热释电红外传感器简介

Pyroelectric infrared sensor Preface Pyroelectric infrared sensor is a very potential applications of the sensor.It can detect people or animals, the infrared transmitter and converted into anelectrical signal output. As early as 1938, it was proposed detection using pyroelectric infrared radiation effect, but not taken seriously. Until the sixties, with the laser, infrared technology is developingrapidly, it has contributed tothepyroelectric effect and research on pyroelectric crystals application development. In recent years, along with the rapid development of integrated circuit technology, as well as the characteristics of the sensor depth study of the relevant application specific integrated circuit processing technology is also growing rapidly. This article first describes the principle of the pyroelectric sensor, and then describe the relevant ASIC processing technology.

Pyroelectric effect

In nature, any more than the absolute temperature (-273K) objects will have infrared spectra, objects at different temperatures the wavelength of infrared energy

released is not the same, so the level of infrared wavelengths is related to temperature, and radiation energy size and surface temperature.

1µm wavelength of visible light is usually less, but more than 1µm light the human eye can not see, but can be an appropriate instrument to detect the energy oradiation.

When some of the crystal is heated, the crystal will have an equal number of both ends of the opposite sign of charge, such as heat of changes in the polarization phenomenon, known as the pyroelectric effect. Typically, the crystals produced by the spontaneous polarization bound charge is attached to the air from the surface of free electrons in the crystal and in its

spontaneous polarization electric moment can not be demonstrated. When the temperature changes, positive and negative charges in the crystal structure of the relative center of gravity shifts, the spontaneous polarization changes, the crystal surface will have run out of charge, charge depletion is proportional to the polarization degree of the situation, Figure 1 shows the

pyroelectric The principle effect of the formation.

Pyroelectric effect can produce a crystal or call the pyroelectricpyroelectric body components, the material commonly used in single crystal (LiTaO3, etc.), piezoelectric ceramic (PZT, etc.) and polymer film (PVFZ, etc.) [ 2] When represented LiTaO3 pyroelectric material is self-polarized state, the absorption of infrared incident, the crystallization of the surface temperature change, since the polarization has changed, crystal surface charge becomes imbalanced, the imbalance taken out of charge voltage can be measured by infrared. Pyroelectric materials produced only when the temperature changes the voltage, if the infrared radiation has been, there is no imbalance in voltage, if no infrared radiation, the crystal surface charge on the in an unbalanced state, so the output voltage Pyroelectric infrared sensors, infrared light irradiation due to gain or lose heat and shelter, resulting in voltage output. In principle should be independent of the wavelength, but the material made by the pyroelectric sensor has a light transmission window, the translucent windows and wavelength selection of a relationship. To SiO2 as the window material, such as sensors, it can almost all visible light, while others near the window material can only 4µm wavelength of light, and some wavelengths of light through 6.1µm, and some through 8µm ~ 14µm wavelength of light, so use a different window materials which can be confirmed that the heat generated by the wavelength of light.