JPS62172536A - Optical information recording and reproducing method - Google Patents

Abstract

PURPOSE:To reduce the deterioration of a semiconductor laser and an optical disc recording film by setting weak the irradiated luminous quantity at the standby of laser collected beam more than the normal reproduction without reproducing recording information. CONSTITUTION:The light output of a semiconductor laser 10 driven by a drive amplifier 27 is monitored by a monitor photo diode 14, the light current of the diode 14 is converted into a voltage signal by a bias voltage application means 23 and a resistor 24 connected in series and outputted as a monitor signal. The monitor signal is compared with a set voltage signal 26 by an error detection amplifier 25 and an amplifier 27 rives the laser 10 so as to make the error zero. The irradiated luminous quantity is weakened more than that at the normal reproduction by using a signal 26 when the laser collected beam is in standby on a specific track without reproducing the recorded information to reduce the deterioration of the laser 10 or the like.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an optical disc that records information by irradiating an optical disc, which is an information recording medium, with a focused laser beam, and that reproduces the recorded information using reflected light from the optical disc. This invention relates to an information recording and reproducing method.

(Prior Art) Optical information recording and reproducing devices using optical discs as information recording media are already known. FIG. 3 shows an example of a conventional optical information recording/reproducing device. In FIG. 3, reference numeral 1 denotes an optical disk, and the optical disk 1 has a transparent substrate 2 and a light-absorbing and reflective recording film 3 formed on one side of the transparent substrate 2. Two sets of recording bodies each consisting of a substrate 2 and a recording film 3 are fixed to each other with an air gap 5 between them with a spacer 4 interposed therebetween. The optical disc 1 is held at its center by a turntable 7 and a presser plate 8 during recording and re-recording, and is rotationally driven by a spindle motor 9. A semiconductor laser 10 is disposed in the recording/reproducing device, and the laser light emitted from the semiconductor laser 10 is turned into a condensed beam 12 by a condensing lens 11 so that it is condensed at the position of the recording film 3 of the optical disc 1. It has become.

Information can be recorded on the optical disc l by a method such as switching a laser beam according to an information signal while rotating the optical disc l. Further, information recorded on the optical disc 1 can be reproduced by detecting reflected light from the recording film 3 of the optical disc 1. The reflected light from the recording film 3 is divided by a half mirror 13 or the like, and then detected by the light receiving element 14. By detecting the amount of light reflected by the reflective film 3 by the light receiving element 14, a reproduced signal can be obtained. .

Information is recorded by forming holes or changing optical properties in the recording film 3 of the optical disc 1 according to the information signal. Thus, the focused laser beam 12 is irradiated with a light intensity P- of sufficient intensity to form a hole in the recording IJ3 or change the optical properties of the recording film 3. This amount of irradiation light P-
is adjusted according to the linear velocity. On the other hand, during normal reproduction, the light is irradiated with a smaller amount of light Pr than the irradiation light amount P- during recording.

Furthermore, in the optical information recording and reproducing method, although not directly involved in reproducing information, there is a standby operation in which a focused laser beam is irradiated onto a specific track of the optical disc. what if,
If the semiconductor laser were to be completely stopped, focus pull-in and tracking pull-in would be required extra before starting the access operation, which would lengthen the access time. Therefore, in order to shorten the access time, the above-mentioned standby operation is performed. However, in the conventional optical information recording and reproducing method, as shown in FIG. The laser beam was irradiated with the same amount of light as the irradiation amount Pr at the time.

However, even though reliability of information reproduction is not required during standby, the optical disc is irradiated with a laser beam for a long time with the same irradiation light intensity Pr as during normal reproduction.
The deterioration of the semiconductor laser has been unnecessarily accelerated, making it more likely to fail, and the damage and deterioration of the recording film of the optical disk has increased significantly.

The present invention has been made to solve these conventional problems, and it is possible to reduce deterioration and damage to semiconductor lasers and optical disks during standby operation, thereby providing a highly reliable optical information recording resetting method. The purpose is to provide

(Structure) In an optical information recording and reproducing method, the present invention makes it possible to set the irradiation light amount of a focused laser beam in two or more stages, and also enables the laser to be focused on a specific track of an optical disc without reproducing recorded information. When the light beam is waiting,
The feature is that the amount of light irradiated is weaker than during normal playback.

Embodiments of the optical information recording and reproducing method according to the present invention will be described below.

The first feature of the present invention is that the amount of laser beam irradiation can be set in two or more levels. FIG. 1 shows an example of setting the amount of laser beam irradiation in two or more stages. In FIG. 1, the optical output of the semiconductor laser lO driven by the drive amplifier 27 is the same as that of the monitor photodiode 1.
4. A bias voltage applying means 23 and a resistor 24 are connected in series to the diode 14, so that the photocurrent of the diode 14 is converted into a voltage signal, and this voltage signal is output as a monitor signal. This monitor signal is sent to the error detection amplifier 25.
is compared with the set voltage signal 26 by
is driven, so that the output of the semiconductor laser 0 is determined by the set voltage signal 26. The set voltage signal 26 can be set by (1) setting using a digital signal using a digital-to-analog converter, or (2) selecting and setting a plurality of voltage sources using a switch.

The second feature of the present invention is that when the laser beam is waiting on a specific track of the optical disc without reproducing recorded information, the amount of irradiation light is made weaker than usual. . FIG. 2 shows an example of setting the amount of laser beam irradiation according to the optical information recording and reproducing method according to the present invention. The light intensity of the focused laser beam can be set in three levels: Prl, Pr2, and Pr3. If the amount of light during playback can be set in many stages, it will be possible to respond precisely to all kinds of conditions, but it is sufficient if it can be set in at least two stages. Now, set the light amount during normal playback to Prl or Pr2.
Then, when a focused laser beam is waiting on a specific track of an optical disk without recording or playing,
The irradiation light amount is set to the irradiation light amount Prl during normal reproduction, and the light amount Pr3, which is weaker than Pr2. From now on, MP r 3 is set to the minimum level within the range where focusing control and tracking control are possible. By doing this,
Deterioration and damage to the semiconductor laser and the recording film of the optical disk due to laser beam irradiation during long standby operation can be prevented, and the reliability of optical information recording and reproduction can be improved.

By the way, there are many types of optical discs currently on the market or about to be put into practical use, with their recording surfaces being metal films, pigment films, alloy films, and magnetic films. Depending on the type, the reflectance varies over a wide range from 10% to 60%, and the recording sensitivity also differs by a factor of 2 to 3. However, in the case where the amount of irradiation light during playback can be set in two or more levels as in the embodiment of the present invention, the amount of light irradiation during playback can be set depending on the type of optical disc. It is also possible to reproduce in the best condition by selecting the amount of irradiation light passed through.

In addition, the reflectance of an optical disc may decrease over time, and the optical disc may become dirty.Also, due to changes in the characteristics of the optical pickup over time or dirt over time, etc.
The reproduced signal level is generally reduced by about 1/2. Therefore, immediately after recording information on an optical disc, it is played back.
When inspecting recorded information by comparing it with input information or checking error detection codes, for example, if the inspection is performed using a light intensity that is approximately 1/2 of the light intensity during normal playback, it is possible to detect small errors that may occur in the future. Defects can be easily discovered and the reliability of inspection can also be improved.

Note that as a method of adjusting the amount of irradiation light, the set voltage 26 in FIG. 1 may be fixed, and the amplification degree of the monitor signal detection section by the photodiode 14 may be made variable. Also, for example, optical filters with different transmittances may be put in and out of the laser optical path, or an optical filter whose transmittance changes continuously in the circumferential direction may be placed in the laser optical path so that the optical filter can be rotated. It is also possible to arrange an optical attenuator in the optical path from the semiconductor laser to the optical disk and adjust the amount of attenuation by the optical attenuator, such as by changing the angle.

Furthermore, by displaying the type of optical disc with a mark or the like, and selecting the mark or the like according to the type of optical disc, it is possible to obtain the amount of irradiation light that is compatible with the type of optical disc.

(Effects of the Invention) According to the present invention, it is possible to set the irradiation light intensity of a focused laser beam in two or more levels, and the focused laser beam is placed on standby on a specific track of an optical disc without reproducing recorded information. During playback, the amount of light irradiated is made weaker than during normal playback, so even if standby operation continues for a long time, deterioration of the semiconductor laser and the recording film of the optical disk can be reduced, and the Laser failures are less likely to occur, and a highly reliable optical information recording and reproducing method can therefore be provided.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an example of a laser beam irradiation amount variable means applicable to the present invention, FIG. 2 is a diagram showing an example of setting the irradiation amount by the method of the present invention, and FIG. 3 is a conventional general method. FIG. 4 is a schematic side view showing an example of an optical information recording/reproducing method. FIG. 4 is a diagram showing an example of setting the amount of irradiation light according to a conventional optical information recording/reproducing method. 1- Optical disk, 12- Laser focused beam.

Claims (1)

[Claims] In an optical information recording and reproducing method in which an optical disk, which is an information recording medium, is irradiated with a focused laser beam and information is reproduced by the reflected light, the irradiation amount of the focused laser beam can be set in two or more levels, and the recorded information is An optical information recording and reproducing method characterized in that when a focused laser beam is waiting on a specific track of an optical disc without performing reproduction, the amount of irradiated light is made weaker than during normal reproduction.