The patent's assignee for patent number 8809763 is
News editors obtained the following quote from the background information supplied by the inventors: "This document relates to the accurate determination of the rotary position of a rotating device. More specifically, this document relates to an optical position sensor system for determining the angular position of a rotating device and method.
"In many applications it is important to measure and to control the angular position of a rotary element with high accuracy. For instance, galvanometers require sensors which must detect the angular position of the rotor with extreme accuracy and repeatability, high temperature stability, and high signal to noise ratio. Angular position transducers are used not only to detect the angular position of the rotatable element but also to control and hold the rotatable element in a desired position. For example, a galvanometer can be used to drive a mirror. The mirror can be used to deflect a laser beam which in turn modifies material or objects in a wide variety of applications.
"There have been a number of different conventional approaches used in the sensing and detecting of rotary motion. One conventional approach uses one or more light emitting diodes (LEDs) as the light source and reflects the light off a diffuser. This approach has uniform illumination on a detector but has the disadvantage of low output signal levels and poor accuracy. Another conventional approach uses direct illumination from an LED source to illuminate a detector. This approach has good output signal levels but has the disadvantage of requiring the LED source to light blocker and light blocker to detector distances to be very small, which leads to issues with maintaining proper clearance during manufacturing."
As a supplement to the background information on this patent, VerticalNews correspondents also obtained the inventor's summary information for this patent: "Aspects of this document relate to an optical position sensor system for determining the angular position of a rotating device and method. These aspects may comprise, and implementations may include, one or more or all of the components and steps set forth in the appended CLAIMS, which are hereby incorporated by reference.
"In an aspect, an optical position sensor system is disclosed for determining the angular position of a rotary member having a longitudinal rotation axis that extends in an axial direction. The system includes a single light source aligned along the rotation axis. A collimating element is adjacent the light source a predetermined distance, the collimating element aligned along the rotation axis to collimate light from the light source along the rotation axis. A detection element is adjacent the collimating element a predetermined distance to receive collimated light from the collimating element and to provide a linear output. A light blocker is inserted between the collimating element and the detection element, the light blocker coupled to the rotary member to rotate therewith about the rotation axis to block portions of the collimated light from the light source and the collimating element from reaching the detection element in direct relationship to the rotary position of the light blocker.
"Particular implementations may include one or more or all of the following.
"The detection element may include four radially aligned detector segments. The four radially aligned detector segments may include four sector-shaped light detector segments.
"Alternatively, each of the four radially aligned detector segments may include a photosensitive surface having a predetermined configuration, and the light blocker may include two light blocking segments. Each of the light blocking segments may be configured either slightly larger than the predetermined configuration of the photosensitive surface of one of the sector-shaped light detector segments, or to substantially match the predetermined configuration of the photosensitive surface of one of the sector-shaped light detector segments.
"The system may further include a mask over the detection element. The mask may be inserted between the light blocker and the detection element. The mask may define an annular radial segment of open active detection area on each of the four radially aligned detector segments. Alternatively, the light blocker may include two light blocking segments. Each of the light blocking segments may be configured either slightly larger than the configuration of the annular radial segment of open active detection area of one of the detector segments, or to substantially match the configuration of the annular radial segment of open active detection area of one of the detector segments.
"The light source may include a light emitting diode. The light emitting diode may include an attached lens that reduces beam spread from the light emitting diode.
"The light blocker may have a butterfly-shaped configuration and be made of a non-reflective, opaque material.
"The collimating element can be a lens. The collimating element can also be a parabolic reflector, where the light source is located within the open center of the parabolic reflector located along an axis at a focal point of the parabolic reflector.
"The lens may be adjacent the light source a distance of about 0.1 to about 2.0 inches, with nominal values of about 0.2 to about 0.6 inches. The detection element may be adjacent the lens a distance of about 0.03 to about 3.0 inches, with nominal values of about 0.05 to about 0.5 inches.
"The foregoing and other aspects and implementations of an optical position sensor system and method may have one or more or all of the following advantages, as well as other benefits discussed elsewhere in this document.
"Implementations of an optical position sensor system may have high signal levels and do not have the close relationship requirement among the LED, light blocker and detector that conventional approaches require. This is because the collimating element is included immediately after the single LED emitter and serves to collimate the light coming from the LED. Since the collimating element collimates the light, the light blocker can be located at a convenient distance from the detector. This eliminates the possibility of contact between the two surfaces during operation. The collimated light also is not affected by the light blocker not being perfectly perpendicular to the rotation axis. The light interacting side of the light blocker faces the same direction as the sensors on the detection element while the non-light interacting side of the mask opposes the sensors. Even a slight alignment error in conventional approaches will result in signal errors.
"The foregoing and other aspects, features, and advantages will be apparent to those of ordinary skill in the art from the DESCRIPTION and DRAWINGS, and from the CLAIMS."
For additional information on this patent, see: Stutz, Glenn E.. Optical Position Sensor for Determining the Angular Position of a Rotating Device. U.S. Patent Number 8809763, filed
Keywords for this news article include: Electronics, Light-emitting Diode,
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