Ultra-compact MiniDisc encoder gives high reliability

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Sick's new SKS/SKM36 standalone encoder is the first of a new generation of optical encoders within the company's SinCos product range. The most notable feature of this line of Sick|Stegmann encoders is the company's innovative MiniDisc (MiDi) technology – which was the subject of a three-year development and £1.3million (EUR1.9million) investment.

This significant research programme has resulted in the creation of a very small code disc, with a tiny 2mm code track radius. However, this small size does not mean there is any lack of performance. Indeed, as well as offering full holistic scan capabilities (the whole disc is scanned constantly, enabling any eccentricity errors in the ball bearing and shaft to be compensated for), the smaller radius also removes many of the issues related to high angular speeds.

Shock and vibration often cause problems for optical encoders; however, the construction of a MiniDisc encoder ensures a very high resistance to both. Unlike encoders that have a small area at the centre of the disc glued to the encoder shaft, the disc of a MiniDisc encoder is fitted inside the shaft and securely held around its circumference. Together with its small size, this makes it virtually impossible to break the disc or shake it loose.

The small disc also offers other important technical features. For example, the physical encoder size is now essentially determined by the mechanical and electrical interfaces. 'Chip On Board' technology is used to reduce the size and number of the electrical components, maintaining the small size and ensuring the highest reliability. The small size of the SinCos SKS/SKM36 standalone encoder will also enable its use in applications with restricted space.

Servo applications

Designed to operate as a master encoder on servo drives equipped with the Hiperface interface, the SKS/M36 standalone encoder enables absolute synchronisation in a compact, robust and cost-effective package. Such master/slave installations are commonplace in packaging, printing, textile and woodworking machinery.

Available in single- and multi-turn variants (SKS and SKM respectively), the IP65-rated encoders offer: industry-standard M12 connectivity; absolute position with a resolution of 4096 steps per revolution (single-turn); measurement of 4096 steps per revolution over 4096 revolutions (multi-turn); an electronic type label so that the drive can automatically recognise the resolution of encoder connected; and a wide operating temperature range of -20 to 100degC.

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