JPH04188404A - Magnetic head device - Google Patents

Abstract

PURPOSE:To enable high density recording in spite of low power consumption by composing a magnetic core of a bar-shaped core while the time, until the start of the magnetic-field generating operation with another polarity after the start of the magnetic-field generating operation with each polarity modulated, is set to be approximately one half of resonance frequency determined by the inductance of a coil and capacity in the periphery of the coil. CONSTITUTION:A material having high permeability such as Mn-Zn ferrite is used as a bar-shaped magnetic core 12. Coils L1, L2 are wound mutually in the opposite directions. The time until a switching element SW2 is turned ON after a switching element SW1 is turned OFF and the time until the switching element SW1 is turned ON after the switching element SW2 is turned OFF are set to be approximately one half of the resonance period of a resonance circuit including the coils L1, L2 respectively by timing circuits 14, 15. Accordingly, loss by the high-frequency resistance component of a magnetic head is reduced, the current rise time of the coils is accelerated in spite of low power consumption, the inversion speed of a magnetic field generated can be increased largely, and recording density can be augmented remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic head device used in a magnetic field modulation type magneto-optical recording device.

[Prior Art] A magneto-optical recording device using a magneto-optical disk as a recording medium is not only capable of high-density recording but also allows information to be rewritten, and therefore has great expectations.

Several recording methods are known for magneto-optical recording devices, but in particular magnetic field that allows for override, which allows information to be rewritten by recording new information on top of previously recorded old information. The modulation method is excellent.

FIG. 5 is a diagram showing a schematic configuration of the magneto-optical recording device using the magnetic field modulation method, where l is a magneto-optical disk (hereinafter simply referred to as a disk) which is an information recording medium, and 2 is a magneto-optical disk provided on the disk 1. This is a magneto-optical recording layer. A magnetic head 3 is disposed on the upper surface of the disk 1, and a magnetic head 3 is disposed on the lower surface.
An optical head 4 is disposed opposite to. magnetic head 3
It has a structure in which coils L, , L are wound around a U-shaped magnetic core 5, and by controlling the current of the coils L, , L with a drive circuit 6, a bias magnetic field corresponding to the recording signal is generated. applied to disk l. Further, the optical head 4 is equipped with a semiconductor laser 7 inside, and the laser beam is focused into a minute spot and irradiated onto the disk 1.

FIG. 6 is a circuit diagram showing an example of the drive circuit 6, in which R,
, R, are resistors for current limiting of coils Ll and Lx, SW
1 and SW2 are switch elements for switching the currents of the coils L, , L. As the switch elements SW], ..., SW2, for example, field effect transistors are used. Reference numerals 8 and 9 are amplifier circuits, respectively, which amplify the recording signal to an appropriate level and drive the switch element SWI.

This circuit is applied to the second control terminal. Further, numeral 10 indicates an inverting circuit which inverts the recording signal and supplies it to the amplifier circuit 9.

Next, in FIG. 6, when the information signal "1" is input to the input terminal S, the switch element SW2 is turned on, and current is supplied to the coil. Note that the switch element SWI is off because a low level signal is input to the control terminal by the inverting circuit 10.

On the other hand, the disk 1 is irradiated with a laser beam of a predetermined intensity from the optical head 4, and the magneto-optical recording layer 2 is heated to a temperature higher than the Curie temperature. Therefore, in this state, coil L2
When a magnetic field is applied by 2, the direction of magnetization of the temperature-increased region of the recording layer is coiled and directed in the direction of the magnetic field by 2.

Moreover, when the information signal becomes "O", the switch element SW2
is off and switch element SWI is on, so coil L
1 is supplied with current. Since the coils L1 and L2 are wound around the core 5 in opposite directions, the magnetic field generated by the coil L1 has a polarity opposite to that of the coil L2. Therefore, when the information signal is "0", the direction of the magnetic field is opposite to the above, and therefore the direction of magnetization of the recording layer is also opposite to the above. By changing the direction of the bias magnetic field in accordance with the information signal in this way, information is recorded by making the direction of magnetization of the recording layer correspond to "1" and "0" of the bit information.

[Problem to be solved by the invention] However, in the above-mentioned conventional magneto-optical recording device,
Since magnetic energy is accumulated in Ll and L2 only by supplying current from the power source (2), the current rise time of each coil becomes long.

Therefore, the reversal speed of the generated magnetic field is slow, which hinders high-density information recording. In order to speed up the current rise in the coil, it is possible to increase the power supply voltage, but this is not preferable because it increases the power consumption of the drive circuit.

For example, coil L3. The inductance of Lx is 186μ
Assuming that the resistance value of the H1 resistors R1 and R2 is 100Ω and the magnetic field reversal time tr is 30 ns, a power supply voltage of 30 V is required. Also, the power consumption P of the drive circuit at this time is 9
It becomes W. -For boat fishing, practically tr<20ns, P<4
Since it is W, the above-mentioned conditions cannot satisfy the requirement.

Therefore, as an attempt to solve the above-mentioned problems, for example, Japanese Patent Application Laid-Open No. 1-130302 proposes a resonant circuit constructed of a coil and a capacitor. However, in this method, the high frequency loss of the magnetic head was large, so the power consumption was high (and a sufficient effect could not be obtained).

The present invention has been made to solve these problems, and its purpose is to provide a magnetic head device that can perform high-density recording while consuming low power.

[Means for Solving the Problems] Such an object of the present invention is to provide a magnetic core having a magnetic core around which at least one coil is wound, and to provide a magnetic core in accordance with an information signal to record current supply operation to the coil. In a device that applies a bias magnetic field modulated in accordance with an information signal to a magneto-optical recording medium by controlling the magnetic core, the magnetic core is constituted by a rod-shaped core, and the magnetic field generating operation of each modulated polarity is started. This is achieved by a magnetic head device characterized in that the time until the start of the magnetic field generation operation of the other polarity is set to approximately 1/2 of the resonance frequency determined by the inductance of the coil and the capacitance around it.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a magnetic head device of the present invention. In FIG. 1, the same parts as those of the conventional device shown in FIG. 5 are given the same reference numerals.

In FIG. 1, reference numeral 11 denotes a magnetic head in which coils L, L2 are wound around the outer periphery of a rod-shaped magnetic core 12. As the magnetic core 12, a material with high magnetic permeability such as Mn--Zn ferrite is used. Further, the coils L, , L, are wound in opposite directions as in the conventional case. 13 is a drive circuit that drives the magnetic head 12 and includes coils L, , L.
This is a circuit that supplies current to 2. In addition, rl indicated by a broken line
.

r2 is a high-frequency resistance component of the magnetic herad 11 isometrically expressed as a resistance. Further, 1 is a magneto-optical disk having magneto-optical recording N2, and 4 is an optical head incorporating a semiconductor laser 7, which are the same as the conventional one.

FIG. 2 is a circuit diagram showing a specific example of the drive circuit 13. In FIG. 2, the same parts as those in the conventional drive circuit shown in FIG. 6 are designated by the same reference numerals. The switch elements SWI and SW2 are current switching switches for the coils L, , L, and use field effect transistors, for example. Resistors R1 and Rx are current limiting resistors, and 10 is an inverting circuit, both of which are the same as those in the conventional circuit.

In addition, 14.15 is a timing circuit, and a switch element S
This is a circuit that drives WI,2.

In this embodiment, these timing circuits cause the time from the OFF of the switch element SWI to the ON of the switch element SW2, and the time from the OFF of the switch element SW2 to the ON of the switch element SWI to respectively reduce the resonance including the coils L, L2. It is set to be approximately 1/2 of the resonance period of the circuit.

Note that the resonant circuit here refers to the inductance of coils L1 and L2, their stray capacitance, and switch elements SWI and 2.
Junction capacitance of diode DI.

This refers to a circuit composed of a junction capacitance of D2.

Of course, a resonance capacitor may be additionally provided in addition to the above.

Next, the operation of the drive circuit 13 will be explained. First, a digital information signal to be recorded on the magneto-optical disk 1 is input to the terminal S. This information signal is the timing circuit 1
4 and the inversion circuit 10 to the timing circuit 15. Timing circuit 14.15 receives the information signal and applies a potential to the control terminal of switch element SWI,2 to drive switch element SW1.2. In this example, when the information signal is 1, switch element SW2 is on and SWI is off, and when the information signal is O, switch element SW2 is on.
is off and SWI is on. This causes the information signal to become 1
When the information signal is O, a current is supplied to the coil L2, and when the information signal is O, a current is supplied to the coil L1. Coil and L
2 are wound around the magnetic core 12 in opposite directions, so the polarity of the generated magnetic field changes in response to the information signal. The bias magnetic field thus modulated according to the information signal is applied to the magneto-optical disk 1. On the other hand, the magneto-optical disk 1 is irradiated with a laser beam from the optical head 4, and information is recorded by the interaction between the irradiation of this beam and the application of a magnetic field.

Here, switch element SW1.3W2 is turned on.

Transient phenomena during off-time will be explained. Switch element SW
When I is on and the other switch element SW2 is off, the diode D8, limiting resistor R3,
A current flows through a current path CHI that includes the winding coil L1 and the switch element SWl. On the other hand, at this time, the diode D2, the limiting resistor R2, the wire-wound coil L2. Switch element S
No current flows through current path CH2 that uses W2 as a path.

In this state, calculate the current flowing through the current path CHI.

Then, the magnetic energy Eo stored in the magnetic herad 11 is Eo=1/2LI,''.

However, L is the self-inductance of the winding coils L, L2.

Here, when the switch element SW1 is turned off, the current flowing through the current path CHI decreases due to the resonance phenomenon between the capacitor and the coil L1 due to the junction capacitance of the switch element SWI. The current flows in the opposite direction and begins to increase again, reaching a maximum value of -01 after 1/2 of the resonance period has passed. Take. Note that α is a coefficient determined by losses occurring in the limiting resistor R1, the high frequency resistance component 1 of the magnetic head 11, and the like. This coefficient α is 0 and α<1, and when the loss is small, a takes a large value. Then, at the maximum value of the current, magnetic energy of 1/2L (-α engineering) 2 = α''Eo is stored in the magnetic herad 11 again. The polarity of the magnetic field will also be reversed.

In this transient phenomenon, the energy E0 initially stored in the magnetic head 11 is transferred and stored in the -degree capacitor as electrostatic energy, and then is stored in the magnetic head 11 again as magnetic energy. The difference before and after energy transfer, that is, (1-α2)Eo, is the limiting resistance R1 and the high-frequency resistance component of the magnetic head 11.
The heat is consumed by the resistance of the switch element SWI and changes into heat.

Further, the current flowing through the current path CHI has a local maximum value -α■.

By turning on the switch element SW2 at the moment when the current occurs, current flows through the current path CH2, and the magnetic herad
1 is supplied with magnetic energy, but in this case, the number α''E (since the energy of 1 is stored, only the energy of Eo, which has already been consumed and is insufficient (1 - α'')) is supplied from the power supply V. Therefore, if the value of α is close to 1, the amount of energy that must be supplied is small, reducing the power consumption of the drive circuit 13, and the reversal speed of the magnetic field is approximately equal to the resonance period. 1/ of
2, it is possible to do it as quickly as possible.

Here, as mentioned above, the value of α takes a larger value as the loss occurring in the high-frequency resistance component +, rx in the magnetic head 11 becomes smaller. In order to increase the reversal speed and record high-density information, α must be made as large as possible. In other words, it is necessary to minimize the loss that occurs in the high-frequency resistance component l + r t. However, this also reduces heat generation in the magnetic helad 11 and leads to highly reliable information recording.

In addition, the high frequency resistance component element + of the magnetic herad 11.

Reducing the loss at r2 means r+.

This means increasing the resistance value of r2.

As a result of repeated research from this viewpoint, the inventor of the present application has confirmed that the one shown in FIG. 3 is the most excellent. In FIG. 3, 12 is a rod-shaped magnetic core made of a material with high magnetic permeability, for example, Mn--Zn ferrite. In this example, a square cross-sectional shape is used, and its dimensions Dxl) are 0.2 x 0.2 mm to 0.2 mm.
3×O, 3mm, length 4 is 1.2-1.8mm. Moreover, 21 is a winding coil, and the conductor diameter is 25~
A combination of 5 to 10 40 μm enameled thin wires was used. Note that the appropriate number of turns was 15 to 30.

As for the shape of the magnetic core, conventionally, for example, Japanese Patent Application Laid-open No. 1-199
As described in No. 301, a U-shape or something similar is common. This U-shaped core is
This method was adopted because it is advantageous in terms of magnetic field generation efficiency, that is, the strength of the generated magnetic field per magnetomotive force (number of coil turns x current). However, in combination with the circuit format,
The one shown in Figure 3 was optimal. That is, according to the experimental results, the conventional magnetic head has a high frequency resistance element '+1rz
was about 900Ω, whereas the maximum resistance of this example was 1500Ω. Therefore, the high frequency resistance component +,
It was confirmed that r2 could be significantly increased compared to the conventional method, and that the resulting loss could be significantly reduced. Therefore, according to the magnetic head of this embodiment, the magnetic field reversal speed is 20 ns.
, it is possible to obtain practically sufficient performance with power consumption of 3W. As for how to use the magnetic head of this embodiment, it is desirable to provide it on an air floating type slider and use it as a floating magnetic head sufficiently close to the disk, similar to conventional magnetic heads.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment is an example applied to a magnetic head using one coil. In FIG. 4, reference numerals 22 to 25 are timing circuits that apply potentials to the control terminals of the switch elements SW3 to SW6 to control ON and OFF states, respectively. A field effect transistor is used as each switch element. Further, L3 is a coil wound around a magnetic core (not shown), R is a current limiting resistor, D, to D6 are diodes, 10 is an inversion circuit, and r3 is a high frequency resistance component of the magnetic head. Note that a rod-shaped magnetic core is used as in the previous embodiment.

The digital information signal input from the terminal S is input to the timing circuit 22.24 via the timing circuit 23.25 and the inversion circuit 10. As a result, the on/off phases of switch element 23.25 and switch element 22.24 are reversed, and when switch element SW4.6 is on, the other switch element SW3.5 is turned off. In addition, when switch element SW4.6 is off, switch element SW
3.5 is turned on. Therefore, since the direction of the current in the coil L3 is switched in response to the information signal of 1.0, the polarity of the generated magnetic field is switched in response to the information signal. The magnetic field modulated by the information signal in this manner is applied to the information recording medium, and in combination with the irradiation of the recording light beam, information is recorded on the recording medium.

Here, each timing circuit has a time period from OFF of switch element SW3.5 to ON of switch element SW4.6, and a time period from OFF of switch element SW4.6 to ON of switch element SW3.
．． The time until the coil L3 is turned on is set to be approximately 1/2 of the period of the resonant circuit constituted by the coil L3 and the capacitance around it, just as in the previous embodiment. In addition, in this embodiment as well, the diode D3 is used as the capacitor of the resonant circuit.
The junction capacitance of ~D, the junction capacitance of switch elements SW3 to SW6, and the floating capacitance of coil L3 are utilized.

Therefore, even in this embodiment, the power consumption of the drive circuit can be reduced (same as the embodiment shown in FIG. By using this, high frequency loss components can be significantly reduced.

[Effects of the Invention] As explained above, according to the present invention, the loss due to the high frequency resistance component of the magnetic head can be significantly reduced compared to the conventional method. In addition, it is possible to speed up the rise time of the current in the coil and significantly increase the reversal speed of the generated magnetic field while consuming low power.

Therefore, it is possible to record at a higher speed, and the recording density can be significantly improved compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magneto-optical recording device according to the present invention, FIG. 2 is a circuit diagram showing a specific example of a drive circuit used in the embodiment of FIG. 1, and FIG. 3 is a magnetic core 4 is a circuit diagram showing another embodiment, FIG. S is a configuration diagram of a conventional device, and FIG. 6 is a drive circuit of the conventional device. It is a circuit diagram. l... magneto-optical disk, 4... optical head, 11...
- Magnetic head, 12... Magnetic core, 13... Drive circuit, 14, 15. 22-25... Timing circuit, L1-L,... Coil, SWI-SW6... Switch element. Figure 1

Claims (2)

[Claims] (1) It has a magnetic core around which at least one coil is wound, and by controlling the current supply operation to the coil according to the information signal to be recorded, the magneto-optical recording medium can be recorded in accordance with the information signal. In the device for applying a modulated bias magnetic field, the magnetic core is constituted by a rod-shaped core, and the time from the start of the magnetic field generation operation of each modulated polarity to the start of the magnetic field generation operation of the other polarity is A magnetic head device characterized in that the resonance frequency is set to approximately 1/2 of the resonance frequency determined by the inductance of the coil and the capacitance around it. (2) The magnetic head device according to claim 1, wherein the capacitance is a capacitance possessed by a circuit element constituting the device.