The working principle and advantages of incremental encoder

Incremental encoder is a kind of rotary encoder, and it is also a commonly used encoder in the market. It converts the displacement into a periodic electrical signal, and then converts the electrical signal into counting pulses. Calculate the displacement, distance, speed, angle. Today, let’s take a look at the working principle and advantages of incremental encoders.

The working principle of incremental encoder:

The pulse code disk that the incremental encoder rotates with the rotating shaft has a uniformly engraved grating, and a number of light-transmitting sections and light-shielding sections are evenly distributed on the code disk. The characteristic of the incremental encoder is: it does not have a fixed starting zero point, it outputs pulses that are proportional to the increment of the rotation angle, and a counter is needed to count the pulses. Therefore, every time it rotates through a light-transmitting area, it sends out a pulse signal, the current value of the counter is increased by 1, and the counting result corresponds to the increment of the rotation angle. Therefore, the encoder is a device that converts angular displacement or linear displacement into electrical signals.

The former becomes a code wheel, and the latter is called a yardstick. According to the reading method, the encoder can be divided into two types: touch type and non-touch type. The touch type uses a brush to output. A brush touches the conductive area or the insulating area to indicate whether the status of the code is "1" or "0"; the non-touch type receiving sensitive element is a photosensitive element or a magnetic sensitive element. When a photosensitive element is selected The light-transmitting area and the opaque area are used to indicate whether the status of the code is "1" or "0".

Advantages of incremental encoder:

The color of the incremental encoder (electronic handwheel) is: non-touch, no conflict and wear, small size, light weight, compact organization, convenient installation, simple protection, small driving torque, high precision, large range measurement , Quick response, digital output characteristics;

Incremental encoders are very suitable for measuring speed and can be accumulated and measured infinitely. However, there are zero accumulated errors and poor anti-interference. The equipment needs to be powered off to recall when it is shut down, and it should be changed or read when it is turned on. These questions can be handled if a positive encoder is selected.

Built-in battery skills: Some encoders use built-in batteries to prevent loss of power-off signals, and some encoders (electronic handwheels) are positive signals, while multi-turn signals are incremental counting methods for built-in batteries and circuits. This is a pseudo-positive encoder, which is affected by factors such as battery life, low-temperature battery failure, and poor battery contacts due to vibration, which greatly reduces reliability.

The general application of incremental encoders is to measure speed, direction of rotation, angle of movement, and distance (relative). The selection of the encoder first selects the type of encoder according to the measurement requirements. The number of pulses transmitted by an incremental encoder is equal to the number of lines of its grating. In the design, the number of lines of the encoder should be determined according to the speed measurement or positioning requirements, and the speed of the encoder. The encoder is installed on the motor shaft, or on a rotating shaft after deceleration, the speed of the encoder is very different. Should also consider whether the highest frequency of the pulse it sends is within the allowable range of the PLC's high-speed counter.