Exploring CPR and LPR for Rotary Encoders

Digital encoders come in many varieties, including linear encoders, shaft encoders, angle encoders and more. Speaking of shaft encoders, also known as rotary encoders, the lines per revolution (LPR) or counts per revolution (CPR) are often used to define their performance. But what do these terms actually mean? This blog aims to outline these terms and their significance.

What are Counts Per Revolution?

The count per revolution of a shaft encoder can be defined as the number of counts or pulses generated by the encoder for one full rotation of the shaft. It is calculated by determining the pulse per revolution of a rotary encoder and multiplying this number by 4. This is done mainly due to the quadrature decoding of both outputs A and B for each state change. This is why the count ends up being 4 times more for each pulse.

What are Lines Per Revolution?

Lines per revolution is another way to understand the resolution of a rotary encoder. It is defined as the number of physical lines etched on the disk of the shaft encoder. Each line signifies the low pulse on the output side. It is equivalent to the measure of pulses per revolution which is used by many encoder manufacturers. 

Importance of CPR and LPR

Both CPR and LPR are important to an encoder because:

- They help determine the most minuscule distance that an encoder can measure accurately

- The resolution of the encoder, measured by these parameters, provides a comprehensive idea of how well a rotary encoder can provide appropriate feedback to the controller.

Walker Machinery is a proud distributor of Heidenhain and Acu-Rite digital encoders in Canada. From linear encoders to rotary encoders, our company offers a wide range of products that vary in accuracy, robustness and specifications. Contact us today at 905-876-0890 to learn more about our products and how they can improve your operations.