JPH0731812B2 - Optical information recording / reproducing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention is an optical recording medium for irradiating an optical disc, which is an information recording medium, with a laser focused beam to record information, and for reproducing recorded information by reflected light from the optical disc. The present invention relates to an information recording / reproducing method.

(Prior Art) An optical information recording / reproducing apparatus using an optical disc as an information recording medium is already known. FIG. 3 shows an example of a conventional optical information recording / reproducing apparatus. In FIG. 3, reference numeral 1 is an optical disc, and this optical disc 1 is a transparent substrate 2.
And a recording film 3 having a light absorbing and reflecting property formed on one side surface of the transparent substrate 2, and the transparent substrate 2 and the recording film 3 are provided.
Two sets of the recording bodies are formed by interposing an air gap 5 between them under the interposition of the spacer 4. Optical disc 1
At the time of recording / reproducing, the central portion of the is held by the turntable 7 and the pressing plate 8 and is rotationally driven by the spindle motor 9. A semiconductor laser 10 is arranged in the recording / reproducing apparatus, and the laser light emitted from the semiconductor laser 10 becomes a focused beam 12 by a focusing lens 11, and the optical disc 1
The light is focused on the position of the recording film 3.

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

By the way, when the information is recorded on the optical disc 1, the recorded information is inspected by reproducing the information immediately after the recording and comparing it with the input information or checking the error detection signal. In this case, the recording is performed again to increase the reliability of the information recording.

Information is recorded by forming holes in the recording film 3 of the optical disc 1 or changing its optical properties in accordance with an information signal, and therefore, at the time of information recording, it is shown in FIG. To form a hole in the recording film 3 or
The focused laser beam 12 is emitted with a light intensity Pw that is strong enough to change the optical properties of the. The irradiation light amount Pw is adjusted according to the linear velocity. On the other hand, at the time of inspection immediately after recording and at the time of normal reproduction, irradiation is always performed with a constant light amount Pr.

However, the reflectance of the optical disc may decrease with time, the optical disc may be contaminated, and the signal level to be reproduced is usually changed due to the change of characteristics of the optical pickup with time or the contamination with time. It drops to about 1/2. Therefore, immediately after recording the information, the inspection is performed by irradiating the same amount of light as that for normal reproduction, and even if the inspection passes, there is a risk of defective reproduction over time and sufficient reliability is obtained. I can not get sex.

The present invention has been made to solve the above conventional problems, and enables inspection in anticipation of characteristic changes with time of optical disks and optical pickups, and enables easy detection of even small defects. It is an object to provide a highly reliable optical information recording / reproducing method.

(Structure) According to the present invention, in the optical information recording / reproducing apparatus method, the irradiation light amount of the laser focused beam at the time of reproduction can be set in two or more steps, and at the time of inspecting the recorded information immediately after recording the information on the optical disc, It is characterized in that the amount of irradiation light is made weaker than usual so that the inspection is performed.

Examples of the optical recording / reproducing method according to the present invention will be described below.

The first feature of the present invention is that the irradiation light amount of the laser beam during reproduction can be set in two or more steps. FIG. 1 shows an example for setting the irradiation light amount of a laser beam in two or more steps. In FIG. 1, the optical output of the semiconductor laser 10 driven by the drive amplifier 27 is monitored by the monitor photodiode 14. A bias voltage applying means 23 and a resistor 24 are connected in series to the diode 14, 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 compared with the set voltage signal 26 by the error detection amplifier 25, the drive amplifier 27 drives the semiconductor laser 10 according to the error signals of both, and the output of the semiconductor laser 10 is determined by the set voltage signal 26. It is like this. This set voltage signal 26 can be set by a method such as (1) set by a digital signal using a digital-analog converter, and (2) set by selecting a plurality of voltage sources with a switch.

A second feature of the present invention is that when the recorded information is inspected immediately after the information is recorded on the optical disc, the amount of irradiation light is made weaker than usual to perform the inspection. FIG. 2 shows an example of setting the laser beam irradiation light quantity by the optical information recording / reproducing method according to the present invention. The light quantity of the laser focused beam at the time of information recording is set to the highest level Pw and the laser at the time of reproducing is set. The light amount of the focused beam can be set in three levels of Pr1, Pr2, and Pr3. If the light amount during reproduction can be set in many steps, it is possible to finely meet all conditions, but it is sufficient if it can be set in at least two steps. Now, assuming that the amount of light during normal reproduction is Pr1 or Pr2,
Immediately after the information is recorded on the optical disc, the light amount at the time of inspection is set to a light amount Pr3 weaker than the light amounts Pr1 and Pr2 at the time of the normal reproduction. This makes it easy to find an error due to a small defect and prevent an error that may occur at a later date. Then, the above light intensity level Pr3
Can be increased to a level commensurate with the reproduction under the worst possible conditions associated with the change over time of the optical disc or the like, and the reliability of optical information recording / reproduction can be enhanced.

Generally, when the irradiation light amount Pw at the time of information recording is 2.0 mW,
The irradiation light amount Pr during reproduction is about 0.2 mW. Therefore, considering that the signal level to be reproduced in the future usually drops to about 1/2, the irradiation light amount Pr3 during inspection immediately after recording and reproduction is
An appropriate value is about 0.1 mW. However, this is an example, and depends on the format of the optical disc and the like.

By the way, there are many types of optical discs that are currently on the market or are about to be put to practical use, whose recording surface is a metal film, a dye film, an alloy film, or a magnetic film, Depending on the type, the reflectance is from 10%
It is distributed over a wide range such as 60%, and there is a difference of 2 to 3 times in recording sensitivity. However, in the case where the irradiation light amount at the time of reproduction can be set in two or more steps as in the embodiment of the present invention, the irradiation light amount at the time of reproduction can be set according to the type of the optical disk. It is also possible to select the irradiation light amount suitable for the above condition and reproduce in the best condition.

Further, according to the above-described embodiment, the irradiation light amount can be set to the minimum level within the range where the focus control or the tracking control can be performed during the standby without the reproduction. The deterioration and the deterioration of the recording film of the optical disk can be reduced, and the reliability is improved.

As a method of adjusting the irradiation light amount, the set voltage 26 in FIG. 1 may be fixed and the amplification degree of the monitor signal detection unit by the photodiode 14 may be variable. Further, for example, an optical filter having a different transmittance is put into and taken out from the optical path of the laser, or an optical filter whose transmittance continuously changes in the circumferential direction is arranged in the laser optical path, and a rotation angle of the optical filter is set. It is also possible to arrange a light attenuator in the optical path from the semiconductor laser to the optical disk and adjust the amount of attenuation by this light attenuator. Then, whether it is the information recording mode, the normal reproduction mode, or the inspection mode is displayed with a mark or the like,
It is also possible to automatically set the irradiation light amount suitable for the operation mode simply by aligning the setting member with the predetermined mark. By doing so, the optimum irradiation light amount for the operation mode can be easily obtained. To be Similarly, it is also possible to display the type of the optical disc with a mark or the like and select the mark or the like according to the type of the optical disc so that the irradiation light amount suitable for the type of the optical disc can be obtained.

(Effect of the Invention) According to the present invention, it is possible to set the irradiation light amount of the laser focused beam at the time of reproduction in two or more steps, and at the time of inspecting the recorded information immediately after the information is recorded on the optical disc, the irradiation light amount is set. Since the inspection is made weaker than usual, it is easy to find small defects, and it is also possible to prevent errors that may occur at a later date in advance, thus providing highly reliable optical information recording. A reproduction method can be provided.

[Brief description of drawings]

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

Claims (1)

[Claims] 1. An optical information recording / reproducing method of irradiating an optical disc, which is an information recording medium, with a laser focused beam, and reproducing information by the reflected light thereof, wherein the irradiation amount of the laser focused beam during playback is two or more steps. The optical information recording / reproducing method is characterized in that when the recorded information is inspected immediately after the information is recorded on the optical disc, the amount of irradiation light is weaker than usual and the inspection is performed.