JPS63188717A - Surface facing power generation type pulse generator - Google Patents

Abstract

PURPOSE:To reduce the size of a pulse generator and to simplify a signal processing circuit by composing a conductor pattern for a PG magnet of a pattern part for PG detection and a pattern part for cancellation which generates an electromotive current in the opposite direction from the electromotive current of the pattern part for PG detection. CONSTITUTION:The conductor pattern 7 for the PG magnet consists of the pattern part 11 for PG detection provided opposite the PG magnet 5 and the pattern part 12 for cancellation which is provided opposite an external magnet 4 while connected in series with the pattern part 11 and generates the electromotive current in the opposite direction from that of the pattern part 1. Consequently, an electromotive current (noise component) is generated at the pattern part 11 by the leak magnetic flux of the magnet 4 and the electromotive current in the opposite direction from the electromotive current of the pattern part 11 is generated at the pattern part 12; and the electromotive current generated at the pattern part 11 is canceled by the electromotive current generated at the pattern part 12, so a PG signal which has almost no noise component is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface facing power generation type pulse generator used in a drum servo of a video head and the like.

[Summary of the Invention] The present invention forms an external magnet by alternately arranging N and S poles substantially evenly in the circumferential direction of the surface of a rotor that is rotatably attached to a shaft via a bearing. A PG magnet is disposed close to the magnet, and a stator having a conductor pattern for the external magnet and a conductor pattern for the PG magnet facing the external magnet and the PG magnet is fixed to the shaft. In the power generation pulse generator, the conductor pattern on the PG magnet side is connected to a PG detection pattern section provided at a position facing the PG magnet, and the external magnet in series with the PG detection pattern section. The canceling pattern is provided at a position facing the PG detection pattern and generates an electromotive current opposite to the electromotive current of the PG detection pattern, so that leakage magnetic flux of the external magnet acts on the PGG output pattern. By canceling the nozzle generated by the noise with the cancellation pattern, this type of pulse generator can be miniaturized and a high S/N can be achieved.
This makes it possible to obtain the ratio.

[Prior Art] Generally, as shown in FIG. 1, a surface facing type pulse generator has a rotor 3 rotatably attached to a fixed shaft 1 via a bearing 2 such as a ball bearing. , an external magnet (driving or FGG magnet) 4 is formed by arranging S poles approximately equally, and a PG magnet 5 is disposed close to the external magnet 4, and these external magnets 4 and It is formed by fixing a stator 8 provided with a conductor pattern 6 for an external magnet facing the PG magnet 5 and a conductor pattern 7 for the PG magnet on the shaft l.

When a current is applied to a drive coil (not shown) provided on the lower surface of the stator 8, the rotor 3 rotates, and the rotational speed of the rotor 3 is detected by the external magnet 4 and the external magnet conductor pattern 6. , or PG magnet 5
A pulse signal is generated by the conductor pattern 7 for the PG magnet, and the rotational speed and rotational phase of the video head are controlled. Note that 9 is the external magnet 4.
and rotor yoke supporting PG magnet 5, 10
is a stator boss fixed to the tip of the fixed shaft 1.

[Problems to be Solved by the Invention] By the way, in the conventional surface facing type pulse generator, as shown in FIGS. 11-12, the external magnet 4
and a conductor pattern 6 for an external magnet are arranged in positions facing each other, so that the conductor pattern 6 for an external magnet is opposed to the external magnet 4, and a PG magnet 5 and a PG magnet are arranged close to the external magnet 4. Since the PG magnet 5 and the PG magnet conductor pattern 7 were arranged in positions facing each other, the following problems occurred.

(1) Since the leakage magnetic flux of the external magnet 4 is directly detected by the conductor pattern 7 for the PG magnet, the PG
As shown in FIG. 14, the noise component N is larger than the PG signal component, and a circuit for setting a slide level is required to detect the PG signal component.

(2) Even if the positions of the external magnet 4 and the PG magnet 5 are slightly different, the PG multiplier signal generation position will be greatly different.
Individuals must be adjusted.

The above problem can be solved by setting the width W of the conductor pattern 7 for the PG magnet to 1/2 (or twice) the magnetic pole width θ of the external magnet 4, as shown in FIGS. 11 and 13. The problem can be solved by preventing the leakage magnetic flux from 4 from being detected by the conductor pattern 7 for the PG magnet and extracting the PG double signal, but with this configuration, the conductor pattern 7 for the PG magnet This spreads by 3/2θ in the width direction, which becomes a major constraint in downsizing the pulse generator. Also, if configured like this, PG
Since the output signal generates two pulses on the positive side, a selection circuit is required to select which of these pulses to use as a reference, which increases the cost. The present invention is a surface-to-surface generation type pulse that can be miniaturized, eliminates the need for a selection circuit as an L pulse on the positive side of the PG double signal, and can solve the problems described in items (1) and (2) above. It was created for the purpose of providing a generator.

[Means for Solving the Problems] The conductor pattern for the PG magnet is connected in series to the PGG output pattern section provided at a position facing the PG magnet and the PG detection pattern section. It is provided at a position facing the external magnet, and the P
It consists of a canceling pattern section that generates an electromotive current opposite to the electromotive current of the G detection pattern section.

[Operation] The electromotive force (noise component) generated in the PG detection pattern section due to leakage magnetic flux from the external magnet is canceled by the electromotive force generated in the cancellation pattern section.

[Example 2] Next, a surface facing power generation type pulse generator of the present invention will be explained with reference to the drawings.

No.! -FIG. 4 shows a first embodiment of the present invention. In Figures 2 to 4, 4 is an external magnet, 5 is a PG magnet, and 6 is an external magnet.
7 is a conductor pattern for an external magnet, and 7 is a conductor pattern for a PG magnet. a canceling pattern section 12 that is connected in series to the PG detection pattern section 11 and is provided at a position facing the external magnet 4, and generates an electromotive force in the opposite direction to the electromotive force of the PG detection pattern section; It consists of The canceling pattern section I2 is arranged on the radially outer side (external magnet 4 side) of the PG detecting pattern section II in a straight line with the PG detecting pattern section II. The conductor pattern 5 is inserted into the recess 13 provided on the inner circumferential side of the conductor pattern 5, and the PG
As shown in FIG. 4, the detection pattern section 11 overlaps the inner circumferential side of the external magnet 4 with a predetermined overlapping dimension d. .

The external magnet 4 and the PG magnet 5 are the first
As shown in the figure, the conductor pattern 6 for the external magnet and the conductor pattern 7 for the PG magnet are arranged on the rotor yoke 9 and used on the stator 8.

The first embodiment has the above-mentioned configuration, and when a current is passed through the drive coil, the rotor 3 rotates, and the PG magnet 5 and P
The conductor pattern 7 for the G magnet generates a PG double signal, and as mentioned above, the conductor pattern 7 for the PG magnet is a PG detection pattern provided at a position facing the PG magnet 5 (overlapping position). 11, and a cancellation pattern section I2 which is connected in series to the PG detection pattern section 11 and is provided at a position facing the external magnet 4, so that leakage from the external magnet 4 is prevented. An electromotive current (noise component) is generated in the PG detection pattern section 11 due to the magnetic flux, and an electromotive current in the opposite direction to the electromotive current of the PG detection pattern section 11 is generated in the cancellation pattern section 2. The electromotive current generated in the detection pattern 1I (II) is canceled by the electromotive current generated in the cancellation pattern section 12, and a PG multiplied signal with almost no noise components as shown in the experimental value shown in FIG. 5 is obtained. It becomes possible.

Note that the amount of cancellation is determined by the above-mentioned polymerization d, so the pattern part for PG detection is determined by the external magnetic flux! The dimension d may be set so that the amount of current generated in (1) and the amount of current generated in the canceling pattern portion 12 due to external magnetic flux are equal. Further, the electromotive current generated in the canceling pattern section 12 by the magnetic flux of the PG magnet 5 acts to reduce the PG signal, but since the canceling pattern section I2 is short and distant from the PG magnet 5, the electromotive current is reduced. The amount is extremely small.

6 to IO show second to sixth embodiments of the present invention. In the second embodiment shown in FIG. Indicates the case where it is increased.

The third embodiment shown in FIG. 7 shows a case where the canceling pattern portion 12 of the conductor pattern 7 for the PG magnet is wound in plural to increase the amount of cancellation.

Embodiments 4 to 6 shown in FIGS. 8 to 10 show cases in which the PG detection pattern portion 11 and the cancellation pattern 112 of the conductor pattern 7 for the PG magnet are arranged with their phases shifted.

[Effects of the Invention] As described above, the present invention includes an external magnet disposed on the rotor, and a PG magnet disposed close to the external magnet, and a stator disposed on the stator facing the external magnet and the PG magnet. In a surface-to-surface power generation pulse generator provided with a conductor pattern for an external magnet and a conductor pattern for a PG magnet, the conductor pattern for the PG magnet is connected to a PG detector provided at a position facing (overlapping) the PG magnet. The detection pattern mark part and the PG detection conductor pattern mark part are provided in a position facing (overlapping) the external magnet in a state where they are connected in series, and in a direction opposite to the electromotive current of the PG detection pattern part. Since the canceling pattern section generates an electromotive current, the following effects can be obtained.

(1) Unlike the conventional example shown in Figure 13, it is no longer necessary to widen the conductor pattern for the PG magnet to 3/2θ with respect to the magnetic pole width θ of the external magnet, and it is independent of the magnetic pole width θ of the external magnet. PG magnet's magnetic pole width and PG
The width of the conductive pattern for the magnet can be reduced, and the pulse generator can be made smaller.

(2) Set the PG double signal generation to one pulse on the positive side,
Alternatively, the pulse width can be narrowed and the signal processing circuit can be simplified.

(3) High S/N by canceling noise components
You can get the ratio.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a surface facing power generation type pulse generator, Figure 2
4 shows the first embodiment of the present invention, FIG. 2 is a plan view showing the arrangement of external magnets and PG magnets, and FIG.
The figure is a plan view showing the arrangement of the conductor pattern for the external magnet and the conductor pattern for the PG magnet, FIG. 4 is a plan view showing the positional relationship between the external magnet and the conductor pattern for the PG magnet, and FIG. 6-10 are plan views of the second to sixth embodiments,
FIG. 1I is a plan view showing the arrangement of the external magnet and PG magnet in the conventional example, FIG. 12 is a plan view showing the arrangement of the conductor pattern for the PG magnet and the conductor pattern for the PG magnet in the conventional example, and FIG. The figure is a plan view showing the arrangement of conductor patterns for a PG magnet in another conventional example, and FIG. 14 is a noise waveform diagram of the same. 3...Rotor, 4...External magnet, 5...P
G magnet, 6... Conductor pattern for external magnet, 7... Conductor pattern for PG magnet, 11.
...Patter mark part 12 for PG inspection detection...pattern part for cancellation. The lice-like wound on the 7th floor of the 7th floor of the 7th floor of the evening's Penguin-face and the physical strength of the body
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Claims (1)

[Claims] An external magnet is disposed on the rotor, and a PG magnet is disposed close to the external magnet, and a conductor pattern for the external magnet that faces the external magnet and the PG magnet, and a conductor pattern for the PG magnet are disposed on the stator. In the surface facing power generation type pulse generator provided, the conductor pattern for the PG magnet is connected in series to a PG detection pattern section provided at a position facing the PG magnet, and the PG detection conductor pattern section. A face-to-face power generation type pulse generator comprising a canceling pattern section that is provided at a position facing the external magnet in the above-mentioned state and generates an electromotive current opposite to the electromotive current of the PG detection pattern section.