Showing papers by "Hewlett-Packard published in 1976"

Multi-wavelength incremental absorbence oximeter

Abstract: Light of two different wavelengths is passed through or reflected from a member of the body so as to be modulated by the pulsatile blood flow therein. The amplitudes of the alternating current components of the logarithms of the respective light modulations are compared by taking their molecular extinction coefficients into account so as to yield the degree of oxygen saturation. By adding a third wavelength of light, the percentage of other absorbers in the blood stream such as a dye or carboxyhemoglobin can be measured. Fixed absorbers reduce the amount of light that passes through or is reflected from the body member by a constant amount and so have no effect on the amplitudes of the alternating current components that are used in making the measurements.

Calculator apparatus with electronically alterable key symbols

Abstract: A calculator system having a transparent keyboard includes an apparatus for electronically labeling the keyboard by displaying alphanumeric symbols through the keyboard. The apparatus comprises a keyboard selection device and a liquid crystal keyboard display device having a predetermined number of display planes each containing preselected symbols. The keyboard selection device operates both as a selection device and as an annunciator-feedback device, for selecting the symbols or legends of a given plane to label or configure the keyboard, and for feeding back to a user of the system the status of the selection device when it is activated. An alternative embodiment of the invention utilizes light-emitting diodes (LED's) for labeling the keyboard.

The Automatic Recognition of Human Faces from Profile Silhouettes

Abstract: A pattern recognition system is described which is capable of identifying human faces from their full profile silhouettes. Each silhouette is preprocessed to remove noise, smooth edges, and extract the front edge. The processed silhouettes are then represented by a 12-dimensional feature vector, the components of which are obtained by a circular autocorrelation function. Using a weighted k-nearest neighbor decision rule it is shown that a recognition accuracy of 90 percent is attainable in a ten-class problem. An adaptive training procedure is also described which is used for setting up the authority files. This training procedure appears to identify those feature vectors representing a class which are either most important, from an information content point of view, or are observed most often. Finally, a comparison is made between the recognition accuracy obtained using circular autocorrelation features and moment invariant features. It is shown that the former outperforms, in this problem, the latter. The system is also compared to human observers with the result that the system performs no worse than the human observers.

Surveying instrument and method

Abstract: A tacheometer utilizes a gallium arsenide laser diode in a phase shifting distance encoder, a sinusoidal interpolator in a phase shifting shaft angle encoder, a mercury pool in a phase shifting two axis off-level encoder, a shared phase to digital decoder and a digital processor, to measure angles and distances corrected for off-level, speed of light variations, refraction and the earth's curvature.

Transient Thermal Compensation for Quartz Resonators

Abstract: Thermal shock induced into ATand BT-cut temperaturecompensated quartz resonators results in transient frequency excursions that are not predicted by simple elastic theory. Compensation for thermally induced transients in quartz resonators was predicted recently by Holland. The experimental work presented here c o n f i i s the theory and predicts an orientation of @J = 21.93\", e = 33.93' for which full static and dynamic compensation for rapidly changing ambient temperatures should be achieved around 65°C. Experimentally, the predicted orientation showsperformance with respect o thermal transients that is two orders of magnitude better than comparable AT resonators.

Flat-band voltage reference

Abstract: A flat-band voltage reference includes two insulated-gate field-effect transistors, hereinafter IGFETs, which are substantially identical except for their flat-band voltage characteristics and which are biased to carry equal drain currents at equal drain voltages. The resulting difference in potential between the gate contacts of the IGFETs produces a voltage reference which is substantially independent of variances in operating points, supply potentials, and temperature.

Digital pattern triggering circuit

Abstract: A digital pattern triggering circuit combines an addressable memory and a processor. Input data patterns address corresponding memory elements whereby data previously stored in the memory by the processor is accessed, providing an indication of whether a preselected data pattern has occurred.

Fiber optic connector with split ferrule assembly

Abstract: The fiber optic connector described herein comprises a three-piece ferrule suitable for very small optical fibers, a boot and a shoulder nut for coupling with outside-threaded split sleeve, and provides closer concentricity tolerances and low-loss transmission of light from the end of one fiber to the end of another.

Gunn domain formation in the saturated current region of GaAs MESFETs

Abstract: A semi-empirical model is proposed to describe the behavior of a 1 µm gate GaAs MESFET in the saturated current region. It divides the MESFET into three sections: an "ideal" gradual channel portion (1); an adjacent stationary Gunn domain region extending to the drain (2); and a leakage path shunting these two portions at high drain bias via the non-ideal interface and substrate (3). In portion (1), a pinchoff potential for an ideally abrupt interface is defined. Properties of portions (2) and (3) are inferred from the implications of the gradual channel approximation for portion (1) and the experimental data.

Quartz resonator cut to compensate for static and dynamic thermal transients

Abstract: A method and apparatus utilizing a quartz crystal resonator with an orientation substantially equal to (yxwl) 21.93°/33.93° vibrating simultaneously in two thickness modes to accurately measure temperature and unknown frequencies or to provide a stable frequency signal source. By combining a quartz crystal resonator of the above type with either digital or analog compensation, the frequency-temperature deviation of one of the crystal mode frequencies is used as an internal thermometer and the second crystal mode frequency as a reference frequency signal. The frequency signal for the thermometer function is utilized by the compensation network to correct the measurements made with, or to stabilize, the frequency of the reference frequency signal. Additionally, the analog or digital compensation is accomplished by means of either a curve-fitting routine or an interpolation look-up table routine.

Electronic calculator with optical input means

Abstract: A keyless electronic calculator includes an optical bar-code reader for entering bar-coded program information, in the form of data and individual commands or complete programs, into the calculator. The calculator also includes a read-write memory unit (RWM) for storing the entered information, a central processing unit (CPU) having a read-only-memory unit (ROM) with pre-stored routines for processing data by executing the entered commands or program under control of the ROM routines, and a display unit for displaying entered data and execution results. An alternative embodiment of the calculator includes both an optical input means and a keyboard.

Medical-analytical gas detector

Abstract: A gas analyzer is provided which is particularly suited for making transcutaneous measurement of the CO2 concentration in the blood. In accordance with one embodiment of the invention, sample gases from the body are circulated in a cavity of the device. A rotating wheel in the cavity includes two reference cells and a sample cell which are sequentially rotated into the optical path between a source and a detector. Three signals are thereby provided which may be combined to give an output indication of the CO2 concentration in the body fluids. In a preferred embodiment, the sample cell is an "inverted cell" being in open communication with the sample gas circulating in the device so that the gas in the sample cell is a portion of the circulating gas which also surrounds the two reference cells. An output indication is thereby obtained which is insensitive to contaminants in the sample. In accordance with another embodiment, the sample cell is isolated from the region surrounding the wheel and positioned so as to be presented in series with the reference cells in the optical detection path. In preferred embodiments, the rotating wheel contains a number of permanent magnets which interact with a number of electromagnets driven in sequence to provide rotation of the wheel.

Barrier height voltage reference

Abstract: A barrier height voltage reference includes two field-effect transistors which are substantially identical except for their gate-to-channel potential barrier characteristics and which are biased to carry equal drain currents at equal drain voltages. The resulting difference in potential between the gate contacts of the two field effect transistors produces a voltage reference which is substantially independent of operating point, supply potential, and temperature.

Enhanced capacitor for one-transistor memory cell

Abstract: Ion implantation has been used to increase the depletion-layer capacitance beneath the inversion layer of an MOS capacitor in order to enhance the charge storage per unit area. Boron and arsenic implants were used to increase the depletion-layer capacitance, approximately halving the area required for a given charge storage.

Schottky diodes and other devices on thin silicon membranes

Abstract: The fabrication of ultra-thin silicon membranes of micron or submicron sizes with thicker supporting frames makes possible improvements in several kinds of electronic devices. We show that the series resistances of some devices can be reduced significantly, thus effecting increases in the cutoff frequencies. The resistance swing of Schottky diodes can also be raised. Initial experimentation relating to some of these applications is presented.

Cylindrical magnetron sputtering source

Abstract: Placement of cylindrical magnets inside of a cylindrical cathode comprising a source of depositing material for sputter depositing of the material upon the interior surface of a substantially cylindrical workpiece, results in improved deposition rates, low power requirements, low workpiece temperatures and purity and cohesiveness in the deposited layer of material.

High-speed GaAs MSI

Abstract: A report on a process for the medium-scale integration of MESFET digital circuits on GaAs will be offered. Gate propagation delays < 100 ps with fanout of two and binary division from dc to 2 GHz have been achieved.

Acoustic imaging apparatus

Abstract: An array of transducers is focussed by insertion of a means for providing a small variable delay between each transducer and a selected tap on a master delay line.

Wrist wearable electronic device with an engagedly stored selected tool

Abstract: Wrist wearable straps and a case are disclosed, each having an interior cavity for engagedly storing a special tool. One wrist device strap is made of a selected material and defines a pocket for holding the special tool. A second wrist device strap includes at least one special link defining an interior cavity for holding the special tool. These special links also include a removable portion to which is attached a special tool. The removable portion blends with the remainder of the link to give the appearance of a regular link when in place. The wrist device case similarly defines a cavity and includes a removable portion to which is attached a special tool. This removable portion enhances the appearance of the case when in place with the special tool held snugly within the cavity.

Apparatus for measuring the period and frequency of a signal

Abstract: The present invention relates to an apparatus for measuring, by cross-correlation, the period and frequency of a substantially periodic signal having random components, such as fetal heart beat signals and other biological signals.

Calculator apparatus with annuity switch for performing begin-and end-period annuity calculations

Abstract: A programmable electronic calculator is provided having a manually operable annuity switch with begin- and end-position settings, enabling a user to specify the type of annuity calculation to be performed. When the switch is set to the begin position, the annuity calculation is performed with payments due at the beginning of each payment period; when the switch is set to the end position, the annuity calculation is performed with payments due at the end of each payment period. The annuity calculation is performed under control of a routine stored in a read-only-memory (ROM) of a data processing unit.

Indices of refraction of potassium pentaborate

Abstract: The indices of refraction of potassium pentaborate, KB5O8·4H2O, have been measured over a range of wavelengths and the results fitted to a Sellmeier equation. No indication of an approaching absorption edge is found in transmission measurements from 0.56 to 0.20 μ.

Interactive wristwatch calculator

Abstract: An apparatus is disclosed comprising an electronic wristwatch and a multifunction electronic calculator in a single wrist mountable case having a common display and keyboard The watch portion of the watch/calculator includes time of day, calendar, stopwatch and alarm functions Each of these functions can be controlled from the keyboard on the watch/calculator The electronic calculator portion of the watch/calculator performs the four standard arithmetic functions: add, subtract, multiply and divide; and has an extra storage register The calculator portion can perform calculations with scalar quantities entered via the keyboard or stored in the calculator as well as calculations with time interval and real time data from the watch portion During the time that calculations are not being performed the calculator goes into a sleep or inactive mode in order to minimize the amount of battery power used by the watch/calculator

Frequency/stress sensitivity of s.a.w. resonators

Abstract: Surface-acoustic-wave resonators can be used as stress sensors for measuring force and pressure Experiments at 160 MHz using rotated y-cut substrates indicate that larger linear changes in resonator frequency can be obtained by deforming the substrate The saw transducers, besides being small in size, are also stable in frequency

IGFET threshold voltage compensator

Abstract: A circuit is described which compensates for variation in the threshold voltage of Insulated Gate Field Effect Transistors (IGFETs) in an integrated circuit by modulating the substrate voltage in response to the variation of the threshold voltage from a desired nominal value

Direct current power supply

Abstract: A direct current voltage power supply in which spaced pulses of current are made to flow through the primary winding of a power transformer. The anode-cathode path of an SCR device is connected from a point on a secondary winding to an output capacitor. A pulse width modulation circuit and a base drive circuit are connected between the output capacitor and the gate electrode of the SCR device so as to apply a pulse to the gate electrode that enables conduction between the source and drain electrodes whenever the voltage across the output capacitor drops below a given reference value.

Adaptive sampling decoder-encoder apparatus and method

Abstract: A decoder-encoder with a biphase or delta-distance to binary decoding circuit adapts the data sampling interval to compensate for a non-centered signal level transition in the preceding sample interval. The location of the signal level transition in the prior sampling interval modifies the location of the subsequent sampling interval. The adaptive sampling maintains relative frequency and phase synchronization between the biphase or delta-distance source and the decoding circuit.

Modulated fluid detector

Abstract: A sample fluid and a reference fluid are alternately applied to a fluid detector and an output signal is derived that is proportional to the difference between the response of the detector to the fluids.

Transistor design for low distortion at high frequencies

Abstract: The design of high-frequency bipolar transistors with very low distortion is described. Simple expressions for distortion are used to select device parameters for the optimization of distortion performance. The effect of epitaxial-layer characteristics on device performance is considered in detail, and the importance of collector depletion in achieving low distortion is shown. The influence of device geometry on distortion is considered, and the degradation caused by MOS capacitance is illustrated.

Adaptable programmed calculator including a percent keyboard operator

Abstract: An adaptable calculator is provided by employing five MOS/LSI circuits interconnected by a multiple line bus system. They include (1) a read-only memory circuit group; (2) a control and timing circuit; (3) an arithmetic and register circuit; (4) a data storage circuit; and (5) an input/output (I/O) circuit. Input and output units include a keyboard input unit and an 18-column output printer unit for printing intermediate results of calculations, entered data, arithmetic operators, and diagnostic notes. The keyboard input unit includes a PERCENT key that may be employed in combination with any of four arithmetic operator keys. The calculator may be operated manually by the user from the keyboard input unit or automatically by a program written in user-level language and stored in a plug-in read-only memory unit (ROM), a plug-in programmable read-only memory unit (PROM) or a read/write memory unit associated with a plug-in magnetic card reading and recording unit.