Leeds & Northrup Company

General Signal Corporation

Thomas J Walsh

Howard S Hoopes

Robert W McClenahan

Michael D Carney

Charles R Scally

Daniel J Carr

James W Zecca

John R Wiese

Bill M McClennen

George Volkodav

An improvement is provided for printer such as the dot matrix or thermal type, in which the printhead is stepped across the paper over a multicolor ribbon supplied from a pivotally mounted cartridge and transported through a plane between the line of traverse of the printhead and the surface of the paper. The ribbon is guided by guiding surfaces positioned on each side of the printhead, close to the printhead, and mounted to move with the printhead across the paper so that the guide surfaces will guide the path the ribbon takes to one which passes between the printhead and the paper with the guide being moveable in steps in a direction normal to the traverse of the printhead and parallel to the plane of the ribbon so as to position a selected color band of the ribbon under the printhead to select the color to be printed as the printhead traverses the paper. The ribbon cartridge is free to pivot in response to movement of the ribbon guide and/or the printhead so as to accommodate the different positions of the ribbon with respect to the printhead, as determined by the ribbon guide and the different positions of the printhead with respect to the paper.

Color change system for multicolor strip chart recorders

A one shot voltage to pulse width converter is provided for producing a digital representation of an analog input signal voltage. The circuit includes an integrating amplifier circuit whose output is kept at a reference potential except when it is being ramped up in response to connection of an input signal to the integrating amplifier during a fixed input sample period or down after the fixed input sample period expires. The circuit also includes a comparator connected to compare the output of the integrating amplifier to the reference potential with the output of the comparator switching an output circuit between two different levels so that the pulse width of the output is related to the magnitude of the input signal. When the input signal is not connected to the integrating amplifier its output is held at reference potential by a negative feedback from the comparator output to the integrating circuit input.

One shot pulse width modulating converter

An end-fill molten metal sampler is provided with a ball type check valve within the entrance passageway to the sample cavity.

End-filling sampler for molten metals

A thermocouple open-circuit detector is made insensitive to noise pick-up in the thermocouple by increasing the bias on the detecting amplifier beyond the point where it would be affected by the noise and providing a means for reducing that bias during the period when the pulses that test the thermocouple are present. The test pulse will then trigger the detecting amplifier on when the thermocouple is open.

Thermocouple open circuit detector

An analog voltage to duty cycle converter is provided using a series connected resistor and capacitor. The capacitor is charged in one direction through the resistor from the difference between the analog voltage and a reference voltage maintained across a zener diode by one polarity of output from a differential amplifier responding to the charge across the capacitor. When the charge across the capacitor reaches the difference necessary to cause the differential amplifier to change the polarity of its output, a positive feedback firmly toggles the output to the other polarity and the capacitor is allowed to charge in the opposite direction due to cut-off of the zener current by a diode in the amplifier output circuit. The capacitor then charges in an opposite direction due to the analog voltage alone and the reference voltage again switches 'on' when the amplifier output goes positive. The duty cycle is then proportional to the analog voltage.

Voltage to duty cycle converter

A preamplifier circuit for a voltage measuring instrument which provides for noninteracting span and zero adjustments. Two voltage follower circuits are used. The first produces a current through the output resistor of the preamplifier proportional to the voltage being measured while the second produces a current through the output resistor proportional to a fixed reference voltage. For both amplifiers, the proportionality is adjustable by a potentiometer which modifies the feedback on the first amplifier and the part of the reference used as input to the second amplifier.

Preamplifier for voltage measuring instrument with non-interacting zero

A string of short pulses is impressed across the input circuit of a multipoint recorder and a pulse magnitude detecting circuit. If the input circuit is open, the magnitude of the pulses appearing at the pulse magnitude detecting circuit is higher than would be the case if the input circuit were completed by a normal input device. The pulse magnitude detecting circuit is operable to apply to the measuring circuit of the multipoint recorder a positive potential whenever the pulse detecting circuit detects pulses of a magnitude indicating that the input circuit is open. As a result, the multipoint recorder is driven upscale to its limit where the particular point which is open-circuited is identified by a printed indicia.

Open circuit detector for multipoint recorder

Measurement with a three-lead resistance thermometer uses two current sources to set up a current I in the thermometer element and each of its potential leads while a current of 2I is established in the current lead with all currents being in a direction such that the currents in the potential leads are in the same direction with respect to the thermometer element. A standard resistor is connected in series with one potential lead and a voltage measurement is made across the potential leads, including the standard resistor, to provide a measure of the temperature being sensed by the resistance thermometer. The current sources each utilizes a voltage divider connected between one terminal of a constant potential source and another terminal along with a follower circuit connected to receive an input from an intermediate point on the voltage divider. The follower circuit has a gain of magnitude corresponding with the reciprocal of the fraction of the potential used from the voltage divider and produces an output into a calibrating resistor through which a specific current is to be maintained. Each current source also includes a second voltage follower circuit for producing the potential at the other terminal of the voltage divider circuit as required to control the current in the calibrating resistor.

Temperature measurement with three lead resistance thermometers

A servo system is disclosed which produces a mechanical position varying in accordance with variations in an electrical input signal. The input signal is applied by an amplifying channel to one input of an error amplifier. The input signal amplifying channel includes an integrating amplifier and a voltage limiting device at the input to the integrating amplifier so that the signal applied to the error amplifier has a limited rate of change. A negative feedback gain determining loop is included in the amplifying channel so that at balance the signal applied to the error amplifier is directly related to the input signal. Applied to the other input of the error amplifier is a signal representative of the positional output from the servo system to form a second rebalanceable loop system. A switched stop circuit is connected from the output of the error amplifier to the input of the integrating amplifier to permit the servo system to be stopped and subsequently to restore the system to normal operation with the rate of change of position of the servo limited by the integrating amplifier.

Growing community of inventors

Hatboro, PA, United States of America

Thomas J Walsh