The new BlueBeam technology for incremental rotary encoders with optical sensing is a spectacular innovation. Due to the increased efficiency in signal generation, Pepperl+Fuchs offers significantly better sensing capabilities with an improved signal quality. Compared to the classic standard infrared variants, this results in considerably higher system accuracy even at maximum rotational speeds. The new ENI58IL BlueBeam rotary encoders thus set a new market standard, offering performance characteristics that were previously only achievable in high-performance special solutions.
Incremental rotary encoders form the bridge between mechanics and electronics. They record measured values for rotation, position, and angular speeds. This is achieved with a periodic signal that is proportional to the movement. The rotary encoder detects a defined number of pulses for each shaft revolution, resulting in a precise determination of the angular position. Measuring the cycle duration and the number of pulses per unit of time provides information on the speed of a movement. If the number of pulses from a reference point is measured, the numerical value represents a measure of the angle displaced and the distance covered around the path. Two-channel rotary encoders—with a phase shift of 90°—enable the downstream electronics to determine the direction of rotation of the shaft and thereby also enable bi-directional positioning tasks. Three-channel incremental rotary encoders provide a zero signal once per revolution. In the optical or photoelectric scanning, a rotating code disc with a radial grid is used as the measuring standard. The rotation of the code disc provides a periodic modulation of the light flux from an emitter LED. The intensity is detected by a sensor element and converted into electrical signals. In line with the current state of the art, infrared light is used here.
The New Market Standard
In the new ENI58IL incremental rotary encoders with BlueBeam technology, Pepperl+Fuchs is now using specially developed blue-light LEDs. “The blue light of the new emitter LED exhibits a decreased diffraction compared to a longer-wave infrared light of the same gap width and can therefore depict sharper images,”, explains Stefan Horvatic, Head of Product Management at Pepperl+Fuchs Drehgeber GmbH. Combined with modern sensing chips, which have finer and thinner structures, the penetration depth of the blue light into the chip is shorter or more energy rich. This increases the efficiency factor of the light source so significantly that the sensing chip can generate much sharper contours. The result is a higher resolution, a significantly improved signal amplitude, and considerably reduced edge jitter. “With the BlueBeam technology, we are reducing the tolerances of the phase position A to B to well below 10 %, for example,” adds Horvatic. This is more than double the signal quality compared to values that are otherwise common on the market and achievable with infrared technology. Horvatic goes on to also mention the significantly higher resolution that results from the more reliable scan rate. The scan rate for the digital signals of an incremental rotary encoder relates to the chronological sequence of the state, i.e., the edge change of logical 1 (high) and logical 0 (low). For tolerances—including due to the previously mentioned jitter—it is becoming more and more difficult to implement pulse multiplications, especially at high speeds. Pulse multiplications are used to increase the number of pulses that can be evaluated by up to a factor of 4. The BlueBeam technology thus makes it possible to guarantee absolute accuracy with the new ENI58IL rotary encoders, even in the highest speed ranges of up to 12,000 rpm. The maximum output frequency of the ENI58IL is a remarkable 400 kHz—up to 50 % higher than for standard rotary encoder variants.
Production Ensures Accuracy
The exceptionally high absolute accuracy of the ENI58IL is also helped by the implementation of tight manufacturing tolerances that is made possible by the BlueBeam technology. This is done in a specially equipped production line with a modern one-piece flow system. “Here, for example, each code disc is also precisely adjusted in an innovative production step,” emphasizes Horvatic.
Each rotary encoder that leaves this production line has a robust design with interlocked bearing units. This enables permanently high bearing loads and prevents the ball bearings from being pressed out, thus ensuring reliable operation and an increased service life. Pepperl+Fuchs also ensures the utmost functional safety in relation to the interference resistance, i.e., the EMC protective circuit. A special protective circuit prevents damage caused by electromagnetic interference. “In global use, there are often requirements that go far beyond some of the CE minimum requirements. For this reason, we comply with a level that is up to four times that of standard tests, to ensure stable and reliable operation in unfavorable conditions,” promises Horvatic.
In conjunction with the robustness, durability, and high functional safety of the ENI58IL, the enormous shock and vibration resistance is also noteworthy. It is however less a result of the special manufacturing, than it is a general advantage of BlueBeam technology: With blue light, the signals are more stable under high mechanical influences because the scanning can cope with more tolerances. The shock resistance (shock 300 g, 6 ms and vibration 30 g, 10 Hz … 2000 Hz) may look like it is just the market standard, but it is remarkable when you look at the high level of precision. The ENI58IL rotary encoders therefore contribute in every way to high process reliability, the prevention of machine downtimes, and to increased plant availability.
Quick Availability from a Batch Size of 1
One result of the modern one-piece flow manufacturing is the quick availability in a great diversity of versions with a complete portfolio of industry-standard rotary encoders. The ENI58IL series was developed with a new design and a modular product architecture. The standard housing is made of seawater-resistant aluminum with a diameter of 58 mm. Solid-shaft, hollow-shaft, and recessed hollow-shaft variants and a wide variety of flange types are available for international use. All shaft versions are available in three variants with clamping, synchro, or square flanges as well as with all common axial and radial connector plugs (M23, M12, or MS plug) or connection cables. A special feature of the ENI58IL is the universal current driver (5 – 30 V) in the form of a TTL/HTL combined interface. Every encoder variant can thus be adapted to the specific application.
Due to the one-piece flow manufacturing, the complete product portfolio can be supplied from a quantity of just 1 within a very short period of time. With the product and interface diversity, virtually any application request can be achieved as a standard solution, up to the highest speed ranges. “Due to the high product diversity already in place, we are also able to implement customer-specific developments very quickly,” adds Horvatic.
The highly precise BlueBeam technology offers the highest signal quality of incremental rotary encoders available on today’s market. The resulting high level of accuracy and process reliability helps to reduce the tolerances in applications and to improve the efficiency factor. In a large number of applications, the efficiency is thus improved by an increased system output and the corresponding cost reduction. This is particularly true where the requirements placed on the dynamics increase. Typical fields of application for the new ENI58IL are motor feedback systems for induction motors. The BlueBeam rotary encoders with their high signal quality are the perfect solution here, even at the highest rotational speeds.
The robustness of the BlueBeam rotary encoders, especially in relation to the interference of shock and vibration or EMC, is reflected especially in demanding applications such as in wind turbines. The innovative incremental rotary encoders are used here in slip-ring transmitters. Their task is to transfer control data for the pitch system. This includes data for the rotor speed and the position of the rotor blades, which are determined using these incremental rotary encoders. The information about which position the rotor blades are in is used by the control loop to dynamically turn the individual blade more into the wind or out of the wind. The speed of the rotor is thus influenced and kept at the optimal, rated speed. In these and similar applications, the new ENI58IL incremental rotary encoders from Pepperl+Fuchs are a decisive factor in significantly improving plant performance—and do so from the standard module system.