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Bruel & Kjaer sensors are sensors that use laser technology for measurement. They consist of a laser, a laser detector, and a measurement circuit. Laser sensors are a new type of measuring instrument; their advantages include the ability to perform non-contact long-distance measurement, high speed, high precision, large measuring range, and strong resistance to optical and electrical interference.

Bruel & Kjaer sensor detection principle

Detects magnetic losses caused by eddy currents generated on the surface of a conductor under the influence of an external magnetic field. This detection method involves generating an AC magnetic field within the detection coil and detecting impedance changes caused by eddy currents in the metallic object being measured. Additionally, other methods include aluminum detection sensors that detect frequency phase components, and all-metal sensors that detect only impedance change components via the working coil. A transformer-like state occurs on the surfaces of both the detected object and the sensor.

Bruel & Kjaer sensor classification

1) Capacitive proximity sensor: This is a capacitive proximity switch with an electrode as the detection terminal. It consists of a high-frequency oscillation circuit, a detection circuit, an amplification circuit, a shaping circuit, and an output circuit. Normally, there is a certain capacitance between the detection electrode and ground, which forms part of the oscillation circuit. When the object being detected approaches the detection electrode, the voltage applied to the electrode causes electrostatic induction and polarization. The closer the object gets to the detection electrode, the more induced charge accumulates on the electrode. Since the electrostatic capacitance of the detection electrode is C, the capacitance C of the detection electrode increases as the charge increases. Because the oscillation frequency of the oscillation circuit is inversely proportional to the capacitance, the oscillation weakens or even stops when the capacitance C increases. These two states—oscillation and cessation—are converted into switch signals by the detection circuit and output externally. 2) Inductive proximity sensor: Consists of a high-frequency oscillation circuit, a detection circuit, an amplification circuit, a shaping circuit, and an output circuit. The sensitive element for detection is the detection coil, which is part of the oscillation circuit. The oscillation frequency of the circuit is L. When AC current flows through the detection coil, an alternating magnetic field is generated around it. When a metal object approaches the detection coil, eddy currents are generated in the metal object, absorbing magnetic energy. This causes the inductance L of the detection coil to change, reducing the oscillation frequency of the circuit until oscillation stops. These two states—oscillation and cessation—are converted into switch signals by the monitoring circuit and output. Note: Similar to capacitive proximity sensors, inductive proximity sensors detect metallic conductors; non-metallic conductors cannot be measured using this method. Amplitude changes vary with the type of metal in the target object, so the detection distance also varies depending on the metal type. 3) Photoelectric proximity sensor: The beam axis of the light-emitting diode (or semiconductor laser tube) and the axis of the phototransistor lie in the same plane and form a specific angle, intersecting at a point in front of the sensor. When the surface of the object being detected approaches this intersection point, the reflected light from the LED is received by the phototransistor, generating an electrical signal. When the object moves away from the intersection point, the reflection area falls outside the phototransistor's field of view, and the detection circuit produces no output. Generally, the drive current supplied to the LED is not DC but an AC current of a specific frequency. Consequently, the receiving circuit also receives an AC signal of the same frequency. Filtering the received signal to allow only signals of this frequency to pass effectively prevents interference from other ambient light and can increase the LED's luminous intensity.

Bruel & Kjaer sensor applications

Proximity sensors are primarily used to detect object displacement and are widely applied in aviation, aerospace technology, and industrial production. In daily life, they are used in automatic doors and automatic heaters in hotels, restaurants, and garages. For security and anti-theft purposes, important locations such as archives, accounting departments, financial institutions, museums, and vaults are typically equipped with anti-theft devices composed of various proximity switches. In measurement technology, they are used for length and position measurements; in control technology, they are extensively used for measuring and controlling displacement, speed, and acceleration.

Weidou Intelligent Technology specializes in selling German Bruel & Kjaer sensors, Bruel & Kjaer proximity sensors, Bruel & Kjaer distance sensors, Bruel & Kjaer vision sensors, Bruel & Kjaer displacement sensors, Bruel & Kjaer torque sensors, Bruel & Kjaer speed sensors, Bruel & Kjaer photoelectric sensors, Bruel & Kjaer position sensors, Bruel & Kjaer angle sensors, Bruel & Kjaer tactile sensors, Bruel & Kjaer temperature sensors, Bruel & Kjaer pressure sensors, Bruel & Kjaer flow sensors, Bruel & Kjaer level sensors, Bruel & Kjaer motion sensors, and Bruel & Kjaer process sensors. All products are original imports from Germany. Customers are welcome to inquire and place orders.