Introduction of Italian eltra incremental encoder and absolute encoder

According to the working principle, encoders can be divided into two types: incremental and absolute:

　　Incremental: Incremental encoder converts the displacement into a periodic electrical signal, and then converts the electrical signal into a counting pulse, and the number of pulses represents the magnitude of the displacement.

　　Absolute: Each position of an absolute encoder corresponds to a certain digital code, so its indication is only related to the start and end positions of the measurement, and has nothing to do with the middle process of the measurement.

　　 Positioning of encoders from proximity switches, photoelectric switches to rotary encoder industry control, proximity switches and photoelectric switches have been quite mature and very useful. However, with the continuous development of industrial control, there are new requirements. In this way, the application advantages of using rotary encoders are highlighted: in addition to positioning, the control room can also know its specific location. Flexible positioning can be flexible in the control room. Adjust the convenience, safety, and longevity of on-site installation: a fist-sized rotary encoder can measure distances from a few μ to several hundreds of meters, with n stations. As long as the problem of safe installation of a rotary encoder is solved, you can Avoid the trouble of mechanical installation of many proximity switches and photoelectric switches on site, which are easy to be damaged, high temperature, moisture and other problems. Because it is a photoelectric code wheel, there is no mechanical loss, as long as the installation position is accurate, its service life is often very long. In addition to positioning, multifunctionalization can also remotely transmit the current position and convert the movement speed, which is particularly important for applications such as inverters and stepper motors. Economicalization For multiple control stations, only the cost of a rotary encoder is required, and the more important installation, maintenance, and loss costs are reduced, and the service life is increased, and its economicalization is gradually highlighted.

The Italian ELTRA encoder is the most important, largest, and most complete encoder in Europe. The main products are: absolute single-turn and absolute multi-turn encoders, incremental encoders, and servo motors with Encoders for commutation signals; encoders for racks, metric measuring wheels, line drive encoders, electronic handwheels, intrinsically safe explosion-proof encoders, absolute single-turn encoders with incremental output, and Absolute encoder for tower tool conversion and absolute encoder with industrial fieldbus interface.

　　 ELTRA encoders have undergone long-term rigorous testing under strict conditions, and the product quality can be strictly guaranteed. At the same time, Eltra’s unique production management system ensures the fastest delivery time. Since entering the Chinese market, Eltra encoders have been widely used in motors, machine tools, metallurgy, textile machinery, printing and packaging machinery, port machinery, chemical energy, etc.

　　Incremental encoder:

　　 When the incremental encoder moves, the encoder will generate a binary pulse stream proportional to the shaft rotation speed (rotary encoder) or movement distance (linear encoder). When using an optical encoder, a specific pattern of code disk or linear code strip placed between the LED light source and the light sensor can alternately turn on or block the light beam, thereby generating an analog signal; then an additional circuit (usually an onboard ASIC) will Convert the analog signal to a square wave. Magnetic encoders can operate in a variety of mechanisms, but they all rotate a magnetic field, resulting in voltage pulses or resistance changes that can be converted into pulses.

　　Single-channel incremental encoder can only output a single pulse stream, so it can only provide limited information. According to the resolution of the encoder, that is, the number of pulses per revolution of the rotary encoder or the movement distance of the linear encoder (mm/inch), the external electronic device can count the pulses and calculate the speed or relative to a certain reference coordinate (starting Position) to determine the encoder position. The single-channel design provides an excellent solution for applications such as one-way conveyor systems.

　　Single-channel encoder is simple to operate, durable and economical, but it has an important defect that it cannot determine the direction of movement. Determining the direction of motion requires the encoder to have more outputs (usually a dual-channel design with a phase difference of 90° is used to achieve independent output of channel "A" and channel "B"). Since the signal output of a dual-channel encoder has 2 rising edges and 2 falling edges, it is sometimes called a quadrature encoder. The direction of motion determines which channel reaches the high level first, which allows the processor to easily monitor the direction of motion. The operator can increase the resolution of the encoder by triggering the leading and trailing edges of one or two channels of pulses-up to 4 times.

　　 Quadrature encoders provide robust solutions for challenging and complex applications. In high-vibration applications, a single-channel encoder may misunderstand a pulse stream generated by shaft jitter relative to the set point as a real displacement, while a quadrature encoder can recognize changes in direction and ignore the pulse stream or change It is treated as noise and filtered out.

　　Absolute encoder:

The absolute value type rotary encoder has a code disc and a fixed grating connected to the shaft, allowing the system to generate a unique binary identifier for each travel point (the working principle of linear sensors is similar to this, for simplicity, this article will Focus on the rotary encoder). As the code wheel rotates to the fixed grating, the system periodically reads the identifier and outputs it as a multi-digit digital signal. The relevant controller or frequency converter can poll the encoder to capture position data, and can directly use the data or process it as speed information.

The fixed grating of the optical encoder has alternating transparent and opaque areas. Similarly, there are transparent and opaque areas on the code disc, which forms a set of code disc circles (code tracks) and forms a radiation area on the code track; each The code channels are read by a pair of different LED light sources/light sensors. The code disc is located on top of the fixed grating, usually on top of the sensor-specific integrated circuit (ASIC) containing the detector matrix and related electronics. As the code wheel rotates, the transparent area of the code wheel regularly coincides with the transparent area on the fixed grating so that the light signal can reach the detector and generate pulses. Each code channel on the code disk corresponds to a bit in the output; when the number of code channels is n, 2n radiation positions can be generated. The current standard resolution of absolute encoders is 12bit, or 4096 positions per revolution. In addition, some models of products can also provide 22bit (4.19x106 positions) or higher resolution.