The principle of measuring the speed of photoelectric sensors do you know

A photoelectric sensor is a sensor that uses a photoelectric element as a detection element. It first converts the measured change into a change in the optical signal, and then uses the photoelectric element to further convert the optical signal into an electrical signal. Photoelectric sensors are generally composed of three parts: light source, optical path and photoelectric element.

Photoelectric sensor classification and working methods

(1) Photoelectric sensor in the form of a trough A phototransistor with a phototransmitter and a receiver mounted face to face on both sides of a trough is trough-shaped photovoltaic. The light emitter emits infrared light or visible light, and the light receiver can receive light in the unimpeded condition. However, when the detected object passes through the slot, the light is blocked and the photoelectric switch is activated. A switch control signal is output, and the load current is cut off or turned on to complete one control action. The detection distance of the trough switch is generally only a few centimeters because of the limitation of the overall structure.

(2) In-beam photoelectric sensor If the light emitter and the light receiver are separated, the detection distance can be increased. A photoelectric switch composed of a light emitter and a light receiver is called a split-type photoelectric switch, or short-beam photoelectric switch. Its detection distance can reach several meters or even tens of meters. When in use, the light emitter and the light receiver are respectively installed on both sides of the path through which the detection object passes. When the detection object passes, the light path is blocked, and the light receiver operates to output a switch control signal.

(3) Reflector type photoelectric switch The light emitter and the light receiver are installed in the same device, and a reflector is installed in front of it, and the photoelectric control function is accomplished by using the principle of reflection.

How to measure the motor speed with a photoelectric sensor

In a garden, the semicircle is milled empty, and the light emitting diode and the photodiode are gathered on both sides. When the blanked part passes, the photodiode is turned on and the pulse is sent. When the part that hasn't been milled passes by, the photodiode is turned off. Cut off, this is a lap count a pulse, with the counter count the number of pulses per second is its motor speed.

What is the reason for the large error and poor stability of the rotation speed measured by the photoelectric sensor?

1. The biggest possibility is that your choice of device is too bad;

2. The selected photoelectric sensor should have high frequency, with background shielding function, and the light spot should be small;

3, on-site environment, such as smoke, water mist, and then electromagnetic interference and so on;

4. The reflectance of the tested part is too high or too low, and the incident angle of the sensor installation is incorrect.

Optoelectronic speed sensor principle

Photoelectric speed sensor is a kind of electronic device that senses the change of intensity of received light according to the working principle of photodiode. When the light emitted by it is reflected or blocked by the target, the receiver will induce the corresponding electrical signal. It contains a modulated light source, an optical system composed of a photosensitive element, an amplifier, a switch, or an analog output device, and its operating principle is shown in FIG.

Photoelectric sensors consist of independent and relatively placed light emitters and light collectors. When the El mark passes between the light emitter and the light receiver and blocks light, the sensor outputs a signal. It is the most efficient and reliable detection device. The slot-shaped (u-shaped) photoelectric switch is a transmissive deformation, which has the advantage of no need to adjust the optical axis.

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