Magnetic line-type position-angle detecting device
To provide a magnetic line-type position-angle detecting device capable of detecting an absolute position on a non-contact basis and with high resolution and inexpensive construction, the magnetic line-type position-angle detecting device includes a magnetic line sensor 1 having a plurality of magnetic sensor elements 1 a arranged in line, and a magnetic generating element 2 confronting the magnetic line sensor and movable in a direction conforming to the line of the magnetic sensor elements 1 a . The magnetic sensor elements 1 a of the magnetic line sensor 1 are sequentially selected by a scanning circuit 3 , a signal from the selected sensor element 1 a is processed into a digital signal through an amplifier 4 , and an analog-to-digital converting circuit 5 . By a calculation processing circuit 6 , a distribution of magnetic fields applied to the magnetic line sensor 1 are measured to calculate the position and/or angle of the magnetic generating element 2.
1. A magnetic line-type position-angle detecting device comprising:
a magnetic line sensor having a plurality of magnetic sensor elements arranged in a linear array;
a magnetic generating element held in face-to-face relation with the magnetic line sensor and movable along the magnetic line sensor in a direction conforming to the direction in which the magnetic sensor elements are deployed;
a scanning circuit to sequentially select one of the magnetic sensor elements of the magnetic line sensor;
an amplifier to amplify a signal outputted from the selected sensor element;
an analog-to-digital converting circuit to convert an output from the amplifier into a digital signal; and
a calculation processing circuit to evaluate a distribution of magnetic fields, applied to the magnetic line sensor, in reference to an output of the analog-to-digital converting circuit to thereby calculate a position and/or an angle of the magnetic generating element,
wherein the calculation processing circuit is capable of detecting a zero-crossing position of a waveform of a sensor signal outputted from the analog-to-digital converting circuit,
wherein the magnetic generating element has two magnetic pole boundaries in a direction in which the sensor elements of the magnetic line sensor are arranged, and
wherein the calculation processing circuit is capable of detecting the position of the magnetic generating element by detecting two zero-crossing positions obtained from a waveform of the sensor signal outputted from the analog-to-digital converting circuit.
2. The magnetic line-type position-angle detecting device as claimed in claim 1 , wherein the magnetic generating element includes a magnet having three N, S and N magnetic poles or three S, N and S magnetic poles confronting the magnetic line sensor and arranged in this specific order so as to have the two magnetic pole boundaries, and the calculation processing circuit is capable of detecting the position of the magnetic generating element in reference to a waveform of a sensor signal obtained from the output of the analog-to-digital converting circuit.
3. The magnetic line-type position-angle detecting device as claimed in claim 1 , wherein the calculation processing circuit is capable of converting the zero-crossing position into an actual position of the magnetic generating element to thereby calculate and output an absolute position.
4. The magnetic line-type position-angle detecting device as claimed in claim 1 , wherein the calculation processing circuit is capable of determining an intermediate point from the two detected zero-crossing positions for outputting the detected position of the magnetic generating element.
5. The magnetic line-type position-angle detecting device as claimed in claim 1 , wherein the magnetic line sensor comprises four magnetic line sensors, and
the four magnetic line sensors are arranged in a square form and the calculation processing circuit is capable of detecting the angle and the position of the magnetic generating element simultaneously.
6. The magnetic line-type position-angle detecting device as claimed in claim 1 , wherein the magnetic generating element is angularly movable generally along the magnetic line sensor in a direction, conforming to the direction in which the magnetic sensor elements are deployed, on an arcuate path about a predetermined rotation axis and the calculation processing circuit is capable of measuring a distribution of magnetic fields applied to the magnetic line sensor for detecting the position of the magnetic generating element above the line sensor, and capable of determining from the detected position, an angle at which the magnetic generating element is positioned about the rotation axis.
7. The magnetic line-type position-angle detecting device as claimed in claim 6 , wherein the calculation processing circuit includes a parameter storage for storing such parameters as a distance of arrangement of the magnetic generating element from the rotation axis and a position of origin of the angle of the magnetic generating element and wherein the parameters to be stored in the parameter storage can be set from outside of the calculation processing circuit.
8. The magnetic line-type position-angle detecting device as claimed in claim 7 , wherein the calculation processing circuit is capable of detecting the position of the magnetic generating element above the magnetic line sensor, by utilizing the parameters stored in the parameter storage, to thereby calculate an absolute angle from the detected position data.