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Erhard sensors precisely measure the actual displacement of the detected product by detecting the absolute position of the movable magnetic ring through internal non-contact measurement and control technology; the high precision and high reliability of these sensors have been widely applied in thousands of practical cases. Since the movable magnetic ring used for position determination does not come into direct contact with the sensitive element, the sensor can be used in extremely harsh industrial environments and is not easily affected by oil stains, solutions, dust, or other contaminants. In addition, the sensor uses high-tech materials and advanced electronic processing technology, enabling it to operate in high-temperature, high-pressure, and high-vibration environments. The sensor output signal is an absolute displacement value; even if the power supply is interrupted and reconnected, data will not be lost, and there is no need to re-zero. Since the sensitive element is non-contact, repeated detection will not cause any wear to the sensor, greatly improving detection reliability and service life.

Erhard sensor principle

Photoelectric sensors achieve control by converting changes in light intensity into changes in electrical signals. Generally, a photoelectric sensor consists of three parts: a transmitter, a receiver, and a detection circuit. The transmitter emits a light beam toward the target; the emitted light beam generally comes from semiconductor light sources, such as light-emitting diodes (LED), laser diodes, and infrared emitting diodes. The light beam is emitted continuously, or the pulse width is varied. The receiver consists of photodiodes, phototransistors, and photocells. Optical components such as lenses and apertures are installed in front of the receiver. Behind it is the detection circuit, which filters out valid signals and applies them. In addition, the structural components of photoelectric switches also include emitter plates and optical fibers.

Erhard sensor classification

1) Slot-type photoelectric sensor: A slot-type photoelectric sensor is formed by mounting a light emitter and a receiver face-to-face on both sides of a slot. The emitter can emit infrared or visible light, and the light receiver can receive the light when unobstructed. However, when the detected object passes through the slot, the light is blocked, causing the photoelectric switch to actuate and output a switching control signal to cut off or connect the load current, thereby completing a control action. Due to limitations imposed by the overall structure, the detection distance of slot-type switches is generally only a few centimeters. 2) Through-beam photoelectric sensor: Separating the emitter and the receiver increases the detection distance. A through-beam separated photoelectric switch, abbreviated as a through-beam photoelectric switch, consists of one emitter and one receiver. The detection distance of through-beam photoelectric switches can reach several meters or even tens of meters. When using a through-beam photoelectric switch, the emitter and receiver are installed on opposite sides of the path through which the detected object passes. When the object passes through and blocks the light path, the receiver actuates and outputs a switching control signal. 3) Retro-reflective photoelectric switch: The emitter and receiver are housed in the same unit, with a reflector plate installed in front. This setup utilizes the reflection principle to achieve photoelectric control and is called a retro-reflective (or mirror-reflective) photoelectric switch. Under normal conditions, the light emitted by the emitter is reflected back by the reflector plate and received by the receiver; once the detected object blocks the light path and the receiver no longer receives light, the photoelectric switch actuates and outputs a switching control signal. 4) Diffuse-reflective photoelectric switch: The detection head of a diffuse-reflective photoelectric switch also contains an emitter and a receiver, but there is no reflector plate in front. Under normal conditions, the receiver cannot detect the light emitted by the emitter. During detection, when the object passes through, it blocks the light and reflects part of it back; the receiver then receives the light signal and outputs a switching signal.

Erhard sensor application cases

1) Application of photoelectric sensors in laser weapons: Since photoelectric sensors are particularly sensitive to infrared radiation, visible light, or both, they are more likely to become targets of laser attacks. In addition, electronic systems and the sensors themselves are highly susceptible to interference from thermal noise and electromagnetic noise generated by lasers, preventing normal operation. The main methods by which battlefield laser weapons attack photoelectric sensors include: using a laser beam of appropriate energy to "blind" the sensor, rendering it unable to detect or continue tracking already detected targets. Alternatively, if the sensor is guiding a weapon toward a target, blinding will cause it to lose the target. In summary, since sensors play an increasingly important role on the battlefield and are vulnerable to laser attacks, they have become the preferred targets for low-energy laser weapons. 2) Application of photoelectric sensors in automatic meter reading systems: With the development of microelectronics, sensor technology, computer technology, and modern communications, photoelectric sensors can be used to develop automatic meter reading systems. The aluminum disk of an electricity meter rotates under the torque generated by eddy currents and magnetic fields. Using a photoelectric sensor converts the number of rotations of the aluminum disk into pulse counts. For example, by partially blackening a rotating shiny aluminum disk and pairing it with a reflective photoelectric emitter-receiver pair, pulses are generated at the blackened areas as the disk rotates. The number of rotations is sampled and converted into corresponding pulse counts, which are then sent via an optocoupler isolation circuit to the T0 port of the CPU for counting processing. Using optocoupler isolators effectively prevents interference signals from entering the microcomputer. Combined with other transmission methods, this forms an automatic meter reading system. 3) Application of photoelectric sensors in monitoring smoke and dust pollution: A photoelectric sensor is a small electronic device that detects changes in received light intensity and achieves control functions by converting these changes into electrical signals. Due to characteristics such as non-contact operation, fast response, and reliable performance, photoelectric sensors are widely used in industrial automation devices and robots. We can utilize the characteristics of photoelectric sensors to detect smoke and dust conditions, meaning the strength of the output signal from the photoelectric sensor reflects changes in flue gas turbidity. 4) Hygienic washdown-proof photoelectric sensors: Washdown-proof sensors provide extremely high reliability and convenience while minimizing operating costs. Equipped with an IO-Link interface and the proTect+ sealing concept, which significantly extends service life, these two new sensors are suitable for demanding application environments and represent an ideal solution for the food and beverage industry.

Weidou Intelligent Technology specializes in selling German Erhard sensors, Erhard proximity sensors, Erhard distance sensors, Erhard vision sensors, Erhard displacement sensors, Erhard torque sensors, Erhard speed sensors, Erhard photoelectric sensors, Erhard position sensors, Erhard angle sensors, Erhard tactile sensors, Erhard temperature sensors, Erhard pressure sensors, Erhard flow sensors, Erhard level sensors, Erhard motion sensors, Erhard process sensors. Original German imports. Welcome inquiries and orders from users.