A photoelectric switch (photoelectric sensor) is short for photoelectric proximity switch. It detects the presence or absence of an object by utilizing the blocking or reflection of a light beam by a detected object, which is then selected by a synchronous circuit. The object is not limited to metal; any object that reflects light can be detected. The photoelectric switch converts the input current into a light signal at the transmitter, and the receiver then detects the target object based on the intensity or presence of the received light. Photoelectric switches are commonly used in security systems, such as smoke detectors, and in industry, they are frequently used to count the number of movements of robotic arms.
1. First, it can be determined that a light-controlled switch does not belong to a photoelectric switch.
2. Photoelectric switches achieve control by converting changes in light intensity into changes in electrical signals.
It utilizes the ability of the object being detected to block or reflect an infrared beam (distinguishing point), and the presence or absence of the object is detected by a synchronous circuit selection. The object is not limited to metal; it can detect any object that can reflect light. A photoelectric switch typically consists of three parts: a transmitter, a receiver, and a detection circuit.
Depending on the detection method, infrared photoelectric switches can be divided into:
(1). Diffuse reflection photoelectric switch
(2). Mirror-reflective photoelectric switch
(3). Through-beam photoelectric switch
(4) Slotted photoelectric switch
(5) Fiber optic photoelectric switch
3. A light-controlled switch, its "on" and "off" functions are achieved by the conduction and blocking of a silicon controlled rectifier (SCR), which in turn is controlled by the brightness of natural light (the dividing point) (or artificial brightness). This device is suitable for use as street lighting, dormitory corridor lighting, or other public place lighting, providing daytime-off and nighttime-on control to save electricity.
4. The environment in which a photoelectric switch is used is a crucial factor affecting its long-term reliability. When a photoelectric switch operates at its maximum detection distance, the optical lens can become clogged with dirt or even corroded by strong acids, thus reducing its performance parameters. However, light-controlled switches are not affected by the "detection distance" parameter.
The difference between photoelectric switches and photoelectric relays
The photoelectric switch generates a modulated pulse from an oscillating circuit, which is then reflected by a light-emitting diode (LED) GL to emit a light pulse. When the object being measured enters the receiver's effective range, the reflected light pulse enters a phototransistor (DU). In the receiving circuit, the light pulse is demodulated into an electrical pulse signal, amplified, and synchronously gating and shaped. Interference is then eliminated using digital integration or RC integration, and finally, a time-delayed (or non-delayed) trigger driver outputs the photoelectric switch control signal.
Photoelectric switches generally have good hysteresis characteristics, so even if the object being detected moves within a small range, it will not affect the output state of the driver, thus keeping it in a stable operating range. At the same time, the self-diagnostic system can also display the light reception status and stable operating range to monitor the operation of the photoelectric switch at any time.
The working principle and characteristics of photoelectric relays. A relay is an electronic control device that has a control system (also known as an input circuit) and a controlled system (also known as an output circuit). It is commonly used in automatic control circuits. In essence, it is an "automatic switch" that uses a smaller current to control a larger current. Therefore, it plays a role in automatic adjustment, safety protection, and circuit switching in circuits.
