High Resolution Optical Encoder Systems, Devices and Methods
First Claim
Patent Images
1. An optical encoder, comprising:
- (a) a light emitter configured to emit a beam of light therefrom;
(b) a code strip or code wheel configured to move along an axis of movement and comprising a plurality of alternating optically opaque and optically transmissive sections disposed along the axis, each of the optically opaque and optically transmissive sections having a width g/2, the optically transmissive sections being spaced apart from one another by a distance g/2, and(c) a light detector comprising a set of light detecting elements, each light detecting element comprising a pair of complementary light detectors arranged substantially parallel to the axis of movement, each light detector in each pair having a width d/2 or d/4, each light detecting element having a width d or 3d/4, the light detecting elements being arranged substantially parallel to the axis of movement;
wherein the light beam shines upon the code strip or code wheel, portions of the light beam project through the optically transmissive sections to sweep across the set of light detecting elements as the code strip or code wheel moves along the axis of movement, g does not equal d, the ratio g/d equals 3M/(3M−
1) when g is greater than d, the ratio g/d equals 3M/(3M+1) when g is less than d, and M is an integer.
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Abstract
Disclosed are various embodiments of front-end analog circuitry for use in conjunction with optical encoders. Highly accurate analog output signals are provided by front-end analog circuitry in incremental or absolute motion encoders to interpolation circuitry, which is capable of providing high interpolation factor output signals having high timing accuracy. The disclosed interpolation circuits may be implemented using CMOS or BiCMOS processes without undue effort.
9 Citations
24 Claims
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1. An optical encoder, comprising:
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(a) a light emitter configured to emit a beam of light therefrom; (b) a code strip or code wheel configured to move along an axis of movement and comprising a plurality of alternating optically opaque and optically transmissive sections disposed along the axis, each of the optically opaque and optically transmissive sections having a width g/2, the optically transmissive sections being spaced apart from one another by a distance g/2, and (c) a light detector comprising a set of light detecting elements, each light detecting element comprising a pair of complementary light detectors arranged substantially parallel to the axis of movement, each light detector in each pair having a width d/2 or d/4, each light detecting element having a width d or 3d/4, the light detecting elements being arranged substantially parallel to the axis of movement; wherein the light beam shines upon the code strip or code wheel, portions of the light beam project through the optically transmissive sections to sweep across the set of light detecting elements as the code strip or code wheel moves along the axis of movement, g does not equal d, the ratio g/d equals 3M/(3M−
1) when g is greater than d, the ratio g/d equals 3M/(3M+1) when g is less than d, and M is an integer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method of generating a sinusoidal signal with an optical encoder, comprising:
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(a) emitting a beam of light from a light emitter; (b) moving a code strip or code wheel along an axis of movement through the beam of light, the code strip or code wheel comprising a plurality of optically transmissive sections disposed along the axis, each optically transmissive section having a width g/2, the optically transmissive sections being spaced apart from one another by a distance g/2; (c) sweeping portions of the light beam projecting through the optically transmissive sections across a set of light detecting elements as the code strip or code wheel moves along the axis of movement, and (d) detecting the portions of the light beam with the set of light detecting elements, each light detecting element comprising a pair of complementary light detectors arranged substantially parallel to the axis of movement, each light detector in each pair having a width d/2 or d/4, each light detecting element having a width d or 3d/4, the light detecting elements being arranged substantially parallel to the axis of movement; wherein g does not equal d, the ratio g/d equals 3M/(3M−
1) when g is greater than d, the ratio g/d equals 3M/(3M+1) when g is less than d, and M is an integer. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification