JPH0511445Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a non-contact all-around potentiometer whose effective range of use is 360 degrees.

[Prior Art] The inventors of the present invention previously proposed a non-contact all-circumference potentiometer in Japanese Patent Application Laid-open No. 162405/1983. This full-circumference potentiometer is designed to enable measurement of the entire circumference of one rotation of the potentiometer, since the linear effective part of the output voltage of conventionally known general potentiometers is very narrow. , which is essentially equipped with two sets of magnetoresistive elements and rotors made of permanent magnets, extracts two voltage outputs whose phases differ by 90 degrees due to these magnetoresistive elements and rotors, and calculates the effective straight line of these output voltages. It is designed to make use of parts.

However, although a non-contact potentiometer with such a configuration can effectively and appropriately detect the rotation angle, it requires the manufacture of a special magnetoresistive element pattern, which is relatively expensive at the initial stage. The problem is that it requires investment.

[Problems to be solved by the invention] The purpose of the invention is to solve the problem by using a commercially available inexpensive magnetoresistive element sensor for detecting the amount of linear movement.
The object of the present invention is to obtain an inexpensive non-contact all-around potentiometer whose effective range is 360°.

[Means for Solving the Problems] In order to achieve the above object, the non-contact all-round potentiometer of the present invention has a convex strip formed around the input shaft by a yoke or a magnet facing the magnet. The installation position of this protrusion moves in the axial direction in proportion to the rotation angle of the input shaft.
It is formed so that it makes one reciprocation in the axial direction while rotating, and two magnetoresistive element sensors for detecting the amount of linear movement are placed at positions opposite to the above-mentioned protrusions, and are shifted in phase by 90 degrees around the input shaft. It is characterized by the fact that it is installed in

[Function] In the non-contact all-circumference potentiometer having the above configuration, two magnetoresistive element sensors installed with a 90° phase difference produce a sensor output with an effective linear portion in any angular range. Therefore, when the input shaft is at an appropriate rotational position, it is possible to logically determine what angular range the input shaft is in from the two sensor outputs, and to determine the valid angle within that range. The rotation angle can be determined from the sensor output having a straight line portion.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

In the non-contact all-around potentiometer shown in Fig. 1, 1 is a case, and 2 is an input shaft rotatably supported by the case. Section 3 is provided. The protruding strip 4 constitutes a yoke by itself or together with the cylindrical portion 3 etc., and the installation position of the protruding strip 4 on the surface of the cylindrical portion 3 is proportional to the rotation angle of the input shaft 2. The input shaft 3 is configured to move in the axial direction, and to reciprocate once in the axial direction during one rotation of the input shaft 3.

Further, within the case 1, two magnetoresistive element sensors 5, 5 for detecting the amount of linear movement are provided at positions facing the protrusion 4 constituting the yoke. These two sensors 5, 5 are installed around the input shaft 2 at positions with a phase shift of 90°.

In the above potentiometer, a permanent magnet 13 is placed behind each magnetoresistive element sensor 5, 5.
is arranged and is opposed to the protruding strip 4 constituting the yoke with the sensing portions of the sensors 5, 5 in between, but the protruding strip itself can also be formed of a magnet.

Magnetoresistive element sensor 5 for detecting the amount of linear movement
has a configuration as illustrated in FIG. That is, in the sensor 5, a pair of magnetoresistive elements 7, 7 constituting a sensing section are arranged on a substrate 6, and electrodes 8, 9, 9, 9 to terminal 1 respectively
0, 11, 11 are derived.

Therefore, if we place the magnet 12 on the sensor 5 and displace the magnet 12 relative to the sensor 5 in the direction of the arrow so that the magnetic flux passes perpendicularly to the surface of the sensing part. Then, the displacement can be detected as a change in electrical resistance between the terminals. That is, the magnetic flux emitted from the magnet 12 differentially passes through the two magnetic resistance elements 7, 7 in the receiving space due to the relative movement between the magnet 12 and the sensor 5, and at this time, the magnetic flux of the magnetic resistance element Since the resistance changes only in the portion under the magnetic pole due to the magnetoresistive effect, the change is detected as a change in resistance between the terminals 10 and 11. Note that even when the permanent magnet 13 is placed behind the magnetoresistive element sensors 5, 5 and is opposed to the yoke as in the embodiment shown in FIG.
Of course, it functions in exactly the same way as described above with reference to FIG.

FIG. 3 shows the characteristic curves obtained by the two magnetoresistive element sensors 5, 5 in the potentiometer.

In the non-contact all-circumference potentiometer having the above configuration, it is possible to obtain a sensor output with an effective straight line portion as shown in FIG. It is possible to logically determine what angular range the input shaft 2 is in from the two sensor outputs, and to determine the rotation angle from the sensor output that has an effective linear portion within that range.

Such potentiometers pose problems such as temperature drift and the influence of external magnetism. Figure 4 shows some of the results of an experiment investigating the effects of external magnetic fields.Even when a magnet with a surface magnetic flux density of 2000 Gauss was brought closest to the case, the output voltage fluctuation was less than 0.1%.
In addition, Figure 5 shows −
Shows the output voltage fluctuation at 3.5 to 50℃. These experimental results show that the temperature drift of the potentiometer and the influence of external magnetism pose virtually no problem in practice.

[Effects of the invention] As can be seen from the detailed description above, the non-contact all-around potentiometer of the present invention uses a very inexpensive magnetoresistive sensor for linear movement detection to Rotation angles over the circumference can be detected.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of the non-contact all-circumference potentiometer according to the present invention, Fig. 2 is a perspective view of the magnetoresistive element sensor used in the potentiometer, and Fig. 3 is the above-mentioned 4 and 5 are diagrams showing the characteristic curve of the potentiometer, and FIGS. 4 and 5 are diagrams showing experimental results for the potentiometer. 2... Input shaft, 4... Convex strip, 5... Magnetoresistive element sensor, 13... Magnet.

Claims (1)

[Scope of utility model registration request] A protruding strip formed by a yoke or a magnet facing the magnet is provided around the input shaft, and the installation position of the protruding strip moves in the axial direction in proportion to the rotation angle of the input shaft. The shaft is formed so that it makes one reciprocation in the axial direction during one revolution, and two magnetoresistive element sensors for detecting the amount of linear movement are installed at positions facing the above-mentioned protrusions at a 90° angle around the input shaft. A non-contact all-around potentiometer characterized by being installed with a phase shift.