JPS58169336A - Optical disc device - Google Patents

Abstract

PURPOSE:To enable optimum recording and reproduction by measuring the light reflectivity or transmittance and optimum recording and reproducing power of an optical disc beforehand. CONSTITUTION:A recording and reproducing head 1 is fixed in the prescribed position of a recording and reproducing device without mounted with a disc 3 so that the light from the head 1 is made incident to a stationary detector 2 and the intensity thereof is corrected exactly. The disc 3 is mounted and laser light is projected thereto. The light reflected from the disc is received in the detector in the head 1 and the intensity thereof is detected. The light transmittance can be measured with the detector 2. The disc 3 is kept rotated during the measurement. The recording laser power from the measured value thereof as well as the irradiation time and the read-out laser power are determined. The recording with the optimum power and irradiation time and the reading-out with the optimum power are made possible by the data obtained in such a way.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses a recording energy beam such as a laser beam to record an FMf-tuned analog signal, such as an audio signal or an electronic signal, onto a recording thin film provided on a predetermined substrate. The present invention relates to a device capable of recording digital information such as computer data and facsimile signals in real time.

Conventionally, in the case of recording and reading with laser light, in the case of a disk-shaped recording medium, even if the recording power on the outer periphery is higher than the recording power on the inner periphery, a device is used to prevent the recording dots from sticking together on the inner periphery. However, it is basically done with a fixed power.However, in the disc manufacturing process, it is not possible to completely eliminate imbalances in the film thickness and composition of the recording medium.Therefore, these If the allowable range for variation is made smaller, the yield rate will worsen.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a source disk device that can perform recording and reading with good reproducibility even if the recording or reading characteristics of the disk change to some extent. .

In order to achieve the above object, the optical disc device of the present invention measures at least one of the optical reflectance and optical transmittance of the disc with the disc mounted, and controls the recording light and the reading light according to the measured value. At least one of the power and the irradiation time of at least one of the sources is changed.

There are several ways to make these changes.

One method is to take measured values of light reflectance or light transmittance discontinuously over long periods, change at least one of the power and irradiation time of recording light and read light according to the measured values, and perform the next measurement. There is also a method of keeping the value at that value until the disc is removed, but there is also a method of taking the above measurement value only once immediately after the disc is installed, and then maintaining the changed power value or irradiation time value until the disc is removed. Included in this.

The other method is to continuously measure light reflectance or transmittance (
(including intermittent periods).

This is a method of continuously changing at least one of the power and irradiation time of the recording source and reading light (including changing discontinuously in short cycles) according to the value. In this case, the film thickness and light transmittance depend on the location on the disc.
Although it can reliably respond to variations in light reflectance,
Control methods become more complex. Especially when measuring and recording light reflectance or light transmittance with a single laser beam, or recording or reading a record, the output of the laser must always be accurately measured using another method. The result of changing the intensity is observed as if the light reflectance had increased, and as the recording light intensity FIILt- is further increased, the recording light intensity becomes increasingly large and becomes uncontrollable.

For example, the dependence of the light reflectance and light transmittance on the thickness and composition of a Te-8e thin film is shown in Figure 1, so if the composition is completely controlled during film formation,
If you know the light reflectance, you know the film thickness], and if you check the recording extensibility t for each combination of composition and film thickness in advance, you will know what values to set for the recording light intensity and irradiation time. The intensity from which the recording is read is also determined according to the light reflectance. - If the film thickness is perfectly controlled, but the composition is incompletely controlled, knowing the one-dimensional reflectance means knowing the composition, and knowing which value the intensity of the recording light should be set to.0 composition Even if there are variations in both the optical transmittance and the optical reflectance, the estimated values of the film thickness and composition can be determined from the 5lh1 diagram, and the optimal recording light intensity and irradiation time can be determined. is next. The recording source strength (Iff) of the recording read source can be controlled by changing at least one of the recording power and irradiation time from the outer circumference to the inner circumference of the disk, in addition to the above-mentioned control. They may be performed in an overlapping manner. We also know the temporal intensity changes of the reflected recording light due to the progress of recording (for example, hole formation), and control the intensity of the recording light (cis light) so that its speed matches the speed for optimal recording. It is also possible to do this in an overlapping manner.

With the device of the present invention, even if different types of discs are shared, if the optical reflectance or transmittance and optimal recording/reproducing power are memorized in advance, optimal recording/reproducing can be performed without the user being aware of it. I can do it. It is a good idea to record the disc name on the disc so that the disc type can be read from the disc.

The present invention will be explained in detail below using examples.

Example 1 As shown in FIG.
- When not installed, the recording/reproducing head 1 is set to stop at a fixed position, and at that position the laser beam from the head enters the fixed detector 2, so that the intensity can be corrected accurately. . Then Te −fJ e
Three disks with recording films of the system are installed, the recording head is stopped at a predetermined position where the laser beam hits the disk surface, and in the next state, one reflected light is detected by a detector for reading signal extraction in the same head l. and detect the strength.

If the head stop position in this case is the same as the head stop position before the disk is mounted, the light transmittance of the disk can be measured using the same detector 2 that detected the laser light output before the disk was mounted. . However, in this case, it is necessary to use a mounting method that prevents the disc from hitting this detector when the disc is mounted. Separately from the recording/playback head, there is a light source (
For example, an LED) or a detector may be provided. It is best to measure reflectance and transmittance while rotating the disk. When measuring only reflectance, please check the film composition! ? The recording laser power, irradiation time, and readout laser power were determined by using a disk made as small as possible and estimating the film thickness from the reflectance using the tube shown in FIG.

When measuring both reflectance and transmittance, we estimated both the film thickness and film composition from these and determined the positioning power and readout laser power.The values of these powers are: For the same track on a disk, it was assumed to be constant until the disk was replaced. However, the number of recording tracks is halved to ensure that a good read signal is always obtained. However, the radius at the outermost periphery and the recording nozzle were set to 1sPO.When replacing the disc, the above operation was performed each time the disc was replaced.

Similarly, it is also possible to deal with changes in disc sensitivity over time. That is, after measuring the initial reflectance or transmittance, the disk is forcibly degraded, and the reflectance or transmittance and the optimum recording time or optimum irradiation time when the disk is degraded are determined. By determining the initial reflectance or transmittance for all disks, optimal recording can be performed even if the disks deteriorate.

The light reflectance measurement immediately after the disk is mounted is carried out at multiple locations by moving the head l in the radial direction of the disk, and superimposes the power change according to the laser beam corresponding to the change in the reflectance in the radial direction. More preferred.

Example 2 A photodiode is attached to the side of the semiconductor laser opposite to the side from which the recording light is emitted, and the laser output can be constantly monitored by receiving the light emitted from the photodiode to prevent output fluctuations. Negative feedback was provided to the laser drive current, and the output fluctuation was kept within ±1%. The reflected light from the disk is reflected in a direction perpendicular to the incident light by a 174 wavelength plate and a polarizing prism so that it does not return to the light source, and is separated into a detector for detecting a tracking signal and a detector for detecting an automatic focusing signal. It is made incident by Any of these signals is also used for read signal detection. The intensity of the read signal, the intensity of the part where there is no recording bit in @-, is proportional to the optical reflectance of the disk. ! Even when the recording pulse is in operation, tracking signal detection and automatic focusing signal detection are performed at low power when no recording pulse is output, and it is possible to output an output proportional to the light reflectance. In this way, by constantly knowing the light reflectance of the part to be recorded or read, the film thickness of that part can be estimated, recorded with the optimum recording power and irradiation time (pulse width), and the readout light is It was also possible to optimize the power level. As detailed above, the device of the present invention can record and record discs.
Even when there are variations in playback characteristics or when using many types of disks, optimal recording and playback can always be performed, and the benefits obtained are extremely large.

FIG. 2 is a diagram showing the relationship with light reflectance, and is a diagram schematically showing an apparatus that is an embodiment of the present invention.

1... Playback head, 2... Detector, 3...
disk.

Part 1 Ken 4 CnML) (b-n Film thickness Shinshi ￥J　　2　Fig.

Claims (1)

[Claims] 1. Measure at least one of the optical reflectance and light transmittance of the optical disc with the optical disc mounted on the recording device, and measure the intensity and irradiation of at least one of the recording light and the reading light depending on the cage. Varying at least one of the times t4! Former disk device with mold.