Bei Electronics LLC

The United States of America as Represented by the Administrator of the

Baldwin Electronics, Inc.

Bei Motion Systems Company, Inc.

Ralph S Hafle

Mark D Love

A fiber optic probe sensor for accurate measurement of displacement of a target over very small distances is disclosed. The probe sensor is comprised of plurality of light emitting fibers exclusively occupying a central region and connected to a light source for illuminating the target; a first and second plurality of light receiving fibers arrayed in two concentric regions exterior to and at two different distances from the central region, and means for measuring reflected light received from the target and for generating an output proportional to the light received and independent of target reflectivity or light source variation.

Fiber optic probe sensor for measuring target displacement

A positional encoder which provides absolute position information from a single code track. A chain code track is positioned on a code disk to supply position words of N consecutive bits, each position word being unique and corresponding to a different position of the code disk. Means are provided for detecting the elements of the chain code as the code disk is rotated with respect to a fixed point. The position data are accumulated in the order received and N consecutive bits are examined to determine the position to which the bits correspond.

Chain code encoder

A multidigit fiber optic encoder having only one or two fiber optic cables between an active zone containing a light source and photodetectors, and a passive zone containing a multidigit code member having a multitude of code tracks. First and second sets of color filters are associated with the code tracks and the photodetectors, so that each code track modulates light of a different color, which is transmitted to only the corresponding photodetector. The light beams of the different colors are combined for transmission between the passive and active zones. A single fiber optic cable may be employed between the active and passive zones for transmitting light in both directions, by providing first and second beam splitters at the active and passive ends of the cable to split the transmitted and received light. Alternatively, two fiber optic cables may be employed to transmit light in the opposite directions, to obviate any need for the beam splitters. The light source provides white light or light containing multiple spectral lines, for illuminating all of the code tracks.

Optical encoder having only one or two fiber optic cables

The disclosed encoder is adapted to produce both digital and analog output signals corresponding to the angular position of a rotary shaft, or the position of any other movable member. The digital signals comprise a series of binary signals constituting a multi-digit code word which defines the angular position of the shaft with a degree of resolution which depends upon the number of digits in the code word. The basic binary signals are produced by photocells actuated by a series of binary tracks on a code disc or member. The analog signals are in the form of a series of ramp signals which are related in length to the least significant bit of the digital code word. The analog signals are derived from sine and cosine tracks on the code disc. Such tracks are read by photocells which produce signals corresponding to the sine and cosine of the shaft angle. Such sine and cosine signals are modulated with cosine and sine timing signals produced by a free-running clock, and the modulated signals are then combined to produce a sine signal at the frequency of the clock but varying in phase in accordance with the shaft angle. By comparing the variable phase signal with hysteresis signals derived from the clock, the variable phase signal is converted into pulses of variable length corresponding to the shaft angle. The hysteresis signals are basically timing pulses as to which alternate pulses are subject to slight timing variations which produce a hysteresis effect. The hysteresis signals eliminate ambiguities in the generation of the analog signals. The variable length pulses are integrated to produce the ramp signals which constitute the analog output. The least significant bit of the digital output is produced by processing the variable phase signal from the analog circuit. All of the other digital signals are synchronized accurately with the least significant bit by correction circuits which insure that the accuracy of all of the binary signals is established by the signal for the least significant bit.

Digital plus analog output encoder

The disclosed system utilizes digital electronic programming to establish the rotational or translational speed of a motor driven member. The desired speed can be selected by manipulating a set of digital switches. A stable oscillator is employed to generate a high frequency signal which is processed by frequency dividers to produce a modulaton frequency signal. The modulation frequency is supplied to an optical encoder having a rotary shaft adapted to be connected to a rotary member, the speed of which is to be controlled. The encoder is constructed and arranged to produce a phase variable output signal at the modulation frequency, the phase of such output signal being variable as a function of the shaft angle. The high frequency signal is also processed by digital circuits under the control of the digital selector switches to produce a variable reference frequency signal having a frequency corresponding to the modulation frequency plus or minus a number which is established by the setting of the selector switches. The speed control system includes means for comparing the frequency of the phase variable signal with the frequency of the reference signal. This comparison circuit controls a motor operating circuit which increases or decreases the speed of the drive motor for the rotary member, until the phase variable signal has the same frequency and phase as the reference signal. The digital generation of the reference frequency signal insures that its frequency is established and maintained with an extremely high degree of accuracy.

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Benton, AR, United States of America

Ralph S Hafle