ELCO photoelectric rotary encoder

We adhere to the principle of integrity-based and quality first, striving for excellent service, reasonable and fair prices, providing various users with excellent and reasonable technical solutions and high-quality pre-sales and after-sales services, and wholeheartedly serving and cooperating with new and old customers!

The Swiss ELCO rotary encoder converts displacement into periodic electrical signals

A rotary encoder is a device used to measure rotational speed and, in conjunction with PWM technology, achieve fast speed regulation. It is a photoelectric typeELCO rotary encoderThrough photoelectric conversion, mechanical quantities such as angular displacement and angular velocity of the output shaft can be converted into corresponding electrical pulses for digital output (REP).

It is divided into two types: single output and dual output. The technical parameters mainly include the number of pulses per revolution (ranging from tens to thousands), and the supply voltage. Single output refers toELCO rotary encoderThe output of the ELCO rotary encoder is a set of pulses, while the dual output ELCO rotary encoder outputs two sets of pulses with a phase difference of 90 degrees between A/B. Through these two sets of pulses, not only can the speed be measured, but also the direction of rotation can be determined.

According to the output type of the signal, it can be divided into voltage output, open collector output, push-pull complementary output, and long line drive output.

Axial type: Axial type can be divided into clamping flange type, synchronous flange type, servo installation type, etc.

Shaft sleeve type: Shaft sleeve types can be divided into semi empty, fully empty, and large-diameter types.

According to the working principle of encoders, they can be divided into photoelectric, magneto electric, and contact brush types.

Encoders can be classified into incremental and absolute types based on the method of engraving holes on the encoder disk.

An incremental encoder converts displacement into a periodic electrical signal, which is then converted into count pulses to represent the magnitude of displacement in terms of the number of pulses. Each position of the absolute encoder corresponds to a specific digital code, so its indication is only related to the starting and ending positions of the measurement, and not to the intermediate process of the measurement.

The rotary incremental encoder outputs pulses when it rotates, and its position is known through a counting device. When the encoder is stationary or powered off, it relies on the internal memory of the counting device to remember its position. In this way, when there is a power outage, the encoder cannot move in any way. When there is a power outage, there should be no interference or loss of pulses during the encoder's output pulse process. Otherwise, the zero point stored in the counting device will shift, and the amount of this shift is unknown. Only when an erroneous result occurs can it be known.

The solution is to increase the reference point, and the encoder will correct the reference position into the memory position of the counting device every time it passes through the reference point. Before the reference point, the accuracy of the position cannot be guaranteed. For this reason, in industrial control, there are methods such as finding a reference point before each operation and finding the change when starting up.

For example, the positioning of a printer scanner is based on the principle of an incremental encoder. Every time it is turned on, we can hear a crackling sound as it searches for the reference zero point before it starts working.

This method is quite troublesome for some industrial control projects, and even does not allow for zero change upon startup (the exact location needs to be known after startup), which led to the emergence of absolute encoders.

Absolute rotary photoelectric encoders, due to their absolute position, anti-interference, and no need for power-off memory, have been increasingly widely used in angle and length measurement and positioning control in various industrial systems.

There are many engraved lines on the optical encoder disc of the absolute encoder, and each engraved line is arranged in sequence with 2 lines, 4 lines, 8 lines, and 16 lines. In this way, at each position of the encoder, by reading the brightness and darkness of each engraved line, a set of binary codes (Gray codes) from the zero power of 2 to the n-1 power of 2 is obtained, which is called an n-bit absolute encoder. This encoder is determined by the mechanical position of the encoder disc and is not affected by power outages or interference.

The absolute encoder is determined by the mechanical position of each position, and it does not require memory, reference points, or continuous counting. It reads its position whenever it needs to be known. In this way, the anti-interference characteristics of the encoder and the reliability of the data are greatly improved.

Due to its obvious superiority over incremental encoders in positioning, absolute encoders have been increasingly applied in industrial control positioning. Absolute encoders have high precision and a large number of output bits. If parallel output is still used, each output signal must be well connected. For more complex working conditions, isolation is required, and there are many cable cores connected, which brings many inconveniences and reduces reliability. Therefore, absolute encoders generally use serial output or bus output in multi bit output types. The absolute encoder produced in Germany has SSI (synchronous serial output) serial output

A photoelectric encoder with a central axis, which has circular markings for light and dark, is read by photoelectric emitting and receiving devices to obtain four sets of sine wave signals combined into A, B, C, and D. Each sine wave has a phase difference of 90 degrees (360 degrees relative to one cycle), and the C and D signals are reversed and superimposed on the A and B phases to enhance stable signals; Additionally, output a Z-phase pulse for each revolution to represent the zero reference position. Due to the 90 degree difference between phase A and phase B, the forward and reverse rotation of the encoder can be determined by comparing whether phase A is ahead or phase B. By using the zero position pulse, the zero position reference position of the encoder can be obtained.

The materials of encoder encoders include glass, metal, and plastic. Glass encoders deposit very thin engraved lines on glass, which has good thermal stability and high accuracy. Metal encoders directly engrave lines with or without lines, which are not fragile. However, due to the thickness of metal, the accuracy is limited, and its thermal stability is one order of magnitude worse than that of glass. Plastic encoders are economical and have low cost, but their accuracy, thermal stability, and lifespan are all inferior.

Resolution - The number of open or closed lines provided by an encoder per 360 degrees of rotation is called resolution, also known as resolution division, or directly referred to as lines. Generally, it ranges from 5 to 10000 lines per rotation