JP2005293657A - Optical disk recording device - Google Patents

Abstract

An optical disk recording apparatus capable of obtaining stable recording quality over the entire surface of an optical disk.
A reflected light receiving means for receiving reflected light from an optical disc being recorded, a reflected light calculating means for calculating a received signal, a reflected light correcting means for correcting the calculated signal, Reflected light detection means 9 for detecting the corrected reflected signal, reflected light A / D conversion means 10 for A / D converting the detected signal, and reflected light A / D for calculating and comparing the A / D converted signal Based on the comparison results of the conversion value calculation means 11, the reflected light A / D conversion value comparison means 12, and the reflected light A / D conversion value comparison means 12, the recording state of the optical disk 1 is detected, and the recording laser power is determined. It has a laser power control means 13 for correcting.
[Selection] Figure 1

Description

  The present invention relates to an optical disk recording apparatus for recording / reproducing information on an optical disk and a recording laser power control process for a recording optical disk.

  As optical disk recording devices, CD-ROM, CD-R / RW, DVD, and the like have already been put into practical use, and application to various fields and development for high performance are being actively carried out.

  In recent years, various recording media have been released with the rapid spread of writable optical disc recording apparatuses, and the recording media characteristics have a great influence on the recording characteristics of the optical disc recording apparatus.

  An optical disc cannot be completely formed in a flat concentric circle due to the limitation of its formation process. That is, on the market, there are optical discs in which the position of the center hole is shifted from the center, optical discs in which the outer peripheral side of the optical disc is warped, and the like. Recently, there is a medium called a printable medium that can print a label surface in an inkjet printer. In the printable media, a dedicated material for enabling printing with an ink jet printer is applied to the label surface, and the material has a property of expanding and contracting due to a temperature change. Therefore, the polycarbonate plate of the optical disk is stretched. As a result, the printable media has a characteristic that the disk surface of the disk warps in the radial direction of the disk due to a change in environmental temperature. In such an optical disk, since the laser irradiation method on the optical disk board surface is different with respect to a constant laser power, the optimum recording power for obtaining the optimum recording quality changes. Therefore, running OPC processing and recording power correction processing by reproducing the recording area have been established as means for varying the recording power emitted from the laser and keeping the optimum recording power on the optical disc surface constant. Yes.

  First, correction of the conventional recording laser power will be described with reference to FIG. FIG. 3 is a block diagram of a laser power control circuit of a conventional optical disk recording apparatus. In FIG. 3, 1 is an optical disk, 2 is a pickup module, 3 is a spindle motor, 4 is a laser diode, 5 is an objective lens, 6 is reflected light receiving means, 7 is laser power detecting means, 8 is reflected light calculating means, 9 Is reflected light detection means, 10 is reflected light A / D conversion means, 11 is reflected light A / D conversion value calculation means, 12 is reflected light A / D conversion value comparison means, 13 is laser power control means, and 14 is laser. Drive current conversion means 15 is a laser drive means. A recording laser power correction process will be described using the laser power control block configured as described above.

When the optical disk 1 is inserted, the optical disk recording apparatus first rotates the spindle motor 3 to apply focus servo and tracking servo. Next, an OPC (Optimum Power Calibration) operation for obtaining the optimum recording power for recording on the optical disc 1 is performed to obtain the optimum recording power. Next, the actual recording operation is started, and when the recording of a certain amount (recording amount A) is completed, the recording operation is intentionally interrupted, and only a part of the final recording area recorded by itself is reproduced. Reflected light returning from the optical disk 1 when reproduced is obtained by the reflected light receiving means 6. When the obtained signal is calculated by the reflected light calculation means 8, the calculated signal is called an RF signal shown in an RF signal waveform diagram obtained when the recorded area of the optical disk in FIG. 4 is reproduced, and 3T to 11T. This is a signal formed by signals of up to nine different lengths. The reflected light detection means 9 detects the signal amplitude of the 11T signal that is the longest signal of the RF signal, the average value level of the 3T signal that is the shortest signal, and the average value level of the 11T signal, and the detected signal is The reflected light A / D conversion means 10 performs A / D conversion, and the reflected light A / D conversion value calculation means 11 calculates an asymmetry value for the converted signal. Here, asymmetry = {(11T average) − (3T average)} / 11T amplitude. The asymmetry obtained at this time is set as a reference asymmetry (AsymK0).

  Next, the recording is resumed, and after recording again by the recording amount A, the recording is interrupted. Here, the asymmetry value is calculated by the same method as described above (AsymK1). Then, the reflected light A / D conversion value comparison means 12 calculates the value of the difference (AsymK0−AsymK1) between the asymmetry value and the reference asymmetry value. The amount of power change corresponding to this difference is calculated by the laser power control means 13, the result is transmitted to the laser drive current conversion means 14, and the current value converted by the laser drive current conversion means 14 is laser driven. By transmitting to the means 15, the recording laser power emitted from the laser diode 4 is corrected. Recording is resumed with the corrected recording laser power, recording is performed for the recording amount A as described above, recording is interrupted, and thereafter, the asymmetry value of the final recording area recorded by the optical disk recording apparatus itself is similarly determined. The reference asymmetry values at the start of recording are compared, the difference is converted into the amount of change in recording power, and the optimum recording power is corrected.

  When recording a certain amount, the laser power control means 13 controls the power based on the signal obtained by the laser power detection means 7 inside the hip-up module in order to keep the power constant during recording.

As a prior example, there are (Patent Document 1) (Patent Document 2) and the like.
JP-A-9-270128 JP 2001-31822 A

  In a conventional optical disk recording apparatus, in the process of correcting the laser power from the amount of change in the asymmetry value in order to optimize the recording laser power, it is necessary to accurately detect the asymmetry value. However, the laser diode used for the optical pickup has the characteristic that when the light output by itself returns to itself, it becomes return light noise, and the laser power fluctuates. Generally called a scoop. Here, a scoop of a conventional optical disk recording apparatus will be described with reference to FIGS.

  FIG. 5 is a diagram showing the relationship between the reflected light from the optical disc and the fluctuation of the laser power of the optical disc recording apparatus. In order to keep the RF signal that is the reflected signal from the optical disc 1 and the laser power constant, an optical pickup is shown. The laser power monitor signal obtained from the laser power detection means 7 provided in the inside is shown. Here, the upper side of the RF signal is a portion where reflection is large, and the lower side is a portion where reflection is low. Here, when the behavior of the laser power monitor signal that can confirm the change in the laser power is confirmed, the laser power is high in the portion where the reflection of the RF signal is large, and the laser power is small in the portion where the reflection is small. It is confirmed. This characteristic is not necessarily the same as this, and the polarity and amount of the behavior vary depending on the optical design of the optical pickup and the reflection state of the optical disk.

  A specific example of a scoop of a conventional recording apparatus will be described with reference to FIG.

FIG. 6 is a waveform diagram showing an example of the relationship between the reflected light from the optical disk of the optical disk recording apparatus and the laser power fluctuation, and shows the RF signal and the laser power monitor signal. The lower side is in a state of large reflection. The laser power monitor signal indicates that the laser power increases toward the upper side of the waveform. In this waveform, it is confirmed that the laser power is increased only when the RF signal is below the threshold value at which the line was drawn as the laser power change level (that is, the portion where reflection is large). In other words, this state indicates a scoop state in which the laser power increases only when the RF signal has a large amplitude reflection of a certain length or more, and the laser power does not change otherwise. ing. The asymmetry value when such a scoop occurs will be described. Since the laser power is increased only when the RF signal has a certain amplitude or more, the longest 11T signal is naturally affected by it. That is, since the laser power increases in the portion where the reflection of the 11T signal is large, the amount of reflected light further increases. However, since the laser power does not change in the portion where the reflection of the 11T signal is small, the amount of reflected light remains as it is. In other words, the apparent 11T signal has an increased amplitude and an 11T average level also increases. Further, since the shortest 3T signal is not affected by the scoop, the laser power does not fluctuate, so that the amount of reflected light does not change.

  From the above, the 11T signal amplitude is increased and the 11T average level is increased. However, since the increase of the 11T average level is significantly larger than the increase level of the 11T signal amplitude, there is no scoop. Thus, the calculated asymmetry value takes a large value.

  Therefore, the asymmetry value obtained from the signal recorded on the optical disk does not change when the means for correcting the recording power is used so that the optimum recording power is obtained based on the change amount of the asymmetry value described above. Nevertheless, when there is an effect of scoop, it is calculated as a value larger than the actual value, and there is a problem that the correction for lowering the recording laser power works and the recording quality is deteriorated.

  The present invention has been made in order to solve the above-described problem. By avoiding erroneous correction of the optimum recording power by causing the optical disk recording apparatus to erroneously calculate the asymmetry value by scooping, the entire disk surface can be avoided. An object of the present invention is to provide an optical disc recording apparatus capable of obtaining stable recording quality.

  The present invention has been made to solve the above-described problems, and is an optical disk recording apparatus that records data on a recording-type optical disk using a laser emission pattern. Light receiving means for receiving reflected light, calculating means for calculating the received signal, means for correcting the calculated signal, signal detecting means for detecting the corrected reflected signal, and A / D conversion of the detected signal A / D conversion means, calculation comparison means for calculating and comparing A / D converted signals, and based on the comparison result of the calculation comparison means, the recording state of the optical disk is detected and the recording laser power is corrected. It has a laser power control means for doing.

  According to the present invention, it is possible to avoid the optical recording apparatus from erroneously correcting the optimum recording power by erroneously calculating the asymmetry value by scoop, and to obtain stable recording quality over the front surface of the disk. An optical disc recording apparatus that can be used can be realized.

The invention according to claim 1 of the present invention is an optical disk recording apparatus for recording data on a recordable optical disk by utilizing a laser emission pattern, and receives light reflected from the optical disk during recording. Means, calculating means for calculating the received signal, means for correcting the calculated signal, signal detecting means for detecting the corrected reflected signal, and A / D converting means for A / D converting the detected signal And an operation comparison means for calculating and comparing the A / D converted signal, and a laser power control for detecting the recording state of the optical disk and correcting the recording laser power based on the comparison result of the operation comparison means An optical disc recording apparatus comprising: means for interrupting a recording operation during the recording operation, receiving reflected light from the recorded area, and receiving the received signal. From the change, by recognizing a change in the laser thermal efficiency of the optical disc board, it is possible to correct the laser power.

  According to the second aspect of the present invention, the reflected light when the recorded area of the optical disk is reproduced is received by the light receiving means, the received signal is calculated by the calculating means, and the calculated signal is calculated. The optical disk according to claim 1, wherein the reflected signal is converted into a DC signal by applying a filter, and a change in thermal efficiency of laser power during recording is detected from a change in level of the DC signal. In the recording apparatus, by converting the reflected signal into a DC signal, a change in the thermal efficiency of the laser power during recording can be detected without the influence of a scoop.

  According to a third aspect of the present invention, a change in the thermal efficiency of the laser power during recording is detected from a change in the level of the DC signal obtained by converting the reflected signal into a DC signal, and the thermal efficiency of the detected laser power is detected. 2. The optical disk recording apparatus according to claim 1, wherein a laser power for achieving an optimum recording power is corrected from the amount of change, wherein the laser power is changed from a change in a signal obtained by converting reflected light into a DC signal. By sensing the amount of change in thermal efficiency and correcting the amount of change, the recording state on the optical disk can be stabilized by varying the recording laser power.

  The invention according to claim 4 of the present invention is characterized in that the reflected light change is measured by measuring the reflected light within one circumference of the optical disk and preventing erroneous detection of the reflected light due to the surface shake component of the optical disk. In the optical disk recording apparatus according to claim 1, by measuring the reflected light for one round of the optical disk, it is possible to prevent an error due to a surface shake component originally possessed by the optical disk.

(Embodiment 1)
The description of the embodiment of the present invention will be described with reference to FIG. 1 and FIG.

  FIG. 1 is a block diagram of laser power control of an optical disk recording apparatus according to an embodiment of the present invention. FIG. 7 is a flowchart of laser power control of the optical disk recording apparatus according to an embodiment of the present invention. In FIG. 1, 1 is an optical disk, 2 is a pickup module, 3 is a spindle motor, 4 is a laser diode, 5 is an objective lens, 6 is reflected light receiving means, 7 is laser power detecting means, 8 is reflected light calculating means, 9 Is reflected light detection means, 10 is reflected light A / D conversion means, 11 is reflected light A / D conversion value calculation means, 12 is reflected light A / D conversion value comparison means, 13 is laser power control means, and 14 is laser. Drive current conversion means, 15 is laser drive means, and 16 is reflected light correction means.

  When the optical disk 1 is inserted (S1), the optical disk recording apparatus rotates the spindle motor 3 to start the activation process, applies focus servo and tracking servo, and moves the objective lens in the pickup module to the recording area on the optical disk. 5 is moved. Next, the optical disc recording apparatus executes an OPC process in order to obtain an optimum recording power for recording on the optical disc. The actual data recording is started (S2) with the recording power obtained by the OPC processing as the recording start power (Pw0).

Here, control for keeping the recording laser power of the optical disk recording apparatus during recording constant will be described. The optical disk recording apparatus inputs a part of the light output from the laser diode 4 to the laser power detection means 7 inside the pickup module 2. The laser power detection means 7 photoelectrically converts light into an electrical signal and outputs the laser power state to the laser power control means 13 as an electrical signal. In the laser power control means 13, since the change in the signal output from the laser power detection means 7 corresponds to the change in the laser power,
A signal for eliminating the amount of change is output. The output signal is converted into a current value by the laser driving current conversion means 14 and transmitted to the laser diode 4 by the laser driving means 15. By configuring the above closed loop control, the laser power during recording can be kept constant.

  With such a configuration, when the recording operation is continued while keeping the laser power during recording constant, and the recording (S3) is completed by the amount (A0) determined in advance by the optical disc recording device, the optical disc recording device The recording operation is temporarily interrupted (S5). Then, the data recorded in the last recorded portion of the recorded area A0 is reproduced for one round of the optical disc (S6). At this time, the reproduction for one round is performed in order to cancel the measurement error due to the deviation within the circumference when the optical disc 1 has a surface shake or the like. It may be an integer multiple such as minutes and three laps. The optical disk recording apparatus reproduces the area recorded by itself and obtains the amount of reflected light by the reflected light receiving means 6. The signal obtained by the reflected light receiving means 6 is calculated by the reflected light calculating means 8 into a signal obtained by adding all the reflected light amounts from the optical disk 1.

  The signal calculated here is called an RF signal. As shown in FIG. 4, the RF signal formed by the reflected light calculation means 8 is formed of signals having nine lengths from the shortest 3T signal to the longest 11T signal. This means that the higher the signal level, the larger the reflected light amount, and the lower the signal level, the smaller the reflected light amount. Here, the stronger the recording power, the darker the mark formed on the optical disk 1, so the amount of reflected light decreases, and the weaker the recording power, the thinner the mark formed on the optical disk 1. The amount of light increases.

  In addition, the optical disk recording apparatus has reflected light noise called a scoop due to its optical design and the influence from the disk 1, and due to the influence of the scoop, the actual reflected light changes the laser power on the long signal side of the RF signal. Will cause a large error. Therefore, the RF signal is input to the reflected light correction unit 16, and the reflected light correction unit 16 corrects the RF signal having an amplitude from 3T to 11T into a DC signal. An RF signal corrected to a DC signal is called an RFDC signal.

Usually, the data formed on the optical disc has an overwhelmingly large probability of existence of a short T such as 3T or 4T. Therefore, an error of a long signal component such as 11T having a scoop effect is converted into a DC signal. Therefore, the level of the RFDC signal becomes a signal that can monitor the change in the thermal efficiency on the optical disc surface of pure recording power. The RFDC signal that is no longer affected by the scoop is detected by the reflected light detection means 9 and output to the reflected light A / D conversion means 10. The RFDC signal A / D converted by the reflected light A / D conversion means 10 is converted into a value used for correcting the recording power by the reflected light A / D conversion value calculation means 11 (S7). The RFDC signal level obtained at this time is set to R0 (S8). Let R0 be the initial value for power correction. After obtaining R0, the optical disc recording apparatus resumes data recording (S9). Then, as described above, when recording is completed for A0, it is confirmed whether or not the initial value R0 has been acquired. If the initial value has been acquired (S4), the recording is interrupted again (S10). A similar means (S11) is used to obtain the RFDC signal level. The RFDC signal level obtained at this time is R1. Here, R1 and R0 are compared by the reflected light A / D conversion value comparison means 12 (S12), and the difference is obtained. The optical disk recording apparatus has its own RFDC signal level and the total reflected light amount from the recorded area of the optical disk in FIG. 2 with respect to the difference between the RFDC signal levels obtained by the reflected light A / D conversion value comparison means 12. Recording power sufficient to correct the difference in the RFDC signal level is calculated by a linear function expression between the recording power and the recording power shown in the characteristic diagram showing the recording power relationship on the disk board surface (S13). A signal for varying the output power of the laser diode 4 by the power amount to be corrected is output to the laser power control means 13, and the laser power control means 13-laser driving current conversion means 14-laser. The recording laser power transmitted to the driving means 15 and emitted from the laser diode 4 is corrected (S14). The optical disk recording apparatus resumes recording with the corrected recording power (S15). After the recording is resumed, the laser power is controlled using the means as described above so that the recording power becomes constant. Similarly, until the data recording is completed, every time recording is performed by the recording amount A0, the recording is interrupted, and when the recording start is the first recording, the RFDC signal level obtained at the n-th recording is Rn. In this case, the difference between Rn and R0 is calculated, and the recording power is corrected using the means as described above. If the remaining amount of data to be recorded is A0 or less, the remaining data amount is recorded, and the recording operation is terminated (S16, S17).

  With the above configuration, when recording power correction is performed, measuring the change in asymmetry, which was a conventional technique, would cause a measurement error due to the effect of scoop, avoiding the problem of erroneously correcting the recording power. Thus, it is possible to realize an optical disc recording apparatus capable of obtaining stable recording quality over the entire surface of the recording type optical disc.

  INDUSTRIAL APPLICABILITY The present invention can obtain stable recording quality over the entire surface of a recording type optical disc, and can be applied to an optical disc recording apparatus used in an electronic device such as a personal computer or used externally.

Laser power control block diagram of an optical disk recording apparatus according to an embodiment of the present invention Characteristic diagram showing the relationship between the amount of total reflected light from the recorded area of the optical disc and the recording power on the disc surface Laser power control block diagram of a conventional optical disk recording apparatus RF signal waveform diagram obtained when the recorded area of the optical disk is reproduced The figure which showed the relation between the reflected light from the optical disk which the optical disk recording device has and the fluctuation of the laser power Waveform diagram showing an example of the relationship between the reflected light from the optical disk and the laser power fluctuation of the optical disk recording device Laser power control flowchart of an optical disk recording apparatus according to an embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Pickup module 3 Spindle motor 4 Laser diode 5 Objective lens 6 Reflected light light-receiving means 7 Laser power detection means 8 Reflected light calculation means 9 Reflected light detection means 10 Reflected light A / D conversion means 11 Reflected light A / D conversion value Calculation means 12 Reflected light A / D conversion value comparison means 13 Laser power control means 14 Current conversion means for laser drive 15 Laser drive means 16 Reflected light correction means

Claims (4)

An optical disk recording apparatus for recording data on a recordable optical disk by utilizing a laser emission pattern, a light receiving means for receiving reflected light from the optical disk being recorded, and a calculating means for calculating the received signal A means for correcting the calculated signal, a signal detecting means for detecting the corrected reflected signal, an A / D conversion means for A / D converting the detected signal, and calculating and comparing the A / D converted signal An optical disk recording apparatus comprising: an operation comparison means for detecting; and a laser power control means for detecting a recording state of the optical disk based on a comparison result of the operation comparison means and correcting a recording laser power. The reflected light when the recorded area of the optical disk is reproduced is received by the light receiving means, the received signal is calculated by the calculating means, and the calculated signal is filtered to convert the reflected signal to DC. 2. The optical disk recording apparatus according to claim 1, wherein the optical disk recording apparatus detects the change in thermal efficiency of the laser power during recording from the change in the level of the DC signal after conversion into a signal. A laser for detecting the change in the thermal efficiency of the laser power during recording from the change in the level of the DC signal obtained by converting the reflected signal into a DC signal, and obtaining the optimum recording power from the detected change in the thermal efficiency of the laser power. The optical disk recording apparatus according to claim 1, wherein power correction is performed. 2. The optical disk recording apparatus according to claim 1, wherein the reflected signal detected for obtaining the amount of change in thermal efficiency eliminates in-plane fluctuation components of the optical disk by reproducing one round of the optical disk.

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