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The EMHART encoder has many optical channel graduations. Each graduation is arranged sequentially with 2 lines, 4 lines, 8 lines, and 16 lines. In this way, at each position of the encoder, by reading the light and dark states of each graduation, a unique 2-ary code (Gray code) is obtained, ranging from the zeroth power of 2 to the n-1th power of 2. This is called an n-bit absolute encoder. Such encoders use an optical code disk for memory. The absolute encoder determines the code based on mechanical position; it requires no memory, no reference point search, and no continuous counting. Whenever the position needs to be known, its position is read directly. This greatly improves the encoder's anti-interference characteristics and data reliability. From single-turn absolute encoders to multi-turn absolute encoders: in a single-turn absolute rotary encoder, the graduations on the optical code disk are measured during rotation to obtain a unique code. When the rotation exceeds 360 degrees, the code returns to the origin, which does not comply with the principle of unique absolute coding. Such coding can only be used for measurements within a rotation range of 360 degrees and is called a single-turn absolute encoder.

EMHART encoder working principle

The magnetic encoder consists of an optical code disk with a central shaft, featuring concentric transparent and opaque tracks. Photoelectric emitting and receiving components read these tracks to obtain four sinusoidal wave signals, which are combined into A, B, C, and D. Each sinusoidal wave has a phase difference of 90 degrees. By inverting the C and D signals and superimposing them onto the A and B phases, signal stability is enhanced. Additionally, one Z phase pulse is output per revolution to represent the zero reference position. Since the A and B phases differ by 90 degrees, the direction of rotation (forward or reverse) of the magnetic encoder can be determined by comparing whether the A phase leads or the B phase leads. The zero reference position is obtained via the zero pulse. Materials for the magnetic encoder code disk include glass, metal, and plastic. Glass code disks have very thin etched lines deposited on glass, offering good thermal stability and high precision. Metal code disks use direct transparent and opaque lines, but due to the thickness of the metal, precision is limited, and their thermal stability is an order of magnitude worse than that of glass. Plastic code disks are an economical option. The principle of magneto-optical encoders is similar to that of optical encoders, but they utilize magnetic field signals. Inside a magnetic encoder, a magnetic rotor and magnetoresistive sensors are used. Rotation of the magnetic rotor causes changes in the internal magnetic field strength. The magnetoresistive sensor detects these changes, and after signal processing by the circuitry, outputs the signal. The number of magnetic poles on the magnetic rotor, the number of magnetoresistive sensors, and the method of signal processing determine the resolution of the magnetic encoder. The advantage of using magnetic field principles to generate signals is that magnetic signals are not affected by dust, moisture, high temperatures, or vibration.

EMHART encoder working principle

It consists of an optical code disk with a central shaft, featuring annular light and dark graduations. Photoelectric emission and receiving devices read these to obtain four sets of sinusoidal signals combined into A, B, C, and D. Each sine wave has a phase difference of 90 degrees (relative to one cycle being 360 degrees). By inverting the C and D signals and superimposing them on the A and B phases, signal stability is enhanced. Additionally, one Z phase pulse is output per revolution to represent the zero reference position. Since the A and B phases differ by 90 degrees, forward and reverse rotation of the encoder can be determined by comparing whether the A phase leads or the B phase leads. The zero reference position of the encoder is obtained via the zero pulse. Code disk materials include glass, metal, and plastic. Glass code disks have very thin graduations deposited on glass, offering good thermal stability and high precision. Metal code disks use direct light/dark graduations and are not brittle, but due to the thickness of the metal, precision is limited, and thermal stability is an order of magnitude worse than glass. Plastic code disks are economical, with low cost, but their precision, thermal stability, and service life are somewhat inferior. Resolution refers to the number of light or dark graduations provided by the encoder per 360 degrees of rotation, also known as analytical division, or simply referred to as the number of lines. Typically, it ranges from 5 to 10000 lines per revolution.

EMHART encoder working principle

Equally angled slots (divided into transparent and opaque parts) are cut along the edge of a code disk. Light sources and photosensitive elements are installed on both sides of the slotted code disk. When the code disk rotates with the working shaft, each slot passed causes a change in light intensity. After shaping and amplification, electrical pulse output signals with specific amplitude and power are obtained. The number of pulses equals the number of slots passed. Sending this pulse signal to a counter allows counting, and the measured digital value indicates the angle rotated by the code disk. To determine the direction of rotation, two sets of photoelectric conversion devices can be used. Their relative spatial positions are arranged to ensure that the signals they produce have a phase difference of 1/4 cycle.

Weidou Intelligent Technology specializes in selling German EMHART rotary encoders, EMHART incremental encoders, EMHART absolute encoders, EMHART photoelectric encoders, EMHART magneto-electric encoders, EMHART shafted encoders, EMHART hollow shaft encoders, EMHART contact brush encoders, EMHART angle encoders, EMHART linear encoders, EMHART digital encoders, EMHART draw-wire encoders, EMHART position encoders, EMHART hollow bore encoders, and EMHART spindle encoders. All EMHART products are original imports from Germany. Customers are welcome to inquire and place orders.