MD switch German MD model MD price

MD switch is a device that converts optical signals into electrical signals. Its working principle is based on the photoelectric effect. The photoelectric effect refers to the phenomenon where electrons in a material absorb photon energy when light strikes certain substances, resulting in corresponding electrical effects. Based on different manifestations of the photoelectric effect, it is classified into three categories: external photoelectric effect, internal photoelectric effect, and photovoltaic effect. Photoelectric devices include phototubes, photomultiplier tubes, photoresistors, photodiodes, phototransistors, and photocells. The performance and characteristic curves of photoelectric devices are analyzed.

MD switch principle

Photoelectric switches achieve control by converting changes in light intensity into changes in electrical signals. Generally, a photoelectric switch consists of three parts: transmitter, receiver, and detection circuit. The transmitter emits a light beam toward the target. The emitted light beam usually originates from semiconductor light sources, such as light-emitting diodes (LED), laser diodes, and infrared emitting diodes. The light beam is emitted continuously or with modulated pulse width. 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, structural components of photoelectric switches include emitter plates and optical fibers.

MD switch classification

1) Slot-type photoelectric switch: A slot-type photoelectric switch is formed by mounting a light emitter and a receiver face-to-face on opposite sides of a slot. The emitter emits infrared or visible light, which the receiver can detect under unobstructed conditions. 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 structural constraints, the sensing distance of slot-type switches is generally only a few centimeters. 2) Through-beam photoelectric switch: Separating the emitter and receiver increases the sensing distance. A through-beam photoelectric switch, abbreviated as through-beam switch, consists of one emitter and one receiver. The sensing distance of through-beam photoelectric switches can reach several meters to 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 object passes. When the object 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. It 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 sensing 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 does not detect the light emitted by the emitter. During detection, when an object passes through, it blocks the light and reflects part of it back. The receiver then detects the light signal and outputs a switching signal.

MD switch application cases

1) Application of photoelectric switches in laser weapons: Since photoelectric switches are particularly sensitive to infrared radiation, visible light, or both, they are more likely to become targets of laser attacks. Furthermore, electronic systems and the switches themselves are highly susceptible to interference from thermal noise and electromagnetic noise generated by lasers, preventing normal operation. Methods of laser weapon attacks on photoelectric switches on the battlefield mainly include the following: using a laser beam of appropriate energy to "blind" the switch, rendering it unable to detect or continue tracking already detected targets. Alternatively, if the switch is guiding a weapon toward a target, blinding will cause it to lose the target. In summary, as switches play an increasingly important role on the battlefield and are vulnerable to laser attacks, they have become the primary targets of low-energy laser weapons. 2) Application of photoelectric switches in automatic meter reading systems: With the development of microelectronics, switching technology, computer technology, and modern communications, photoelectric switches can be used to develop automatic meter reading systems. The aluminum disk of an electricity meter rotates driven by torque generated under the influence of eddy currents and magnetic fields. Using a photoelectric switch 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 rotation count is sampled and converted into corresponding pulse counts, 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 switches in monitoring smoke and dust pollution: A photoelectric switch 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 switches are widely used in industrial automation equipment and robotics. We can utilize the characteristics of photoelectric switches to detect smoke and dust conditions; thus, the strength of the output signal from the photoelectric switch reflects changes in flue gas turbidity. 4) Hygienic washdown-resistant photoelectric switches: Washdown-resistant switches provide extremely high reliability and ease of use while minimizing operating costs. Equipped with IO-Link interfaces and the proTect+ sealing concept, which significantly extends service life, these two new switches are suitable for demanding applications and represent an ideal solution for the food and beverage industry.

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