JPS5925011Y2 - Rotation speed and/or phase detection device - Google Patents

Description

[Detailed description of the invention] The present invention is intended to easily detect the rotational speed and/or rotational phase. It is intended to be used as a.

When trying to control the rotational speed of a rotating body, such as a turntable included in a video disc player, a rotating conductor is provided on the drive shaft of the turntable, and an electromagnet is associated with it to control the current applied to the excitation coil that constitutes the electromagnet. The speed is controlled by controlling the speed.

At this time, the applied current must be changed according to the rotational speed of the rotating conductor, and the detection method is to use the output of a separate magnetic or optical detector connected to the rotating conductor. I was trying to do that.

The present invention focuses on the fact that when a rotating conductor is rotated in a different configuration alternately along its circumferential direction, a current change is observed in the excitation coil of the speed control electromagnet in accordance with the rotation. The purpose is to make it possible to derive a rotation detection signal from the excitation coil.

In order to derive the rotation detection signal from the excitation coil in this way, the following three methods can be considered based on the configuration of the rotating conductor.

Namely, the first method is to alternately arrange conductors with different magnetic coefficients in the circumferential direction as shown in FIGS. The third method is to arrange magnets magnetized in the radial direction so that the polarities of their surfaces are alternately opposite, as shown in FIGS. 3A to 3C.

Next, the present invention will be explained based on its embodiments.

In FIG. 1A, a cylindrical rotating conductor 1A is constructed by two types of conductors 2A and 3A having different magnetic viscosity and a block 4A that circumscribes these conductors in the circumferential direction, and an electromagnet 5A is associated with this. The signal from the coil 6A constituting the fourth
It is provided to a processing circuit 7A as shown in the figure, and a rotation detection signal is derived as its output.

In FIG. 1B, the rotating conductor 1B has a disk shape, and is composed of a block 4B and two types of conductors 2B and 3B having different magnetic coefficients.

5B is an electromagnet having a coil 6B, and 7B is a signal processing circuit.

In FIG. 1C, the rotating conductor 1C is cup-shaped, and two types of conductors 2 with different magnetic coefficients are placed on the outer circumferential side of the cup-shaped block 4C.
C and 3C are arranged alternately.

5C is an electromagnet having a coil 6C, and 7C is a signal processing circuit.

In each of these embodiments, considering the impedance seen from both ends of the coil that constitutes the electromagnet, the impedance (L!) changes depending on the position of the rotating conductor as the magnetic resistance of the magnetic circuit changes. I can understand.

Therefore, the current flowing through this coil changes around the constant current Io as shown in FIG. 5a.

2A to 2C, each of the rotating conductors 10A and 10B is used instead of the rotating conductor of FIGS.

Concave portions 11A, 11B, 11C and convex portions 12A each constitute substantial unevenness in the circumferential direction of 10C.
, 12B.

12C are formed alternately.

The electromagnets and signal processing circuits for each rotating conductor 10A, 10B, 10C are substantially the same as those shown in FIG.

In each of these embodiments, changes in the eddy current flowing through the rotating conductor are captured as changes in the impedance (RJl & min) seen from the coil, and as in the case of FIG.
It is possible to stop the current trending as shown in Figure a.

FIG. 3A-C shows each rotating conductor 2OA, 20B, 2
0 C, each block 21 A, 21 B, 21
Magnets 22 A, 22 B magnetized in the radial direction at C
, 22C are arranged so that the magnetic properties of their surfaces alternate in opposite polarities in the circumferential direction,
In these embodiments, induced power is generated based on the rotation of the magnet, so similar to the embodiments shown in FIGS. 1 and 2 above, a current with a tendency as shown in FIG. This means that the liquid can be stopped.

In each of these embodiments, a current with a tendency as shown in FIG. 5a flows through the excitation coil.
The signal processing circuit or coupling capacitor 31 shown in the figure.
If the signal is supplied to an amplifier 32 and a pulse shaping circuit 33, a rotation detection signal as shown in FIG. 5C can be derived as its output.

This rotation detection signal expresses the rotational speed of the rotating conductor by its frequency, and the rotational phase of the rotating conductor by its phase.

Note that when trying to control the rotation of a rotating conductor by changing the brake current using an electromagnet, the DC component Io in the waveform shown in Figure 5a tends to change, but the frequency of this change is generally low. , frequency separation from the AC waveform shown in the figure is easy.

If this separation is difficult, the number of pairs of magnetic conductors and non-magnetic conductors, which is four pairs in the embodiment of FIG. 1, for example, may be increased in order to increase the frequency of the rotation detection signal.

As mentioned above, the present invention has different configurations of the rotating conductor alternately in the circumferential direction, so that when the rotating conductor is rotated, the coils constituting the electromagnet arranged to apply an electromagnetic brake to the rotating conductor are , it is possible to stop the alternating current as shown in Fig. 5a, and by detecting the change in the current, the rotational speed and/or rotational phase of the rotating conductor can be detected. The device for detecting rotation is simple and practical.

[Brief explanation of the drawing]

Figures 1A-C1, 2A-C1, and 3A-C respectively show models of different embodiments of the present invention according to the first, second, and third systems, and Figure 4 shows a signal processing circuit. Example, 5th
Figures a to c are waveform diagrams of each part. 1A...Rotating conductor, 5A...Electromagnet (
magnetic flux generator), 6A... coil, 7A...
...Signal processing circuit.

Claims (4)

[Scope of utility model registration request] (1) A rotating conductor having a different configuration alternately along the circumferential direction, a magnetic flux generating device that applies a brake by generating eddy currents in this rotating conductor, and a brake flowing to a coil that constitutes the magnetic flux generating device. means for frequency-separating a current and its variation from a current change corresponding to the rotation of the rotating conductor; and a pulse for deriving a rotation detection signal based on the current change corresponding to the rotation of the rotating conductor separated by the separating means. A rotation speed and/or phase detection device comprising a shaping circuit. (2) The rotational speed and/or phase detection device according to claim 1, wherein the rotating conductor has conductors having different magnetic coefficients arranged on its circumference. (3) The rotational speed and/or phase detection device according to claim 1, wherein the rotating conductor has shape differences alternately provided on its circumference. (4) The rotating conductor is provided with magnets magnetized in the radial direction in the circumferential direction and arranged so that the magnetic properties of the surfaces thereof are alternately different. Phase detection device.