Broadcom offers a variety of mylar film, glass or metal encoder code wheels to meet the needs of various applications. Encoder code wheels are glass, patterned disc or strips that translate a mechanical position into a representative electrical signal when used with incremental or absolute encoders. Encoder code wheels contain data tracks that are a series of alternating clear and opaque areas. When light is projected onto the moving encoder code wheels’ data tracks, the tracks act as a gate that enables and prevents light penetration at intervals. These series of sequential actions from the encoder code wheels create moving shadows (pulse) that fall on the photodiodes located on the detector. The photodiodes then generate output or signal. Encoder code wheels are used for rotary motion.
Each of the three encoder code wheel materials offers certain advantages. Metal codewheels are the most versatile with a temperature rating up to 100 degrees C, resolution to 512 CPR (28 mm diameter), and 2 and 3 channel outputs. Film encoder code wheels offer higher resolution (up to 1024 CPR on a 28 mm diameter) with an operating temperature of 70 degrees C. Glass encoder code wheels combine the best of film and metal, offering a temperature rating of 100 degrees C and resolutions to 1024 CPR on a 28 mm diameter.
In addition, each material offers a specific reliability rating. It is important to consider the specific application operating environment, long term operating conditions, and temperature ranges when choosing a codewheel material.