초록 ▼

The device proposed comprises a Hall sensor (101) with an associated magnet (102), a pulse-generation wheel (104) rotating at an angular speed w and fitted with teeth having a rising and falling face, the wheel turning in front of the sensor to generate a curve which corresponds exactly to the tooth

The device proposed comprises a Hall sensor (101) with an associated magnet (102), a pulse-generation wheel (104) rotating at an angular speed w and fitted with teeth having a rising and falling face, the wheel turning in front of the sensor to generate a curve which corresponds exactly to the tooth-face positions and which can be used to determine precisely the position of the rotating shaft. The Hall sensor 9101) registers the variation with time of the magnetic flux density through the pulse-generation wheel (104) as a Hall voltage signal. This signal is converted by a differentiator circuit (103.2) into a differentiated signal. The maxima and minima of the differentiated signal are determined and a digital output signal (AS) is generated form the differentiated signal, the low-level to high-level transitions in the output signal corresponding to the maxima of the differentiated signal and the high-level to low-level transitions corresponding to the minima.

대표청구항 ▼

[ What is claimed is:] [1.] In a device for determining the position of a rotating shaft, said device comprising a wheel, connected to said shaft, that rotates at an angular speed w in front of a Hall generator and a magnet, wherein the wheel is provided with cogs (Z) that have an ascending edge (ZF

[ What is claimed is:] [1.] In a device for determining the position of a rotating shaft, said device comprising a wheel, connected to said shaft, that rotates at an angular speed w in front of a Hall generator and a magnet, wherein the wheel is provided with cogs (Z) that have an ascending edge (ZFA) and a descending edge (ZFF) and produce variations in the magnet's flux density B over time, wherein the Hall generator detects the variations and emits a proportional signal B(t), said device further comprising a differentiator that converts the signal B(t) into a differentiated signal (SMP1), the improvement comprising an inflection-point detection circuit coupled to the differentiator for identifying the maxima (SMP1.sub.max) and minima (SMP1.sub.min) of the differentiated signal, said detection circuit producing a digital output signal (AS) in which the transitions from the low level (ASL) to the high level (ASH) of the digital output signal represent the maxima and the transitions from the high level to the low level represent the minima of the differentiated signal, thereby indicating the positions of the ascending edges (ZFA) and descending edges (ZFF) of the cogs, and wherein the said detection circuit comprises a differential amplifier to which the differentiated signal is input to a first input terminal thereof and wherein the output terminal of the said amplifier is connected to a first terminal of a bi-directional driver, a first input terminal of the said amplifier is connected to a first input terminal of a first comparator and to a first input terminal of a second comparator, and a second input terminal of the said amplifier is connected to a ground-referenced capacitor and a second input terminal of the first comparator, to which a second terminal of the bi-directional driver is also connected, and a third terminal of the bi-directional driver is connected to the output terminal of the second comparator, a second input terminal of which is ground-referenced.