JPH0512605A - Magnetic head driving device - Google Patents

Abstract

PURPOSE:To enable a remarkable reduction of current consumption and a high speed changeover of coil current in a magnetic head to be executed by supplying the recording current to a coil of the magnetic head through a transformer which is formed by a primary coil and a secondary coil with the number of windings less than that of the primary coil. CONSTITUTION:The transformer T1 is formed by the primary coil Lt1 and the secondary coil Lt2 with the number of windings less than that of the coil Lt1, and a magnetic field generated in the coil Lt1 is supplied to the coil Ln of magnetic head 3 through the coil Lt2. At this time, the ON/OFF operations of switching elements S1-S4 are controlled in accordance with a recording information, then the direction of the current supplied to the coil Lt1 is changed over. By this constitution of transformer, the current made to flow in the coil Lt1 becomes small and the current consumption is remarkably reduced, then a high speed transistor with small allowable current can be used for the switching element, thereby the coil current of magnetic head can be changed over at high speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a magnetic head used in a magnetic recording device.

[0002]

2. Description of the Related Art Conventionally, several methods are known as a method for recording information on a magneto-optical recording medium, but in particular, new information is directly overwritten (overwritten) on old information that was previously recorded. It is said that the magnetic field modulation method that can do this is excellent. FIG. 4 is a block diagram schematically showing the magneto-optical recording apparatus of the magnetic field modulation system, in which 1 is a magneto-optical disk which is an information recording medium, and 2 is a magneto-optical recording layer provided on the disk 1. is there. A magnetic head 3 is arranged on the upper surface of the magneto-optical disk 1, and an optical head 4 is arranged on the lower surface so as to face the magnetic head 3. In this magnetic field modulation method, when information is recorded, first, a recording light beam of a semiconductor laser provided inside the optical head 4 is irradiated so as to be focused on the magneto-optical recording layer 2, and the temperature of the irradiation site is set to the Curie point temperature. Increase above. On the other hand, the magnetic head 3 applies a magnetic field modulated according to the recording information by driving the driving circuit 5 to the temperature rising portion of the magneto-optical recording layer 2. As a result, the direction of magnetization of the temperature rising portion of the magneto-optical recording layer 2 is oriented in the direction of the magnetization of the bias magnetic field, so that the information magnetic domain corresponding to the recorded information can be recorded on the magneto-optical recording layer 2.

FIG. 5 is a circuit diagram showing a conventional example of a drive circuit 5 for driving the magnetic head 3. This drive circuit includes four switch elements S _{1 to} S ₄ , a diode D ₁ ,
It is composed of D ₂ and a current limiting resistor R ₁ and switches the direction of the current of the coil Lh of the magnetic head 3 by the current switching operation of the switch elements S _{1 to} S ₄ . That is, by controlling the switching elements S ₁ , S ₃ and S ₂ , S ₄ to turn on alternately, the direction of the current of the coil Lh is switched alternately, and the polarity of the generated magnetic field is switched according to the recorded information. Is. FIG. 6 is a circuit diagram showing another conventional drive circuit. In this drive circuit, the switch elements S ₄ and S ₅ are alternately turned on, and the direction of the current of the coil Lh is switched as in the example of FIG. Then, the polarity of the generated magnetic field is switched. Incidentally, L ₁ and L ₂ are auxiliary coils for switching the current of the coil Lh at high speed.

[0004]

However, in the conventional drive circuit shown in FIG. 5, the current of the coil Lh of the magnetic head can be switched at high speed in order to stably form a magnetic domain in the magneto-optical recording layer. Since it is required, it is necessary to set the power supply voltage of the drive circuit to a somewhat high level, which causes a problem that the power consumption of the drive circuit increases. For example, if the power supply voltage is 12V and the current supplied to the magnetic head 3 is 0.3A, the power consumption is 3.6W. Further, in the drive circuit of FIG. 6, the current of the coil Lh can be switched at high speed by the action of the auxiliary coil, so that the power supply voltage of the drive circuit may be lower than that of FIG. However, since the current supplied to the auxiliary coil is almost the same as the current supplied to the magnetic head, the current needs to be doubled, and the power consumption also increases. For example, when the power supply voltage is 5 V and the magnetic head current is 0.3 A, the total current amount is 0.6 A including the auxiliary coil current, and the power consumption is 3 W.
Further, the current flowing through the switch elements S ₄ and S ₅ is the total amount of the magnetic head and the auxiliary coil as described above, but in general, due to the characteristics of the transistor used as the switch element,
Since a transistor having a larger allowable current has a longer switching time, it is disadvantageous to switch the current of the coil Lh of the magnetic head at a high speed.

The present invention has been made in order to solve such a problem, and its purpose is to significantly reduce power consumption and also to enable high-speed switching of the coil current of the magnetic head. To provide.

[0006]

The object of the present invention is to control the current of the magnetic field generating coil of the magnetic head according to the recording information, and to generate the magnetic field of the magnetic head corresponding to the recording information. In a magnetic head drive device which modulates the polarity, a transformer having a primary coil and a secondary coil having a smaller number of turns or less inductance than the primary coil is provided, and the primary coil of the transformer is used for generating a magnetic field. It is achieved by a magnetic head drive device characterized in that the magnetic field generating coil is connected to a current supply path and the secondary coil side of the transformer is connected.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of a magnetic head driving device of the present invention. In FIG. 1, the same parts as those of the conventional device shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted in this embodiment. In FIG. 1, T ₁ is 1
The transformer is composed of a secondary coil Lt ₁ and a secondary coil Lt ₂ , and the coil Lh of the magnetic head 3 is connected to the secondary side thereof. The number of turns of the primary coil Lt ₁ of the transformer T ₁ is n ₁ , the inductance is l ₁ , the number of turns of the secondary coil Lt ₂ is n ₂ , and the inductance is l ₂ , and n ₁ and n ₂
Is n ₁ > n ₂ , and the relationship between l ₁ and l ₂ is l ₁ > l ₂ . As described in FIG. 5, the switch elements S _{1 to} S ₄ act to switch the direction of the current of the coil Lh. When the switch elements S ₁ and S ₃ are turned on, the switch element S ₃ and the diode D ₁ are turned on. , the primary coil Lt ₁ transformer T _1, resistors R _1, current is supplied to the path of the switching element S _1. At this time, the secondary coil L of the transformer T ₁
At t ₂ , a current is induced according to the supplied current, and the magnetic head 3
An electric current is supplied to the coil Lh. Further, when the switching element S _2, S ₄ is turned ON, the switch element S _4, diode D _2, resistors R _1, the primary coil Lt ₁ transformer T _1, the current path of the switching device S ₂ supplied To be done.
In this case, a current is induced on the secondary side of the transformer T _{1 in} the same manner as described above, and a current in the opposite direction to the above is supplied to the coil Lh of the magnetic head 3. In this way, the switch element S ₁ ,
By alternately turning on S ₃ , S ₂ , and S ₄ , the direction of the current of the coil Lh of the magnetic head 3 is switched alternately, and the polarity of the magnetic field is switched according to the recorded information.

Here, the turns ratio of the transformer T _{1 is} , for example, n
_{When 1} : n ₃ = 3: 1, the power supply voltage is 12 V, and the current supplied to the coil Lh of the magnetic head 3 is 0.3 A, the current supplied to the primary coil Lt ₁ of the transformer T ₁ is 0.1.
Since it is A, the power consumption of the drive circuit is about 1.2W. As the power consumption on the secondary side of the transformer T _1, the power consumed by the stored energy (1/2 · Lh · i ² ) of the coil Lh is about 0.2 W, but this amount is ignored. And Therefore, in this embodiment, the transformer T
_Although the current in the secondary coil Lh of 1 is the same, 1
Since the current on the secondary side can be reduced, the current in the resistor R ₁ is reduced, and the power consumption of the drive circuit can be significantly reduced compared to the conventional case. In addition, since the current flowing through the switch element can be significantly reduced as compared with the conventional one, a transistor having a small allowable current can be used as the switch element. Therefore, since a high-speed transistor can be used, high-speed current switching of the coil Lh is possible, and the polarity of the magnetic field can be reversed at high speed.

FIG. 2 is a circuit diagram showing another embodiment of the present invention. 2, the same parts as those of the conventional device shown in FIG. 6 are designated by the same reference numerals, and the description thereof will be omitted here. In FIG. 2, T ₁ is the same transformer as in the above embodiment, the number of turns of the primary coil Lt ₁ is n ₁ , the inductance is l ₁ , the number of turns of the secondary coil Lt ₂ is n ₂ , and the inductance is l ₂ . .. The relationship between the number of turns and the inductance is n ₁ > n ₂ and l ₁ > l ₂ . In this example,
As described with reference to FIG. 6, the switching elements S ₅ and S ₆ are alternately turned on to switch the direction of the current of the coil Lh of the magnetic head 3. That is, when the switch element S ₅ is turned on, the auxiliary coil L _1, the primary coil Lt ₁ transformer T _1, resistors R _1, current flows through the path of the switch element S _5, 2 coil Lt of the transformer T _{1 An} electric current is induced in ₂ . As a result, a current is supplied to the coil Lh of the magnetic head 3, and a magnetic field having a polarity corresponding to the current direction of the coil Lh is generated. When the switch element S ₆ is turned on, current is supplied to the auxiliary coil L ₂ , the resistor R ₁ , the primary coil Lt ₁ of the transformer T ₁ , and the path of the switch element S ₆ . As a result, the secondary coil Lt of the transformer T _1
Since a current is induced in ₂ , the coil Lh of the magnetic head 3 is
Is supplied with a current in the opposite direction to the above, and the magnetic head 3 generates a magnetic field of opposite polarity. As described above, in this embodiment, by alternately turning on the switch elements S ₅ and S ₆ , the current of the coil Lh is alternately switched, and the polarity of the magnetic field corresponds to the recorded information. Can be switched.

Here, the turns ratio of the transformer T ₁ is set to n ₁ : n
₂ = 3: 1, the power supply voltage is 5 V, and the current supplied to the coil Lh of the magnetic head 3 is 0.3 A, the current flowing through the primary side of the transformer T ₁ including the auxiliary coil is 0. 2A, so the power consumption of the drive circuit is about 1
W. Therefore, even in this embodiment, the power consumption of the drive circuit can be significantly reduced by appropriately selecting the winding ratio of the transformer T _{1, and} a high-speed transistor can be used. You can flip it with.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention. This embodiment has two transformers T ₂ , T ₂ .
₃ is used to supply a current to the coil Lh of the magnetic head 3, and the coil Lh of the magnetic head 3 is connected between the secondary windings of the transformers T ₂ and T ₃ . Transformer T ₂ , T
₃ of the relationship between each of the primary and secondary windings of the relationship with the inductance, as in the example _{n 1> n 2, l 1} > l
_It is set to ₂ . Further, a switching element S ₇ is connected in series to the primary winding of the transformer T ₂ , and a switching element S ₈ is connected in series to the primary winding of the transformer T ₃ , and the switching elements S ₇ and S ₈ are alternately turned on. By the coil Lh
The current directions of are switched alternately. First, the switch element S
_{When 7} is turned on, current is supplied to the path of the diode D ₃ , the resistor R ₂ , the primary coil Lt ₁ of the transformer T ₂ , and the switch element S ₇ , and the current is induced in the secondary coil Lt ₂ of the transformer T _2. To be done. As a result, a current is supplied to the coil Lh of the magnetic head 3 to generate a magnetic field. When the switch element S ₈ is turned on, a current is supplied to the path of the diode D ₄ , the resistor R ₃ , the primary coil Lt ₁ of the transformer T ₃ , and the switch element S ₈ , and the secondary of the transformer T ₂ is supplied. A current is induced in the coil Lt ₂ . As a result, a current is supplied to the coil Lh of the magnetic head 3 in the opposite direction to the above,
The magnetic head 3 generates a magnetic field of opposite polarity. In this embodiment, as in the embodiment of FIG. 1, the turns ratio of the transformers T ₂ and T ₃ is n ₂ : n ₁ = 3: 1, and the power supply voltage is 12V.
When the current supplied to the coil Lh is 0.3 A, the power consumption of the drive circuit is about 1.2 W, and the power consumption can be greatly reduced as in the embodiments of FIGS. 1 and 2.

[0012]

As described above, according to the present invention, the power consumption of the magnetic head driving device can be significantly reduced as compared with the conventional one, and a high-speed current switching element can be used. There is an effect that the reversal time of the magnetic field can be shortened.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a magnetic head driving device of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention.

FIG. 4 is a configuration diagram schematically showing a magneto-optical recording apparatus of a magnetic field modulation system.

FIG. 5 is a circuit diagram showing a conventional magnetic head drive circuit.

FIG. 6 is a circuit diagram showing another conventional magnetic head drive circuit.

[Explanation of symbols]

1 magneto-optical disk 3 magnetic head Lh coil L _1, L ₂ auxiliary coil T ₁ through T ₃ transformer Lt ₁ 1 primary coil Lt ₂ 2 coil S ₁ to S ₈ switch elements

Claims (1)

Claim: What is claimed is: 1. A current of a magnetic field generating coil of a magnetic head is controlled according to recording information, and a polarity of a magnetic field generated by the magnetic head is modulated in accordance with the recording information. In the magnetic head driving device, a transformer having a primary coil and a secondary coil having a smaller number of turns or less inductance than the primary coil is provided, and the primary coil of the transformer is connected to a current supply path for generating a magnetic field, A magnetic head driving device, wherein the magnetic field generating coil is connected to a secondary coil side of the transformer.