Match binary decoder logic
Weighted optical tracks provide the code convention expected by a compatible natural-binary decoder.
Binary Code Encoder Discs
Natural binary encoded in glass
A natural-binary encoder disc assigns binary weights to optical tracks. The matching reader combines their states into a single-turn position word.
Each concentric track represents a weighted bit. Because several bits can change at one natural-binary boundary, bit order, reading direction and transition handling must be explicit.
- Code sequence
- Natural binary
- Track weighting
- MSB to LSB
- Line-width tolerance
- ±0.2 µm
- Mechanical cutting
- ±0.02 mm
What the optical pattern does
The code disc supplies a passive optical reference. The readhead, electronics, mechanical mounting and control algorithm determine how that reference becomes a usable position signal.
Identify absolute position
The combined bit state identifies the current angular sector from the approved map.
Control multi-bit transitions
The reader and electronics must account for boundaries where more than one bit changes.
Glass, pattern and code
Common manufacturing capability and product-specific code geometry are shown together. Final dimensions and acceptance values follow the approved drawing.
| Property | Specification |
|---|---|
| PropertySubstrate | SpecificationB270 / K9 / soda-lime glass; fused silica by request |
| PropertyPattern medium | SpecificationChromium-on-glass or a specified clear/opaque pattern |
| PropertyPhotolithographic line-width tolerance | Specification±0.2 µm |
| PropertyMechanical cutting accuracy | Specification±0.02 mm |
| PropertyThickness | Specification≥0.4 mm |
| PropertyTotal thickness variation (TTV) | Specification≤2 µm |
| PropertySurface figure | Specificationλ/4 |
| PropertyOptical mode | SpecificationTransmissive or reflective, matched to the readhead wavelength |
| PropertyMaximum disc diameter | Specification1500 mm |
| PropertyPattern-to-bore concentricity | Specification≤0.02 mm |
| PropertyCode map | SpecificationComplete natural-binary sequence or a drawing-defined custom map |
| PropertyBit order | SpecificationExplicit MSB/LSB track locations and radial order |
| PropertyMechanical reference | SpecificationAbsolute zero and reading direction related to the bore or mounting feature |
| PropertyOptical interface | SpecificationTrack contrast, wavelength, readhead gap and transition timing |
Component tolerances do not state the accuracy of the complete encoder. Readhead geometry, eccentricity, bearing motion, interpolation and installation also contribute to system error.
Confirm every weighted track
Choose it for an existing binary-weighted reading architecture with a defined method for sampling and resolving code transitions.
Supply the actual readhead geometry and decoding convention with the drawing. Matching only the outside diameter is not enough to make two code discs interchangeable.
- Absolute encoders using natural-binary decoding
- Replacement discs for an established binary track architecture
- Custom code maps tied to machine safety or zero conventions
Match the disc to the reader
Substrate, chromium pattern, clear and opaque regions, outer geometry and mounting references are reviewed together. Transmissive and reflective reading require different optical definitions.
Substrate and outline
Select the glass, diameter, bore, thickness, edge finish and mounting datum for the mechanical assembly.
Optical contrast
Define clear-area transmission or the reflective contrast pair at the actual readhead wavelength and geometry.
Pattern registration
Relate tracks, transitions and zero marks to the bore or another stable mechanical datum.
Acceptance and drawing inputs
Confirm these items after the code type and core geometry are selected. They define how the finished disc is manufactured, checked and documented.
Inspection and acceptance
Compare the manufactured code map with the approved sequence and inspect transition positions, radial registration, concentricity and any ambiguous or damaged code cells.
What to provide in the drawing or inquiry
- Outer diameter, bore, thickness, edge format and mechanical datums
- Complete track drawing or code map, polarity and viewing direction
- Track radii, critical line widths, pitch and registration requirements
- Optical mode, operating wavelength, readhead gap and required contrast
- Zero datum, rotation direction and relationship to mounting features
- Inspection items, report format, quantity and drawing revision
Send the complete code map, mechanical drawing and readhead requirements for manufacturing and inspection review.
Discuss your encoder discSelection notes
Binary-code absolute encoder discs represent angular position with natural-binary optical tracks.
Define MSB and LSB locations, transition boundaries, mechanical zero and sampling convention as a consistent system.
Information for your inquiry
Bit count, MSB/LSB order, track boundaries, angular direction, zero and optical window.
How does natural binary differ from Gray code?
Natural binary can change several bits at a boundary; adjacent Gray words change one bit. The readhead and sampling scheme must support the selected code.