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| [[Fichier:HallEffect.jpg|150px]] | | [[Fichier:HallEffect.jpg|150px]] |
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− | *** IMAGE RARE EARTH AIMANT ***
| + | [[Fichier:Aimant-Rare-Earth.jpg|150px]] |
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| === Comment cela fonctionne === | | === Comment cela fonctionne === |
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| [[Fichier:TheHallEffect.jpg]] | | [[Fichier:TheHallEffect.jpg]] |
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− | [[Fichier:Aimant-Rare-Earth.jpg|150px]] | + | La tension de Hall peut être calculée comme VHall = σB où |
| + | * VHall = Champ Electro Magnétique en volts |
| + | * σ= Sensibilité en Volts/Gauss |
| + | * B= Le champ magnétique appliqué en Gauss |
| + | * I= Courant induit (bias current) |
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| + | Initialement la première utilisation de cette découverte fût axée sur la classification périodique des éléments chimiques. Le développement des semi-conducteurs indium arsenic en 1950 à conduit à la création des premiers instruments à effet Hall utiles. Les senseurs à effet Hall permettait de mesurer des champs magnétiques continu ou static mais nécessitaient que le senseur soit en mouvement. En 1960 la popularisation des semi-conducteurs silicon conduisit à la création des premiers composants combinant un capteur à Effet Hall et un amplificateur opérationnel. Cela produisit ce qui nous appelons classiquement aujourd'hui un Switch Effet Hall à sortie digital (digital output Hall switch). |
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| + | [[Fichier:HallEffectSwitch.jpg]] |
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| + | The continuing evolution of Hall transducers technology saw a progression from single element devices to dual |
| + | orthogonally arranged elements. This was done to minimize offsets at the Hall voltage terminals. The next pro- |
| + | gression brought on the quadratic of 4 element transducers. These used 4 elements orthogonally arranged in a |
| + | bridge configuration. All of these silicon sensors were built from bipolar junction semiconductor processes. A |
| + | switch to CMOS processes allowed the implementation of chopper stabilization to the amplifier portion of the |
| + | circuit. This helped reduce errors by reducing the input offset errors at the op amp. All errors in the circuit non |
| + | chopper stabilized circuit result in errors of switch point for the digital or offset and gain errors in the linear out- |
| + | put sensors. The current generation of CMOS Hall sensors also include, a scheme that actively switched the |
| + | direction of current through the Hall elements. This scheme eliminates the offset errors typical of semiconduc- |
| + | tor Hall elements. It also actively compensates for temperature and strain induced offset errors. The overall |
| + | effect of active plate switching and chopper stabilization yields Hall-Effect sensors with an order of magnitude |
| + | improvement in drift of switch points or gain and offset errors. |
| + | Melexis uses the CMOS process exclusively, for best performance and smallest chip size. The developments to |
| + | Hall-Effect sensor technology can be credited mostly to the integration of sophisticated signal conditioning cir- |
| + | cuits to the Hall IC. Recently Melexis introduced the world’s first programmable linear Hall IC, which offered |
| + | a glimpse of future technology. Future sensors will programmable and have integrated microcontroller cores to |
| + | make an even “smarter” sensor. |
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| == Montage == | | == Montage == |