关于磁性传感器,你想知道的在这里(中英文)
磁性传感器是检测磁铁或电流产生的磁力和地磁力大小的传感器。有许多不同类型的磁性传感器。
本节介绍典型的传感器类型及其特性。
A magnetic sensor is a sensor that detects the magnitude of magnetism and geomagnetism generated by a magnet or current. There are many different types of magnetic sensors.
This section explains the typical sensor types and their features.
线圈 / Coiled
线圈是可以检测磁通密度变化的简单磁性传感器。如图所示,当磁铁靠近线圈时,线圈中的磁通密度增加ΔB。然后,在线圈中产生在阻碍磁通密度增加的方向上产生磁通的感应电动势/感应电流。相反,将磁铁移离线圈会降低线圈中的磁通密度,因此线圈中会产生感应电动势和感应电流,从而增加磁通密度。
Coils are the simple magnetic sensors that can detect changes of the magnetic flux density. As shown in the figure, when a magnet is brought close to the coil, the magnetic flux density in the coil increases by ΔB. Then, an induced electromotive force/induced current that generates a magnetic flux in a direction that hinders an increase in magnetic flux density is generated in the coil. Conversely, moving the magnet away from the coil reduces the magnetic flux density in the coil, so induced electromotive force and induced current will be generated in the coil to increase the magnetic flux density.
而且,当磁体不移动时磁通密度没有变化,因此不会产生感应电动势或感应电流。通过测量该感应电动势的方向和大小,可以检测磁通密度的变化。
由于其结构简单,线圈不易损坏。然而,输出电压取决于磁通量的变化率。可能无法使用线圈来检测固定磁铁或变化非常缓慢的磁通量。
Also, since there is no change in the magnetic flux density when the magnet is not moved, no induced electromotive force or induced current will be generated. By measuring the direction and magnitude of this induced electromotive force, it is possible to detect the change in magnetic flux density.
Because of its simple structure, a coil is not easily damaged. However, the output voltage depends on the rate of change of the magnetic flux. It may not be possible to use a coil to detect a fixed magnet or magnetic flux that changes very slowly.
干簧管(磁簧开关) / Reed Switch
干簧管是一种传感器,将从左右两侧伸出的金属片(簧片)封装在玻璃管内,在簧片重叠的位置处留有间隙。当外部施加磁场时,这些簧片就会被磁化。当簧片被磁化时,重叠部分相互吸引并接触,然后开关接通。
A reed switch is a sensor in which metal pieces (reed) extending from both the left and right sides are enclosed in a glass tube with a gap at the overlapping position of the reeds. When a magnetic field is applied externally, these reeds are magnetized. When the reeds are magnetized, the overlapping parts attract each other and come into contact, then the switch turns on.
霍尔元件 / Hall Elements
霍尔元件是利用霍尔效应的器件。“Hall”源自霍尔博士发现霍尔效应的名字。它基于这样的现象:当向电流流过的物体施加垂直于电流的磁场时,电动势出现在与电流和磁场都正交的方向上。
当电流施加到薄膜半导体时,通过霍尔效应输出与磁通密度及其方向相对应的电压。霍尔效应用于检测磁场(如图所示)。
A Hall element is a device that uses the Hall effect. “Hall” came from Dr. Hall's name for discovering Hall effect. It is based on the phenomenon that the electromotive force appears in the direction orthogonal to both the current and the magnetic field when applying a magnetic field perpendicular to the current to the object through which current is flowing.
When a current is applied to a thin film semiconductor, a voltage corresponding to the magnetic flux density and its direction is output by the Hall effect. The Hall effect is used to detect a magnetic field, (shown in the figure).
霍尔元件即使在磁通密度没有变化的静态磁场的情况下也可以检测磁场。因此,霍尔元件被用于各种应用,例如与磁铁组合使用的非接触式开关、角度传感器和电流传感器。使用霍尔元件的地磁传感器广泛用于智能手机和其他应用。
Hall elements can detect a magnetic field even in the case of a static magnetic field with no change in magnetic flux density. Therefore, Hall elements are used in various applications, such as non-contact switches used in combination with magnets, angle sensors, and current sensors. Geomagnetic sensors using Hall elements are widely used in smartphones and other applications.
磁阻元件 / Magnetoresistive Element
使用材料检测磁场的元件,当施加磁力时电阻会发生变化,这种元件称为磁阻(MR)元件。
除了半导体磁阻元件(SMR)之外,作为使用铁磁薄膜材料的磁阻元件的代表示例,还有各向异性磁阻元件(AMR)、巨磁阻元件(GMR)和隧道磁阻元件(TMR)三种传感器。
An element that detects a magnetic field using a material, that resistance changes when magnetic force is applied, is called a magnetoresistive, (MR), element.
Other than semiconductor magnetoresistive element, (SMR), there are three kinds of sensors as representative examples of the magnetoresistive element using a ferromagnetic thin film material such as anisotropic magnetoresistive element, (AMR), giant magnetoresistive element, (GMR), and tunnel magnetoresistive element, (TMR).
半导体磁阻元件(SMR)
Semiconductor Magnetoresistive Element (SMR)
霍尔元件是测量洛伦兹力产生的霍尔电压的传感器,而磁阻元件是利用洛伦兹力引起的电阻值变化的传感器。下图显示了AKM也生产的N型半导体磁阻元件(SMR:半导体磁阻)的电阻值如何变化。SMR结构中,金属电极放置在半导体薄膜上。当如图所示的顺时针方向的电流流过半导体薄膜时,作为N型半导体的载流子的电子逆时针方向流动,将矢量的速度设为“v”。当施加如图所示方向的磁场 B 时,电子受到洛伦兹力,路径随着弯曲而变长,
Whereas the Hall element is a sensor that measures the Hall voltage generated by the Lorentz force, the magnetoresistive element is a sensor that utilizes the change in the resistance value caused by the Lorentz force. The following figure shows how the resistance value of an N-type semiconductor magnetoresistive element (SMR: Semiconductor Magnetoresistive), which AKM also produces, changes. Metal electrodes are placed on a semiconductor thin film in the structure of SMR. When a clockwise current as shown in the figure flows through the semiconductor thin film, electrons which are carriers of N-type semiconductors flow counterclockwise, and the velocity of the vector is assumed as "v". When applying a magnetic field B oriented as shown in the figure, electrons undergo Lorentz force and the path becomes longer as being bent, so that the resistance value increases.
各向异性磁阻元件 (AMR)
Anisotropic Magnetoresistive Eelement (AMR)
电子的散射程度在强磁性膜的磁化方向与电流方向平行的情况(a)和磁化方向与电流方向垂直的情况(b)之间变化。因此,电阻值也会发生变化。
The scattering degree of electro changes between the case (a) where the magnetization direction of the ferromagnetic film is parallel to the direction of current and the case (b) where the direction of magnetization is vertical to the current direction. Therefore, the resistance value also changes.
巨磁阻元件 (GMR)
Giant Magnetoresistive Element (GMR)
在铁磁材料(固定层)、非磁性金属和铁磁材料(自由层)的层叠膜的情况下,电子的散射程度根据固定层和自由层的磁化方向是否反平行而变化(a) 或平行 (b)。因此,电阻值发生变化。
In the case of a laminated film of ferromagnetic material, (pinned layer), nonmagnetic metal and ferromagnetic material, (free layer), the scattering degree of electron changes depending on if the direction of magnetization of the pinned layer and the free layer are antiparallel (a) or parallel (b). Therefore, the resistance value changes.
隧道磁阻元件 (TMR)
Tunnel Magnetoresistive Element (TMR)
在铁磁材料(固定层)、绝缘体和铁磁材料(自由层)的层叠膜的情况下,穿过绝缘体的电子比例由于隧道效应而变化,并且电阻值根据方向而变化固定层和自由层的磁化强度是反平行(a)或平行(b)。
In the case of a laminated film of ferromagnetic material, (pinned layer), insulator and ferromagnetic material, (free layer), the proportion of electrons passing through the insulator changes due to the tunnel effect and the resistance value changes depending on if the direction of magnetization of the pinned layer and the free layer are antiparallel (a) or parallel (b).
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