RGH20F incremental encoder with RESR20 rotary (angle) ring
- Readhead size: 36 x 13.5 x 10.5 mm
- Resolutions to 5 nm
- Speed up to 5 m/s (up to 1 836 rpm depending on ring size and resolution)
- Analogue or digital outputs
- Low Sub-Divisional Error (SDE): typically ±0.05 µm
- High accuracy ring
- High resolution outputs
- Ultra-compact readhead
- Auto Gain Control (AGC) for excellent signal integrity
What is RGH20F?
The RGH20F compact readhead offers reliable, high speed, open, non-contact performance with excellent immunity to dust, scratches and light oils on the scale.
The RGH20F readhead is used with the REF interface, which incorporates automatic gain control and unique self-tuning adaptive electronics. Combined with the readhead's filtering optics, these ensure excellent signal integrity and low Sub-Divisional Error (SDE). The REF interfaces are available with high resolution digital outputs or with industry standard 1 Vpp analogue output.
What is RESR20 scale?
RESR20 is a one-piece stainless steel ring with 20 µm pitch graduations marked directly on the periphery. Two versions are available in a wide range of sizes (Ø52 mm to Ø550 mm).‘A' section rings, which offer an impressive installed accuracy, feature a taper mount system which reduce the need for highly toleranced machined parts and eliminate eccentricity. ‘B' section thin rings, which are low inertia and mass, are also available. Both 'A' and 'B' section rings have a large internal diameter for flexible integration. The non-contact format eliminates backlash, shaft wind-up (torsion) and other mechanical hysteresis errors that are inherent in traditional enclosed encoders.
Why choose this encoder system?
The RESR20 ring offers impressive graduation accuracy to ±0.5 arc seconds for a variety of demanding precision applications.
Using the REF interface, the RGH20F readhead is capable of resolutions up to 5 nm.
The low profile RGH20F readhead allows for easy integration into all but the most restricted of spaces.
The REF interface incorporates automatic gain control (AGC) and unique self-tuning adaptive electronics which, combined with the filtering optics, ensure excellent signal integrity, and give a low cyclic error.
One-piece low profile stainless steel ring. Standard ‘A' section with tapered internal diameter or low inertia ‘B' section
Readhead size (LxWxH)
36 mm x 13.5 mm x 10.5 mm
|Coefficient of thermal expansion at 20 °C||15.5 ±0.5 μm/m/°C|
Ring outer diameter
52 mm to 550 mm
8 192 to 86 400 (depending on ring size)
Uni-directionally repeatable to 1 unit of resolution with magnetic actuator
±4 to ±0.4 arc seconds (depending on ring diameter)
±5.6 to ±0.5 arc seconds (depending on ring diameter)
(See data sheet for details)
1 836 rpm (5 μm resolution RGH20F with REF on 52 mm RESR)
Sub-Divisional Error (SDE)
Typically < ±0.05 μm
Dynamic signal control
Self-tuning active correction including Auto Offset Control (AOC), Auto Gain Control (AGC) and Auto Balance Control (ABC) for optimised performance during operation
1 Vpp (20 μm period)
Resolutions from 5 μm to 5 nm
(See data sheet for details of angular resolutions)
1.5 m, 3 m and 5 m cable lengths with D-sub connectors (9 pin and 15 pin) or flying lead
5 V -5% +10%, 200 mA (unterminated)
100 m/s2 max @ 55 Hz to 2 000 Hz
1 000 m/s2, 6 ms, ½ sine
Operating temperature (system)
0 °C to +55 °C
*System accuracy is graduation error plus SDE. Graduation accuracy is the maximum difference between the angle measured by a single readhead and the true rotation of the encoder as graduated. Application disturbances such as eccentricity are not included.
Refer to data sheets for full details.
- 3D model: REF/REE interface
- 3D model: RESx 52 mm A section ring
- 3D model: RESx 57 mm A section ring
- 3D model: RESx 75 mm A section ring
- 3D model: RESx 100 mm A section ring
- 3D model: RESx 103 mm A section ring
- 3D model: RESx 104 mm A section ring
- 3D model: RESx 150 mm A section ring
- 3D model: RESx 200 mm A section ring
- 3D model: RESx 206 mm A section ring
- 3D model: RESx 209 mm A section ring
- 3D model: RESx 255 mm A section ring
- 3D model: RESx 300 mm A section ring
- 3D model: RESx 350 mm A section ring
- 3D model: RESx 413 mm A section ring
- 3D model: RESx 417 mm A section ring
- 3D model: RESx 550 mm A section ring
- 3D model: RESx 52 mm B section ring
- 3D model: RESx 75 mm B section ring
- 3D model: RESx 100 mm B section ring
- 3D model: RESx 115 mm B section ring
- 3D model: RESx 150 mm B section ring
- 3D model: RESx 165 mm B section ring
- 3D model: RESx 200 mm B section ring
How it works
Within the readhead, an infra-red LED emits light laterally onto a scale with reflective and non-reflective areas. The light is directed back off the reflective areas through a transparent phase grating.
This produces sinusoidal interference fringes at the detection plane within the readhead. The optical scheme averages the contributions from many scale graduations and effectively filters out signals not matching the scale period. This ensures signal stability even when the scale is contaminated or slightly damaged.
With the unique optical design of the readhead and the Auto Gain Control (AGC) and Auto Offset Control (AOC) features of the REF interface, low short-term errors are assured, typically giving less than ±0.05 μm Sub-Divisional Error (SDE).
The REF interface features a set-up LED, which lights green when optimum installation has been achieved.
A reference mark or a single limit are available with this readhead. The reference mark provides a repeatable home or zero position, whilst the limit is used as an end of travel indicator.