JPH08106669A - Detecting circuit for temperature of disk of magneto-optical disk player - Google Patents

Abstract

PURPOSE: To enable performing correctly recording operation of a signal and to make constitution simple by providing a temperature detecting circuit detecting temperature of a disk by voltage between both ends of a coil of a magnetic head. CONSTITUTION: This temperature detecting circuit is used for a magneto-optical disk player recording a signal in a disk by a laser emitted from an optical pickup and magnetic variation outputted from a disk contact type magnetic head. This circuit has a magnetic coil 1 constituting the magnetic head contacting with the disk at the time of operation for detecting temperature in the circuit. And temperature of the disk is detected by making the prescribed current flow in the magnetic coil 1 and detecting voltage between its both ends A, B, and an output of a laser emitted from the optical pickup is set based on the temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk player configured to record a signal on a disk by a laser emitted from an optical pickup and a magnetic change output from a disk contact type magnetic head.

[0002]

2. Description of the Related Art Recently, a device called a magneto-optical disc player, which can not only reproduce a signal recorded on a disc but also repeatedly record the signal on the disc, is becoming widespread.

Such a magneto-optical disc player raises the temperature of the surface of the recording film constituting the disc to a predetermined temperature by the laser emitted from the optical pickup, and changes the magnetism output from the disc contact type magnetic head. It is configured to record the signal on a disc.

[0004]

In a magneto-optical disc player configured to raise the temperature of the recording film surface constituting a disc to a predetermined temperature by a laser emitted from an optical pickup, a constant laser output is used. When recording is performed, the ambient temperature changes depending on the environment in which the disc player is used, so the temperature of the disc also changes according to the ambient temperature.
As a result, the characteristics of the signal recorded on the disc change depending on the temperature, which has a problem of affecting the recording / reproducing operation of the signal.

In order to solve such a problem, a technique has been developed in which the output of the laser is changed in response to the temperature change. However, since such a technique detects the temperature of the device, When a cold disk is used, the temperature rise may not reach a predetermined value, which may hinder the signal recording operation.

The present invention is intended to provide a disk temperature detecting circuit which solves such a problem.

[0007]

A temperature detecting circuit of the present invention detects a voltage across a coil constituting a magnetic head when a predetermined current is applied to the magnetic head, and detects the temperature of a disk based on the detected voltage. Is detected.

[0008]

According to the present invention, the temperature of the disk is detected by utilizing the magnetic head which is in contact with the disk.

[0009]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, reference numeral 1 is a magnetic coil constituting a magnetic head that contacts the surface of the disk, and 2 and 3 are first and second auxiliary coils having a function of inverting the current supplied to the magnetic coil 1 at high speed. And one end thereof is commonly connected to each other and connected to the power supply line 4, and the other end thereof is connected to the ends A and B of the magnetic coil 1, respectively.

Reference numeral 5 is a first field effect transistor whose drain is connected to an end A which is a connection point between the magnetic coil 1 and the first auxiliary coil 2 and whose source is grounded. A second field-effect transistor which is connected to the end B which is a connection point between the magnetic coil 1 and the second auxiliary coil 3 and whose source is grounded, 7 is the same as the level of the signal input to the input terminal This is a buffer amplifier circuit that outputs a level signal, and its output terminal is connected to the gate of the first field effect transistor 5. Reference numeral 8 is an inverter circuit having an input terminal connected to the input terminal of the buffer amplifier circuit 7 and outputting a signal of a level obtained by inverting the level of the signal input to the input terminal, the output terminal of which is the first terminal. 2 is connected to the gate of the field effect transistor 6.

Reference numeral 9 denotes a temperature detecting selection switch which is switched to the position shown in the figure during the temperature detecting operation. The movable terminal 9a is connected to the input terminal of the buffer amplifying circuit 7 and the input terminal of the inverter circuit 8 and a predetermined terminal. DC voltage B1
And a second fixed terminal 9c to which a data signal, which is a recording signal, is applied. 1
Reference numeral 0 denotes an interlocking switch which is interlocked with the temperature detecting selection switch 9 and includes a movable terminal 10a connected to the power supply line 4, a first fixed terminal 10b to which a predetermined DC voltage B2 is applied, and a recording operation. When the movable terminal 10
The second which is connected to a and to which a predetermined voltage V is applied
The fixed terminal 10c is provided.

Reference numeral 11 is an amplifier circuit in which a + side input terminal is connected to the end B and a − side input terminal is connected to the end A in order to detect the voltage across the magnetic coil 1. The temperature detecting operation is performed. Reference numeral 12 is an A / D conversion circuit for converting the DC voltage, which is the output signal of the amplifier circuit 11, into a digital signal according to its level. Reference numeral 13 denotes a laser generator that constitutes an optical pickup (not shown) and generates a laser. Reference numeral 14 denotes a laser drive circuit that drives the laser generator 13 and has a function of adjusting the laser output.

Reference numeral 15 is a control circuit for controlling the operation of the laser driving circuit 14 based on the signal output from the A / D conversion circuit 12. The control operation of the laser driving circuit 14 outputs from the laser generator 13. It serves to adjust the output of the laser.

The present invention is constructed as described above,
Next, the operation of such a circuit will be described. The signal recording operation in this magneto-optical disc player is performed with the temperature detection selection switch 9 and the interlock switch 10 switched to the opposite side of the illustrated state.

When the signal recording operation state is established, a pulsed data signal is passed through the temperature detecting selection switch 9 to the buffer amplifying circuit 7 and the inverter circuit 8.
Applied to the input terminal of. The level of the data signal is H
When it is at the (high) level, the output signal of the buffer amplifier circuit 7 becomes the H level and is applied to the gate of the first field effect transistor 5, and the output signal of the inverter circuit 8 is at the L (low) level. Is applied to the gate of the second field effect transistor 6.
As a result, the first field effect transistor 5 becomes conductive and the second field effect transistor 6 becomes non-conductive. Therefore, in such a state, the recording current flows through the magnetic coil 1 from the end B side to the end A side.

On the contrary, when the level of the data signal is L level, the output signal of the buffer amplifying circuit 7 becomes L level and is applied to the gate of the first field effect transistor 5 and the inverter circuit 8 is provided. Output signal of H level is applied to the gate of the second field effect transistor 6. As a result, the first field effect transistor 5 becomes non-conductive and the second field effect transistor 6 becomes conductive. Therefore,
In such a state, the magnetic coil 1 has the end portion B from the end portion A side.
The recording current will flow to the side.

As described above, when the pulsed data signal is input, the first field effect transistor 5 and the second field effect transistor 6 alternately repeat the conducting operation and the non-conducting operation. From 1, a magnetic field for recording is generated. Then, in such a state, a laser is generated by the laser generator 13 by the driving operation of the laser driving circuit 14 and the recording track of the disc is irradiated with the laser, so that the temperature of the recording film surface of the disc reaches a predetermined temperature. Can be raised. As a result of such operation, a data signal, for example, a music signal can be recorded on the disc.

As described above, the signal recording operation according to the present invention is performed. Next, the temperature detecting operation will be described.
Such detection operation is performed by switching the temperature detection selection switch 9 and the interlocking switch 10 to the illustrated state. When switched to such a state, the amplification circuit 11 and the A / D conversion circuit 12 are in a state of performing amplification operation and conversion operation, respectively.

When the temperature detection selection switch 9 is switched to the illustrated state, a DC voltage B1, that is, an H level signal is applied to the input terminals of the buffer amplification circuit 7 and the inverter circuit 8 through the temperature detection selection switch 9. To be done. Therefore, the output signal of the buffer amplifier circuit 7 is H
As a result, the output signal of the inverter circuit 8 becomes L level and is applied to the gate of the second field effect transistor 6, and as a result, the first field effect transistor 5 is applied to the gate of the first field effect transistor 5. Since the field-effect transistor 5 becomes conductive and the second field-effect transistor 6 becomes non-conductive, in such a state, a current flows through the magnetic coil 1 from the end B side to the end A side. Become. In the state where the temperature detecting operation is performed, a predetermined DC voltage B2 is supplied to the power supply line 4, and the DC voltage B2 is set so that, for example, the current value flowing through the magnetic coil 1 is 10 mA. Is set to.

Here, the resistance value of the magnetic coil 1 is 1
It has a positive temperature coefficient of about 0.4% per ℃, 25 ℃
When the resistance value at 1.1 is 1.1Ω, the resistance value at 50 ° C. is 1.1 + 1.1 × (50−25) × 0.004 =
1.21Ω, and the resistance value at 0 ° C is 1.1+
It becomes 1.1 * (0-25) * 0.004 = 0.99 (ohm).

Therefore, the resistance value of the magnetic coil 1 changes from 0.99Ω to 1.2 when the temperature changes from 0 ° C to 50 ° C.
Since it changes to 1Ω, its changing resistance value becomes 0.22Ω, and when a current of 10 mA flows through the magnetic coil 1, its changing voltage value becomes 2.2 mV. Therefore, by detecting the voltage across the magnetic coil 1,
The temperature of can be detected. Since the magnetic head incorporating the magnetic coil 1 is in contact with the disk, the temperature of the magnetic head becomes the temperature of the disk, and as a result, the temperature of the disk can be detected.

The voltage appearing across the magnetic coil 1 is
A / D conversion circuit 12 after being amplified by the amplification circuit 11
Is input to As a result of such a voltage being input to the A / D conversion circuit 12, a digital signal corresponding to the value of the DC voltage input to the A / D conversion circuit 12 is converted into the A / D conversion circuit 12
Is output and input to the control circuit 15. Therefore, the control circuit 15 detects the temperature of the disk.

When the temperature of the disk is detected by the control circuit 15, a control signal is output to the laser drive circuit 14 in order to obtain the laser output suitable for the detected temperature. When such a signal is output from the control circuit 15 to the laser drive circuit 14, the laser drive circuit 14 performs drive control operation on the laser generator 13, so that the laser generator 13 changes the temperature of the disk. A laser of corresponding output will be generated. Therefore, the signal recording operation on the disk can be performed with the optimum laser output, and the signal recording operation can be performed accurately.

It should be noted that the temperature detection operation of the disk should be performed not only before the signal recording operation is started, but also during the signal recording operation state while the signal recording operation is suspended. You can also According to this structure, the laser output can be set in accordance with the temperature change of the disk, so that the signal recording operation can be performed more accurately.

[0025]

According to the present invention, the temperature of the disk is detected instead of the temperature of the magneto-optical disk player, so that the signal recording operation can be performed accurately. Also,
Since the temperature of the disk is detected using the magnetic head that contacts the disk, not only can accurate detection be performed, but a special detection member is not required, which simplifies the configuration. The present invention has

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a disk temperature detection circuit of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 magnetic coil 5 1st field effect type transistor 6 2nd field effect type transistor 9 temperature detection selection switch 11 amplification circuit 12 A / D conversion circuit 13 laser generator 14 laser drive circuit 15 control circuit

Claims (2)

[Claims] 1. In a magneto-optical disc player configured to record a signal on a disc by a laser emitted from an optical pickup and a magnetic change output from a disc contact type magnetic head, a predetermined current is applied to the magnetic head. A disk temperature detecting circuit for a magneto-optical disk player, wherein a voltage across both ends of a coil forming the magnetic head is detected when the magnetic head is flowed, and the temperature of the disk is detected based on the voltage. 2. The disk temperature detecting circuit according to claim 1, wherein the output of the laser emitted from the optical pickup is set based on the detected temperature of the disk.