JP4479750B2 - Optical disc recording / reproducing apparatus - Google Patents

Description

  The present invention relates to an optical disc recording / reproducing apparatus for recording information on an optical disc and reproducing information recorded on an optical disc, and more particularly to a disc discriminating function for discriminating the type of an inserted optical disc.

  2. Description of the Related Art Conventionally, an optical disc recording / reproducing apparatus that records information on an optical disc such as a DVD (Digital Versatile Disc) and reproduces information recorded on the optical disc has been widely used. DVDs include optical disks such as a DVD-ROM that can only read data, a DVD-R (Recordable) that can write data only once, and a DVD-RW (Re-Writable) that can rewrite data. . Since such optical discs have greatly different reflectivities with respect to laser light depending on the type, the optical disc recording / reproducing apparatus discriminates the type of optical disc when it is inserted, and outputs laser light with the optimum output for that type of optical disc. It is configured to write or read data by irradiation.

By the way, in the conventional optical disc recording / reproducing apparatus, the process of discriminating the type of the optical disc is performed such that the optical spot emitted from the optical pickup is focused on the track of the optical disc after the optical disc is inserted. Measures the level of the total addition signal obtained based on the output signal from the optical pickup during focus search, which is the operation until the focus is turned on, and uses this total addition signal level as a discriminating value for disc discrimination If the determination value is equal to or greater than a predetermined threshold value, it is determined that the inserted optical disk is a high reflectivity disk (R-type optical disk). If the determination value is less than the predetermined threshold value, the optical disk is inserted. It is determined that the optical disc is a low reflectivity disc (RW type optical disc).
JP 2004-171614 A JP 2006-31779 A Japanese Patent Laying-Open No. 2005-302083

  However, in the write-type discs such as the DVD-R optical disc and the DVD-RW optical disc as described above, the R-recorded optical disc (high reflectivity disc) and the RW non-recorded optical disc (low reflectivity disc). As a result, the reflectivity approaches, and the disc discrimination accuracy is poor. For example, if a high-reflectance optical disc has already been recorded, the average reflectivity decreases, so the level of the total addition signal acquired during focus search also decreases. In this case, the level of the total addition signal is low reflection. This approach approaches the level of the fully added signal when the optical disc is unrecorded, and there is no margin in the disc discrimination threshold, resulting in a decrease in disc discrimination accuracy. In other words, in the conventional optical disc recording / reproducing apparatus, disc discrimination is performed only with the full addition signal. Therefore, even with the same type of optical disc, the disc discriminating value obtained during the focus search in the recorded state or unrecorded state is used. There is a problem that variations occur, there is no margin in the disc discrimination threshold, and the disc discrimination accuracy is poor.

  In the prior art of Patent Document 1, after the focus is turned on, a comparison is made between the DC level of the reproduction signal output from the optical detector of the optical pickup that has received the reflected light from the optical disc and a preset threshold value. The reflectance is measured, and the measured reflectance is compared with the upper threshold value and the lower threshold value to discriminate the disc. However, when receiving light reflected from an optical disk having a different reflectance by the photodetector, the gain of the photodetector must be switched in accordance with the reflectance before the focus is turned on. Since the disc cannot be discriminated at the time of focus search before starting, the gain of the photodetector cannot be set appropriately, and the accuracy of the reproduction signal output from the photodetector may be inferior. There arises a problem that the accuracy of disc discrimination is also lowered.

  In the prior art of Patent Document 2, for example, disc discrimination between DVD ± R and DVD ± RW is performed by comparing the amplitude value of the RPP signal with a threshold value, but the optical disc is a recorded optical disc. As described above, since the reflectance is different even in the case of an unrecorded optical disc, the problem that the accuracy of disc discrimination is inferior arises in such a case.

  In the prior art of Patent Document 3, a recording surface of a loaded optical disk is irradiated with laser light a plurality of times while changing the emission intensity, the reflected light is received, and the variation in the reflection level, the size of the reflection level, and the laser From the tendency of the change in the reflection level with respect to the light emission intensity, the type of the loaded optical disc and disc discriminating whether it is a recorded disc or an unrecorded disc are determined. Since the focus search is also performed, it takes time to discriminate, and it is determined whether or not data is recorded on a recordable optical disc based on the variation in the reflection level. It is not always the same for each, and the variation is only a variation. Even if the disk identification in the quasi accuracy of disc discrimination can be said that not improved.

  The present invention has been made to solve the above problems, and provides an optical disc recording / reproducing apparatus capable of accurately discriminating between a high reflectivity optical disc and a low reflectivity optical disc during a focus search. For the purpose.

In order to achieve the above object, the invention of claim 1 is an optical disc recording / reproducing apparatus for recording information on an optical disc or reproducing information recorded on an optical disc. when the pickup is performing a focus search prior to focus on for the optical disc, and the signal measuring means for measuring the amplitude level and the RF signal of the full addition signal obtained based on the output signal of the optical pickup , whether the judgment value calculating means for calculating a judgment value for disc discrimination by adding the amplitude of the RF signal to the level of the whole addition signal is the measurement, the calculated determination value is not smaller than the predetermined threshold value a determination value determining means for determining, when the determination value is determined to the not less than the predetermined threshold value, the inserted optical disc is a high reflectivity disc Determines that, when the determination value is determined to the is smaller than the predetermined threshold value, the inserted optical disc is characterized in that and a disk determination means determines that the low reflectivity disc An optical disc recording / reproducing apparatus is provided.

In this configuration, after the optical disc is inserted, when the focus search is performed before the optical pickup is focused on the optical disc, the level of the total addition signal obtained based on the output signal of the optical pickup and the RF The amplitude of the signal is measured, and the amplitude of the RF signal is added to the level of the measured total added signal, and a determination value for disc discrimination is calculated. When it is determined that the calculated determination value is greater than or equal to a predetermined threshold value, the inserted optical disk is determined to be a high reflectivity disk, and the determination value is determined to be less than the predetermined threshold value The inserted optical disc is determined to be a low reflectivity disc.

According to this configuration, it is possible to use a disc discrimination determination value in which the amplitude of the RF signal is added to the level of the total addition signal. Therefore, a high reflectivity optical disc and a low reflectivity during a focus search before the focus is turned on. The optical disc can be discriminated with high accuracy, thereby reducing variations in the disc mounting time, and the device can start up stably in terms of time.

According to a second aspect of the present invention, in the first aspect of the invention, the optical pickup includes a photodetector that receives reflected light from the optical disc , and determines whether the optical pickup is a high reflectivity disc or a low reflectivity disc. Since the gain of the photodetector is set before the focus is turned on according to the reflectance of the optical disc, the gain of the photodetector can be appropriately set before the focus is turned on and is output from the photodetector. The accuracy of the detection signal is increased, and as a result, the accuracy of disc discrimination can be improved .

According to a third aspect of the invention, in the first or second aspect of the invention, the full addition signal is a low frequency component from each detection signal output from a photodetector having a four-part photodetection region in the optical pickup. a is a signal obtained by averaging removed, the amplitude of the RF signal, so combines the detection signal of the photodetector having four divided light detection areas in the optical pickup is the amplitude obtained by detecting The average level of the reflected light from the optical disk can be detected as a fully added signal, and if the amplitude of the RF signal is added to the level of the fully added signal, the determination for disc discrimination in the unrecorded optical disk A judgment value as high as the value can be obtained.

As described above, according to the present invention, the disc discrimination determination value obtained by adding the amplitude of the RF signal to the level of the total addition signal can be used. Therefore, an optical disc having a high reflectivity at the time of focus search before the focus is turned on. And a low-reflectance optical disc can be discriminated with high accuracy, thereby reducing variations in disc mounting time, and the device can start up stably in terms of time. In addition, since disc discrimination can be performed during focus search before focus on, the gain of the photodetector can be set appropriately before focus on, and the accuracy of the detection signal output from the photodetector increases. As a result, the accuracy of disc discrimination is also improved.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing an optical disc recording / reproducing apparatus according to an embodiment of the present invention.

  In FIG. 1, an optical disk recording / reproducing apparatus includes an encoder 1, a modulation circuit 2, a laser drive circuit 3, a laser power adjustment circuit 4, an optical pickup 5, a signal generation circuit 6, a demodulation circuit 7, a decoder 8, a servo circuit 9, and a spindle motor. 12 and the system controller 10.

  The encoder 1 performs an encoding process such as adding an error correction code to the input recording data, and inputs the encoded recording data to the modulation circuit 2. The modulation circuit 2 performs predetermined modulation on the input recording data, further generates a recording signal, and outputs the recording signal to the laser driving circuit 3. The laser drive circuit 3 outputs a drive signal corresponding to the recording signal from the modulation circuit 2 at the time of recording for CD (infrared light; wavelength 780 nm), for DVD (red light; wavelength 650 nm), for HD DVD (blue-violet light) A wavelength of 405 nm) is output to the corresponding laser diode 51, and at the time of reproduction, a drive signal for emitting a laser beam having a constant intensity is output to the corresponding laser diode 51. The laser power output from the laser diode 51 is adjusted and set by the laser power adjustment circuit 4.

  The laser power adjustment circuit 4 sets and adjusts the laser power in accordance with a command from the system controller 10. In the disc discrimination processing, adjustment is performed so that the laser diode 51 for HD / DVD outputs laser light at a reproduction power level. The optical pickup 5 includes a laser diode 51 and a photodetector 52, and further includes an objective lens actuator (not shown) for adjusting the irradiation state of the laser light to the track, and the laser light emitted from the laser diode 51 as an objective lens. And an optical system (not shown) for guiding the reflected light from the optical disk 11 to the photodetector 52.

  The laser diode 51 has three laser diodes that emit laser light for CD (infrared light; wavelength 780 nm), DVD (red light; wavelength 650 nm), and HD / DVD (blue-violet light; wavelength 405 nm), respectively. It is composed of In addition, among the constituent elements constituting the optical system, the objective lens is configured so that the HD / DVD laser beam can be properly converged on the optical disc 11. In addition, when an optical system uses an aberration correction element (such as a diffraction element or a phase correction element) for suppressing aberrations that occur when a DVD laser beam and a CD laser beam are used, or a CD laser beam. Includes a numerical aperture limiting element (liquid crystal shutter, diffraction element, etc.) for limiting the numerical aperture with respect to the objective lens.

  The signal generation circuit 6 amplifies and calculates a signal received from the photodetector 52 having four photodetection regions divided by the track direction axis of the optical disc 11 and an axis orthogonal to the track direction axis. A signal is generated and the various signals are output to a corresponding circuit. That is, the signal generation circuit 6 generates an RF signal by synthesizing each signal from the four light detection areas a, b, c, and d, and also outputs each signal from the light detection areas a, b, c, and d. A full addition signal ABCD is generated by adding the signals A, B, C, and D of DC components obtained by taking out and averaging low frequency components. The signal generation circuit 6 performs an operation of (A + C) − (B + D) from the signals A, B, C, and D to perform a focus error signal and the signals A, B, C, and D to (A + D) − (B + C). ) To generate a tracking error signal.

  The demodulation circuit 7 demodulates the RF signal from the signal generation circuit 6 to generate reproduction data, and outputs it to the decoder 8. The decoder 8 performs decoding processing such as error correction on the reproduction data from the demodulation circuit 7 and outputs the decoded data to a subsequent circuit (not shown). The servo circuit 9 generates a focus servo signal and a tracking servo signal based on the focus error signal and tracking error signal from the signal generation circuit 6 and outputs them to the objective lens actuator of the optical pickup 5. The servo circuit 9 servo-controls the spindle motor 12 based on the synchronization detection signal from the signal generation circuit 6.

  The system controller 10 includes a CPU (not shown) that performs processing for controlling each component, a flash memory (not shown) that stores programs and data necessary for the operation of the CPU, and necessary for processing of the CPU. A RAM (not shown) for temporarily storing data is provided to control the entire apparatus. As a feature of the present embodiment, the system controller 10 determines that the level of the total addition signal ABCD from the optical pickup 5 and the RF when the optical pickup 5 performs a focus search on the optical disk 11 after the optical disk 11 is inserted. A signal measuring means for measuring the amplitude of the signal; a judgment value calculating means for calculating a judgment value for disc discrimination by adding the level of the measured full addition signal ABCD and the amplitude of the RF signal; and the calculated judgment Determination value determining means for determining whether or not the value is equal to or greater than a predetermined threshold; and when the determination value is determined to be equal to or greater than the predetermined threshold, the inserted optical disk 11 is a high-reflectance disk (R system) When the determination value is determined to be less than a predetermined threshold value, the inserted optical disk 11 has a low reflectivity value. And a disk determination means determines that click (RW family optical disc).

  FIG. 2 illustrates a case where disc discrimination is performed based on a difference only in the level of a fully added signal, and a case where disc discrimination is performed based on a difference between signals obtained by adding the amplitude of an RF signal to the level of a fully added signal as in the present embodiment. It is a figure for doing.

  In FIG. 2, L1 indicates the level of the total addition signal based on the signal read from the R-system unrecorded optical disk, and L2 indicates the level of the total addition signal based on the signal read from the R-system recorded optical disk. Show. L3 indicates a level obtained by adding the amplitude of the RF signal to the level L2 of the fully added signal based on the signal read from the R-system recorded optical disc. L4 indicates the level of the fully added signal based on the signal read from the RW unrecorded optical disk, and L5 indicates the level of the fully added signal based on the signal read from the RW recorded optical disk. L6 indicates a level obtained by adding the amplitude of the RF signal to the level L5 of the total addition signal based on the signal read from the RW recorded optical disk. Note that the RW-based recorded optical disk also adds the amplitude of the RF signal to the level of the fully added signal, but this allows the threshold for the discriminating value for disc discrimination to be set to a constant level. However, since the process of adding the amplitude of the RF signal to the level of the fully added signal is performed regardless of the type of the disk at the time of disc discrimination, of course, the level of the fully added signal is also applied to the RW type recorded optical disc. The amplitude of the RF signal is added.

  L7 represents a level difference between the level L1 of the total addition signal based on the signal read from the R-type unrecorded optical disc and the level L4 of the total addition signal based on the signal read from the RW-type unrecorded optical disc. Show. L8 indicates a level difference between the level L2 of the total addition signal based on the signal read from the R-system recorded optical disc and the level L4 of the total addition signal based on the signal read from the RW-type unrecorded optical disc. L9 indicates a level difference between the level L4 of the total addition signal based on the signal read from the RW unrecorded optical disk and the level L5 of the total addition signal based on the signal read from the RW recorded optical disk. L10 indicates a level difference between the level L3 and the level L4 described above.

When discriminating between an R-type unrecorded optical disc and an RW-type unrecorded optical disc, since there is a sufficient level difference L7, disc discrimination can be performed reliably.
When discriminating between the R-type recorded optical disc and the RW-type unrecorded optical disc, the level difference becomes small like the level difference L8 of only the total addition signal, so that disc discrimination is likely to be missed. Therefore, when the level difference L10 is obtained when the amplitude of the RF signal is added to the level of the fully added signal, it becomes possible to reliably discriminate between the R-type recorded optical disc and the RW-type unrecorded optical disc. .

  FIG. 3 is a flowchart for explaining processing for disc discrimination in the present embodiment. Processing for disc discrimination will be described with reference to this flowchart and FIGS.

  First, when the system controller 10 detects that the optical disk 11 has been inserted into the apparatus (step S1), it starts disk mounting (step S2). When disk mounting starts, the system controller 10 drives the laser diode 51 of the optical pickup 5 via the laser drive circuit 3 (step S3). After the laser diode 51 is driven, the system controller 11 operates until the light spot by the laser light emitted from the laser diode 51 of the optical pickup 2 is focused on so that the track of the optical disc 1 is in focus. A focus search is performed (step S4).

  When this focus search is being performed, the signal measuring means of the system controller 10 determines the level of the full addition signal ABCD obtained based on the detection signal from the photodetector 52 of the optical pickup 5 and the amplitude of the RF signal. Measure (Step S5). That is, the signal measuring means measures the level of the full addition signal ABCD generated by the signal generation circuit 6 and detects the RF signal generated by the signal generation circuit 6 to measure the amplitude of the RF signal. Next, the determination value calculation means of the system controller 10 adds the calculated level of the full addition signal ABCD and the amplitude of the RF signal to calculate a determination value for disc determination (step S6).

  Thereafter, the determination value determination unit of the system controller 10 determines whether or not the calculated determination value is equal to or greater than a predetermined threshold (step S7). That is, for example, as shown in FIG. 2, the determination value determination means determines whether or not the determination value that is a level L3 obtained by adding the level of the fully added signal ABCD and the amplitude of the RF signal is equal to or greater than a predetermined threshold E. Determine whether. When it is determined that the determination value at the level L3 is equal to or greater than the predetermined threshold E, it is determined that the type of the inserted optical disk 11 is a high reflectance disk (step S8).

  The level L3 and the predetermined threshold E are compared, but the same applies to the comparison between the level L1 and the predetermined threshold E. Since no data is recorded on an R-type unrecorded optical disc, no RF signal is detected, and even if the process of adding the level of the full addition signal ABCD and the amplitude of the RF signal is performed, only the full addition signal ABCD is obtained. Therefore, the level used as the determination value is the level L1.

  On the other hand, when it is determined that the determination value at the level L3 is less than the predetermined threshold E, it is determined that the type of the inserted optical disk 11 is a low reflectance disk (step S9). For example, as shown in FIG. 2, the level L4 for an RW unrecorded optical disk and the level L6 for an RW recorded optical disk are less than a predetermined threshold E, so the type of the inserted optical disk 11 is low. It is determined that the disk is a reflectance disk.

  As described above, according to the present embodiment, the disc discrimination determination value obtained by adding the amplitude of the RF signal to the level of the full addition signal ABCD can be used. It is possible to accurately discriminate the reflectivity from the optical disc, thereby reducing variations in disc mount time, and the device can start up stably in time. In addition, when the reflected light from the optical disk having a different reflectance is received by the photodetector 52, the gain of the photodetector 52 must be switched according to the reflectance of the optical disk 11 before the servo circuit 9 focuses on. However, in this embodiment, since disc discrimination can be performed at the time of focus search before the focus is turned on, the gain of the photodetector 52 can be appropriately set before the focus is turned on, and the detection output from the photodetector 52 is detected. The accuracy of the signal is increased, and as a result, the accuracy of disc discrimination is also improved.

  The present invention can be used for a disc discriminating function of an optical disc recording / reproducing apparatus (DVD recorder or the like), and can discriminate between a high reflectivity optical disc and a low reflectivity optical disc with high accuracy.

1 is a block diagram showing an optical disc recording / reproducing apparatus according to an embodiment of the present invention. FIG. 5 is a diagram for explaining a case where disc determination is performed based on a difference only in the level of a total addition signal, and a case where disc determination is performed based on a difference between signals obtained by adding the amplitude of an RF signal to the level of a total addition signal as in the present embodiment. It is. It is a flowchart for demonstrating the process which discriminates in the said embodiment.

Explanation of symbols

5 optical pickup 10 system controller (signal measurement means, judgment value calculation means, judgment value judgment means, disk judgment means)
11 Optical Disk 52 Photodetector

Claims (3)

In an optical disc recording / reproducing apparatus for recording information on an optical disc or reproducing information recorded on an optical disc,
After an optical disc is inserted, when the optical pickup is performing a focus search prior to focus on for the optical disc, the level and RF signals of all addition signal obtained based on the output signal of the optical pickup amplitude Signal measuring means for measuring
A determination value calculation means for calculating a judgment value for disc discrimination by adding the amplitude of the RF signal to the level of the whole addition signal is the measurement,
Determination value determination means for determining whether or not the calculated determination value is equal to or greater than a predetermined threshold;
When said determination value is determined to the not less than the predetermined threshold value, the inserted optical disc is determined to be a high reflectivity disc, when the determination value is determined to the is less than the predetermined threshold value, An optical disc recording / reproducing apparatus comprising: disc determination means for determining that the inserted optical disc is a low reflectivity disc. The optical pickup includes a photodetector that receives reflected light from the optical disc,
2. The gain of the photodetector is set before focusing on in accordance with the reflectivity of the optical disc, which is discriminated as a high reflectivity disc or a low reflectivity disc. 2. An optical disk recording / reproducing apparatus according to 1. The full addition signal is a signal obtained by taking out and averaging low frequency components from each detection signal output from a photodetector having a four-part photodetection region in the optical pickup,
Amplitude of the RF signal, to claim 1 or claim 2, characterized in that combines the detection signal of the photodetector having four divided light detection areas in the optical pickup is the amplitude obtained by detecting The optical disk recording / reproducing apparatus as described.

Images