What Is a Linear Scale?
A linear scale, also known as a linear encoder, measures position or distance along a straight line with high precision, outputting this information as an electrical signal. These devices come in two main types: absolute, which calculates travel from a fixed point, and incremental, which measures distance traveled without a fixed reference point.
Linear scales employ either electromagnetic detection, based on electromagnetic induction, or optical detection, which involves reading light passed through a coded pattern. Electromagnetic versions are more common due to their broader application range.
Uses of Linear Scales
Linear scales are integral in machine tools and semiconductor manufacturing for precise movement control and measurement. Electromagnetic types, favored for their simplicity, are widely used in versatile tools like digital calipers, essential in numerous manufacturing settings for measuring distances between two points.
Principle of Linear Scales
The electromagnetic linear scale operates on electromagnetic induction, generating an electromotive force that correlates with distance variations between its main scale and detector coil. This indirect measurement translates movement into distance data. Although simple and robust, these scales are not suitable for environments with strong magnetic fields.
Optical linear scales, on the other hand, function by emitting light across a main scale and reticle grating, creating interference fringes that are converted into electrical signals for precise positioning. These scales offer higher accuracy and are unaffected by magnetic fields but are more sensitive to external light and typically larger.
Other Information on Linear Scales
1. How to Use Linear Scales
Employed in semiconductor production and machine tooling, linear scales are crucial for detecting and controlling exact positions. They are often used in conjunction with laser interferometers and encoders for enhanced precision. The rapid advancement in semiconductors, propelled by Moore’s Law, demands increasingly accurate position detection in manufacturing, making linear scales indispensable for the precision fabrication of electronic devices and mechanical parts.
2. Installation of Linear Scales
Given their pivotal role in precision equipment, linear scales must be mounted with utmost accuracy to maintain their high precision, sometimes requiring resolutions of a micron or less. Proper installation, as detailed in manufacturers’ manuals, is crucial to a linear scale’s performance, often necessitating custom jigs or manual adjustments during setup to achieve the necessary alignment and precision.