The HEDS-9141 series are three channel optical incremental encoder modules. When used with a codewheel, these low cost modules detect rotary position. Each module consists of a lensed LED source and a detector IC enclosed in a small plastic package. Due to a highly collimated light source and a unique photodetector array, these modules provide the same high performance found in the HEDS-9000/9100 two channel encoder family.
The HEDS-9040 and 9140 have two channel quadrature outputs plus a third channel index output. This index output is a 90 electrical degree high true index pulse which is generated once for each full rotation of the codewheel.
The HEDS-9040 is designed for use with a HEDX-614X codewheel which has an optical radius of 23.36 mm (0.920 inch). The HEDS-9140 is designed for use with a HEDS-5140 codewheel which has an optical radius of 11.00 mm (0.433 inch).
The quadrature signals and the index pulse are accessed through five 0.025 inch square pins located on 0.1 inch centers.
The Transmissive Encoder is an emitter/detector module. Coupled with a code wheel, this transmissive encoder translates rotary motion of a shaft into digital output. The transmissive encoder contains a single Light Emitting Diode (LED) as its light source. The light is collimated into a parallel beam by means of a single polycarbonate lens located directly over the LED. Opposite the emitter is the integrated detector circuit.
This IC consists of multiple sets of photodetectors and the signal processing circuitry necessary to produce the digital waveforms. The code wheel rotates between the emitter and detector of the transmissive encoder, causing the light beam to be interrupted by the pattern of spaces and bars on the code wheel. The photodiodes which detects these interruptions are arranged in a pattern that corresponds to the radius and design of the code wheel. These detectors are also spaced such that a light period on one pair of detectors corresponds to a dark period on the adjacent pair of detectors. Avago offers an extensive range of transmissive encoders to meet the different needs of a wide variety of applications.