Maintenance and troubleshooting of photoelectric switch

Keywords: photoelectric switch photoelectric switch manufacturer photoelectric switch model photoelectric switch price photoelectric switch wiring diagram photoelectric switch principle photoelectric switch type photoelectric switch application

Photoelectric switch:

The photoelectric switch is the abbreviation of the photoelectric proximity switch. It utilizes the shielding or reflection of the light beam by the detected object, and the circuit is connected by the synchronization loop to detect the presence or absence of the object. Objects are not limited to metal, all objects that can reflect light (or block light) can be detected. The photoelectric switch converts the input current into a light signal on the transmitter, and then the receiver detects the target object according to the intensity or presence of the received light. The common photoelectric switch smoke alarm in the security system is often used in the industry to count the number of movements of the robotic arm.

Photoelectric switch model:

The photoelectric switch is a kind of sensor, which converts the change of the intensity of light between the transmitting end and the receiving end into the change of current to achieve the purpose of detection. Since the output circuit and input circuit of the photoelectric switch are electrically isolated (ie, electrically insulated), it can be used in many occasions. A new generation of photoelectric switch devices manufactured using integrated circuit technology and SMT surface mounting technology has intelligent functions such as delay, widening, external synchronization, anti-interference, high reliability, stable working area and self-diagnosis. This novel photoelectric switch is an active photoelectric detection system electronic switch that adopts pulse modulation. The cold light sources it uses include infrared light, red light, green light and blue light, etc., which can be non-contact and rapid without damage. And control the state and action of various solids, liquids, transparent bodies, black bodies, soft bodies and smoke. It has the advantages of small size, multiple functions, long life, high accuracy, fast response speed, long detection distance and strong resistance to optical, electrical, and magnetic interference.

Photoelectric switch manufacturers:

Use optical elements to change the light beam in the middle of the propagation medium; use the light beam to reflect the object; make the light beam return instantaneously after being emitted over a long distance. The photoelectric switch is composed of three parts: transmitter, receiver and detection circuit. The transmitter is aimed at the target to emit a beam, and the emitted beam generally comes from a light emitting diode (LED) and a laser diode. The beam is emitted continuously, or the pulse width is changed. The radiation intensity of the pulsed beam has been selected many times in the launch, and it runs towards the target without indirectly. The receiver is composed of a photodiode or phototransistor. In front of the receiver, optical components such as lens and aperture are installed. Behind it is the detection circuit, which can filter out the effective signal and apply the signal.

Working principle of photoelectric switch:

After the modulated pulse generated by the oscillation circuit passes through the reflection circuit, the light pulse is radiated from the luminous tube GL. When the measured object enters the range of the light receiver, the reflected light pulse enters the photosensitive transistor DU. The photoelectric switch demodulates the optical pulse into an electrical pulse signal in the receiving circuit, and then is amplified by the amplifier and synchronized gating and shaping, and then the interference is eliminated by digital integration or RC integration, and finally the driver is triggered by a delay (or no delay) Output photoelectric switch control signal. Photoelectric switches generally have good hysteresis characteristics, so even if the detected object shakes in a small range, it will not affect the output state of the driver, so that it can be kept in a stable working area. At the same time, the self-diagnostic system can also display the light receiving status and stable working area to monitor the work of the photoelectric switch at any time.

Types of photoelectric switches:

The amplifier separation type is to separate the amplifier and the sensor, and is made with a dedicated integrated circuit and a mixed installation process. Because the sensor has the characteristics of ultra-small and multi-variety, the amplifier has more functions. Therefore, this type adopts the terminal block connection method and can be used for both AC and DC power supplies. With on and off delay function, you can set the light and sound switch, can control 6 kinds of output states, and have two output modes of contact and level.

The built-in type of amplifier integrates the amplifier and the sensor. It is made by ASIC and surface mounting technology, and it works with DC power supply. Its response speed situation (there are two kinds of 0.1ms and 1ms), can detect small and high-speed moving objects. Changing the polarity of the power supply can switch between bright and dark movement, and can set a self-diagnostic stable work area indicator. Both voltage and current output modes can prevent mutual interference, which is very convenient in system installation.

The built-in power supply unit integrates the amplifier, sensor and power supply device, and is made with a dedicated integrated circuit and surface mount technology. It generally uses AC power and is suitable for replacing contact type limit switches at the production site, and can be directly used for strong current control circuits. You can also set self-diagnostic stable working area indicator lights by yourself. The output is equipped with SSR solid state relay or relay normally open and normally closed contacts, which can prevent mutual interference and can be installed tightly in the system.

Photoelectric switch price:

Strong light source: The photoelectric switch can generally work stably when the ambient illuminance is high. However, it should be avoided that the optical axis of the sensor faces strong light sources such as sunlight and incandescent lamps. When the angle between the optical axis of the sensor (receiver) and the strong light source cannot be changed, a light-shielding plate or a long light-shielding tube can be installed around the sensor.

Mutual interference: MGK series of new photoelectric switches usually have the function of automatically preventing mutual interference, so there is no need to worry about mutual interference. However, when several groups of HGK series through-beam infrared photoelectric switches are installed in parallel and close to each other, the adjacent groups and mutual interference should be prevented. The most effective way to prevent this kind of interference is to set the emitter and the receiver crosswise, and open the group distance when more than 2 groups. Different frequency models can also be used.

The effective way of HGK series reflective photoelectric switch to prevent mutual interference is to open the interval. And the farther the detection distance is, the larger the interval should be, and the specific interval should be determined according to the debugging situation. Of course, models with different operating frequencies can also be used.

Photoelectric switch wiring diagram:

The slot photoelectric switch is usually a standard U-shaped structure. The transmitter and receiver are located on both sides of the U-shaped groove and form an optical axis. When the detected object passes through the U-shaped groove and blocks the optical axis, the photoelectric switch The detected switch signal is generated. The slot photoelectric switch is safer and more suitable for detecting high-speed changes and distinguishing transparent and semi-transparent objects.

Optical fiber photoelectric switches use plastic or glass optical fiber sensors to guide light, so as to realize the detection of objects not in the vicinity. Generally, fiber optic sensors are divided into through-beam type and diffuse reflection type.

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Photoelectric switch article:

When repairing the photoelectric switching power supply, the step-down overhaul method can be used. The method is: connect the power plug of the display to an AC voltage regulator, and then adjust the output voltage of the voltage regulator to about 100V, then power on for maintenance, and gradually increase the power supply voltage for maintenance.

Fault example 1: The fuse is burned out when the machine is turned on, and the output voltage is zero. This situation is generally caused by the breakdown of the switch tube and the short circuit between the emitter and the collector. At this time, the switch tube can be removed first, and the resistance of the emitter and collector to the ground can be measured. If it is zero or very small, just replace it. But it is necessary to check whether there are any problems with other components before booting.

Fault example 2: "S"-shaped distortion of the grating appears. This kind of problem should focus on checking the filter circuit and the voltage stabilizing circuit. Generally, it is because a diode is open, which changes from full-wave rectification to half-wave rectification. This may also be caused by the reduction in the capacity of the filter capacitor.

Fault example 3: AC 220V rectifier filter circuit has a short-circuit fault, and the fuse is burned when the machine is turned on. First check whether the rectifier diode is short-circuited and the filter capacitor is leaking seriously. You can also unplug the degaussing coil to check whether the degaussing thermistor has short-circuit faults, and replace it if necessary. Failure example 4: No grating, no display, power indicator does not light up, but the insurance is not burned. At this time, check whether the AC mutual inductance transformer is open, whether the current-limiting resistance of the rectifier circuit is open (burned), or whether the rectifier diode is open.

Fault example 5: No grating, no display, and abnormal noises in the machine. If a "squeak" sound is made, it indicates that the oscillation frequency is low, and the components related to the oscillation should be checked. If a "click" sound is made, it indicates that the power supply is over-current protection, and the over-current protection circuit should be checked.