Dynamics Research Corporation

Sidney A Wingate

Christopher W Liessner

Gregory J Rust

John A Sotir

William L Cotter

Herbert L Aronson

Richard A Brisk

Elmo J Pacini

Edward L Dreano, Jr

A linear position encoder is provided which is not affected by ambient light, smoke, moisture, particulate matter, and also not affected by electrical interference such as may be caused by stray fields or permanent magnets or magnetic particles. The encoder comprises a linear scale having an excitation loop disposed along the length of the scale and having electrical terminals preferably disposed at one end of the scale. An alternating current is applied to the excitation loop to create an alternating magnetic field. At least one periodic conductive pattern is provided on an outer side of the excitation loop. The periodic pattern has electrical terminals preferably at the same end of the scale as the terminals of the excitation loop. A sensor is provided on a small printed circuit card that is movable in relation to the scale. The card has a pickup loop which receives energy coupled from the scale excitation loop and which induces current in the periodic pattern. The resulting magnetic field is spatially modulated and motion of the sensor in relation to the scale amplitude modulates the output signals to provide an output indication of linear travel along the scale.

Linear position detecting system

A magnetic encoder is disclosed that provides a uniform magnetic field which is time modulated at a carrier frequency and space modulated by a repetitive pattern of eddy-current conducting lands that move with variable motion. The time modulation is provided by driving an electrical coil in a resonant tank circuit. The space modulation provides areas of higher and lower magnetic field intensity which change in correspondence with the motion of the conducting lands. The intensity of the varying magnetic field is detected by a series connected pair of stationary coils that are positioned orthogonal to both the direction of the changing magnetic field and the direction of the motion of the conducting lands. The pair of stationary coils yield a differential electrical signal that is representative of the motion of the conducting lands.

Magnetic encoder for sensing position and direction via a time and space

A light beam encoder for measuring absolute distance over a linear path with an accuracy of at least that provided by incremental optical encoders, but over longer ranges than can readily be achieved with optical linear encoders due to the difficulty of providing a sufficiently long optical scale with the requisite accuracy and resolution. The resolution provided by the light beam encoder can be approximately 1-10 microns. A high frequency amplitude modulated light beam is reflected by a reflector disposed at the distance to be measured, and the phase lag of the reflected light beam is determined to provide an absolute measure of the distance. The encoder mixes a local oscillator signal generated by a phase locked loop with both a reference oscillator signal and the distance signal. Thus, the heterodyne mixers provide two low frequency signals preserving the phase lag between the two optical signals. In a preferred embodiment, high-resolution computation of the phase lag is accomplished with a microprocessor receiving precise crossover time information indicating time delays and periods over several cycles of the low frequency signals using linear and nonlinear filtering and averaging algorithms.

Light beam distance encoder

An absolute encoder providing a multi-bit output binary code indicative of the position of a rotary or linear scale. The encoder employs a code track, which contains a serial code, and a clock track. The encoder may be either rotary or linear, and may be implemented optically, magnetically, inductively, capacitatively or by any other binary sensing technique.

Single track absolute encoder

A compensation system for a position encoder which automatically compensates for scale and other similar errors along the entire path of relative motion. The phase of the encoder signals is altered by a small amount for each small increment of relative motion to provide encoder signals compensated for the scale error. The phase correction is added or subtracted from the phase of the encoder signals depending upon the sense of relative motion.

Position encoder compensation system

A press brake control system and apparatus including a vertical ram extension controller and back gauge system which together determine respectively the angle and location of successive sheet metal bends according to a stored operating sequence. The control system and apparatus is attached to an existing and unmodified press brake to which the press brake control system automatically adapts its control functions according to the mechanical parameters and conditions of the particular press brake. Futhermore, the press brake control system elements communicate according to a communication system having redundancy and error-checking features to be operable in hostile electrical and physical environments.

Two dimensional press brake control system and apparatus

A gaging system especially adapted for use with a press brake and which employs a direct drive servo motor directly coupled to a movable table and linear encoder directly coupled to the movable table for providing electrical output signals representative of actual gage position. One or more gage stop assemblies are supported by the movable table and are manually adjustable to both coarse and fine degrees. Closed loop servo control of gage position is provided to control motor drive in response to actual position signals derived from the linear encoder.

Gaging system

A gaging stop is disclosed for use with a press brake which employs a direct drive servo motor directly coupled to a movable table and linear encoder directly coupled to the movable table for providing electrical output signals representative of actual gage position. One or more gage stop assemblies are supported by the movable table and are manually adjustable to both coarse and fine degrees. Closed loop servo control of gage position is provided to control motor drive in response to actual position signals derived from the linear encoder.

Gage stop assembly

A linear encoder especially adapted for location of the position of a magnetic read/write head of a disk memory system and having a modular light source and modular detector each easily replaceable and adjustable. The modularity of construction allows use of the encoder in other measuring systems of different mechanical configurations.

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Concord, MA, United States of America

Sidney A Wingate