JPS62132102A - Position detector - Google Patents

Abstract

PURPOSE:To achieve miniaturization and wt. reduction and to enable the detection of an absolute position, in at least a part of the magnetic field generating means on the same truck, by generating inverse magnetic fields at an interval different from that in the other part on said track. CONSTITUTION:A magnetic field generating pattern 2 is formed of a magnetizing pattern 201 wherein N-poles and S-poles are alternately arranged on the same track at an equal interval having a pitch length P and magnetizing patterns 211, 212 provided to both sides of said pattern 201 so that N-poles and S-poles having polarities respectively different from those at both terminals of the magnetizing pattern 201 are alternately arranged at an equal interval having a pitch length P/2. A magnetic sensor 1 is opposed to the pattern 2 and has at least four or more of magnetic resistance effect elements 31-34 arranged to the surface opposed to the pattern 2 at an equal interval having a pitch length P/4 in a predetermined displacement direction. When the sensor 1 and the pattern 2 are relatively displaced and the elements 31, 32 are opposed to the patterns 201, 211, the difference between the resistance values of the elements 31, 32 is respectively shifted by 90 deg., 180 deg.. By utilizing this difference, a predetermined position represented by a boundary position is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a detector for relative position change between a magnetic field generating means and a magnetoresistive element, and is particularly suitable for use in absolute position detection. Concerning vessels.

The invention of the conventional weight weighing device was published in the magazine National Technical Report Mol.
30-6, December 1984 issue, pp. 31, the magnetic field generating means used for absolute position detection was arranged on a different track from the magnetic field generating means used for displacement detection. However, such a device inevitably has a large size, and the detection device as a whole tends to be large.

[Purpose of the invention]

An object of the present invention is to provide a position detector that is small, lightweight, and capable of absolute position detection.

(Summary of the Invention) A position detector according to the present invention generates a reverse magnetic field in at least a part of the magnetic field generating means on the same track at different intervals from other parts on the same track, and is representative by the boundary position. This feature is characterized in that the absolute position of the object is detected.

[Embodiment of the Invention] An embodiment of the present invention will be described below. FIG. 1 shows an embodiment of the position detector of the present invention. FIG. 2 is an enlarged explanatory diagram of the magnetic sensor 1 in FIG. 1, and shows a magnetic sensor using a magnetoresistive element.

Please refer to FIGS. 1 and 2. The magnetic field generation pattern 2 includes a magnetization pattern 201 in which N poles and S poles are arranged alternately and at equal intervals (pitch length P) on the same track, and polarities on both shoulders of the magnetization pattern 2010 on both sides of the magnetization pattern 2010. Magnetization patterns 211 and 212 are formed, each having a different polarity and in which N and S poles are alternately arranged at equal intervals with a pitch length of P/2.

A magnetic sensor 1 includes at least four magnetoresistive elements arranged at equal intervals with a pitch length P/4 on a surface facing the magnetic field generation pattern 2 and in a predetermined displacement direction. (31, 52, 33, 34).

FIG. 3(C) shows a resistance value change 811 of the magnetoresistive element 31 and a resistance value change 82 of the magnetoresistive element 62 when the magnetic sensor 1 and the magnetic field generation pattern 2 are relatively displaced.
1 is shown.

FIG. 3(A) shows the magnetic field due to the magnetic field generation pattern 2. When the magnetoresistive elements 31 and 32 both correspond to the magnetization pattern 201, the difference in resistance value of the magnetoresistive elements 51 and 52 is shifted by 90° in phase difference.

The magnetoresistive elements 51 and 52 are both magnetized patterns 21
1, the magnetoresistive effect elements 31 and 32
The difference in resistance value is shifted by 180° due to phase difference.

Therefore, when the output 40 is obtained by a circuit as shown in FIG. 4(A), an output voltage waveform 831 shown in FIG. 5 is obtained.

Therefore, by setting the threshold value to a maximum voltage of 10 or higher obtained when both magnetoresistive elements 31 and 52 face the magnetization pattern 201, the magnetoresistive elements 51 and 52 both face the magnetization pattern 211. Whether or not they are facing each other can be determined from the output 41 in FIG. 4(B).

FIGS. 5 and 6 show an embodiment in which the position detector of the present invention is used in a head feeding mechanism of an electronic still camera. In FIG. 5, the magnetic field generating no-turn 2 is attached to a head carriage 75, and the magnetic sensor 1 is fixed. In addition, FIG. 6 shows the magnetic sensor 1 attached to the head carriage,
The magnetic field generation pattern 2 is fixed. In the embodiments shown in FIGS. 5 and 6, it is possible to detect predetermined tracks. In addition, 72 is a magnetic head, 74 is a feed screw, and 71 is a magnetic sheet.

75 is a guide rod.

(Effects of the Invention) According to the present invention, since the absolute position rIIL can be detected using the magnetization pattern on the same track, the position detection mechanism can be downsized and quantified.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main part of the position detector of the present invention, FIG. 2 is a perspective view of the magnetic sensor in FIG. 1, FIG. 5 is a waveform diagram showing the sensor length-output of the above embodiment, The figure is a block diagram showing an example of a comparison circuit and a magnetic sensor detection circuit constituting the above embodiment, FIG. 5 is a perspective view of an embodiment in which the present invention is applied to a head feeding mechanism, and FIG. FIG. 3 is a perspective view of an embodiment adopted as a head feeding mechanism. 1... Magnetic sensor, 2... Magnetic field generation pattern, 31.52, 55.34... Magnetoresistive flux element.

Claims (1)

[Claims] 1) A first magnetic field pattern that generates a reverse magnetic field at every certain first interval and a second magnetic field pattern that generates a reverse magnetic field at every second interval are alternately and consecutively arranged. and a magnetic sensor including at least two magnetoresistive elements located opposite to the magnetic field generating means and shifted by a predetermined distance along the direction of the magnetic field pattern, The method utilizes the fact that when the generating means and the magnetic sensor are moved relative to each other, the output of the sensor changes with the boundary position between the first magnetic field pattern and the second magnetic field pattern in the magnetic field generating means as a boundary. A position detector characterized in that the position detector detects a predetermined position represented by the boundary position. 2) In the position detector according to claim 1,
A position detector characterized in that the magnetic field generating means comprises a rectangular coil. 3) In the position detector according to claim 1,
A position detector characterized in that the magnetic field generating means comprises a magnetic recording medium.