RGH20F incremental encoder with RESR rotary (angle) ring
- Readhead size: 36 x 13.5 x 10.5 mm
- Resolutions to 5 nm
- Speed 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 readhead is used with the REF interface, which incorporates automatic gain control and unique self-tuning adaptive electronics. Combined with the readheads 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 RESR scale?
The RESR is a one piece low profile stainless steel ring with 20 µm scale marked directly on the periphery. The RESR offers impressive accuracy with resolution to 0.008 arc second. The RESR is available in a wide range of sizes (Ø52 mm to Ø550 mm diameter) and line counts, all of which feature a large internal diameter for easy integration. The non-contact format eliminates backlash, shaft wind-up (torsion) and other mechanical hysteresis errors that plague traditional enclosed encoders. A standard 'A' section ring with tapered internal diameter as well as a low inertia 'B' section ring are available.
Why choose this encoder system?
The RESR 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.
RESR: 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
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
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/s2max @ 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.
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.