JPH063457B2 - Rotation direction detector - Google Patents

Description

The present invention relates to a moving direction detecting device for a moving body, and in particular,
The present invention relates to a moving direction detection device for a moving body that magnetically detects the moving direction of the moving body and extracts the moving direction as an electric signal.

Detection of the moving direction of the moving body includes detection of the rotating direction of the rotating body, detection of the linear moving direction of the linear moving body, and the like. Hereinafter, detection of the rotating direction of the rotating body will be mainly described.

Conventionally, for example, the detection of the rotating direction of a rotating body such as a magnetic recording / reproducing apparatus has been determined by the application direction of a drive voltage of a motor or the like that drives the rotating body. However, when trying to switch the rotation direction rapidly, the drive voltage and the actual rotation direction may not necessarily match due to the inertia of the motor or the like. For example, even if a voltage that causes reverse rotation is applied to a motor that is rotating at high speed in the forward direction, the rotation of the motor continues to rotate in the forward direction for a finite period of time and then to the reverse rotation because of its inertia. Switch. As described above, in the method of detecting the rotation direction based on the direction in which the drive voltage is applied, when the rotation direction is switched within a short time, an erroneous determination may be made. Therefore, for example, when switching from high-speed playback in the forward direction to high-speed playback in the reverse direction while the magnetic tape is being sent by the capstan, an erroneous determination is made and the reel device determines the winding direction of the running magnetic tape. There is a possibility that the tape may be damaged due to switching, resulting in loosening of the tape or excessive tension of the tape.

According to the present invention, the direction of rotation of a rotating body such as a motor to which a frequency generator magnet for controlling the rotation speed is attached is not determined from the direction in which a drive voltage of the rotating body is applied, but one of the leakage fluxes from the magnet is determined. It is intended to eliminate the drawbacks of the above-mentioned conventional ones by making the magnetic flux density uneven by using a portion and detecting the rotational direction directly from the change of the magnetic flux accompanying the rotation.

SUMMARY OF THE INVENTION In summary, the present invention provides a magnet for frequency generator attached to a rotating body with a magnetic three-change generating means adapted to generate density of magnetic flux density by using a part of leakage flux thereof, This is a rotation direction detection device that detects a change in the absolute value of the magnetic flux density that occurs in the vicinity of the moving path of the magnetic flux change generation means and detects the rotation direction of the rotating body.

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

FIG. 1 is a perspective view showing the vicinity of a flywheel according to the present invention. A flywheel 3 is attached to a rotary shaft 2 of a capstan motor 1 that drives a magnetic tape 16. The flywheel 3 has a notch 4 and a permanent magnet 9
Is attached and is made of a soft magnetic material (for example, iron). The permanent magnet 9 is a ring-shaped permanent magnet that is magnetized in the axial direction. Two Hall elements 5 and 6 are provided near the movement path of the cut 4. When the rotating shaft 2 is rotated by the capstan motor 1, the flywheel 3 attached to the rotating shaft 2 also rotates. At this time, when the cut 4 provided in the flywheel 3 faces the Hall elements 5 and 6, the magnetic flux emitted from the permanent magnet 9 and interlinking with the Hall elements 5 and 6 is small, while the cut 4 is formed. When the Hall elements 5 and 6 are not opposed, that is, when they are opposed to the magnetic material portion, the magnetic flux interlinking with the Hall elements 5 and 6 is larger than that in the former case.

FIG. 2 is a partial plan view showing the positional relationship between two Hall elements. The circumferential angle of the notch 4 is θ, and the Hall element 5
The circumferential angle φ between and is 6/2. This φ is θ / 2 because of the operation of the D-type flip-flop described later.
However, 0 <φ <θ may be satisfied.

FIG. 3 is a block diagram of an electric circuit according to the present invention. This circuit includes two Hall elements 5 and 6, two voltage comparators 7 and 8, and one D-type flip-flop 11, which are respectively connected between a power supply terminal 10 and a ground. The outputs of the Hall elements 5 and 6 are connected to the two inputs of the voltage comparators 7 and 8, respectively. The output of the voltage comparator 7 is connected to the data terminal 12 of the D-type flip-flop 11, and the output of the voltage comparator 8 is connected to the clock terminal 13 of the D-type flip-flop 11. The Hall elements 5 and 6 output a voltage according to the magnetic flux interlinking with it. The voltage comparators 7 and 8 shape the output waveforms of the Hall elements 5 and 6. The D-type flip-flop 11 stores the logic applied to the data terminal 12 at the time when the clock is applied to the clock terminal 13 and outputs it to the output terminal 14. Hereinafter, the entire operation of this circuit will be described with reference to FIGS.
This will be described with reference to the drawings and FIG.

FIG. 4 shows signal waveforms at various parts of the circuit shown in FIG. now,
In FIG. 1, the rotary shaft 2 is clockwise when viewed from the motor side.
And consider the case where the flywheel 3 rotates (in the direction of the arrow in FIG. 1). Regarding the output voltage of the Hall element 5, if the cut 4 of the flywheel faces the Hall element 5, the interlinkage magnetic flux decreases and the output voltage also decreases. To do. The output of the Hall element 5 and the output of the voltage comparator 7 that shapes the waveform of the output at this time are shown in FIGS. 4 (a) and 4 (b). The output voltage of the hall element 6 also repeatedly decreases and rises according to the same principle as that of the hall element 5, but the positional relationship with the hall element 5 deviates by θ / 2 as described above (second The outputs of the Hall element 6 and the voltage comparator 7 are shown in FIGS. 4 (c) and 4 (d). That is, the waveforms (c) and (d) are more than θ / 2 than the waveforms (a) and (b).
Is delayed by the time corresponding to. The clock of the D-type flip-flop 11 operates when the clock terminal 13 changes from "L" to "H" (for example, point A in FIG. 4 (d)). At this time, input (b) of the data terminal 12
Is "H" (for example, point B in FIG. 4B), the flip-flop 11 outputs "H" to the output terminal 14.

Next, consider the case where the rotary shaft 2 and the flywheel 3 rotate counterclockwise as viewed from the motor side in FIG. With the same principle as in the case of clockwise rotation, the Hall element 6
The output waveforms of the voltage comparator 8 are shown in FIG.
(D). On the other hand, the output of the Hall element 5 whose waveform is shaped by the voltage comparator 7 is as shown in FIG. That is, the waveform (e) is delayed from the waveform (d) by a time corresponding to θ / 2. When these signals are applied to the clock terminal 13 and the data terminal 12 of the D-type flip-flop 11, when the clock of the D-type flip-flop operates, the input (e) of the data terminal 12 is "L" (for example, FIG. 4). (E) Point C), the D-type flip-flop 11 outputs "L" to its output terminal 14. In this way, the output terminal 14 of the D-type flip-flop 11 outputs "H" for clockwise rotation and "L" for counterclockwise rotation, thereby detecting the rotation direction of the rotating body. it can. As can be seen from FIG. 4, the input of the clock terminal 13 of the D-type flip-flop 11 has the input of the data terminal 12 changed from "L" to "H" (or "H" to "L"). It may be input later, while the changed state continues. Therefore, the circumferential angle φ between the Hall elements 5 and 6 described above may be 0 <φ <θ.

FIG. 5 is a perspective view showing another embodiment of the present invention.
The difference between this embodiment and the above-described embodiment is that the permanent magnet 9
Is the frequency generator magnet 91 for controlling the rotation speed of the motor that drives the rotating body. That is, a part of the leakage magnetic flux from the permanent magnet 91 for the frequency generator facing the generator coil 15 of the frequency generator and having the uneven surface is used. This eliminates the need for a special magnet for detecting the direction of rotation. In this case, it is preferable that the cut 4 on the flywheel 3 be provided at a position separated from the permanent magnet 91 by a distance such that the magnetic flux change component due to the unevenness is sufficiently attenuated and can be regarded as only the average magnetic flux amount.

Although the above-described embodiment has been described with respect to the detection of the rotational direction of the rotating body, the present invention can also detect the linear movement direction of the linear moving body according to the same principle as described above. That is, the application of the present invention can be easily inferred by considering that the rotating body is developed in the linear direction.

As described above, according to the present invention, it is possible to directly detect the rotation direction of the rotating body such as the motor regardless of the application direction of the drive voltage of the motor or the like. Therefore,
The detection is accurate, and it is possible to prevent the conventional error detection.

Furthermore, since a part of the leakage magnetic flux from the existing frequency power generation magnet is used to detect the rotation direction of the rotating body, it is not necessary to provide a magnet having a specific configuration to detect the rotation direction. As the magnetic flux change generating means, for example, a flywheel having a notch made of a soft magnetic material that can be easily processed may be used. It is also easy to bend the peripheral part of the flywheel so that the notch part is along the side surface of the frequency power generation magnet, and to change the magnetic flux density near the side surface of the magnet. It is possible to correctly detect the rotation direction of the rotating body regardless of the magnetic surface. As a result, according to the present invention, the rotation direction of the rotating body can be accurately detected with a small number of parts, and the entire apparatus can be downsized.

[Brief description of drawings]

FIG. 1 is a perspective view showing the vicinity of a flywheel according to the present invention. FIG. 2 is a partial plan view showing the positional relationship between two hole terminals. FIG. 3 is a block diagram of an electric circuit according to the present invention. FIG. 4 is a diagram showing signal waveforms of respective parts of the circuit of FIG. FIG. 5 is a perspective view showing another embodiment of the present invention. In the figure, 1 is a capstan motor, 3 is a flywheel, 4 is a notch, 5 and 6 are hall elements, 7 and 8 are voltage comparators, 9 is a permanent magnet, 91 is a magnet for a frequency generator, 1
1 is a D-type flip-flop, 12 is a data terminal, 13 is a clock terminal, 14 is an output terminal, and 15 is a generator coil of a frequency generator.

Claims (4)

[Claims] 1. A rotation direction detecting device for detecting the rotation direction of a rotating body to which a frequency generator magnet for controlling the rotation speed is attached, wherein the rotation direction detecting device is attached to the magnet and a part of a leakage magnetic flux from the magnet. And a plurality of magnet detectors that are provided in the vicinity of the moving path of the magnetic flux change generating means and that detect changes in the magnetic flux in the vicinity of the moving path. Means, a plurality of waveform shaping means for shaping the outputs from the plurality of magnetic flux detecting means, and an electric circuit according to the rotation direction of the rotating body in response to the outputs from the plurality of waveform shaping means. A rotation direction detection device, comprising: an output unit that outputs a signal. 2. The rotation direction detecting device according to claim 1, wherein the output means is a D-type flip-flop. 3. The rotation direction detecting device according to claim 1, wherein the magnetic flux detecting means is a Hall element. 4. The rotation direction detecting device according to any one of claims 1 to 3, wherein the waveform shaping means is a voltage comparator.