Optical reflection encoder systems, devices and methods

Abstract

The invention provides optical reflection encoder systems, devices and methods. Disclosed are various embodiments of high-speed, high-performance, low-noise optical encoders having various means for preventing undesired stray light from reaching light detectors incorporated therein. Structures employed to block stray light in the optical encoders include light barriers, air gap trenches, and coatings disposed between first and second sides of a substrate of the encoder. Also disclosed are compact single track optical encoders having a single dome lens disposed thereover, and dual track tripledome lens optical encoders. Methods of making such optical encoders are also disclosed.

Description

technical field [0001] Various embodiments of the invention described herein relate to the field of optical encoders, and assemblies, devices, systems and methods related thereto. Background technique [0002] Optical encoders are often used as motion detectors in applications such as closed-loop feedback control in motor control systems. Many optical encoders are constructed to convert rotary or linear motion into a two-channel digital output for position encoding. [0003] Many optical encoders use LEDs as light sources. In a transmissive encoder, the light is collimated into a parallel beam by a mechanism such as a lens placed above the LED. Opposite the emitters are photodetectors and signal processors, usually composed of photodiode arrays. As a codestick, such as a code wheel or tape, moves between the light emitter and light detector, the light beam is interrupted by a pattern of bars and spaces on the codestick. Similarly, in a reflective or imaging encoder, a le...

AI Technical Summary

Problems solved by technology

Additionally, imaging optical encoders suffer from low diffuse reflection and typically cannot operate at very high speeds

[0007] Reflective optical encoders known in the art typically suffer from various performance and application issues, such as stray light generated at the light emitter that directly illuminates the photodetector, which can cause contrast degradation, reduce encoding performance, and limit contrast

Known reflective optical encoders also typically include an encapsulated dome in which the transmitter-encoder pair is arranged, which dome often results in poor light collimation and thus limits encoding performance and resolution

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