Magnetic detection apparatus

1. A magnetic detection apparatus comprising:

a magnetic detection sensor which includes a magnetoelectric transducer for detecting a magnetic field intensity, and a signal processing circuit for processing an output signal of the magnetoelectric transducer so as to output a signal of rectangular wave, and which detects a movement position and a moving direction of a magnetic moving object that gives a change to a magnetic field applied to the magnetoelectric transducer; and

a computer unit which processes an output signal of said magnetic detection sensor so as to detect the movement position and moving direction of the magnetic moving object;

wherein said magnetic detection sensor generates the output signal whose high level and low level have different potentials in accordance with the moving direction of the magnetic moving object; and

said computer unit includes three comparator circuits and detects the output signal of said magnetic detection sensor with three levels of comparison threshold values.

2. A magnetic detection apparatus as defined in claim 1 , wherein:

the output signal of said magnetic detection sensor based on a movement of the magnetic moving object in a forward direction becomes a maximum and a minimum of an output potential range; and

the high level S[high-1] and low level S[low-1] of the output signal of said magnetic detection sensor based on the movement of the magnetic moving object in the forward direction,

the high level S[high-2] and low level S[low-2] of the output signal of said magnetic detection sensor based on a movement of the magnetic moving object in a reverse direction, and

potentials C 1 [high] and C 1 [low], C 2 [high] and C 2 [low], and C 3 [high] and C 3 [low] of hystereses of respective comparison threshold value signals C 1 , C 2 and C 3 of the first, second and third comparator circuits, satisfy the following:

S[high-1]>C1[high]>S[high-2],

C1[high]>C1[low]>S[low-2],

S[high-2]>C2[high]>C2[low]>S[low-2],

S[high-2]>C3[high]>C3[low], and

S[low-2]>C3[low]>S[low-1].

3. A magnetic detection apparatus as defined in claim 2 , wherein the potentials C 1 [high] and C 1 [low], C 2 [high] and C 2 [low], and C 3 [high] and C 3 [low] of the hystereses of the signals of the respective comparison threshold value signals C 1 , C 2 and C 3 of three levels in said computer units, satisfy the following:

S[high-1]>C1[high]>S[high-2]>C1[low]>S[low-2],

S[high-2]>C2[high]>C2[low]>S[low-2], and

S[high-2]>C3[high]>S[low-2]>C3[low]>S[low-1].

4. A magnetic detection apparatus as defined in claim 3 , wherein the potentials C 1 [low] and C 3 [high] of the hystereses of signals C 1 and C 3 among the comparison threshold value signals C 1 , C 2 and C 3 of the three levels in said computer unit, satisfy the following:

C3[high]>C1[low].

5. A magnetic detection apparatus as defined in claim 1 , wherein:

the output signal of said magnetic detection sensor based on a movement of the magnetic moving object in a forward direction becomes a maximum and a minimum of an output potential range;

the high level S[high-1] and low level S[low-1] of the output signal of said magnetic detection sensor based on the movement of the magnetic moving object in the forward direction,

the high level S[high-2] and low level S[low-2] of the output signal of said magnetic detection sensor based on a movement of the magnetic moving object in a reverse direction, and

potentials C 1 [high] and C 1 [low], and C 2 [high] and C 2 [low] of hystereses of signals C 1 and C 2 among respective comparison threshold value signals C 1 , C 2 and CR of the first, second and third comparator circuits of said computer units, satisfy the following:

S[high-1]>C1[high]>S[high-2]>S[low-2]>C1[low]>S[low-1], and

S[high-2]>C2[high]>C2[low]>S[low-2]; and

the other comparison threshold value signal CR is a signal obtained by inverting an output signal of the first comparator circuit.

6. A magnetic detection apparatus as defined in claim 1 , which is used especially as an on-vehicle rotation detection apparatus.