JP3198753B2 - Optical disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive for recording and / or reproducing data on and from an optical disk, and more particularly, to detecting the position of a laser beam spot on a groove or a land of the optical disk. It is related to the configuration to be performed.

[0002]

2. Description of the Related Art Conventionally, in an optical disk apparatus for recording and / or reproducing data on and from an optical disk, it is designed to detect whether a laser beam spot is located on a land or a groove.

As a detection method, for example, there is a detection method by comparing the amount of reflected laser beam spot from an optical disk with a certain reference level. That is, the detection method utilizes the fact that the signal level based on the amount of reflected laser beam spot from the optical disk differs between the land portion and the groove portion as shown by R in the figure, for example, as shown in FIG. Then, the reflected light amount is compared with a reference level ref indicated by a dashed line in the figure (a signal level based on the reflected light amount is compared with the reference level ref).
The position where the amount of reflected light is lower than the reference level ref (the position where the signal level based on the amount of reflected light is lower than the reference level ref) is detected as a groove portion, and the position where the reflected light amount is higher is the land portion. It is a method of detecting.

[0004]

However, the above detection method has the following problems. That is,
(1) Due to a difference in reflectivity between optical disks or a difference in groove shape between optical disks, the amount of reflected laser beam spot from the optical disk changes, and the DC level of a signal based on the amount of reflected light changes. AC level changes, (2) Even within the same optical disk, differences in reflectivity at each position within the same optical disk, or slight differences in groove shape at each position within the same optical disk As described above, the DC level and the AC level of the signal based on the amount of reflected light change due to a significant difference, and (3) the DC level also varies due to the difference in the reflectance between the recorded portion and the unrecorded portion of the information in the optical disk. , AC level changes, and (4) changes over time in the optical disk drive (power changes in the laser oscillator, changes in the photodetector). By etc.), there are problems such as that the above similarly DC level, an AC level changes.

Due to these problems, erroneous detection or undetection occurs at a preset reference level. Therefore, it is very difficult to presuppose a reference level that does not cause the erroneous detection or non-detection.

In view of the above, the present invention has been made in consideration of the above-described variations in the reflectance between optical disks, the variations in the reflectance in the same optical disk, and the reflectance in the recorded portion and the unrecorded portion in the optical disk. Optical disk drive that can prevent erroneous detection or undetection regardless of the difference of the device and the aging of the device, and can accurately detect whether the laser beam spot position is on the land or groove. It is intended to be.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and has an information recording and / or recording method.
Alternatively, immediately after inserting an optical disc having a predetermined area consisting of a land portion and a groove portion not used for information recording and / or reproduction together with a use area consisting of a land portion and a groove portion used for reproduction, the irradiation position of the laser beam is A laser beam irradiation position moving unit for moving the laser beam onto the predetermined area; a reflection light amount sample unit for sampling a reflection light amount of the laser beam irradiated on the predetermined area from the optical disc; Reference level determining means for determining a reference level, and in a normal operation, detecting whether a laser beam spot position is on a land portion or a groove portion based on the reference level and the amount of reflected light from the optical disk. It is characterized by the following.

Here, the predetermined area is provided before, after, or at the center of the information recording and / or reproduction start position of the use area, or is provided at a plurality of places. Is determined based on the amount of reflected light from these predetermined areas. When a predetermined area is provided at a plurality of locations, the laser beam irradiation position moving means moves the laser beam irradiation position over a plurality of predetermined areas provided at a plurality of positions in the optical disk, and the reflected light amount sampling means. Samples a plurality of reflected light amounts from the plurality of predetermined positions, and the reference level determination means determines a reference level based on the plurality of sample values.

[0009]

According to the present invention, a predetermined area comprising a land portion and a groove portion provided on an optical disk and not used for information recording and / or reproduction is not recorded (or not recorded). There is no change in the amount of reflected light due to the writing of the data, there is a clear difference in the amount of reflected light between the land portion and the groove portion, and the reference level is set for each optical disk based on the amount of reflected light from the predetermined area. Therefore, even if the reflectance varies among the optical disks, an optimum reference level can be set for each optical disk.

When a plurality of predetermined areas are provided in the same optical disk, a reference level is set based on the amount of reflected light from each of the plurality of predetermined areas, thereby increasing the appropriateness of the reference level.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical disk drive according to an embodiment of the present invention.
As shown in (1), insertion of an optical disc having a predetermined area consisting of a land portion and a groove portion not used for information recording and / or reproduction together with a use area consisting of a land portion and a groove portion used for information recording and / or reproduction. Immediately afterward, an optical block moving mechanism 11 as a laser beam irradiation position moving means for moving the irradiation position of the laser beam from the laser oscillator of the optical block 1 onto the predetermined area, and a laser beam irradiation mechanism for moving the laser beam irradiated on the predetermined area. A maximum sample and hold circuit 13 and a minimum sample and hold circuit 12 as a reflected light amount sampling means for sampling a reflected light amount (signal S corresponding to the reflected light amount) from the optical disk; and a sampled value of the reflected light amount (maximum sample value max) , The minimum sample value min) to determine the reference level ref The controller 14 and the reference value generator 15 as reference level determining means to determine the position of the laser beam spot on the land portion based on the reference level ref and the amount of light reflected from the optical disk during normal operation. And a comparator 16 as detecting means for detecting position information indicating whether the position is on the groove portion.

That is, in the optical disk device of the present embodiment shown in FIG. 1, the optical block 1 is provided with a laser oscillator such as a laser diode, a collimator lens, etc., although not shown in the drawing. A laser beam from a laser oscillator passes through a beam splitter 2 and is focused on an optical disk 20 by an objective lens 3. Thereby, a laser beam spot is formed on the optical disk 20.

The reflected light of the laser beam spot from the optical disc 20 is reflected by the beam splitter 2 via the objective lens 3 and then condensed on the photodetector 5 by the condenser lens 4. The light detection signal from the photodetector 5 is amplified by the amplifier 10. The signal level of the output signal S of the amplifier 10 corresponds to the reflected light amount of the laser beam spot from the optical disk 20.

Here, the optical disk device of this embodiment is
Immediately after inserting the optical disk 20 into the optical disk device, the laser beam spot is moved to the predetermined area. The movement of the laser beam spot onto the predetermined area is performed immediately after the optical disk 20 is inserted into the apparatus of the present embodiment by the controller 14 controlling the optical block moving mechanism 11 to move the optical block 1. This is performed by moving the optical disk 20 to a position corresponding to the predetermined area.

As described above, a predetermined area of the optical disk 20 is irradiated with the laser beam and the focus is locked (tracking is not taken).
Then, for example, the optical disk 20 is rotated (or the rotating optical disk is irradiated with a laser beam).
Then, due to the eccentricity normally present on the optical disk 20, the laser beam spot crosses the land portion and the groove portion on the predetermined area. The signal level (reflected light amount) of a signal (ie, a so-called traverse signal) S obtained by the laser beam spot crossing the land portion and the groove portion is, for example, A in FIG.
The result is as shown by R in FIG.

The predetermined area is an area that is not used for information recording and / or reproduction (an area where information recording is not performed or is not performed), so that the amount of reflected light changes as in the case where information is recorded. Therefore, there is a clear difference in the amount of reflected light between the land portion and the groove portion. Therefore, as shown by R in the drawing of FIG. 2, the signal S also has a clear signal level difference at a portion corresponding to the land portion and the groove portion.

Such a signal S is sent to the maximum sample and hold circuit 13 and the minimum sample and hold circuit 12.

The maximum sample and hold circuit 13 samples and holds the maximum value of the signal S, and the minimum sample and hold circuit 12 samples and holds the minimum value of the signal S. The maximum sample value max (max1 in the example of FIG. 2A) and the minimum sample value min (min1 in the example of FIG. 2A) from the maximum sample hold circuit 13 and the minimum sample hold circuit 12 are sent to the controller 14. Can be

The controller 14 comprises, for example, a so-called microprocessor (MPU). For example, an average value (an average value as digital data) of the maximum sample value max and the minimum sample value min is obtained, and the data of the average value is used as a reference. Send to value generator 15.

The reference value generator 15 has, for example, a digital / analog converter, converts the average value data from the controller 14 into an analog signal level, and converts the analog signal level to the reference level re.
f (the reference level ref1 in the example of FIG. 2A) is sent to the comparator 16.

After setting the reference level ref as described above, the optical disk device of the embodiment shifts to a normal operation. During the normal operation, a laser beam spot is irradiated onto the use area of the optical disc 20. Thereby, the signal S based on the reflected light from the use area is supplied to the comparator 16.

As shown in FIG. 2, the comparator 16 compares the signal level of the signal S based on the reflected light from the use area with the reference level ref, and compares the comparison result with the laser beam spot position. It is output as detection data (that is, detection data of a land portion and a groove portion). That is, this detection data indicates that the position on the optical disk 20 where the signal level of the signal S is lower than the reference level ref is the groove portion of the use area,
Conversely, this indicates that the position on the optical disk 20 that is higher is the land portion of the use area.

As described above, the normal operation is performed in the optical disk device. At this time, the position of the laser beam spot on the optical disk 20 is determined by comparing the signal S with the reference level ref in the comparator 16. Can be detected as a groove portion or a land portion. The detection data is sent from the terminal 17 to the subsequent configuration.

Incidentally, the optical disk 20 usually has a variation in reflectance for each disk. Therefore, for example, as shown in FIGS.
If the optical disk is different, the level of the signal S corresponding to the amount of reflected light may be different. Therefore, for example, the reference level r corresponding to the signal S of FIG.
If ef1 is used for position detection with respect to another optical disk from which the signal S of FIG. 2 can be obtained, for example, the position detection of the groove portion and the land portion cannot be performed.

However, even in such a case, according to the optical disk device of this embodiment, as described above, when the optical disk is inserted into the device, the reference level ref based on the amount of light reflected from the predetermined area is used. Since the reference level ref2 is obtained in the example of FIG. 2B, the position detection (laser beam spot position detection) of the groove portion and the land portion using the optimum reference level ref can be performed for each optical disk. Become like

That is, the signal S as shown in FIG. 2A is obtained by exchanging the optical disk to be inserted into the optical disk device. For example, the signal level as shown in FIG. Even if the signal S is different from
By determining the reference level ref2 based on the maximum sample value max2 and the minimum sample value min2 of the signal S of FIG. 2B, position detection of the groove portion and the land portion with respect to the laser beam spot for this optical disk (groove) (The detection of the laser beam spot position with respect to the portion and the land portion) can be performed accurately.

The above-mentioned predetermined area is located before or after the start position of the information recording and / or reproduction of the used area,
Alternatively, it can be provided at the center or at a plurality of places.

For example, if a plurality of predetermined areas are provided in the same optical disk, a reference level (for example, an average value of each sample value) ref is determined using a plurality of sample values obtained from the plurality of predetermined areas. The reference level re for that optical disc.
The appropriateness of f can be increased.

When the predetermined area is provided at a plurality of locations, a reference level may be obtained for each position on the same optical disc. According to this, it is possible to more accurately detect the positions of the lands and the grooves for each position in the same optical disk.

In the above description of the embodiment, the optical disk 20 in which the amount of light reflected from the groove is smaller than the amount of light reflected from the land is taken as an example. According to the optical disk device of the present embodiment, the land portion and the groove portion can be detected even if the optical disk has a larger amount of reflected light. In this case, the detection data from the comparator 16 indicates that the position on the optical disk where the signal level of the signal S is lower than the reference level ref is the land, and conversely the position on the optical disk where the signal level is higher than the reference level ref. This indicates that it is a groove portion. Alternatively, in the configuration of FIG. 1, for example, if the signal S to the comparator 16 is inverted or the output of the comparator 16 is inverted, the same detection data as in FIG. 2 can be obtained.

As described above, the effect of the optical disk apparatus of the present invention is as follows. First, by measuring the state of each optical disk, the DC of the signal obtained by the reflected light of the laser beam spot is measured. It is possible to remove the difference (reflectance variation) between the disks, which is the biggest problem that the level and AC level change. Also,
Secondly, it is possible to eliminate the influence of the above-mentioned aging of the apparatus (change of laser power, change of photodetector, etc.). Third, by increasing the number of sample points on the same disk, differences within the same disk (variations in reflectance at each position within the same disk) can be further absorbed. Fourth, the sample operation is automatically performed when a disc is inserted, so that the user does not require any special operation and does not feel a change in usability.

[0033]

As described above, according to the present invention, immediately after the insertion of an optical disk having a predetermined area composed of a land portion and a groove portion not used for information recording and / or reproduction, the irradiation position of the laser beam is changed to the predetermined area. It moves upward and samples the amount of reflected laser light from the optical disk irradiated onto a predetermined area, determines a reference level based on the sampled value of the reflected light, and during normal operation, the reference level and the reflected light By detecting the position information of whether the laser beam spot position is in the land portion or in the groove portion based on the above, variations in reflectance between optical disks and variations in reflectance within the same optical disk, Regardless of the difference in reflectance between the recorded part and the unrecorded part in the optical disc, and aging of the device,
It is possible to prevent erroneous detection and non-detection from occurring, and to accurately detect whether the laser beam spot position is on the land portion or on the groove portion.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a main part of an optical disk device according to an embodiment of the present invention.

FIG. 2 is a diagram for describing setting of a reference level for each optical disk in the optical disk device of the present embodiment.

FIG. 3 is a diagram for explaining a conventional method for detecting a land portion and a groove portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Optical block 2 ... Beam splitter 3 ... Objective lens 4 ... Condensing lens 5 ... Photodetector 10 ... · Amplifier 11 · · · · Optical block moving mechanism 12 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ..... Comparator 20 ... Optical disc

Continuation of the front page (56) References JP-A-2-166642 (JP, A) JP-A-2-165428 (JP, A) JP-A-1-122034 (JP, A) JP-A-5-67342 (JP) , A) JP-A-5-109093 (JP, A) JP-A-1-169742 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 7/085 G11B 7/09-7/095

Claims (5)

(57) [Claims] 1. Immediately after insertion of an optical disc having a predetermined area consisting of a land and a groove not used for information recording and / or reproduction together with a use area consisting of a land and a groove used for information recording and / or reproduction. A laser beam irradiation position moving means for moving the irradiation position of the laser beam over the predetermined area; a reflected light amount sampling means for sampling a reflected light amount of the laser beam irradiated on the predetermined area from the optical disk; Reference level determining means for determining a reference level based on the sampled value of the reflected light amount. In a normal operation, the laser beam spot position is determined based on the reference level and the reflected light amount from the optical disk. An optical disc device for detecting whether it is on an upper portion or a groove portion. 2. The apparatus according to claim 1, wherein the reference level is determined based on the amount of reflected light from the predetermined area provided before a start position of information recording and / or reproduction in the use area. Optical disk device. 3. The apparatus according to claim 1, wherein the reference level is determined based on the amount of reflected light from the predetermined area provided after an information recording and / or reproduction end position of the use area. Optical disc device. 4. The optical disk device according to claim 1, wherein the reference level is determined based on the amount of reflected light from the predetermined area provided at the center of the used area. 5. The laser beam irradiation position moving means,
Moving the irradiation position of the laser beam onto a plurality of predetermined areas provided at a plurality of positions in the optical disk; the reflected light amount sampler samples the plurality of reflected light amounts from the plurality of predetermined positions, and The level determining means determines a reference level based on the plurality of sample values.
The optical disc device according to any one of the preceding claims.