JP3762712B2 - Information recording / reproducing apparatus and laser intensity setting method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an information recording / reproducing apparatus for recording / reproducing information using a laser beam and a laser intensity setting method suitable for the information recording / reproducing apparatus.
[0002]
[Prior art]
When recording and reproducing information using laser light, it is necessary to set the laser light to an optimum intensity in each mode of recording and reproduction. Among these, the laser intensity at the time of reproduction is set so weak that it does not erase information recorded on the medium. On the other hand, the laser intensity at the time of recording is set to an intensity at which the temperature of the medium can be increased to a recordable level.
[0003]
For example, in a magneto-optical recording / reproducing apparatus, it is necessary to increase the temperature of the recording layer to such an extent that the magnetization direction of the recording layer can be changed by applying a magnetic field. However, if the laser intensity is increased too much, the temperature of the adjacent track rises, and information on the adjacent track may be rewritten or erased by mistake. Therefore, the laser intensity must be set to such an extent that the temperature rises sufficiently only at the recording position.
[0004]
A method for setting the recording laser intensity in the magneto-optical recording / reproducing apparatus will be described with reference to FIG. This figure shows an example of a magneto-optical disk in which grooves (grooves) are spirally formed on the disk. Information is recorded on such a groove and a land interposed between adjacent grooves.
[0005]
When setting the recording laser intensity, first, information is recorded on a predetermined land. Next, information is recorded at a predetermined laser intensity on the groove adjacent to the land. Then, the previously recorded land information is reproduced, and the bit error amount generated during the reproduction is measured. If there are many such bit errors, land information is frequently erased by recording in the groove. Similarly, the previously recorded groove information is reproduced, and the amount of bit error generated during the reproduction is measured. If there are many such bit errors, recording to the groove has not been sufficiently stabilized.
[0006]
FIG. 10 shows the relationship between the recording laser power, the bit error amount during land reproduction, and the bit error amount during groove reproduction. As shown in the figure, when the recording laser intensity is low, the bit error amount during groove reproduction increases, and conversely, when the recording laser intensity is high, the bit error amount during land reproduction increases. Therefore, the recording laser intensity needs to be set to an intensity (PwC) at which both bit error amounts during groove reproduction and land reproduction are small.
[0007]
Usually, the optimum laser intensity is set by measuring the bit error amount with a plurality of recording laser intensities. That is, from the bit error measurement results of the plurality of recording laser intensities, the minimum recording laser intensity setting value PwL in which the bit error amount during groove reproduction is less than the threshold value Bs and the maximum bit error amount during land reproduction is less than the threshold value Bs. The recording laser intensity setting value PwH is detected, and the center laser intensity PwC sandwiched between the PwL and PwH is set as the optimum laser intensity.
[0008]
[Problems to be solved by the invention]
The recording laser intensity is set as described above. However, such setting is not required to be performed only once at the initial stage, but needs to be performed again according to the environment of the apparatus.
[0009]
For example, if the outside temperature of the apparatus changes, the temperature of the medium and the recording layer also changes accordingly. However, if the temperature of the recording layer changes in this way, even if the laser beam with the same intensity is irradiated, the recording by that The arrival point of the bed temperature varies. Therefore, even if the optimum laser intensity is set in advance, if the outside air temperature is different from the outside air temperature at that time, even if recording is performed with the optimum laser intensity, the bit error may frequently occur. Therefore, the setting of the optimum laser intensity needs to be repeatedly performed every time recording is performed on the medium, and more preferably even during recording on the medium.
[0010]
Conventionally, the setting of the recording laser intensity has been performed every time the apparatus is started. However, as described above, the setting of the recording laser intensity requires a complicated processing operation such as repeated recording and reproduction. For this reason, a certain time is required from the start to the normal mode, which hinders quick start. Further, it is extremely difficult to set the recording laser power during the recording due to the complicated processing operation.
[0011]
Accordingly, the present invention provides an information recording / reproducing apparatus and a laser power setting method capable of eliminating such inconvenience and quickly setting the recording laser power by a simple process.
[0012]
[Means for Solving the Problems]
The present invention detects a phase difference between a reproduction signal recorded with a laser beam having an optimum intensity and a reproduction signal recorded with a laser beam having a predetermined intensity, and the recording laser beam is detected based on the phase difference. The strength is set.
[0013]
For example, assume that the optimum laser intensity is set by the method shown in FIG. When information is recorded on the medium with such a laser intensity, the information is held in the recording layer with a predetermined delay from the laser irradiation to the medium according to the temperature characteristics at that time. For example, if the temperature of the recording layer is low, the delay time becomes large. Conversely, if the temperature of the recording layer is high, the delay time becomes small. Thus, the delay time varies according to the temperature characteristics of the recording layer.
[0014]
However, since the optimum laser intensity is set so that the bit error can be minimized as described above, the delay time generated at the time of setting the optimum laser intensity is determined at the subsequent setting. This is also a standard that can minimize bit errors. That is, if the laser intensity is set so that the delay time is reached, the laser intensity becomes an optimum intensity according to the temperature characteristics during the recording.
[0015]
The present invention intends to estimate the laser intensity that will cause such a delay time from the phase of the reproduction signal. That is, the invention according to each claim has the following features.
[0016]
According to the first aspect of the present invention, in an information recording / reproducing apparatus for recording / reproducing information using a laser beam, a reproduction signal at the time of recording with a laser beam of a predetermined intensity and a reproduction at the time of recording with an optimal intensity laser beam at the first start It has phase difference detection means for detecting a phase difference between the signal and laser intensity setting means for setting the intensity of the laser beam in accordance with the phase difference.
[0017]
According to a second aspect of the present invention, there is provided the information recording / reproducing apparatus according to the first aspect, wherein the laser intensity setting means calculates the current optimum laser intensity based on the phase difference information from the phase difference detection means. It has the means.
[0018]
According to a third aspect of the present invention, in the information recording / reproducing apparatus according to the first or second aspect of the present invention, the information recording / reproducing apparatus further includes an address detecting unit for detecting an information recording position on a recording medium, It is performed on the non-user area detected by the detecting means.
[0019]
According to a fourth aspect of the present invention, in any one of the first to third aspects, the recording with the laser beam having the predetermined intensity is performed a plurality of times by the laser beam having a plurality of intensities, and the phase detection means Detecting the phase difference between the reproduction signal recorded with the laser beam and the reproduction signal recorded with the laser beam having the optimum intensity, and the laser intensity setting means detects the intensity of the laser beam according to each detected phase difference. Is set.
[0020]
The invention of claim 5 is a laser intensity setting method for setting the intensity of a recording laser beam in an optical recording apparatus, a recording step for recording information with a laser beam of a predetermined intensity, and a reproduction signal for reproducing the recorded information And a phase difference detection step for detecting a phase difference between a reproduction signal when recording with an optimum intensity laser beam at the time of initial activation, and a laser intensity setting step for setting the intensity of the laser beam in accordance with the phase difference; It is characterized by having.
[0021]
The invention of claim 6 is the laser intensity setting method according to claim 5, wherein the laser intensity setting step calculates a current optimum laser intensity based on phase difference information from the phase difference detection step. And
[0022]
A seventh aspect of the present invention is the laser intensity setting method according to the fifth or sixth aspect, further comprising an address detecting step of detecting an information recording position on a recording medium, wherein the recording with the laser beam having the predetermined intensity is performed by the address. This is performed on the non-user area detected by the detection step.
[0023]
The invention according to claim 8 is the laser intensity setting method according to any one of claims 5 to 7, wherein the recording by the recording step is performed a plurality of times by laser beams having a plurality of intensities, and the phase detection step includes: Detecting a phase difference between a reproduction signal recorded with an intensity laser beam and a reproduction signal recorded with an optimum intensity laser beam, and the laser intensity setting step is performed according to each detected phase difference. The intensity of the laser beam is set.
[0024]
The features of the present invention will become more apparent from the following description of embodiments.
[0025]
The “phase difference detecting means” in the claims corresponds to the phase adjustment circuit 29 and the phase comparison / phase determination circuit 30 in the embodiment. The “laser intensity setting means” in the claims corresponds to the control circuit 20 and the laser drive circuit 15 in the embodiment. The “address detection means” in the claims corresponds to the address detection circuit 31 in the embodiment.
[0026]
The “recording step” in the claims corresponds to step S103 in the embodiment. The “phase difference detection step” in the claims corresponds to step S107 in the embodiment. The “laser intensity setting step” in the claims corresponds to steps S108 and S109 in the embodiment.
[0027]
However, the following embodiment is merely one embodiment of the present invention, and the meaning of the terminology of the present invention or each constituent element is not limited to that described in the following embodiment. Absent.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0029]
First, FIG. 1 shows the structure of a magneto-optical disk according to an embodiment. The magneto-optical disk 100 has a planar structure in which grooves and lands are alternately formed in the radial direction. The groove and the land are formed in a spiral shape or a concentric shape. A frame as a recording unit is allocated on the groove and land. Each frame is composed of n segments S0, S1,... Sn.
[0030]
A fine clock mark (FCM) for generating a data recording / reproducing clock is arranged at the head of each segment. Such an FCM is formed by providing a land with a fixed length at regular intervals in the groove and providing a groove with a fixed length at regular intervals on the land. In the segment S0 which is the head of the frame, following the FCM, an address indicating a position on the magneto-optical disk 100 is recorded by wobbling the wall surface of the groove and land. Such wobbles are preformatted when the magneto-optical disk 100 is manufactured.
[0031]
Note that the FCM area and segment S0 of each segment are not used as user data recording areas. User data is recorded in a user data area in a segment other than the segment S0.
[0032]
FIG. 2 shows the configuration of the recording / reproducing apparatus according to the embodiment.
[0033]
In the figure, 1 is a magnetic head for applying a magnetic field to a groove or land, 2 is a magnetic head drive circuit for driving the magnetic head 1, and 3 is a laser beam irradiated on the groove or land on the magneto-optical disk and the reflected light is irradiated. An optical head 4 that receives light and outputs a reproduction signal 4 is a laser driving circuit that drives a semiconductor laser of the optical head 3.
[0034]
Here, the optical head 3 includes a semiconductor laser 31 and a photodetector 32, and a pulse beam is output from the semiconductor laser 31 at a clock corresponding to each recording bit during recording. On the other hand, the magnetic head drive circuit 1 applies a magnetic field modulated according to the recording signal. As a result, a signal magnetized in accordance with the recording signal is magneto-optically recorded on the groove.
[0035]
A recording signal generation circuit 5 generates a recording signal from the recording data or the reference pattern. Here, whether to select recording data or reference pattern data depends on a command from the control circuit 7. Reference numeral 6 denotes an encoder that encodes recording data with an error correction code.
[0036]
7 is a control circuit for controlling each part, 8 is a servo mechanism for focus control and tracking control of the beam from the optical head 4, 9 is a spindle motor for rotationally driving the magneto-optical disk 100, 10 is a servo mechanism 8 and a spindle motor 9 is a servo circuit for controlling 9.
[0037]
Here, the servo circuit 10 drives the servo mechanism in accordance with the focus error signal and tracking error signal from the reproduction signal amplifier circuit 11. Further, the spindle motor 9 is rotationally controlled so that the angular velocity is constant according to the FCM detection signal (TPP) from the reproduction signal amplifier circuit 11.
[0038]
11 is a reproduction signal that generates a magneto-optical reproduction signal (RF), a focus error signal and a tracking error signal, a tangential push-pull signal (TPP), and a radial push-pull signal (RPP) based on the detection output from the photodetector 32. It is an amplifier circuit. A method of generating each signal will be described in detail later.
[0039]
Among the signals generated by the reproduction signal amplifier circuit 11, the RF signal is output to the band pass filter 12. The TPP signal is output to the external clock signal generation circuit 16 and the servo circuit 10. Further, the focus error signal and the tracking error signal are output to the servo circuit 10.
[0040]
Reference numeral 12 denotes a band-pass filter that cuts noise of the RF signal, reference numeral 13 denotes an AD conversion circuit that AD converts the RF signal, and reference numeral 14 denotes an RF signal obtained by removing waveform interference generated on the RF signal by the recorded magnetization signal and AD conversion. An equalizer 15 that detects a phase shift of the zero cross point of the PRML (Partial Response Maximum Likelihood) 15 decodes the signal from which the waveform interference has been removed and outputs a binarized reproduction signal.
[0041]
A method for detecting the phase shift of the zero cross point in the equalizer 14 will be described in detail later.
[0042]
16 is an external clock signal generation circuit that generates a clock signal CK based on the TPP signal supplied from the servo signal, and 17 is a delay circuit that delays the clock signal CK in the positive or negative direction based on the signal from the phase adjustment circuit 18. , 18 is a phase adjustment circuit that supplies a phase adjustment signal to the delay circuit 17 based on the phase shift detection signal from the equalizer 14 and outputs information on the total adjustment amount and adjustment direction to the phase comparison / phase determination circuit 19; Compares the total adjustment amount supplied from the phase adjustment circuit 18 with the total adjustment amount at the time of recording at the optimum laser intensity to detect the phase difference between them, and from the adjustment direction information from the phase adjustment circuit 18. This is a phase comparison / phase determination circuit that detects the phase difference direction and outputs the detected phase difference information to the control circuit 7.
[0043]
Details of processing in the phase adjustment circuit 18 and the phase comparison / phase determination circuit 19 will be described later.
[0044]
An address detection circuit 20 generates address information based on a radial push-pull signal (RPP) supplied from the reproduction signal amplifier circuit 11. The address detection circuit 20 detects the shape of the wobble of the segment S0 from the RPP signal, thereby reproducing the address information recorded as the shape in the wobble.
[0045]
Next, a method for generating an RF signal, an RPP signal, and a TPP signal from the magneto-optical disk 100 will be described with reference to FIG. In the figure, the relationship between the grooves and lands and the laser beam LB, the configuration of the photodetector 32, and a generation circuit for generating an RF signal, an RPP signal and a TPP signal from each sensor output of the photodetector ( The addition / subtraction circuits 321 to 327) are shown at the same time.
[0046]
The photodetector 32 includes six sensors A, B, C, D, E, and F. These six sensors respectively detect the reflected light in the A region, B region, C region, and D region of the laser beam LB irradiated on the magneto-optical disk. The sensors E and F have different polarization planes for the laser light reflected by the entire A region, B region, C region, and D region of the laser light LB depending on the Wollaston prism (not shown) in the optical pickup 3. Each laser beam diffracted in two directions is detected.
[0047]
The reproduction signal RF is generated by calculating the difference between the output [E] detected by the sensor E and the output [F] detected by the sensor F. Such calculation is performed by the subtraction circuit 321. Further, the radial push-pull signal RPP is obtained by calculating the detection output [C] of the sensor C and the detection output [D] of the sensor D from the sum of the detection output [A] of the sensor A and the detection output [B] of the sensor B. Generated by subtracting the sum. Such calculation is performed by the addition circuits 322 and 323 and the subtraction circuit 324. Further, the tangential push-pull signal TPP is obtained from the sum of the detection output [A] of the sensor A and the detection output [D] of the sensor D, and the detection output [B] of the sensor B and the detection output [C of the sensor C]. ] Is subtracted from the sum. Such calculation is performed by the addition circuits 325 and 326 and the subtraction circuit 327.
[0048]
Next, a method for generating a clock (CK) from the tangential push-pull signal TPP will be described with reference to FIGS.
[0049]
First, FIG. 4 shows a configuration of a PLL circuit built in the external clock signal generation circuit 16 of FIG.
[0050]
The PLL circuit includes a phase comparison circuit 161, an LPF 162, a voltage controlled oscillator (VCO) 163, and a 1 / n frequency divider 164. The 1 / n divider 164 divides the clock (CK) output from the VCO 163 by 1 / n. The phase comparator 161 compares the phase of the clock (CK1) divided by the 1 / n frequency divider 164 with the phase of the tangential push-pull signal TPP, and generates an error voltage corresponding to the phase difference. As a result, the PLL circuit generates a clock (CK) that is synchronized with the tangential push-pull signal TPP and that has a period of 1/532 of the tangential push-pull signal TPP.
[0051]
FIG. 5 shows a process in which the clock signal CK is generated from the tangential push-pull signal TPP. Note that the PLL circuit actually generates the clock signal CK in response to the supply of the FCMT signal shown in FIG.
[0052]
The tangential push-pull signal TPP generated by the reproduction signal amplifier circuit 11 is converted into a pulse signal FCMP by the external clock signal generation circuit 16. The pulse signal FCMP rises in synchronization with the point where the polarity of the tangential push-pull signal TPP changes. A fine clock mark detection signal FCMT is generated in synchronization with the rising edge of the pulse signal FCMP. The signal FCMT is supplied to the PLL circuit, thereby generating a clock signal CK.
[0053]
Next, delay control (adjustment control) of the clock signal by the equalizer 14, the phase adjustment circuit 18 and the delay circuit 17 will be described with reference to FIG.
[0054]
The RF signal AD-converted by the AD converter circuit 13 has a positive and negative stepped amplitude as shown in FIG. The upper part of the figure shows a state in which the phase between the RF signal and the clock signal is matched. Further, the middle stage and the lower stage in the figure show a state where the phase of the RF signal is advanced and a state where the phase of the RF signal is delayed, respectively.
[0055]
In the phase matching state in the upper part of the figure, the zero cross point of the RF signal is synchronized with the clock at timing t1. Therefore, the amplitude value of the RF signal at the timing t1 is zero. On the other hand, in the phase progress state in the middle of the figure, the amplitude value of the RF signal at timing t1 is a negative value, and in the phase delay state in the middle of the figure, the amplitude value of the RF signal at timing t1 is positive. Value.
[0056]
The equalizer 14 samples the amplitude of the RF signal at the timing t 1 and outputs the polarity of the sampled value to the phase adjustment circuit 18. The phase adjustment circuit 18 that has received the output outputs a command to delay the phase of the clock CK to the delay circuit 17 if the polarity is positive. On the other hand, if the polarity is negative, a command to advance the phase of the clock CK is output to the delay circuit 17. The delay circuit 17 delays or advances the phase of the clock CK by a predetermined time in response to the command.
[0057]
The above control is repeated until the sample value at the timing t1 becomes zero in the equalizer 14. As a result, the zero cross point of the RF signal and the clock at the timing t1 are synchronized, and the phases of the clock and the RF signal are matched.
[0058]
During the phase adjustment period, the phase adjustment circuit 18 refers to the polarity information supplied from the equalizer 14 and counts the number of times of polarity plus and the number of times of polarity minus. When phase matching is reached, the total number of minus times is subtracted from the total number of plus times, and this is output to the phase comparison / determination circuit 19. The phase comparison / determination circuit 19 compares the count result with the count result when recording is performed at the minimum laser intensity, and outputs the comparison result to the control circuit 7. In response to this, the control circuit 7 calculates the optimum laser intensity at the time of recording as will be described later, and outputs a laser intensity command corresponding to the calculation result to the laser drive circuit 4.
[0059]
Next, the operation of the recording / reproducing apparatus will be described.
[0060]
First, the operation during normal recording will be described. When a recording command is issued, the recording data is encoded by the encoder 6 and then input to the drive signal generation circuit 5. The drive signal generation circuit 6 generates a recording signal of a predetermined format from the recording data, and the recording signal is recorded in the segments S1 to Sn while referring to the clock signals from the external clock signal generation circuit 16 and the delay circuit 17. Thus, the magnetic head drive circuit 3 and the laser drive circuit 5 are driven. Accordingly, the recording data is sequentially allocated and recorded in the segments S1 to Sn on the groove and land.
[0061]
Next, the operation during normal playback will be described.
[0062]
When a reproduction command for predetermined recording information is issued, the control circuit 7 commands the servo circuit 10 to access the recording information in order to reproduce the recording information. In response to the command, the optical head 3 reads the recording information from the disk 100. The information read in this way is processed by the reproduction system from the reproduction signal amplifier circuit 11 to the PRML circuit 15 and decoded by a decoder (not shown).
[0063]
Next, the recording laser intensity setting operation will be described. The following is the operation when the recording laser intensity is set using the non-user data area (empty area following the address area) arranged in the segment 0 on the groove or land.
[0064]
First, prior to this setting operation, the optimum laser intensity is set by the method shown in FIG. 10, for example, and recording is performed with the laser beam having the optimum laser intensity. The setting of the optimum laser intensity is performed at the timing when the disk 100 is first activated after the disk 100 is mounted on the recording / reproducing apparatus. Such recording is performed using reference pattern data in the non-user data area (hereinafter referred to as “non-user data area A”) of segment 0 in a predetermined frame. Access to the non-user data area A is performed based on address data from the address detection circuit 20.
[0065]
After the reference pattern data is recorded with the laser beam having the optimum intensity in this way, for example, when the disk 100 is activated at the next activation timing, the predetermined pattern other than the one recorded with the optimum laser beam is used. Reference pattern data is recorded at a predetermined laser intensity in a non-user data area (hereinafter referred to as “non-user data area B”). The laser intensity at the time of recording is set based on, for example, recommended laser power information recorded in advance on the disc 100.
[0066]
Thus, after recording in the non-user data area B, the non-user data area A is reproduced next. At the time of such reproduction, the above-described clock adjustment control is performed. That is, the equalizer 14 outputs the polarity information to the phase adjustment circuit 18 as described above. The phase adjustment circuit 18 refers to the polarity information supplied from the equalizer 14 and counts the number of times of polarity plus and the number of times of polarity minus. When phase matching is reached, the total number of minus times is subtracted from the total number of plus times, and this is output to the phase comparison / determination circuit 19. The phase comparison / determination circuit 19 holds the subtraction result Ca.
[0067]
When the count result from the non-user data area A recorded at the optimum laser intensity is held in this way, the non-user data area B recorded at the time of activation is then reproduced. In the same manner as described above, the phase comparison / determination circuit 19 holds a subtraction result Cb between the total number of plus times and the total number of minus times during the reproduction.
[0068]
Thereafter, the phase comparison / determination circuit 19 compares Ca and Cb, and outputs the comparison result to the control circuit 7. In response to this, the control circuit 7 calculates the optimum laser intensity at the time of recording as described later, and outputs a laser intensity setting command corresponding to the calculation result to the laser driving circuit 4.
[0069]
Incidentally, Ca and Cb represent the phase difference between the zero cross point of the RF signal shown in FIG. 6 and the clock CK at the timing t1 in the figure as the subtraction result. Of these, Ca indicates a phase shift when recording is performed at the optimum laser intensity. Therefore, if the laser intensity is set so that the phase shift represented by the Ca occurs even at the start-up, the laser intensity becomes the optimum intensity at the time of recording. Therefore, the gap between the subtraction results Ca and Cb corresponds to the gap between the optimum laser intensity at the start-up and the recording laser intensity to the non-user data area B.
[0070]
The relationship between the phase shift and the laser intensity will be described with reference to FIG. The horizontal axis in the figure represents the laser intensity when recording is performed on the non-user data area B. The vertical axis represents the difference (phase difference) between the phase shift amount recorded at the laser intensity and the phase shift amount recorded at the optimum laser intensity. S1 and S2 are relational characteristics when temperature environments such as outside air temperatures are different.
[0071]
For example, if recording is performed at a recording power of 8 mw, the phase difference from the optimum laser intensity is + d1 in the characteristic S1, and the phase difference from the optimum laser intensity is −d2 in the characteristic S2. Therefore, it is necessary to set the laser intensity to 8 mw−p1 in the characteristic S1, and to 8 mw + p2 in the characteristic S2. Here, p1 and p2 can be approximately calculated from the phase differences d1 and d2 based on a characteristic function that defines the characteristic.
[0072]
The difference between the subtraction results Ca and Cb supplied to the control circuit 7 corresponds to the phase difference d1 or d2 in FIG.
[0073]
Returning to FIG. 2, the control circuit 7 obtains, for example, d = Ca−Cb from the supplied Ca and Cb, and further calculates a deviation p of the recording laser intensity from the d and the characteristic function. Then, the optimum laser intensity is obtained by adding the shift amount p (which can take positive and negative polarities) to the recording laser intensity to the non-user data area B. Accordingly, the recording laser power is set to the optimum laser intensity.
[0074]
By the way, in the laser intensity setting operation, the reference pattern data is recorded with respect to the non-user data area B with one kind of laser intensity. However, as described above, the recording laser power deviation amount p is approximately calculated from the characteristics Ca and Cb using a characteristic function. Therefore, approximation from only one subtraction result Cb may increase the approximation error. There is. The problem of the approximation error can be avoided by preparing a plurality of subtraction results Cb and setting the optimum laser power comprehensively from the plurality of subtraction results. For example, a method may be employed in which a plurality of deviation amounts are calculated from the plurality of subtraction results Cb, and this is added and averaged to the recording laser intensity to calculate the optimum laser intensity.
[0075]
FIG. 8 shows an example in which reference pattern data is recorded in two non-user data areas B with two types of laser intensities. For example, the reference pattern data is recorded with a higher laser intensity (PwH) in a predetermined segment 0, and the reference pattern data is recorded with a lower laser intensity (PwH) in the next segment 0. In addition, the reference pattern data can be recorded in different non-user data areas with three or more laser intensities.
[0076]
FIG. 9 shows a flowchart for setting the recording laser intensity.
[0077]
When the setting process of the recording laser intensity is started, first, in step S101, the non-user data area A is reproduced, and the subtraction result Ca is obtained. Thereafter, in steps S102 to S106, reference pattern data is recorded in a plurality of non-user data areas B with a plurality of recording laser intensities. If the recording laser intensity is one type, reference pattern data is recorded in one non-user data area B with one type of recording laser intensity in steps S102 to S106.
[0078]
Thereafter, in step S107, each of the non-user data areas B is reproduced, and a plurality of subtraction results Cb are obtained. The subtraction result Cb is compared / subtracted with the subtraction result Ca acquired in step S101 in step S108, and phase differences d1 to dn are generated. Thereafter, in step S109, the optimum recording laser intensity Pws is calculated based on the phase differences d1 to dn and the characteristic function. Then, the optimum recording laser intensity Pws is set as the recording laser power at the time of the recording (step S110).
According to the above embodiment, as long as the reference pattern data is recorded at the optimum laser intensity at the initial startup, the reference pattern data is recorded at the predetermined laser intensity at the subsequent startup, and the two recorded references are recorded. Since it is only necessary to reproduce the pattern data and compare the phases, the optimum laser intensity can be set quickly. Therefore, it is possible to suppress the rise time of the apparatus at the time of startup, and to improve user convenience.
[0079]
In addition, by achieving the rapid setting of the optimum laser intensity in this way, the optimum laser intensity can be adjusted using the seek period during normal recording. For example, after the optimum laser intensity is set by the above method at the time of activation, the reference pattern data is recorded in the non-user data area B during the recording operation period. Then, after the predetermined data recording, the recorded reference pattern data is reproduced during the idle time until the next data recording, and the optimum laser power is reset. As described above, when the method of the above embodiment is employed, the optimum laser intensity can be readjusted during a normal recording operation. Such adjustment is effective when the optimum laser intensity changes as the apparatus temperature rises due to the recording operation.
[0080]
As mentioned above, although various embodiment which concerns on this invention was described, this invention is not limited to this embodiment, It cannot be overemphasized that a various change is possible other than that. For example, in the above embodiment, the reference pattern data is recorded in the non-user data area B, but instead, it may be recorded in a predetermined user data area. In the above embodiment, the optimum laser intensity at the time of initial startup is set by the method shown in FIG. 10, but other setting methods can be adopted. Further, in the above embodiment, the equalizer 14, the phase adjustment circuit 18, and the phase comparison / phase determination circuit 19 are used to detect a phase shift from the optimum laser intensity. The phase shift may be detected.
[0081]
In addition, the embodiments of the present invention can be variously modified as appropriate within the scope of the technical idea of the present invention.
[0082]
【The invention's effect】
As described above, according to the present invention, the laser intensity at the time of recording can be set by extremely simple processing such as information recording with a predetermined laser intensity, reproduction of the recorded information, and phase comparison. Therefore, the convenience of the apparatus can be improved.
[0083]
Further, by speeding up the processing, the recording laser intensity can be reset without alienating the normal recording operation not only during the start-up of the apparatus but also during the recording. For this reason, even if the laser intensity becomes inappropriate due to a temperature change during the recording operation, it becomes possible to reset the laser intensity to an appropriate laser intensity, thereby realizing a stable recording operation.
[0084]
Thus, according to the present invention, it is possible to improve the convenience of the apparatus and stabilize the recording operation at the same time, and to realize an excellent information recording / reproducing apparatus with high practicality.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a magneto-optical disk according to an embodiment.
FIG. 2 is a diagram showing a configuration of a recording / reproducing apparatus according to an embodiment
FIG. 3 is a diagram for explaining a method for generating various signals according to the embodiment;
FIG. 4 is a diagram showing a configuration of a PLL circuit according to an embodiment
FIG. 5 is a diagram for explaining a clock generation process according to the embodiment;
FIG. 6 is a diagram for explaining the principle of laser intensity adjustment according to the embodiment;
FIG. 7 is a diagram for explaining a clock phase adjustment method according to the embodiment;
FIG. 8 is a diagram showing intensity settings of a recording laser according to an embodiment
FIG. 9 is a flowchart showing an optimum laser intensity setting operation according to the embodiment.
FIG. 10 is a diagram showing a conventional method for setting the optimum laser intensity according to the embodiment.
[Explanation of symbols]
4 Laser drive circuit
7 Control circuit
14 Equalizer
16 External clock signal generation circuit
17 Delay circuit
18 Phase adjustment circuit
19 Phase comparison / phase judgment circuit
20 Address detection circuit

Claims (8)

In an information recording / reproducing apparatus for recording / reproducing information using laser light,
A phase difference detecting means for detecting a phase difference between a reproduction signal recorded with a laser beam of a predetermined intensity and a reproduction signal recorded with a laser beam of an optimum intensity at the first activation ;
Laser intensity setting means for setting the intensity of the laser beam according to the phase difference;
An information recording / reproducing apparatus comprising: 2. The information recording / reproducing apparatus according to claim 1, wherein the laser intensity setting means includes optimum intensity calculation means for calculating a current optimum laser intensity based on phase difference information from the phase difference detection means.   3. The apparatus according to claim 1, further comprising an address detection unit that detects an information recording position on the recording medium, wherein the recording with the laser beam having the predetermined intensity is performed on a non-user area detected by the address detection unit. An information recording / reproducing apparatus. In any one of Claim 1 to 3, the recording by the laser beam of the predetermined intensity is performed a plurality of times by a laser beam having a plurality of intensities,
The phase detection means detects a phase difference between a reproduction signal when recording with laser light of each intensity and a reproduction signal when recording with laser light of optimum intensity,
The laser intensity setting means sets the intensity of the laser beam according to each detected phase difference;
An information recording / reproducing apparatus. A laser intensity setting method for setting the intensity of a recording laser beam in an optical recording apparatus,
A recording step of recording information with a laser beam of a predetermined intensity;
A phase difference detection step for detecting a phase difference between a reproduction signal obtained by reproducing the recorded information and a reproduction signal obtained by recording with a laser beam having an optimum intensity at the first activation ;
A laser intensity setting step for setting the intensity of the laser beam according to the phase difference;
A laser intensity setting method characterized by comprising: 6. The laser intensity setting method according to claim 5, wherein the laser intensity setting step calculates a current optimum laser intensity based on phase difference information from the phase difference detection step.   7. The method according to claim 5, further comprising an address detection step of detecting an information recording position on a recording medium, wherein the recording with the laser beam having the predetermined intensity is performed on a non-user area detected by the address detection step. A laser intensity setting method characterized by the above. The recording according to any one of claims 5 to 7, wherein the recording by the recording step is performed a plurality of times by laser beams having a plurality of intensities,
The phase detection step detects a phase difference between a reproduction signal when recording with laser light of each intensity and a reproduction signal when recording with laser light of the optimum intensity,
The laser intensity setting step sets the intensity of the laser beam according to each detected phase difference.
And a laser intensity setting method.

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