Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
1999-06-12
2001-06-12
Font, Frank G. (Department: 2877)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
Reexamination Certificate
active
06246049
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to optical transducers, and more particularly to optical transducers for determining position, orientation, direction, revolution, acceleration, fluid flow, torque, and the like.
2. Description of the Related Art
Prior art angular position transducers typically include a transparent encoder disk and a circumferential track imprinted thereon. A light source is positioned on one side of the disk in alignment with the track and a pair of spaced photodetectors are positioned opposite the light source on the other side of the disk. Typically, each track comprises a series of equally-spaced opaque bars separated by transparent sections. As the disk rotates, the bars and transparent sections cause the photodetectors to alternate between high and low states. A microprocessor typically receives the high and low states of each photodetector and determines the direction of disk rotation depending on which photodetector goes high or low first. The number of high or low states are then added or subtracted (depending on the direction of disk rotation) in order to determine the angular position of the encoder disk.
Although these types of transducers perform adequately for their intended purpose, they can be relatively difficult and costly to manufacture and their resolution is typically limited by the number of bars in the circumferential track, the spacing between bars, the relative size of the transducers, and other factors. The bars must be accurately positioned on the disk, and the light source and photodetectors must be positioned very accurately with respect to the bars so that direction of disk rotation can be ascertained.
SUMMARY OF THE INVENTION
According to the invention, an optical transducer comprises a light source for emitting radiant energy, an elongate light collector spaced from the light source for receiving radiant energy from the light source, a light blocking member, and at least one photosensor. The light collector has opposite ends and is formed such that radiant energy emitted from the light source can be gathered along a length of the light collector and transmitted to the light collector ends. The light blocking member extends between the light source and at least a portion of the elongate collector for blocking at least a portion of the radiant energy from the light collector. The light blocking member is movable with respect to the light collector in response to an applied force on the light blocking member for varying the position of the radiant energy incident on the light collector to thereby vary the amount of radiant energy transmitted to the light collector ends. The at least one photosensor is positioned proximal at least one of the light collector ends for detecting the amount of radiant energy transmitted thereto. With this arrangement, the amount of radiant energy received by the light collector and detected by the photosensor is indicative of the applied force. The applied force may be in the form of acceleration (including deceleration), gravity, rotation, torque, torsion, bending, fluid flow, vibration, and so on.
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Font Frank G.
Nguyen Tu T.
Wirthlin Alvin R.
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