Ultrasonic Sensor

A: Ultrasonic single-sheet and double-sheet sensors are a commonly used ultrasonic measurement technology. The difference between single-sheet and double-sheet sensors lies in the way ultrasonic waves are reflected during propagation. Single-sheet sensors have only one crystal, which sends sound waves after detecting an object and monitors its reflected signal; while double-sheet sensors have two crystals, one for sending sound waves and the other for receiving reflected signals. The working principle of ultrasonic single-sheet and double-sheet sensors is based on the speed of sound and the reflection of sound waves. By emitting ultrasonic waves to an object and measuring the time difference of the reflected signals, the distance between the object and the sensor is calculated. The distance between the object and the sensor is determined by calculating the propagation time of the sound wave, thereby achieving non-contact object detection.

A: Single-sheet and double-sheet sensors are widely used in paper printing machines, assembly machines, folding machines, packaging machinery, solar cells, silicon wafer manufacturing, labeling, PCB manufacturing, etc.

A: The advantages of ultrasonic sensors include:

1. Recognition ability is not affected by object color or transparency: Ultrasonic sensors detect objects through sound wave reflection, so the color or transparency of objects will not affect their readings.

2. Operable in the dark: Unlike proximity sensors that rely on light or vision, ultrasonic sensors can still effectively detect in dark environments.

3. Strong anti-interference ability: Ultrasonic sensors are not easily affected by dust, dirt, or high humidity environments, especially under extreme conditions, and they can provide more accurate readings than many other sensors.

4. High precision demonstrated in applications: Ultrasonic sensors can provide high measurement accuracy in measuring the thickness or distance of parallel surfaces.

5. Strong penetration: Ultra sonic sensors have high sensitivity and penetration, and can detect external objects, even deep objects.

6. Strong ability to resist environmental interference: Ultrasonic sensors can work stably under any lighting conditions, whether indoors, outdoors, or in complex lighting environments. They are capable of non-contact detection of light, smoke, dust, color, and materials, so in some applications, ultrasonic sensors are more effective than infrared sensors, which may be affected by smoke or black substances.

7. Wide application range: Ultrasonic sensors can be used for various applications such as water level detection, unmanned aerial vehicle applications, automatic obstacle avoidance applications, distance detection, etc.

8. Multifunctionality: Ultra sonic sensors can be used for presence detection, level detection, position detection, distance detection, etc., which can meet the needs of most non-contact detection.

The limitations of ultrasonic sensors include:

1. Cannot work in vacuum: Ultrasonic waves cannot be used in vacuum because they require air to propagate.

2. Not suitable for underwater applications: Water absorbs sound waves, affecting the detection capability of sensors.

3. Soft materials affect detection accuracy: If the surface of an object is covered with very soft materials, it may absorb more sound waves, making it difficult for the sensor to detect the target.

4. Temperature changes affect accuracy: Temperature changes may affect the accuracy of ultrasonic sensors. Although modern sensors provide temperature compensation functions that can be calibrated based on temperature and voltage changes, they may still be affected.

5. Small objects are difficult to detect: If an object is too small, it may not reflect enough sound waves to be detected by sensors.

6. Specific shapes are difficult to detect: The shape or position of certain objects may cause sound wave reflections to deviate from the sensor.

A: Ultrasonic sensors have the function of detecting liquid levels, transparent objects, and materials. Ultrasonic sensors can control tension and measure distance, mainly used in equipment transportation for packaging, bottle making, material handling, coal inspection, plastic processing, and the automotive industry. Ultrasonic sensors can be used for process monitoring to improve product quality, detect defects, determine presence or absence, and other aspects.

A: In terms of installation, first of all, the accuracy of the sensor installation position should be ensured. It should be kept perpendicular to the paper transmission path, so that the ultrasonic wave can be vertically projected to the paper and the most accurate reflection signal can be obtained. The installation height must also be adjusted strictly according to the equipment manual. Being too close or too far from the paper may affect the detection accuracy. For example, being too close may cause the reflected wave to be too strong and saturated, while being too far may cause the reflected wave to be too weak to be effectively detected. During use, the transmitting and receiving ends of the sensor should be cleaned regularly to prevent dust, paper scraps and other impurities from accumulating and affecting the transmission and reception of ultrasonic waves. At the same time, pay attention to the temperature and humidity of the working environment, because extreme temperature and humidity conditions may change the propagation characteristics of ultrasonic waves, thereby affecting the reliability of detection. For example, in a humid environment, water vapor may interfere with ultrasonic propagation and cause misjudgment.

A: In general, high-quality ultrasonic single-sheet and double-sheet sensors have very high detection accuracy, and the correct recognition rate of single-sheet and double-sheet paper can reach more than 99%. Its accuracy mainly depends on the hardware performance of the sensor, such as the sensitivity of the transmitting and receiving elements, the accuracy of the signal processing circuit, etc. At the same time, it is also related to factors such as the material and thickness of the paper. For paper with uniform thickness and stable material, the sensor can achieve extremely high detection accuracy. However, for some special materials, such as paper with coating or uneven texture on the surface, the accuracy may be slightly affected, but through appropriate parameter adjustment and calibration, a high detection accuracy can still be guaranteed. For example, in fields such as banknote printing, which require extremely high accuracy in detecting single and double sheets of paper, ultrasonic single and double sheet sensors can fully meet production requirements after fine debugging and effectively guarantee product quality.

A: The service life of ultrasonic single-sheet and double-sheet sensors is affected by many factors, and its service life is generally around 3-10 years.

1. Internal component quality factors The quality of the core components of the sensor, such as ultrasonic transmitters and receivers, is the key. Transmitting and receiving components made of high-quality piezoelectric ceramics and other materials can be used for a long time under normal use conditions. For example, some sensors that use high-purity piezoelectric materials and undergo fine manufacturing processes can maintain stable performance of their internal components for a long time, and their service life may reach 8-10 years. The quality of the signal processing circuit will also affect the service life. If the circuit design is reasonable and high-quality electronic components, such as durable capacitors, resistors and integrated circuit chips, are used, it can reduce failures caused by aging of electronic components and help extend the overall life of the sensor. 2. Environmental factors The temperature of the working environment has a significant impact on the life of the sensor. In the appropriate temperature range, such as 0-40 degrees Celsius, the performance of the internal components of the sensor is relatively stable. However, if it is in a high temperature environment for a long time (such as more than 60 degrees Celsius), it may accelerate the aging of components, especially plastic housings and electronic components. High temperatures may cause the housing to deform, the circuit solder joints to loosen, and affect the performance of the ultrasonic components, shortening the life of the sensor to 3-5 years or even shorter. Humidity is also an important factor. High humidity environments may cause moisture inside the sensor, causing short circuits or corrosion. In a humid environment, if there is no good waterproof and moisture-proof measures, the life of the sensor may be greatly reduced. Dust and impurities in the environment are also not conducive to the long-term use of the sensor. Dust may accumulate on the surface of the ultrasonic transmitter and receiver, affecting the efficiency of ultrasonic transmission and reception. Long-term accumulation may damage the surface of the component, reduce the performance of the sensor, and thus shorten the service life.

3. Frequency and intensity factors of use High frequency of use will accelerate the wear of the sensor. If the sensor needs to be tested continuously, such as in a high-speed paper production line, where multiple tests are performed per second, the internal components will wear out faster than in low-frequency use. The sensor may also be damaged by large mechanical shock or vibration. Frequent mechanical movement near the installation location or impact during equipment transportation may cause the internal components of the sensor to shift or be damaged, thereby shortening its service life.

A: When using single-sheet and double-sheet ultrasonic sensors, customers must ensure that the angles of the two probes are aligned during installation and that the angle of the two probes cannot be offset to ensure that the vertical transmission and reception are in an equal relationship during the transmission and reception process.

A: Ultrasonic double sheet sensor can be installed perpendicular to the paper. When detecting ordinary paper and film, the swing of the paper will not affect the function of the system. For thin metal sheets and thicker plastic films (such as credit cards), it is recommended to install the system at a 27° tilt. For special types of thicker paper, the system should be installed at a 27° to 30° tilt.

A: A high-frequency ultrasonic transmitter emits an ultrasonic beam from the bottom of the sheet. The sound wave causes the sheet to vibrate, which in turn generates a very small sound wave on the other side of the sheet. This small sound wave is received by the ultrasonic receiver. If there are two sheets, one on top of the other, the signal becomes even weaker and basically cannot reach the receiver.