JPS6032997B2 - polyphase potentiometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a potentiometer, and particularly to a potentiometer that uses a semiconductor magnetoresistive element to receive two or more outputs with different phases.

A conventional potentiometer is constructed as shown in FIG.

That is, a rotating shaft made of a non-magnetic material, such as aluminum, is supported by bearings 12 and 13 in a bearing holder 11 made of a non-magnetic material, such as plastics, aluminum, etc.; pure iron,
By fixing a plate 14 made of permalloy or the like to the bearing holder 1 with screws (not shown), the bearings 12 and 13 are prevented from coming off from the holder 1. Holder 11
A permanent magnet 15 is bonded to the tip of the shaft 10 located inside with an adhesive such as epoxy resin, with the magnetic pole oriented in the axial direction of the shaft as shown in the figure. The magnetic pole end face 16 of the magnet 15 is formed into a long shape and occupies approximately half of the end face of the shaft 10. A substrate 17 made of plastic material is fixed to the side of the bearing holder 11 on which the permanent magnet 15 is present with adhesive or screws.

A cylindrical magnetic piece 18 is buried in the center of the substrate 17 with a portion exposed. The board 17 also includes terminal pins 20,
21 and 22 are embedded in the same way as the magnetic piece 18 with both ends protruding from the substrate 17. A terminal plate 19 is mounted on the substrate 17 and engages with terminal pins 20, 21, 22 and is connected to the printed circuit. A pair of magnetoresistive elements 23 and 24 are stuck on the magnetic piece 18, and a lead frame connected to the electrodes is connected to a printed circuit of the terminal board 19.

The holder 11 and the substrate 17 are housed in a bottomed cylindrical case 25 made of a conductive magnetic material such as pure iron or permalloy.

At this time, one ends of the terminal pins 20, 21, 22 are insulated and protrude outside the case 25. FIG. 2 shows an enlarged view of the relationship between the magnetic pole end face 16 of the magnet 15 and the magnetoresistive elements 23 and 24 outside the potentiometer having such a configuration. The pair of magnetoresistive elements 23 and 24 are configured together in a notched circular shape, and are provided with an output terminal electrode 26 and input terminal electrodes 27 and 28. The magnetic pole end face 16 for the annular magnetoresistive element is positioned such that one side thereof passes through the shaft axis 29 of the rotating shaft 10. In the above configuration, when the shaft 10 is rotated by 360 degrees, there is a drawback that a flat portion occurs in the output at the angular position where the maximum output is produced, as shown in FIG.

This is particularly noticeable when the magnetic pole end face 16 is located at a position that includes the electrodes 27 and 28. This is because the magnetoresistive effect does not occur at the electrodes, as shown in the figure. In order to eliminate such output characteristics, it is possible to reduce the size of the non-magnetoresistance effect, but this results in the disadvantage that it becomes difficult to form the electrode portion. Further, in recent years, there has been an increasing demand for phase control potentiometers for servo motors and coreless motors.

There are contact type potentiometers of this type, but they have the disadvantage of short lifespans due to wear.Also, with potentiometers using magnetoresistive elements such as those mentioned above, it is difficult to form terminal electrodes, making it difficult to form a multiphase multiphase with good linearity. Output potential has not been obtained. For this reason, two or three potentiometers with the same characteristics are connected in parallel at different mounting angles, but variations in each potentiometer are unavoidable, and a satisfactory state has not been reached. SUMMARY OF THE INVENTION An object of the present invention is to provide a potentiometer that is inexpensive and generates a highly accurate multiphase output. To describe the features of the potentiometer of the present invention, the magnetic sensor section, which receives the action of a magnetic field from a permanent magnet fixed to the tip of the rotating shaft, is equipped with a plurality of semicircular arc-shaped magnetoresistive elements, and among these elements, A pair of two magnetoresistive elements whose string sides face each other and are offset in opposite directions with respect to the shaft axis, and the sum of the magnetically sensitive surfaces of each pair of elements occupies an angular range of 360. In addition, the chord direction of the magnetoresistive elements is arranged at a predetermined angular interval for each pair, and a plurality of phase-shifted outputs are obtained by rotating the shaft.

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

The overall configuration of the potentiometer is the same as that of the conventional example shown in FIG. 1, except for a part, so a description of that part will be omitted. Also, the same numbers are used for the same parts as in FIG. FIG. 4 shows a magnetically sensitive sensor section 80 outside the potentiometer of the present invention.

In the figure, semicircular arc-shaped magnetoresistive elements 30, 40,
50 and 60 are formed by forming a semiconductor material such as silicon, indium antimonide, indium arsenide, etc. on a substrate 70 that has been diced or scribed into square shapes using a well-known method of deposition or etching. There is.
The substrate 70.1 is made of a magnetic material such as ferrite, or a non-magnetic material such as glass or ceramic. Each pair of magnetoresistive elements 30, 40, and 50, 60 are
The center of the arc of each element is connected to the rotating shaft 10 in FIG.
A pair of magnetically sensitive surfaces 31 of a pair of elements 30, 40 and 50, 60 are arranged to be equidistantly offset in mutually opposite directions with respect to the shaft axis 29 along lines 71, 72 passing through the shaft axis 29 of the elements. 41, and 51, 61 are formed to occupy an angular range of 3600 degrees.

The lines 71 and 72 are then spaced at an angular interval of 90 degrees. On the magnetically sensitive surfaces 31, 41, 51, 61 of the magnetoresistive elements 30, 40, 50, 60, metal bars 32, made of a good conductor such as gold or indium are installed so as to cross the magnetically sensitive surfaces.
A large number of elements 42, 52, and 62 are provided to adjust the sensitivity of the elements 30, 40, 50, and 60 when the magnetic pole end face 16 rotates. That is, since the center of each element is offset from the shaft axis 29, the metal bars 32, 42, 62
, 62 are provided to adjust the sensitivity of the elements 30, 40, 60, 60 when the magnetic pole end face 16 rotates. That is, since the center of each element is offset from the shaft ring 29, if the metal bars 32, 42, 52, and 62 are formed at equal intervals, when the shaft 10 is rotated at a constant angular velocity, the magnetic field will be The area of the magnetically sensitive surface subjected to the action does not increase or decrease at a constant rate, and an output with good linearity cannot be obtained. For this reason, the magnetically sensitive surfaces 31, 41, 51, 61
The metal bars 32, 42, 52, and 62 are provided so that the magnetic sensitivity at each angle is approximately equal when the magnetic pole end face 16 is rotated, and the distance between the metal bars is increased as the distance from the shaft axis 29 increases, so that the magnetic sensitivity per unit area is increased. The magnetic sensitivity of the magnetic field is gradually lowered. Magnetoresistive elements 30, 40
, 50, 60, electrodes 33, 34, 43, 44, 53, 54, 63 are made of a good conductor such as gold or indium.
, 64 by vapor deposition, and the electrode 3 near the shaft axis 29
3, 43, 53, 63 to lead parts 35, 45, 55,
65 is formed by vapor deposition to form extraction electrodes 36, 46, 56,
Connected to 66.

Electrodes 34, 36, 44, 46, 54, 56, 64, 66
A lead frame (not shown) is bonded and connected to the printed circuit of the terminal board 19.

In the above configuration, when the shaft 10 is rotated, the magnetic pole end face 16
When rotated counterclockwise from the position of green 71 in Figure 4,
From the pair of magnetoresistive elements 30 and 40, the outputs shown in FIG. 5a are obtained, and from the pair of elements 50 and 60,
G star b output is generated.

The pair of magnetoresistive elements 30, 40 and 50, 6
As shown in FIG. 6, output terminals 74 and 75 are connected in series to both ends of a constant voltage power supply 73, and between elements 30 and 40 and between elements 50 and 60.

Further, resistors 76 and 77 are connected in series to both ends of the power supply 73, and an output terminal 78 is provided between them. Thus, the output shown in Fig. 5 a is obtained from terminals 74 and 78, the output shown in Fig. 5 b is obtained from terminals 75 and 78, and the output obtained by combining a and b in Fig. 5 is obtained from between 74 and 75. is obtained.

In the above embodiment, a potentiometer that generates two outputs with a phase difference of 900° was explained, but three pairs of semicircular arc magnetoresistive elements are formed, and these are connected at a 120° angle.
When arranged at an angular interval of , three outputs having different phases of 60 degrees can be obtained simultaneously.

By increasing the number of magnetoresistive elements in this way, more output can be obtained. As described above, the present invention obtains multiphase output by using a plurality of semicircular arc-shaped magnetoresistive elements without substantially changing the overall structure of the potentiometer. An inexpensive potentiometer can be obtained without having to use the potentiometer, and the phase angle of the generated output can be highly accurate because the magnetoresistive element is formed at the same time by vapor deposition or etching. Therefore, there is no wear and tear. In addition, each magnetoresistive element has 1
Since it has a magnetically sensitive surface within an angular range of 80 degrees, the output characteristics do not change depending on the electrode portion, unlike in the conventional case.

Furthermore, since the lead wires from the electrodes of the element can be drawn out with sufficient margin without impeding the magnetoresistive effect of the element, it becomes easy to form the entire element that outputs multiphase output.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of a conventional potentiometer.
Fig. 2 is a plan view of a conventional magnetically sensitive sensor section, Fig. 3 is an output characteristic diagram of a subordinate potentiometer, Fig. 4 is a plan view of a magnetically sensitive sensor section in the potentiometer of the present invention, and Fig. 5 is a diagram showing the output characteristics of a subordinate potentiometer. FIG. 4 is an output characteristic diagram of a potentiometer using the sensor section shown in FIG. 4, and FIG. 6 is an output circuit diagram in which the magnetic resistance elements of the sensor section shown in FIG. 4 are connected. 1 in the figure is a rotating shaft, 15 is a magnet, 16 is a magnetic pole end face, 29 is a shaft axis, 30, 40, 50, 60 are magnetoresistive elements, 31, 41, 51, 61 are magnetically sensitive surfaces, 32
, 42, 52, and 62 are metal bars, and 80 is a magnetic sensor section. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1. A permanent magnet whose magnetic pole end surface occupies approximately half of the shaft tip is fixed to the tip of the rotating shaft, and a magnetic sensor section facing the magnetic pole tip includes a plurality of magnetoresistive elements each having a semicircular arc-shaped magnetic sensing surface. The inner chord sides of the elements face each other and are offset in opposite directions with respect to the shaft axis, and each pair is arranged at a predetermined angular interval to produce a multiphase output. A polyphase potentiometer characterized by obtaining.