Encoders can be categorized into standard definition (SD) encoders, high definition (HD) encoders, and full HD encoders based on the resolutions they support. The higher the resolution and the higher the frame rate, the clearer the video.
1. What does encoder resolution mean?
The resolution of an encoder refers to the number of through or dark lines that the encoder provides per 360 degrees of rotation. It is also called resolution scale or simply the number of lines, and is generally between 5 and 10,000 lines per revolution.
Encoders can be categorized by the resolution they support: Standard Definition (SD) encoders (720x480 and below, PAL frame rate up to 50, NTSC frame rate up to 60), High Definition (HD) encoders (1280x720 and below, PAL frame rate up to 50, 1920x1080, PAL frame rate up to 25), and Full HD encoders (1920x1080, PAL frame rate up to 50, NTSC frame rate up to 60). Higher resolution and higher frame rate result in clearer video. Topology encoders achieve Full HD resolution.
An encoder is a device that encodes and converts signals (such as bitstreams) or data into a signal form that can be used for communication, transmission, and storage. Encoders convert angular or linear displacement into electrical signals; the former is called a code disk, and the latter a code scale. According to the readout method, encoders can be divided into contact and non-contact types; according to their working principle, they can be divided into incremental and absolute types. Incremental encoders convert displacement into periodic electrical signals, and then convert these electrical signals into counting pulses, using the number of pulses to represent the magnitude of the displacement. Each position of an absolute encoder corresponds to a specific digital code; therefore, its reading depends only on the starting and ending positions of the measurement, and is independent of the intermediate steps of the measurement.
2. How is encoder resolution calculated?
The most commonly used encoder resolution is the incremental photoelectric encoder, whose resolution is also called the number of lines. For example, a 2500-line encoder with 4x frequency multiplication has a resolution of 2500 * 4 = 10000 pulses.
The higher the encoder resolution, the smaller the minimum scale of the motor, which means the smaller the angular displacement of the motor rotation and the higher the control precision.
3. Relationship between encoder resolution and pulse number
The encoder has a photoelectric code disk with a central shaft. It has circular light and dark markings and photoelectric transmitting and receiving devices that read the code to obtain four sets of sine wave signals, which are combined into A, B, C, and D. Each sine wave is 90 degrees out of phase (360 degrees in one cycle). The C and D signals are reversed and superimposed on the A and B phases to enhance signal stability. In addition, a Z-phase pulse is output every revolution to represent the zero reference position.
Whether it's lines or bits, you need to know how many pulses the encoder outputs per revolution. The concept of lines is often seen in incremental encoders, which divide the encoder's code disk into 2500 (2500 lines) lines, so the code can output 2500 pulses per revolution.
