Two-wire position-to-D.C. current transducer
AssigneePennwalt Corporation
InventorDonald Edwin Van Dyck
Life of this patent
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Abstract
A two-wire transmitter for converting a motion input into a D.C. milliampere output signal that varies linearly with the angular rotation of a mechanical arm. The transmitter employs a position balance principle accomplished by reflecting a light beam from a light emitting diode against a mirror of a D'Arsonval movement upon a dual element photocell. Movement of the input arm displaces the light beam to unbalance a bridge circuit, the increase voltage thereof increasing the current in an output loop which is fed back through the D'Arsonval motor coil. Rotation of the coil rotates the mirror to swing the light beam toward the center of the photocell and rebalance the system to meet new input conditions.
Claims11
A transducer for converting a motion input into a D.C. milliampere electrical signal which varies linearly with angular rotation of a mechanical input arm comprising:
- a. a mirror hingedly supported about a predetermined axis including motor means for rotating said mirror in response to an error signal;
- b. a light source on said input arm and directing a beam of light against said mirror for reflection upon a photocell;
- c. a photocell comprising a dual element photosensitive system, said elements being disposed in opposing arms of a bridge circuit in order to compensate for variations in intensity of the light beam, said first zone being centrally disposed between said dual elements;
- said light source being directed upon a predetermined zone of said photocell in response to a first position of said input arm and displaced toward a second zone of said photocell in response to a second position of said input arm;
- said photocell delivering an error signal when the light beam is displaced from said first to said second zone thereof;
- d. servo means responsive to the error signal and actuating said motor means until the mirror is rotated in a direction that swings the light beam toward the first zone of said photocell to cancel said error signal;
- and
- e. electronic means delivering an output current signal, proportional to the error signal from said photocell.
A transducer for converting a motion input into a D.C. milliampere electrical signal which varies linearly with angular rotation of a mechanical input arm, comprising:
- a. a mirror mounted on an input arm hingedly supported about a predetermined axis including means for rotating said mirror in response to an error signal;
- b. a photocell;
- c. a light source on said input arm and directing a beam of light against said mirror for reflection upon said photocell, said beam of light being directed upon a predetermined zone of said photocell in response to a first position of said input arm and displaced toward a second zone of said photocell in response to a second position of said input arm, said photocell delivering an error signal when the light beam is displaced from said first to said second zone thereof;
- d. servo means responsive to the error signal and actuating said means for rotating said mirror until the mirror is rotated in a direction that swings the light beam toward the first zone of said photocell thereby tending to cancel said error signal;
- e. electronic means delivering an output current signal, proportional to the error signal from said photocell;
- f. a sensor responsive to a variable condition and developing a displacement with respect thereto, said sensor comprising rotationally positioned indicator means;
- g. linkage means coupling said sensor to said input arm, said linkage means comprising a cam rotatable with said indicator means, including a follower in engagement with said cam and connected to said input arm.
Apparatus for determining changes in the position of a float means in a fluid and for producing a direct current output signal which varies linearly with changes in the position of the float, comprising:
- a. a float means suitably disposed to rise and fall upon changes in a fluid level;
- b. a moment arm pivotably coupled to said float means for converting linear displacement of said float means into a rotational displacement;
- c. magnetic coupling means to connect said moment arm to a shaft means;
- d. shaft means for transmitting rotary motion to a sensor means;
- e. sensor means, said sensor means further comprising:
- i. a pointer means fixed to said shaft by a hub means;
- ii. casing means rotatably supporting the shaft means in a bearing means;
- iii. bearing means;
- iv. hub means;
- and
- v. dial means for allowing the visual determination of relative movement of said pointer means;
- f. cam means affixed to said shaft means and having an internal eccentrically disposed slot therein;
- g. cam follower means disposed within said internal eccentrically disposed slot in said cam means and being pivotably mounted with respect to a transducer mounted within a housing;
- h. a transducer means for producing a direct current output signal which varies directly proportionally to the rise and fall of said float means;
- i. a housing surrounding said transducer, said housing having a slot therethrough;
- j. an extension portion of said cam follower means, extending through said slot in said housing to said transducer, said extension portion acting as a motion arm input to said transducer.
Dependencies are inferred from the claim text.