US 4,052,612 AGranted

Analog-to-digital encoder unit employing a pre-encoded film with improved film tensioning means

AssigneeE. & J. Gallo Winery

InventorKenneth A. Larkin

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Abstract

An optical encoder for use with a liquid level measuring device including a pre-encoded film strip bidirectionally translatable between a pair of film reels past a detection station. The film is driven by a sprocket coupled to the spring motor of a perforated tape level gauge, and motion translating means enable the film to be unwound smoothly in either direction. The film has a plurality of digitally encoded tracks which enable an optical detection station to provide information specifying the level of the liquid. The motion translating means includes first and second hub members rotatably secured to a support member for rotation about the axis of a different one of the film reels, each hub member being provided with a gear portion for mutual driving engagement. The tension maintaining means includes first and second spring members each coupled between a film reel and a hub member, and received in a central recess of the associated hub member. Each spring member comprises a spiral wound blade spring having inner and outer ends coupled, respectively, to the associated film reel and hub member.

Claims20

Dependent claims

In an optical encoder unit for generating digital electrical signals defining the absolute position of a movable member from a rotatable shaft coupled to said movable member, said optical encoder unit comprising a support member;

first and second film reels rotatably secured to said support member;
motion translating means for transferring motion between said reels;
guide means secured to said support member;
a radiation detection station mounted adjacent said guide means, said station including a radiation source for generating a plurality of spaced radiation beams and a radiation detector assembly having a plurality of radiation sensitive means each associated to a different one of said beams for generating said electrical signals;
a pre-encoded film strip received by said reels and guided by said guide means past said detection station, said film strip having a plurality of laterally spaced, longitudinally extending coded tracks, each arranged to occupy the radiation path between said source and a different one of said plurality of radiation sensitive means;
a non-slip film drive means engageable with said film strip and having an input shaft adapted to be coupled to said rotatable shaft;
and means for maintaining tension in said film strip as said strip is translated past said detection station from reel-to-reel in response to rotation of said film drive means;
the improvement wherein said motion translating means comprises first and second hub means each rotatably secured to said support member for rotation about the axis of a different one of said first and second film reels, respectively, and each provided with a toothed peripheral portion for mutual driving engagement in an interference region;
and
wherein said tension maintaining means comprises first and second spring members each coupled between a different one of said first and second film reels and said first and second hub means for providing intercoupling therebetween.

7 more elements

In a system for measuring the level of a liquid in a reservoir, said system having translatable means for following variations in the level of said liquid and means rotated in response to movement of said translatable means, an optical encoder unit for generating digital electrical signals defining the level of said liquid, said optical encoder unit comprising:

a support member;
first and second film reels rotatably secured to said support member;
motion translating means coupled to said reels for transferring motion therebetween;
guide means secured to said support member;
a radiation detection station mounted adjacent said guide means, said station including a radiation source for generating a plurality of spaced radiation beams and a radiation detector assembly having a plurality of radiation sensitive means each associated to a different one of said beams for generating said electrical signals;
a pre-encoded film strip received by said reels and guided by said guide means past said detection station, said film strip having a plurality of laterally spaced, longitudinally extending coded tracks each arranged to occupy the radiation path between said source and a different one of said plurality of radiation sensitive means;
a nonslip film drive means engagable with said film strip and having an input shaft coupled to said rotated means;
and
means for maintaining tension in said film strip as said film strip is translated past said detection station from reel to reel in response to rotation of said film drive means;
said motion translating means comprising first and second hub means each rotatably secured to said support member for rotation about the axis of a different one of said first and second film reels, respectively, and each provided with a toothed peripheral portion for mutual driving engagement in an interference region;
said tension maintaining means comprising first and second spring members each coupled between a different one of said first and second film reels and said first and second hub means for providing intercoupling therebetween.

8 more elements

Dependencies are inferred from the claim text.