a known relationship to the center of the atomic transition line at which the laser action occurs.

The future of electroluminescent solids in display applications

Abstract: A thorough investigation of human color vision and vectorial color space is linked to chemicophysical properties of electroluminescent (EL) solids. Three separate cases are discussed: a single color, several discriminable colors, and full-color-gamut EL displays. A review of chromaticness discrimination, chromatic abberation, color vision abnormalities, and color naming experiments indicates that the preferred monochromatic colors for solid-state displays are 590 nm yellow, 620 nm red, 480 nm blue, and their mixtures. Green is found least suitable under white ambient viewing and should be below 500 nm. It is concluded that while no present commercial material satisfies optimal criteria for any of the three cases, several materials offer a reasonable promise to satisfy the first case, and in part, the second. The long-range prospects of the third case are estimated. Past, present, and future state of the art of electro-luminous yields of the more prominent crystals are analyzed and projected. The future of research and technology throughout the next 25 years is forecast. There seem to be no fundamental obstacles to a significant growth rate of EL displays throughout the rest of this century.

Regulation and stabilization in a switching power supply

Abstract: A switching-type power supply is provided in which switching transistors are switched off periodically in response to an oscillator to establish a basic operating frequency, but switched on at varying times during the basic period, in response to a signal from a first feedback loop, whenever the sensed output voltage level is less than a desired voltage level. When the duty cycle of the switching transistors is less than 50 percent, stability is provided by augmenting the sensed output voltage by an additional voltage with a parabolic waveform. In accordance with one embodiment of the invention, a second feedback loop responsive to slow variations in the load provides an input to the first feedback loop.

Programmable electronic calculator for evaluating mathematical problems

Abstract: A programmable electronic calculator is disclosed for numerical evaluation of mathematical problems through application of one or more basic mathematical operators, properly grouped, to each input numerical operand of a mathematical problem according to the accepted rules of mathematical combinations. One may select any numerical operand, any of the four basic arithmetic operators, left parenthesis and right parenthesis to denote groupings, a storage register for receiving a numerical operand to be used in a computation or a numerical operand representing a result of a partial or final computation, or a storage register whose contents it is desired to print. Entry of each numerical operand and mathematical operator is accompanied by a printed record of that numerical operand and that mathematical operator so that the mathematical problem may be continually monitored as it is being entered. Depression of an equals key is followed by evaluation of previously designated operations and printing of the result. Selection of a left (or opening) parenthesis causes the contents of first and second accumulator registers in an arithmetic unit to shift to third and fourth accumulator registers in the arithmetic unit respectively. Selection of a right (or closing) parenthesis causes the shifting and combining of previously stored numerical operands to produce the result of the arithmetic combination embraced within a sequence denoted by a mating left parenthesis. One may select a learn mode in which steps are entered in a learn memory by working out a mathematical problem, each selected operation corresponding to a step in the learn memory. Thereafter, one may select an automatic computation mode to cause the operations previously stored in the learn memory to be carried out in sequence until a desired result is obtained or a predetermined point in the program stored in learn memory is reached.

Metallization structure and process for semiconductor devices

Abstract: A semiconductor device comprising a resistor formed by a region of a layer of tantalum nitride (Ta.sub.2 N), said tantalum nitride layer also serving at another region as an adhesion layer and a barrier diffusion layer for the gold contacts and interconnects of the semiconductor device. A layer of tantalum nitride is also employed to form a mask for the metallization layer of a semiconductor device, the metallization layer thereafter being etched by sputter etching to produce very fine line electrical patterns for the integrated circuit.

Method and apparatus for measuring the average liquid flow of a reciprocatory pump

Abstract: A liquid storage means and a flow passage resistant means are connected between a reciprocatory pump and the input to a liquid chromatography system. The pressure variations caused by the pumping action induce proportional variations of the storage volume of the liquid storage means. These pressure variations are sensed and supplied to a signal processing means which includes a differentiating circuit. The movement of the plunger of the pump is scanned in order to derive timing signals related to a certain portion of the pump cycle. These timing signals control the signal processing means such that output signals are obtained which are related to the pressure drop of the liquid storage means during said portion of the pump cycle. The output signals are indicative of the average liquid flow being pumped.

Infrared radiation source

Abstract: A source of infrared radiation is provided which includes a thin film resistive heater of high emissivity evaporated onto a substrate. The thin film heater is positioned between a pair of thin metal elements on the substrate. The resulting structure provides a well-defined, mechanically stable source. In one embodiment of the invention, the resistive element is coated with an antireflecting layer to enhance its emissivity.

High efficiency power supply

Abstract: A high efficiency, AC-to-DC power supply is provided in which a novel a rectifier bridge coupled to the input line. This rectifier bridge is comprises a pair of inductors mutually inductively coupled and inter-connected so as to be aiding around the bridge in one mode to rectify the incoming voltage from a 115 volt line and in a second mode to rectify the incoming voltage from a 230 volt line, the output voltage from the bridge is being the same amplitude for either mode of operation. A novel ripple voltage frequency doubling circuit is provided, to decrease the size of the components needed to filter the ripple. A novel circuit is provided for converting incoming line voltage variations to changes in the turn on time of the bridge control devices, e.g. SCRs, thus maintaining a regulated level of output voltage with varying amplitude input voltage. A modified switching transistor circuit is also provided wherein the switching transistor is operated in saturation and the driving transistor is out of saturation resulting in substantial power savings in the switching transistor circuit.

Gas Chromatographic Analysis of Drugs and Drug Metabolites in Biological Samples

Abstract: 1. Sample preparation procedures, derivative formation, conditions for separation, qualitative identification and quantitative evaluation of foreign compounds and their metabolites by g.l.c. are described and discussed.2. The selective nitrogen flame ionization detector and the linear electron capture detector are proposed for use in the detection of the low therapeutic concentrations of drugs and drug metabolites in biological samples. The advantages in using selective detectors are : simplified sample extraction procedure, high detection sensitivity even for small sample volumes, sensitivity independent from sample matrix, speed of analysis.

Time interval phase detection in distance measuring apparatus

Abstract: TIME INTERVAL PHASE DETECTIONIN DISTANCE MEASURING APPARATUS Abstract of the Disclosure The phase difference between a modulated light signal transmitted to and reflected back from a distant target and that of a signal transmitted through an internal reference path is determined by digital time interval means to automatically provide a direct indication of distance to the target.

Calculator having preprogrammed user-definable functions

Abstract: A calculator has one or more keys which initiate the performance of user-defined subroutines. When the calculator is turned on, the calculator memory is programmed with a predetermined subroutine which may subsequently be changed or replaced by the user.

Characteristics of high performance microwave transistors fabricated by ion implantation

Abstract: In this paper the characteristics and fabrication of implanted microwave transistors are discussed. By use of arsenic implanted emitter and boron implanted base, devices can be fabricated with f T between 4.0 and 7.0 GHz, while f max ranges from 18.0 to 25.5 GHz. Noise figures range from 3.8 to 5.5 db at 4 GHz. Results will be presented from devices implanted with arsenio emitter energies from 27 to 30 KeV and boron base energies from 20 to 38 KeV. Boron base doses range from 5 \times 10^{12} to 1013B/cm2, while emitter dose was 1 \times 10^{15} to 2 \times 10^{15} As/cm2. It was found that (Q E /D E ) eff ranged from 1.5 to 2.5 \times 10^{13} cm-4sec for all emitter implants. A discussion of improvement of uniformity and yield is included along with some wafer yield data.

Housing structure and magnetic biasing for bubble memories

Abstract: A completely enclosed housing of a magnetically permeable material contains a pair of magnetic discs. A magnetic bubble chip mounted in a gap between the magnetic discs is thereby subjected to a d.c. magnetic bias field provided by the discs but is also shielded from the effects of external magnetic fields. The device may be precisely magnetized by applying in succession two external magnetic fields of suitable magnitude, in opposite directions.

Microwave transistor package

Abstract: A package for containing a microwave transistor chip is constructed so that a surface on which the transistor chip is to be mounted is recessed below a metallized surface which serves as an electrical ground. By means of this construction, a mounted transistor chip will be positioned with its top surface just below the plane of the electrical ground surface. Thus, the leads which connect the transistor to the electrical ground surface may be very short, thereby reducing the occurrance of package parasitics, and in particular minimizing the spurious common emitter inductance. According to one embodiment of the invention, a cap is used which is in electrical contact with the electrical ground surface of the package, the cap having a recessed inner portion to assure that no contact is made between the cap and any leads which are bonded to the transistor chip and the package.

EFL logic family for LSI

Abstract: A highly-efficient LSI logic family combining the advantages of multi-emitter structures with the performance of ECL logic will be discussed. Simplified gate structure has been found to reduce propagation delay, power and number of logic levels required for logic function realization. Conventional processing affords 2-5 pJ performance.

The Effects of Package Parasitics on the Stability of Microwave Negative Resistance Devices

Abstract: The results of investigations of the effect of parasitic package elements on the behavior of negative resistance amplifiers are presented. Three different package styles were considered. Also two different lead configurations were used. The packages were all mounted in 7-mm coaxial transmission line. The impedance of packages with and without leads was measured from 4 to 18 GHz using a manual network analyzer. These data were used as the basis for calculations to determine the values of elements in a simple three-element equivalent circuit model of the package. Using the equivalent circuit model experimentally derived for each package style, the impedance seen by the chip through the package to a 50-/spl Omega/ load was calculated. Broad-band curves of the impedance seen by the chip are presented. The experimentally derived model of the package permits matching of chip and package for stability.