Abstract: There is disclosed: a measurement scale suitable for use with scale reader for determining displacement; various tracks all for holding the scale and all having a channel into which the scale is magnetically attracted; and a scale tensioner which in use tensions the scale in situ by release of a preload, prior to the scale being secured to a substrate, the tensioner being removable thereafter.

Abstract: There is disclosed: a measurement scale suitable for use with scale reader for determining displacement; various tracks all for holding the scale and all having a channel into which the scale is magnetically attracted; and a scale tensioner which in use tensions the scale in situ by release of a preload, prior to the scale being secured to a substrate, the tensioner being removable thereafter.

Abstract: A length of scale (1) which has a profile consisting of a sequence of troughs (18) and crests (16) is subjected to a process to make the shapes of the crests more regular, thus increasing and making more predictable the signal reflected from the crests on the scale. The process comprises passing a length of scale (1) between upper (20) and lower (22) cylindrical rollers. The lower roller (22) may be driven or the length of scale (1) may be pulled through. Reference marks or identification marks may be added to the scale by appropriately marking the upper roller (20). Alternatively, the marks may be added at an initial embossing step which imparts the troughs and crests profile to the scale or at a separate subsequent step.

Abstract: There is disclosed: a measurement scale suitable for use with scale reader for determining displacement; various tracks all for holding the scale and all having a channel into which the scale is magnetically attracted; and a scale tensioner which in use tensions the scale in situ by release of a preload, prior to the scale being secured to a substrate, the tensioner being removable thereafter.

Abstract: An opto-electronic scale reading apparatus includes a scale 10 and a readhead 14 movable one relative to another. The readhead produces a pair of quadrature pulses which enable the generation of an incremental count corresponding to the displacement of the readhead 14 relative to a reference mark 80. The reference mark 80 is a permanent magnet mounted on the scale substrate inside a non-ferromagnetic casing 90. A pair of differential Hall sensors 62A,B within the readhead, and associated processing circuitry generate a step-change ZERO pulse when the readhead 14 and scale 10 are in a particular relative position. This relative position can be adjusted to enable corresponding adjustment of the relative phase of the quadrature pulses emitted from the readhead and the ZERO pulse, by means of a ferromagnetic adjusting screw 92.

Abstract: Opto-electronic linear encoding apparatus includes a scale and a readhead movable relative to the scale in a direction of spacing of the scale lines. The readhead is formed of a single semi-conductor substrate, typically made of gallium arsenide. The substrate is divided into two regions, the first region including a light emitting diode having a plurality of elongate electrodes provided on its upper surface and spaced in the direction of spacing of the scale lines. The light emitting diode region, the elongate electrodes and the substrate cooperate to produce a plurality of coplanar elongate light emitting regions between the elongate electrodes which perform the combined functions of a diffused light source and an index grating. The second region is an analyzer having a plurality of elongate photosensitive elements spaced apart in the direction of spacing of the scale lines.