JPH0375566A - Detecting device of fg signal and pg signal - Google Patents

Abstract

PURPOSE:To enable detection of a PG (pulse generation) signal and an FG (frequency generation) signal by one device by a method wherein a cut part of a prescribed width which changes the duty of one FG signal is provided in a part of one pole of a multipole magnet ring and the PG signal is detected therefrom. CONSTITUTION:A magnetic sensor 6 detecting an FG signal is disposed oppositely to the peripheral surface of a magnet ring 5 of multiple pole (e.g. 30 poles) which is fixed to a rotating shaft 3, and a delay circuit 7 and an NAND circuit 10 which output a PG signal on the basis of the FG signal are provided, while a cut part 8 is provided in one pole of the ring 5. With the ring 5 rotating, the sensor 6 converts alternation of N and S poles into the FG signal. When the cut part 8 faces the sensor 6, a waveform changes by one mode. The FG signal Vc (1) outputted from the sensor 6 is compared 9 with a reference signal Vf (2) and turned into a rectangular wave (3). This rectangular wave (3) and a rectangular wave (4) delayed by a prescribed amount in the circuit 7 are inputted to the circuit 10. An output of the circuit 10 becomes an H signal (5) only at a position corresponding to the cut part 8. This signal is fetched as the PG signal (5).

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a PG (frequency oscillation) signal and a PG (pulse) signal for controlling the position and speed of a rotary head drum of a video device, a spindle motor of a disk drive device, etc. (outgoing)
PG multiplier signal for detecting signals [Summary of the invention] The present invention provides a multipolar magnet ring that is fixed to a rotating shaft and has N poles and S poles alternately magnetized in the circumferential direction, and a multipolar magnet ring that is opposed to the multipolar magnet ring. a magnetic sensor which is arranged as
A cutout part for changing the duty of one FC signal is provided in a part of the pole or S pole, and the F whose duty is changed is provided.
By using a configuration that includes a PG signal detection circuit that extracts the PG multiplied signal from the G multiplied signal, one device can extract the PG multiplied signal FG.
It is possible to detect double signals, thereby reducing the number of parts and assembly man-hours, reducing costs, and saving space.

[Prior Art] In a brushless motor that rotates the head of a conventional video tape recorder, there is a device that outputs a PG double signal for synchronization that switches two heads arranged on a rotating drum every half cycle ( Utility Model Publication No. 61-195781).

In FIG. 14, a ring-shaped driving magnet 11 is provided on the rotor 2 side of the brushless motor 1.

As shown in FIG. 15, this drive magnet 11 has north and south poles alternately magnetized in the circumferential direction. A pair of V-shaped notches 12 are formed at opposing positions on the upper end side of the driving magnet 11. The magnetic core 14 of the stator 13 has protrusions 15 extending radially, each of which is wound with a drive coil 16, and an induction coil 17 for detecting changes in the strength of magnetic force is attached to the tip of one of the protrusions 15 that extend radially. It is provided opposite to 11. A U-shaped iron core 18 is arranged at the center of this induction coil 17.

Then, the rotor 2 and the driving magnet 3 rotate,
When the notch 12 passes in front of the induction coil 17, the first
As shown in Fig. 6, an induced voltage is generated and a PG multiplied signal...■ is detected.

[Lesson 1i that the invention attempts to solve! ft] However, the drive magnet 11 and the induction coil I7 cannot detect both the PG multiplication signal and the PG multiplication signal necessary for accurate speed control. In order to detect this FG multiplied signal, it is necessary to use a multi-pole magnet with many N/SW, for example, 30 poles, 60 poles, etc.
A separate magnetic sensor must be provided that can detect changes in polarity. This is because the driving magnet +1 has a small number of N and S poles, such as 6 and 8 poles, in the - film and causes uneven rotation when used for FG signal detection.

Therefore, there are problems such as an increase in the number of parts, an increase in the number of assembly steps, an increase in cost, and a need for space.

The present invention has been made to solve the above problems, and aims to reduce the number of parts, reduce assembly man-hours, reduce costs, and save space by detecting PC signals and FC signals with one device. shall be.

[Means for Solving the Problems] The present invention provides a multipolar magnet ring that is fixed around a rotating shaft and has N poles and S poles alternately magnetized in the circumferential direction, and a magnet ring that is opposed to the multipolar magnet ring. a magnetic sensor configured to convert the change in the N-S pole into a FG-fold signal;
and a delay circuit for delaying the signal by a factor of two, the one N
Part of the pole or south pole! The structure is such that a notch having a predetermined width is provided to change the duty of the two FG multiplied signals, and the FG multiplied signal and the delayed FG multiplied signal are compared to detect the PG multiplied signal.

[Function] When the multi-pole magnet rotates, the magnetic sensor converts the change in the north and south poles into an FG times signal.

Furthermore, since the direction of the magnetic field changes by a predetermined angle in the notch portion of a predetermined width provided at one N pole or S pole, the duty of one FG multiplied signal changes. A PC signal corresponding to the notch is detected by a PG signal detection circuit which extracts a PG multiplied signal from the FG multiplied signal whose duty has been changed.

[Example] Hereinafter, an example of the present invention will be described based on FIGS. 1 to 11.

In FIG. 2, the stator side of the brushless motor 1 is provided with a magnetic core (not shown) and a driving coil wound around the magnetic core. On the rotor 2 side, a driving magnet (not shown) is arranged opposite to the driving coil. The brushless motor 1 receives an FG multiplication signal P.
A G signal detection device 4 is provided. Figures 1 and 2
In the figure, the FG multiplier signal PG signal detection device 4 includes a multipolar magnet ring 5 fixed to the rotating shaft 3, and a magnetic sensor 6 arranged opposite to the circumferential surface of the multipolar magnet ring 5 for detecting the FG multiplier signal. , a delay circuit 7 as a PG signal detection circuit that outputs a PC signal from the FG multiplied signal, and N
AND circuit 8.

The multipolar magnet ring 5 is magnetized with 30 N poles and 30 S poles alternately. One of the 30 poles, the N pole or the S pole (the S pole in this embodiment), is provided with a notch 8 for detecting the PC signal. This notch 8 is formed to a predetermined depth in the direction of the boundary axis between the north pole and the south pole.

The magnetic sensor 6 detects the direction of the magnetic field, and the third
The two magnetic field resistance elements RA shown in the figure have different resistance characteristics,
Equipped with RB. This magnetic field resistance element R^, Ra is the fourth
As shown in the graph in the figure (here, if the magnetic field rotation angle θ = 0 when the direction of the magnetic field is in the y-axis direction, the resistance value changes as if to draw a cos wave as the magnetic field rotates.Magnetic field resistance element R
The resistance of A is maximum when it is in the y-axis direction (θ=o', tsoo), and it is the minimum when it is in the X-axis direction (θ·S0'', 270°).

The magnetic field resistance element R8 is minimum in the y-axis direction and maximum in the X-axis direction, and varies by 90° with respect to RA. The magnetic sensor 6 has these elements RA and RB forming an equal charge circuit as shown in FIG. It has become.

In FIG. 1, the output Vc of the magnetic sensor 6 is guided to one input terminal of a comparator 9, and the reference voltage Vf is introduced to the input terminal of the comparator 9. The base/$ voltage Vf is configured to be variable by a variable resistor VR. The output of the comparator 9 is led to one input terminal of a NAND circuit 10,
The output of the comparator 9 which has passed through the delay circuit 7 is led to the other input terminal of this NANDAND circuit. The delay circuit 7 is composed of a resistor VRt, a variable resistor VR, and a capacitor C2, and controls the delay amount ΔS by changing the resistance value of the variable resistor VR.

Next, the operation of the above embodiment will be explained.

In FIGS. 1 and 2, when a predetermined voltage is applied to a drive coil (not shown), the rotor 2 rotates.

When the rotor 2 rotates, as shown in FIG. 7, the magnetic sensor 6 alternately faces the north and south poles, and a sine wave voltage shown in FIG. 8 is output depending on the direction of the magnetic field. FG
The signal is extracted twice. FG at the rising point P of each mode
The signal is extracted twice.

As shown in FIG. 9, when the notch 8 faces the magnetic sensor 6, the direction of the magnetic field at the notch 8 changes Δθ, unlike in the case where there is no notch 6, as shown by the imaginary line. The waveform changes only in the mode as shown by the solid line. That is, as shown by the virtual line, when there is no notch 6, a sine wave voltage is output, and the duty L:M=1. :l, whereas
When there is a notch 8, the l-mode waveform changes by +ΔT as shown by the solid line, and the duty also changes as Q:m. At this time, the notch 8 has a duty f of l mode.
Since only fl:m is set to a different range of width, the rising point P of the next signal! does not shift, and the provision of the notch 8 prevents the PG multiple signal frequency from being disturbed.

In Fig. 1, the FG multiplied signal output from the Vc...
■ is compared with the reference signal Vf...■ by a comparator and converted into a rectangular wave...■. This rectangular wave...■ and the rectangular wave...■ delayed by △S in the delay circuit 7 are NAN
The D circuit 10 is manually powered. The output of the NAND AND circuit becomes the double signal . . . only at the position corresponding to the notch 8. In this way, since the H signal corresponds to the notch 8, it is extracted as a PG multiplied signal .

Note that in the embodiment described above, a NANDAND circuit D circuit may be used.

FIG. 12 shows a modification of the above embodiment, in which the notch 8
A predetermined width is cut out from the center of the S pole to the N pole side on the left side of the figure. The direction of the magnetic field of the notch 8 changes by -Δθ, the waveform output from Vc deviates by 1ΔT, and the duty of mt:12t changes, so the FG multiplied signal PG is generated as in the previous embodiment. The signal is extracted twice.

Further, although the above embodiment used a multipolar magnet with 30 poles, it may be used with 60 poles. Further, the width of the notch may be a certain width or more that can be detected by the magnetic sensor, and within a range in which the rising position of the next FG multiplied signal of the signal for detecting the notch 8 does not deviate.

[Effects of the Invention] As is clear from the above description, the present invention provides a multipolar magnet ring that is fixed to a rotating shaft and has N poles and S poles alternately magnetized in the circumferential direction, and this multipolar magnet. a magnetic sensor arranged opposite to the ring and converting the change in the N-S pole into an FG multiplied signal; and a delay sensor arranged to delay the FG multiplied signal.
a circuit, and a cutout portion for changing the duty of one FG multiplied signal is provided in a part of the one N pole or the S pole,
Since a PG signal detection circuit is provided to extract the PG multiplied signal from the FC signal whose duty has changed, one device can detect the P
It is possible to detect a G-multiple signal and an FG-multiple signal, which has the effect of reducing the number of parts and assembly man-hours, reducing costs, and saving space.

[Brief explanation of drawings]

1 to 11 show embodiments of the present invention.
The figure is a plan view and PC signal detection circuit diagram of the FG double signal PC signal detection device, Figure 2 is a perspective view of the multipolar magnet and magnetic sensor, Figure 3 is a structural diagram of the magnetic sensor, and Figure 4 is the direction of the magnetic field. Figure 5 is a circuit diagram configuring the magnetic sensor, Figure 6 is a graph showing the relationship between magnetic field rotation angle and output voltage, Figure 7 is a graph showing the relationship between the magnetic field rotation angle and the resistance value of the magnetoresistive element, and Figure 7 is a graph showing the relationship between the magnetic field rotation angle and the output voltage. Fig. 8 is a graph showing the FG multiplier signal detected by the magnetic sensor, Fig. 9 is a partial plan view showing the multipolar magnet and the direction of its magnetic field, and Fig. 10 is the magnetic sensor. Graph showing the F'G signal detected in the first
Figure 1 is a graph of each output voltage of ■, ■, ■, ■, ■ in the circuit diagram of Figure 1, and Figures 12 and 13 show modifications of the above embodiment. is a partial plan view showing the multipolar magnet and the direction of the magnetic field, Fig. 13 is a graph showing the FC signal detected by the magnetic sensor, Figs. 14 to 16 are conventional examples, and Fig. 14 is a brushless morph. FIG. 5 is a perspective view of the driving magnet and the induction coil, and FIG. 16 is a graph showing the PG multiplied signal detected by the induction coil. 3... Rotating shaft, 4... FG double signal PG signal detection device, 5... Multipolar magnet, 6... Magnetic sensor, 7...
... Delay circuit, 8... Notch. Multipolar magnet's net section
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Claims (1)

[Claims] (1) A multipolar magnet ring that is fixed to a rotating shaft and has N and S poles alternately magnetized in the circumferential direction, and an FG that is placed opposite to this multipolar magnet ring and that detects changes in the N and S poles.
a magnetic sensor that converts the signal into a signal, a notch part that changes the duty of one FG signal in a part of the one N pole or S pole, and a PG signal that extracts the PG signal from the FG signal whose duty has changed. An FG signal/PG signal detection device characterized by being provided with a detection circuit.