China OEM IR Wave Sensor,Capacity Sensor,PIR Sensor Factory

Hawking will publish a memoir, which is the first book written entirely on his own without the help of others. How has Hawking talked and delivered speeches with others?

Originally, the computer installed under and behind Hawking's wheelchair contains an audio amplifier and sound synthesizer, which are controlled by the IR wave sensor on Hawking's glasses and can respond to light changes caused by facial movement. Therefore, we can see that IR wave sensor technology has been very mature, which has been integrated into people's daily life.

Before we know about IR wave sensors, first of all, we should know what IR wave is.

What is an IR wave?

We know that light is also a kind of radiated electromagnetic wave. In human experience, it usually refers to the light wave domain visible to the naked eye, which can be felt by human eyes from 400nm (purple light) to 700nm (red light).

IR wave is a kind of light invisible to the human eye, so it has all the characteristics of light. But at the same time, the IR wave also has a very significant thermal effect. All substances above absolute zero, i.e. - 273 ℃, can produce IR wave rays.

Therefore, simply speaking, an IR wave sensor is a sensor that uses IR waves as the medium for data processing.

Types of IR wave sensors

According to different emitting methods, IR wave sensors can be divided into active and passive.

• Working principle and characteristics of active IR wave sensor

The transmitter of the active IR wave sensor sends out a modulated infrared beam and is received by the infrared receiver to form a warning line composed of infrared beams. In the case of leaves, rain, small animals, snow, dust, and fog, the alarm will not be given, and the alarm will be given when people or objects of a considerable volume are blocked.

Active IR wave detector technology mainly adopts one engine and one receiver, which belongs to linear prevention. Now it has developed from the initial beam to multi-beam, and can also double engine and double receiver to minimize the false alarm rate, to enhance the stability and reliability of the product.

• Working principle and characteristics of passive IR wave sensor

The passive IR wave sensor works by detecting the infrared emitted by the human body. The sensor collects the external infrared radiation and then gathers it on the IR wave sensor. IR wave sensors usually use pyroelectric elements, which will release charge when the temperature changes after receiving infrared radiation and generate an alarm after detection and processing.

This kind of sensor is aimed at detecting human body radiation. Therefore, the radiation-sensitive element must be very sensitive to infrared radiation with a wavelength of about 10 μm. To be sensitive to the infrared radiation of the human body, its radiation surface is usually covered with a special filter, so that the interference of the environment is controlled.

The passive IR wave sensor consists of two pyroelectric elements connected in series or parallel. Moreover, the two electric polarization directions are exactly opposite, and the environmental background radiation has almost the same effect on the two pyroelectric elements so that the pyroelectric effects are offset each other, so the detector has no signal output.

According to different energy conversion methods, IR wave sensors can be divided into photon type and pyroelectric type.

• Photon IR wave sensor

Photon IR wave sensor is a sensor that works by using the photon effect of infrared radiation. The so-called photon effect refers to that when an IR wave ray is incident on some semiconductor materials, the photon flow in infrared radiation interacts with electrons in semiconductor materials, changing the energy state of electrons, resulting in various electrical phenomena.

The main characteristics of photon detector are high sensitivity, fast response speed, and high response frequency, but the disadvantage is that the detection band is narrow and generally works at low temperature (to maintain high sensitivity, liquid nitrogen or thermoelectric refrigeration are often used to cool the photon detector to a lower working temperature).

• Pyroelectric IR wave sensor

Pyroelectric IR wave sensor uses the temperature change of the element itself caused by the thermal effect of infrared radiation to detect some parameters. Its detection rate and response speed are not as good as the photon sensor.

However, because it can be used at room temperature and its sensitivity is independent of wavelength, it has a wide range of applications. Pyroelectric IR wave sensor based on ferroelectric pyroelectric effect has high sensitivity and has been widely used.

Development of IR wave sensors

In recent years, the development trend of IR wave sensors is mainly reflected in the following four aspects:

First, new materials and processing technology are adopted to improve the infrared detection rate of the sensor, increase the response wavelength, shorten the response time, improve the pixel sensitivity and pixel density, improve the anti-interference performance and reduce the production cost.

The second is the large-scale and multifunctional sensor. With the development of microelectronic technology and the continuous expansion of the application field of sensors, IR wave sensors are developing from small and single function to large-scale and multi-function.

Such as the large-scale IR wave sensor developed abroad (16×16 to 64×64 pixels) in addition to the measurement of temperature field, can also obtain the functions of human body detection or safety monitoring in large areas that are not possessed by advanced and small IR wave sensors. It is very suitable for applications in home automation, medical care, safety protection, and so on.

The third is the intelligence of sensors. The new intelligent IR wave sensor usually has multiple microprocessors built-in, with advanced digital signal processing or compensation functions such as Fourier transform and wavelet transform, self-diagnosis function, two-way digital communication, and other functions, which greatly improves the stability, reliability, signal-to-noise ratio, and convenience of the sensor.

Fourth, further miniaturization and integration of sensors. Using on-chip integration technology, other new device structures, and new manufacturing technology, driven by MEMS (microelectromechanical system) and even NEMS (nanoelectromechanical system) based on nanotechnology, the size of IR wave sensor is greatly reduced, the power consumption is greatly reduced and the integration degree is significantly improved.

Due to the superior performance of IR wave sensors, many mainstream instrument research units and manufacturers invest more and more in their R&D. 

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China OEM IR Wave Sensor,Capacity Sensor,PIR Sensor Factory