JPH02179913A - Rotary head cylinder device - Google Patents

Abstract

PURPOSE:To obtain the PG signal of head switching only with the coil formed on a printed circuit board without requiring a PG magnet by subjecting one pole of a rotor magnet which generates the main magnetic field of a motor to magnetization of a reverse polarity. CONSTITUTION:This device has the rotor magnet 22 which has n-pairs (n is a positive integer) of the magnetic poles and is subjected in a part of at least one pole of the magnetic poles to the partial magnetization of the area smaller than the magnetizing pole as well as a phase detecting coil means 30 which is formed with a forward pattern and return pattern in the position part by nX360 deg.E (n is a positive integer) electrical angle in the part facing the partially magnetized part of the printed circuit board mounted with the driving coil and generates a phase detection signal as the rotor magnet 22 rotates. The PG signal is generated only by the coil formed on the printed circuit board in this way and, therefore, the inexpensive and compact PGA signal generator is obtd. without requiring the PG magnet, magneto-resistance element, power source, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotary head cylinder device useful for use in a magnetic recording/reproducing device.

Conventional technology In recent years, rotating head cylinder devices have become smaller and lighter.

Cost reduction is desired.

An example of the above-mentioned conventional rotary head cylinder device will be described below with reference to the drawings.

FIG. 4 shows the configuration of a conventional rotating head cylinder device.

To explain this configuration and operation, first, a switching signal for switching the operation of the plurality of magnetic heads 11 provided on the rotating drum 13 is provided on the outer periphery of the rotor unit 10 of the motor that rotationally drives the rotating magnetic heads 11. The magnetic field change caused by the rotation of the PG magnet 12 is detected by the magnetoresistive element 14, and a PG signal 16 shown in FIG. 6 is obtained. Thresholding the PG flaw signal 6 at a potential indicated by V,
Create switching signals.

Problems to be Solved by the Invention However, the above configuration not only requires the PG magnet 12 for phase detection, but also requires a magnetoresistive element 14, a power source, and a power supply line, which increases the number of parts. Not only that, but they also had problems in terms of cost and space.

In view of the above problems, the present invention provides a rotating head cylinder device configured so that a PG flaw signal for head switching can be obtained only by a coil formed on a printed circuit board without particularly requiring a PG magnet.

Means for Solving the Problems In order to solve the above problems, the rotating head cylinder device of the present invention has n pairs (n is a positive integer) of magnetic poles, and a portion of at least one of the magnetic poles has the A rotor magnet that is partially magnetized with an opposite polarity and has an area smaller than the magnetized pole,
A forward pattern and a return pattern are formed at positions separated by n x 360JC (n is a positive integer) in electrical angle at a portion of the printed circuit board on which the driving coil is mounted, facing the partially magnetized portion, and the rotor magnet a phase detection coil means for generating a phase detection signal as the rotor magnet rotates;
The phase detection coil means is located on the inner circumferential side, and the partially magnetized portion of the rotor magnet is provided on the inner circumference of the rotor magnet so as not to face the frequency generating coil means.

Function The present invention has the above-described configuration, and the FC coil and PG coil can be mounted on the same substrate without providing a P0 magnet or a magnetoresistive element.
By configuring the coil, it is possible to obtain a stable PG flaw signal and FG multiplied signal that does not affect the FG multiplied signal at all.

EXAMPLE Hereinafter, a rotating head cylinder device according to an example of the present invention will be described with reference to the drawings.

Fig. 1 shows a sectional view of the motor part of a rotary head cylinder device according to an embodiment of the present invention, Fig. 2 is a plan view showing the main part configuration, and Fig. 3 is a diagram illustrating the operation. be.

The operation of the rotating head cylinder device configured as described above will be described below with reference to FIGS. 1, 2, and 3.

First, in FIG. 1, a shaft 26 rotatably supported by a bearing 23 of a fixed drum 21 has a rotating drum (not shown) equipped with a magnetic head at the upper end, and a motor 20 for driving the rotating drum at the lower end. is provided. The motor 20 is provided in a main magnetic field from a rotor magnet 22 and is rotationally driven by energization of a stator coil 24 fixed to a fixed drum 21 . The stator coil 24 includes an FG coil 28 for frequency power generation and a PG coil 30 for phase detection signal power generation, which are formed by plating or etching on a sheet-like substrate 26 as shown in FIG.
are layered.

The PG coil 30 has an electrical angle of 3601! (Hereinafter, the electrical angle will be expressed as "0E") The forward pattern 36 and the backward pattern 40 are formed at separate positions.

Note that this example shows an example of an 8-pole magnet, so 360° IC is 90°M in mechanical angle (hereinafter, mechanical angle is "
0M”).

The rotor magnet 22 is superimposed on the 8-pole magnetization of alternating N and S for generating the main magnetic field of the motor, and the PG near the inner circumference
A partially magnetized pole 32 for PG with opposite polarity is located at a position where the magnetic flux intersects with the forward pattern 36 and return pattern 40 of the coil 30.
is being carried out. In this embodiment, the S-pole portion is subjected to N-pole magnetization.

Next, to explain this operation, the rotor magnet 2
2 rotates in the direction of arrow R.

In FIGS. 3C and 3D, the horizontal axis indicates the rotation angle of the rotor magnet 22, the position of the vertical line F is the position shown in FIG. 2, and the position rotated 90 M (360 E) from there is H, The position after one rotation (360°M) is F'.

When the positive side is connected to the terminal 34 and the negative side is connected to the terminal 3B, the voltage induced in the PG coil 30 is as follows at the position shown in Fig. 3, assuming that Ni generates electricity in the positive direction and the S pole in the negative direction. Since the partially magnetized pole 32 generates a positive voltage in the forward pattern 36 of the PC coil 3o, it generates a peak portion 44 shown in FIG. 3G.

Furthermore, when the rotor magnet 22 rotates 90 M and the partially magnetized pole 32 reaches the H position, and the partially magnetized pole 32 passes through the return pattern 4o, the winding is in the opposite direction, so that the peak of the negative voltage is Generates 6o.

In the portion where the partially magnetized pole 32 does not face the PG coil 30, the forward pattern 36 is
In the return pattern 4o, magnets with the same polarity face each other and generate voltages of the same level and opposite polarity, so they cancel each other out, and the sum of the currents flowing between the terminals 34 and 38 becomes almost 0, as shown in Fig. 3C. The waveform 46 shown in FIG.

Therefore, the waveform of the current obtained at the terminals 34 and 38 of the PG 30 is such that a rising pulse 44 and a falling pulse 6o are obtained once per revolution from 1 to V, as shown in FIG. 3C.

This signal is thresholded at the potential shown by V in FIG. 3C, and the waveform is shaped to produce a switching signal for the magnetic head shown in D.

Next, to explain the operation of the ya mi coil shown in FIG. 2, the FG coil 28 generates a signal with a frequency corresponding to the rotation speed by the rotation of the rotor magnet 22 (in FIG. 2, 4 cycles per rotation). AC signal) This signal is compared with a reference signal to control the rotation speed of the motor 20.

At this time, the partially magnetized pole 32 for PG is located on the inner circumferential side of the radial direction pattern 29 that contributes to the FG multiplied signal power generation, and does not cross the pattern 29, so it does not affect the FG multiplied signal power generation at all. .

As a result, a distortion-free signal waveform is obtained in the FG coil 28, and the rotation of the motor 20 can be controlled with high accuracy.

Effects of the Invention As described above, the present invention applies opposite polarity magnetization to one pole of the rotor magnet that generates the main magnetic field of the motor, and generates a PG double signal using only the coil formed on the printed circuit board. In particular, excellent effects such as an inexpensive and compact PG signal generator that does not require a PG magnet, a magnetoresistive element, a power supply, etc. can be obtained.

Furthermore, since the partially magnetized pole for PG is provided at a position that does not face the FG pattern, it does not affect the yG multiplied signal response.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of the motor portion of a rotary head cylinder device according to an embodiment of the present invention, Fig. 2 is a plan view showing the configuration of the main parts, Fig. 3 is an explanatory diagram of the same operation, and Fig. 4 is a conventional FIG. 6 is a front view showing the configuration of the rotary head cylinder device, and is an explanatory view of the same operation. 22... Rotor magnet, 28... FG coil, 3o... PG coil, 32... Partially magnetized pole, 36... Outward rotation, 40...・
...Return pattern, 44...Peak part. Name of agent: Patent attorney Shigetaka Awano and 1 other person21
1-FG Go 4 noshi 30- PG coil 32--Ichiji 8J no hook J mo 3cm 1 branch! ! 1\'curso

Claims (2)

[Claims] (1) a rotor magnet having n pairs (n is a positive integer) of magnetic poles, and at least one of the magnetic poles is partially magnetized with an opposite polarity and a smaller area than the magnetized pole; A forward pattern and a return pattern are formed at positions separated by n×360°E (n is a positive integer) in electrical angle at a portion of the printed circuit board on which the driving coil is mounted, which faces the partially magnetized portion, and A rotating head cylinder device comprising: phase detection coil means for generating a phase detection signal in accordance with rotation of a rotor magnet. (2) A frequency generating coil means for generating a signal at a frequency corresponding to the rotational speed by the rotation of the rotor magnet is located on the outer circumferential side, and the phase detection coil means is located on the inner circumferential side, so that the partially magnetized portion of the rotor magnet is 2. The rotating head cylinder device according to claim 1, wherein the rotating head cylinder device is provided on the inner circumference of the rotor magnet so as not to face the generating coil means.