The superiority of photoelectric sensor detection

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 instantly after 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 light emitting 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 electric 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:

The use of photoelectric sensors to detect advanced systems in automation equipment and devices is also the basis for advanced process control, operation optimization, and energy-saving strategies.

In this paper, through the statistical analysis of the photoelectric sensor circuit principle and test results, it has obtained more applicable, operational feasibility, and parameter optimal performance indicators, which created favorable conditions for on-site use.

1. Working principle The photoelectric sensor is a switch that emits a light source through infrared or invisible light. The chip receives the signal and makes a corresponding action to detect the presence or absence of an object within a certain distance, as shown in Figure 1.

1.1 The transmissive type is shown in Figure 2. Install the emitter and receiver face to face, adjust the position and sensitivity of the optical axis and connect the power supply; then adjust the emitter and receiver to the left and right, and fix the switch on the action indicator. Center position; adjust the position in the up and down direction according to the same method; after the adjustment is completed, place the detection object on the optical axis and fix it in a stable action position.

※ If the detection object is translucent or small (∮16mm or less), it may not be detected because the light can pass through;

※ For the sensitivity adjustment method, please refer to the setting and adjustment method of the diffuse reflection photoelectric switch.

1.2 Mirror emission type As shown in Figures 3 and 4, the mirror reflection type photoelectric sensor and the mirror (MS-2) are placed face to face and then the power is turned on. Then, fine-tune the position of the reflector and photoelectric switch left and right, confirm the operating range of the action indicator, and fix it at the center position; adjust the up and down position in the same way; after the adjustment is completed, place the detection object on the optical axis, and It is fixed at the stable action position;

※ If two or more photoelectric switches are used at the same time in parallel, the distance between them should be greater than 30cm, leave enough space between the switch and the measured object, or place the measured object and the optical axis at an angle of 30-45 degrees, (close distance detection For objects with high emissivity, a photoelectric switch with a built-in polarizing mirror can be selected for use) ※ For the sensitivity adjustment method, please refer to the setting and adjustment method of the direct reflection photoelectric switch.

1.3 The reflection type of the polarizer is shown in Figure 5. When the light emitted by the illuminator passes through the polarizer, it will be changed into horizontal and transverse light and reach the mirror MS-2 (MS-3), and then it is caused by the mirror. It changes into a vertical light and reaches the polarizing mirror of the light receiver. This detection object can also be detected by a general mirror.

1.4 The diffuse reflection type is shown in Figures 6 and 7. Generally, it can be used at the maximum sensitivity position, but considering the influence of the background object and the installation surface, the sensitivity must be adjusted; the detection object is placed in the detection position, and the sensitivity adjustment knob Slowly adjust from the minimum sensitivity position (Min.) to the action indicator (yellow LED) ON and the self-diagnosis indicator (green LED) OFF position, record this position as; remove the detection object, continue to slowly increase the sensitivity knob to When the action indicator (yellow LED) is OFF and the self-diagnostic indicator (green LED) is ON, mark this position as. [When the self-diagnosis indicator (green LED) and action indicator (yellow LED) are both OFF, the maximum sensitivity (Max.) position is the position]; the middle position of the and is the best sensitivity position;

※ The above sensitivity adjustment method is based on the light incident action, the action indicator light (yellow LED) during the shading action is the opposite;

※ The detection distance stated in the product specification is based on the size of white matte paper. The detection distance varies with the size of the detection object, the surface condition, and the presence or absence of gloss.

2. The application confirms the passage of objects in the narrow aisle, detects the presence of transparent bottles, determines the shape of accessories, detects the pins of accessories, determines the presence or absence of threads, determines the direction of the IC, detects the elevator position, detects whether the bottle falls, and the product is automatically transported Line and so on.

3. Parameter comparison Product model: BX series Features: timing mode selection, built-in timer, built-in voltage reverse connection protection, over-current protection (see Table 1)

※ (*1) Equipped with MS-4, the detection distance is the same, and it can detect within less

than 0.1m; ※ (*2) With MS-2, the detection distance is 0.1-2m, and it can be detected within 0.1m;

※ (*3) Matte white paper (200mmX200mm).

4. Analysis and comparison

4.1 The detection distance of the photoelectric sensor has certain specifications;

4.2 The standard detection objects of through-beam type, specular reflection type, polarized reflection type and diffuse reflection type are different;

4.3 The hysteresis distance specification requirements of the through-beam type, specular reflection type, polarized reflection type, and diffuse reflection type are different;

4.4 The light sources of through-beam type, specular reflection type, polarized reflection type and diffuse reflection type are different;

4.5 The accessories and weights of the through-beam type, specular reflection type, polarized reflection type, and diffuse reflection type are different. 5. Concluding remarks The superior and advanced detection performance of photoelectric sensors, such as excellent protection, sensitivity and accuracy, is widely used in automatic equipment detection devices. However, it is still restricted by the conditions of use. It is strictly forbidden to use strong light, sunlight, spotlights, and direct incident photoelectric switches. Within the direction angle, it is necessary to use a shading plate, a support plate and other requirements for use.