JPH0423236A - Optical disk device and optical disk - Google Patents

Abstract

PURPOSE:To record information under an excellent S/N state and to improve recording accuracy by detecting infrared rays radiated from an optical disk with the aid of an infrared rays detector and controlling the recording power of a laser beam based on the detected output. CONSTITUTION:The infrared rays 11 radiated from the magneto-optical disk 1 is detected by the infrared rays detector 13a and the detection signal thereof is inputted in a signal processing circuit 14. The CPU 14b of the circuit 14 stores the correlation of the temperature and the S/N value of the disk 1, calculates the optimum recording power of the laser beam 3 based on the output of the detector 13a and outputs a command to a laser modulator 8. The modulator 8 controls a current supplied to a laser head 4 based on the command. Thus, the temperature of the disk is accurately detected at a high speed and an information signal 6 is recorded under an optimum state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical disc device for recording and reproducing information on an optical disc.

Conventional technology Recording and reproducing methods using optical discs usually use a laser to form a beam spot with a diameter of about 1 μm, which causes a local temperature rise on the recording film of the optical disc to cause a physical change on the recording film, thereby generating an information signal. This is what is called thermal recording. For example, when using a magneto-optical disk as an optical disk, the Curie point temperature of the recording film (
(approximately 200 degrees Celsius), a local temperature rise occurs on the recording film at t, and at the same time a magnetic field is applied to perform recording.

As shown in FIG. 2, a conventional optical disk device includes a magneto-optical disk, a motor 2 for rotationally driving the magneto-optical disk 1, a laser head 4 for irradiating a recording laser beam 3 onto the magneto-optical disk 1, and a magneto-optical disk. It is composed of a magnetic field generator 5 that applies a magnetic field to the disk 1, and the like. The information signal 6 to be recorded is input to the laser modulator 8 via the encoder 7, and the laser modulator 8 controls the output power [recording power] of the laser beam 3 emitted from the laser head 4 according to the information signal 6. are doing.

Note that there is no specific area on the surface of the conventional magneto-optical disk 1 where the emissivity is adjusted to a set value.
The emissivity of the surface of the magneto-optical disk 1 is not constant depending on the type of magneto-optical disk 1 used.

This invention aims to solve the problems of conventional optical disc storage! Now, if the temperature of the magneto-optical disk 1 during recording increases by 30 degrees Celsius from the standard state, the recording conditions will change and the S/N ratio of the recorded information signal will change undesirably. This S/N
In order to improve the deterioration of the recording film, some systems measure the ambient temperature during recording and change the recording conditions, but the ambient temperature and the temperature of the recording film of the magneto-optical disk do not necessarily match, It was difficult to set the conditions accurately.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc device that can record information signals in a better condition than before even when the temperature of the optical disc rises above the standard state.

Means for Solving the Problems An optical disc device according to claim 1 records and reproduces information signals by irradiating an optical disc with a laser beam, and
3. The apparatus according to claim 2, further comprising an infrared detector for detecting infrared rays radiated from the optical disk, and a recording head of the laser beam is controlled in accordance with a detection output of the infrared detector. The optical disc is characterized in that at least part of the optical disc has a specific region whose emissivity is adjusted to a preset value.

According to the configuration of claim 1, the infrared detector detects infrared rays radiated from the rotating optical disc, so that the temperature of the rotating optical disc can be measured without contact. Therefore, recording accuracy can be improved by controlling the recording power of the laser beam based on this detection output.

According to the configuration of claim 2, since the optical disc has a specific area with a predetermined emissivity, the infrared detector connected to the optical disc device of claim 1 detects the temperature of this specific area. By doing so, it is possible to improve the accuracy of measuring the temperature of the optical disc and to improve the recording accuracy of the negative layer.

Example An embodiment of the present invention will be described below with reference to FIG.

Components having the same functions as those in FIG. 2 showing the conventional example will be described with the same reference numerals.

As shown in FIG. 1, the optical disk device of the present invention has an infrared detector 1-3affi installed to detect infrared rays radiated from a magneto-optical disk 1 as an optical disk. The infrared rays 11 enter the infrared detector 13a via the objective lens 12. The output signal of the infrared detector 13a is input to the signal processing circuit 14 via the preamplifier 13b. The signal processing circuit 14 includes an A/D converter 14a and a CP
tJ 14b, and an infrared detector 13a.
The output signal of c p u
Input to i4b. CPU14b is magneto-optical disk 1
The infrared detector 1 stores the correlation between the temperature of
An appropriate recording power of the laser beam 3 is calculated based on the output signal of the laser beam 3a, and the command signal thereof is given to the laser modulator 8.

A laser modulator 8 that amplitude-modulates the laser beam emitted from the laser head 4 according to the output signal of the information signal 6 via the encoder 7 uses the digital signal that is the command signal as a reference signal, and uses the digital signal built in the laser head 4 as a reference signal. A part of the output of the laser beam is detected by the sensing section, and compared with the reference signal, and the laser head is adjusted so that the recording modulation pulse width is kept constant and the recording power of the laser beam 3 approaches the designated optimal recording power. Controls the current supplied to 4.

Table 1 above shows the recording characteristics when the temperature of the magneto-optical disk 1 is changed, and the C/N when signals are recorded and reproduced on the magneto-optical disk 1 at temperatures of 20 degrees C and 50 degrees C.
<Ratio of W signal to noise> was measured. It can be seen that if the recording power of the recording laser beam 3 is controlled according to these temperatures, it is possible to record with higher quality than Ik.For example, if the temperature of the magneto-optical disk 1 is 20 degrees C.
When the recording power of laser beam 3 is set to 8 mW, and when the temperature is 50 degrees C, it is set to 7 mW.
The configuration is such that a command signal is given to the laser modulator 8 from U14b, and the maximum C/N is obtained with the minimum laser power.

In general, semiconductor laser elements with lower output power are cheaper, and when using lasers with the same rating, the lifespan is longer when used with the lowest possible power, so if the same C/N is obtained, It is preferable to lower the output laser power as much as possible, and from this point of view as well, the optical disk device of this embodiment can reduce the cost and extend the life of the laser head 4.

In the above embodiment, the laser modulator 8 keeps the recording modulation pulse width constant and adjusts the intensity of the laser beam to approach the recording power of the film. It is also possible to bring the recording power closer to the optimum recording power.

In the above embodiment, the infrared detector 13a is provided separately from the magnetic field generator 5 that applies a magnetic field to the position where the laser beam 3 is focused, or the infrared detector 13a is provided separately from the magnetic field generator 5 and the infrared detector 13a.
It is also possible to provide them together.

In this case, since the recording position and the temperature detection position are close to each other, the temperature detection accuracy of the magneto-optical disk 1 becomes high.

Further, when the temperature of the magneto-optical disk 1 is detected by the amount of infrared radiation as described above, the amount of radiation changes depending on the surface condition of the magneto-optical disk 1, which deteriorates the accuracy of temperature detection.

In order to avoid fluctuations in the accuracy of temperature detection, it is necessary to set the surface of the magneto-optical disk 1 at a predetermined emissivity, for example 1.
It would be better to process it so that it is close to . Specifically, the emissivity can be brought close to 1 by applying a black matte paint to lower the reflectance of the surface, or by creating fine irregularities on the surface. The specific area having the emissivity Hp is not provided over the entire area of the optical disc, but is provided only in a part other than the recording/reproducing track, and the configuration is such that the amount of infrared radiation from this specific area can be detected by the infrared detector 13a. You may. However, in this case, a mark is attached to identify the specific area.

In the above real square example, we used a magneto-optical disk that records information by changing the magnetic properties of the recording track.
The same method can be applied to optical discs in which information is recorded by changing the optical characteristics of the recording tracks.

Effects of the Invention As described above, according to the optical disc device according to claim 1, an infrared detector for detecting infrared rays radiated from the optical disc is provided, and the recording power of the laser beam is adjusted according to the detection output of the infrared detector. Because the configuration is configured to control the temperature of the optical disc, even if the temperature of the optical disc becomes higher than the standard temperature, or if an optical disc in a cartridge that has been stored in a low-temperature environment is used by inserting it into a working optical disc device, the disc will temperature can be detected accurately and at high speed, and information signals can be recorded with good S/N.

Furthermore, according to the optical disc according to claim 2, since a specific area whose emissivity is adjusted to a preset value is formed in at least a part of the optical disc, infrared rays from the specific area can be emitted from the optical disc apparatus according to claim 1. By detecting the radiation amount with an infrared detector and measuring the temperature of the optical disk, temperature detection accuracy is improved and recording accuracy can be further improved. Further, even if the optical disk is replaced, the temperature of the optical disk can be accurately measured, and good recording conditions can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the optical disc device of the present invention, and FIG. 2 is a block diagram of a conventional optical disc device. DESCRIPTION OF SYMBOLS 1... Magneto-optical disk [optical disk], 3... Laser beam, 4... Laser head, 6... Information signal,
8... Laser modulator, 13a... Infrared detector, 14
...Signal processing circuit. Figure f Figure H... 1L Tato Ito; Figure 2

Claims (1)

[Claims] 1. An infrared detector is provided for recording and reproducing information signals by irradiating an optical disc with a laser beam, and detecting infrared rays radiated from the optical disc, and detects the infrared rays according to the detection output of the infrared detector. An optical disc device configured to control the recording power of a laser beam. 2. An optical disc in which at least a portion thereof has a specific area whose emissivity is adjusted to a preset value.