Encoder are for glass scale applications.

Press Release Summary:

RG40 linear encoder system combines precision of non-contact, contamination-tolerant optical RG readheads with accuracy and thermal behavior of glass scales. In lengths of 300, 500, 750 and 1000mm, glass scales use clip mounts to expand with thermal change for wide range of materials. Encoder system is for use by makers of precision stages, linear motor stages, pick & place equipment, and other exact positioning technologies.

Original Press Release:

Renishaw Lowers Cost, Widens Applications For Glass Scale Encoders With New Shop-Hardened RG-40 Linear Encoder System

Renishaw lowers cost, widens applications for glass scale encoders with new shop-hardened RG40 linear encoder system
New RG40 linear encoders take glass scale applications beyond clean environments with patented dirt-tolerant optics, proven reliability, and simple set-up

October 2001 Renishaw takes glass scale encoders out of clean environments and makes them practical for a wide range of industrial applications with the new RG40 linear encoder system. The RG40 open system design combines the precision and reliability of non-contact, contamination-tolerant optical RG readheads, proven by Renishaw in hundreds of industrial applications, with the predictable accuracy and thermal behavior of glass scales.

Renishaw's first glass scale encoder design, the RG40 complements its broad line of open, non-contact industrial encoders with self-adhesive, cut-and-mount flexible metal scales. The RG40 design meets requests for glass scales by makers of precision stages, linear motor stages, semiconductor handling systems, pick & place equipment. printing machinery, and other exact positioning technologies.

The RG40 encoders deliver better than ±5microm/meter accuracy from a 40microm pitch RGS40-G glass scale with chrome Ronchi grating and a high-gain RGH40 readlhead with patented side-lit filtering optics. The glass scale comes in standard lengths of 300, 500, 750 and 1000mm. Clip mounts allow the scale to expand freely with thermal change for use on a wide range of materials -metals, granite, ceramics, composites, etc. A center reference "dot" enables easy clip alignment.

The RGH40 readhead uses Renishaw patented wide-angle filtering optics to scan and average reflections from 80 scale facets. This effectively filters out signals which do not match the scale period, ensuring superior signal stability and accuracy even with dust, dirt, fingerprints, smudging or other localized contamination of the scale. Non-contact operation eliminates friction, hysteresis and wear for dependable, lasting positioning precision.

The industrial-strength RG40 design provides greater application range at lower cost than high-end glass scale encoders which use delicate phase gratings, are limited to clean working environments, and can require tight system set-up tolerances.

Unique to RG readheads is a signal condition monitoring circuit which drives an integral two-color LED and an alarm signal for remote conditioning of the control. The LED facilitates quick installation with visual confirmation of optimum scale alignment,
while the alarm signal alerts the control of low signal amplitude. eliminating the danger of unrecognized encoder-count loss.

The digital readheads produce differential line-driven quadrature signals in 5.0, 1.0, 0.5 and 0.1 micron-resolution outputs to industry standard EIA/RS422. This differential line-driver outputs provide exceptional noise immunity, perfect for applications involving lone cable runs and continuous operation in harsh electrical/magnetic environments. The digital unit perform interpolation inside the readhead, eliminating the need for external electronics.

A magnetic reference mark can be epoxy-mounted to the glass scale at user-selected point. The Renishaw scale features a reference mark alignment line to assist with reference mark installation. The scale design allows light switches to be mounted in a variety of ways.

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