JP2002367175A - Recording light quantity controller for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording light quantity controller which realizes a running OPC of high accuracy by exactly detecting the monitor signal level of a reflected light quantity without using a high-accuracy analog-to-digital converter. SOLUTION: This controller has means 16 for emitting light from a light source which causes the light source 4 to emit light respectively at a first light quantity level value and a second light quantity level value greater than this first light quantity level value, means 6 for detecting the signal level value of the reflected light before information recording which irradiates the recording medium 1 with the light from the light source 4 before the information recording and detects the signal level value of the reflected light, means 9 for recording and holding the reference level value, means 6 for detecting the signal level value of the reflected light after the start of the information recording to the light emitted from the light source after the start of the information recording and means 16 for regulating driving current which causes the light source 4 to emit the light in accordance with the result of comparison between the detected signal level value and the reference level value. The controller is provided with signal gain switching means and gain selecting means which are capable of changing the signal gains of both of the reflected light signal level values to at least two state stages by both detecting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording light amount control device for writing information on an optical disk, and more particularly, to a laser power optimization (OPC) for recording information.
The present invention relates to an optical disk optimum recording light amount control device capable of performing bration).

[0002]

2. Description of the Related Art In recent years, CD-R,
Optical recording media such as CD-RWs have become widespread, and the laser beam output when writing information on these optical disks is higher than the laser beam output when reading information. For example, in an optical disk using an organic dye recording film such as a CD-R (Compact Disc-Recordable), reading (Rea
d) Output P1 level and P2 higher than read level
Information is recorded by alternately generating write output P2 levels (P2> P1). When the recording medium is irradiated with the laser at the P2 level, the dye is decomposed and the substrate is deformed to form holes (pits). On the other hand, when the laser is irradiated at the P1 level, the dye is not decomposed and the substrate is not deformed. (Land). Also, in a CD-R, a level of P3 (P3> P2) having an output higher than the P2 level is provided, and an output waveform at the time of recording may be generated with three values of P1, P2, and P3. This is because the writing is positioned at the head of the pit and the pit edge is sharpened. On the other hand, CD-RW (Compac
In a rewritable medium of a phase change type such as Disc-ReWritable, a ternary (P3>P2> P1) is provided as a laser beam output similarly to the above-described CD-R, and the laser beam outputs P3 and P1 are set to a high speed. To make the phase change recording layer of the recording medium amorphous (amorphous), and to maintain the laser output P2 to crystallize the phase change recording layer of the recording medium. The data is recorded so that the crystallization and crystallization correspond to the information data. The output of these laser beams such as P2 and P3 is
For example, when writing information on an optical disc such as a CD-R / RW, before writing the information, the recording laser power optimization (OPC: Optical Power Calibration) is performed on a power calibration area (PCA: Power Calibration) at the innermost circumference of the optical disc. Area). However, even if recording is started at the optimum output determined by OPC performed by the PCA at the innermost circumference of the optical disc,
The output may change from the optimal output due to a change in the area to which the optical disk is written or an apparent change in the laser output due to a change in temperature over time. Therefore, when recording information, a laser power optimization method called running OPC is generally performed. For example, JP-A-9-
The technique disclosed in Japanese Patent No. 270128 discloses a running OP.
At the timing of emitting light at a high output to form a pit, the reflected light from the optical disk being written is sampled, and this output signal is monitored, and the output signal is monitored. As compared with the similar monitor signal, the laser output is always optimized so as to have the same signal level.

[0003]

However, when the writing and reading speeds to and from the recording medium are increased and the laser output at the time of recording is increased, or the types of recording media are widely spread, There is a problem that the range of the signal level corresponding to the reflected light from the optical disk to be monitored is widened, and the detection sensitivity of the monitor signal is naturally deteriorated. Further, in order to increase the detection sensitivity of the monitor signal, it is necessary to use an analog-to-digital converter for detecting the signal with high accuracy, but there is a problem that it becomes expensive. Further, JP-A-9-270
As described in JP-A-128, when a detection system is configured by an electric circuit, a dynamic range of a signal to be detected is narrowed due to an electric offset, or a signal is out of a dynamic range when an offset amount is too large. And the signal cannot be detected satisfactorily. The present invention has been made in view of the above-described problems, and has a high precision analog-
It is an object of the present invention to provide a recording light amount control device that realizes highly accurate running OPC by accurately detecting a reflected light amount monitor signal level without using a digital converter.

[0004]

According to a first aspect of the present invention, there is provided a recording light amount control device according to the present invention, wherein when recording information, a light source is set to a first light amount level value and the first light amount level value. A light source light emitting means for emitting light at a second light amount level value greater than one light amount level value, and a light emitted from the light source before irradiating the recording medium with information before recording information on the recording medium, and a signal of a reflected light thereof A pre-information recording reflected light signal level value detecting means for detecting a level value; and a reference level value recording and holding means for recording and holding the signal level value detected by the pre-information recording reflected light signal level value detecting means as a reference level value. Information recording start reflected light signal level value detecting means for detecting the signal level value of the reflected light from the recording medium with respect to the light emitted from the light source after the start of information recording on the recording medium, Comparing means for comparing the signal level value detected by the reflected light signal level value detecting means after the start of information recording with the reference level value recorded and held in the reference level value recording and holding means, based on the comparison result by the comparing means Drive current adjusting means for adjusting a drive current for causing the light source to emit light, and the reflected light signal level value detecting means before the information recording and the reflected light signal level value detecting means after the information recording is started. There are provided signal gain switching means for changing the signal gain of the signal level value in at least two stages, and gain selection means for selecting the gain of the signal gain switching means based on a selection command. In the invention according to claim 2 of the recording light amount control device according to the present invention, the light source is set to a first light amount level value, a second light amount level value larger than the first light amount level value, and a second light amount level value larger than the second light amount level value. Light source light emitting means for emitting light based on the three light quantity level values, and information for irradiating the recording medium with light emitted from the light source before recording information on the recording medium, and detecting a signal level value of the reflected light. Reflected light signal level detection means before recording; reference level value recording and holding means for recording and holding the signal level value detected by the reflected light signal level before information recording as a reference level value; Means for detecting a signal level value of reflected light from the recording medium with respect to light emitted from the light source after the start of information recording; and a means for detecting a reflected light signal level value after the start of information recording. Comparing means for comparing the signal level value detected by the optical signal level value detecting means with the reference level value recorded and held by the reference level value recording and holding means; and illuminating the light source based on the comparison result by the comparing means. A drive current adjusting means for adjusting a drive current to be applied, wherein the reflected light signal level value detecting means before the information recording and the reflected light signal level value detecting means after the information recording start detect both reflected light signal level values. A signal gain switching means whose gain can be changed in at least two stages; and a gain selection means for selecting a gain of the signal gain switching means based on a selection command. The drive current of the light source is set so that the light source emits light at the second reference level value based on the comparison result of the comparing means when the light source emits light at the light amount level value. While settling, the second
Means for adjusting a drive current for causing the light source to emit light based on the third light amount level value based on an efficiency value obtained based on a relationship between a value corresponding to the light amount level value and a value corresponding to the drive current. Was provided.

[0005] Claim 3 of the recording light amount control device according to the present invention.
According to the present invention, in the recording light amount control device according to any one of claims 1 and 2, the gain switching command is made in accordance with the detected reflected light signal level value when the reflected light signal level value before information recording is detected. Switched the gain. According to a fourth aspect of the present invention, in the recording light amount control device according to any one of the first and second aspects, the gain switching command is determined based on a digital modulation speed of the light source. did. According to a fifth aspect of the present invention, in the recording light amount control device according to any one of the first and second aspects, the gain switching command is determined based on a type of the recording medium. . According to a sixth aspect of the present invention, in the recording light amount control device according to any one of the first and second aspects, the gain switching command is transmitted to the second light amount for recording information. Determined based on the size of the level. According to a seventh aspect of the present invention, in the recording light amount control device according to any one of the first and second aspects, the gain switching command is transmitted to the second light amount for recording information. The level detection method was determined based on whether peak detection using a sample-and-hold method or average value detection using a low-pass filter.

[0008] A recording light amount control device according to the present invention.
According to the invention described above, when recording information, a light source light emitting means for causing a light source to emit light at a first light amount level value and a second light amount level value larger than the first light amount level value, and information recording on a recording medium A light emitted from the light source before irradiating the recording medium and detecting a signal level value of the reflected light before the information recording; and a reflected light signal level value before the information recording. Means for recording and holding the signal level value detected as a reference level value, and a signal level of reflected light from the recording medium with respect to light emitted from the light source after information recording on the recording medium is started. A reflected light signal level value detecting means for detecting a value after the start of information recording, a signal level value detected by the reflected light signal level value detecting means after the information recording is started, and the reference level value The information recording apparatus comprising: a comparison unit that compares a reference level value recorded and held in a record holding unit; and a drive current adjustment unit that adjusts a drive current that causes the light source to emit light based on a comparison result by the comparison unit. An offset for giving an arbitrary signal amount offset to both reflected light signal level values when the light source is not emitting light by the pre-reflected light signal level value detecting means and the reflected light signal level value detecting means after the start of information recording. It has an injection means. According to the ninth aspect of the recording light amount control device according to the present invention, the light source is set to the first light source.
Light emitting means for emitting light based on a light amount level value, a second light amount level value larger than the first light amount level value, and a third light amount level value larger than the second light amount level value, and information on a recording medium. Irradiating the recording medium with light emitted from the light source before recording, and a reflected light signal level value detection unit before information recording for detecting a signal level value of the reflected light;
Reference level value recording and holding means for recording and holding the signal level value detected by the reflected light signal level value detection means before information recording as a reference level value; and light emitted from the light source after the start of information recording on the recording medium. Information recording start reflected light signal level value detecting means for detecting a signal level value of reflected light from the recording medium with respect to the signal level, the signal level value detected by the reflected light signal level value detecting means after the information recording start, and the reference A comparing means for comparing a reference level value recorded and held in a level value recording and holding means, and a driving current adjusting means for adjusting a driving current for causing the light source to emit light based on a comparison result by the comparing means; The drive current adjusting means emits light at the second reference level value based on the comparison result of the comparing means when the light source emits light at the second light quantity level value. The drive current of the light source is adjusted as described above, and the light source is adjusted to the third light source based on an efficiency value obtained based on a relationship between a value corresponding to the second light amount level value and a value corresponding to the drive current. A means for adjusting a drive current when emitting light based on a light amount level value is provided, and the light source emits light by the reflected light signal level value detecting means before information recording and the reflected light signal level value detecting means after information recording start. And an offset injection means for giving an offset of an arbitrary signal amount to both reflected light signal level values when they are not.

[0007] A recording light amount control device according to the present invention.
10. The recording light amount control device according to claim 8, wherein the offset removal by the offset injection means is performed by the comparison means by a predetermined reference level and a reflected light signal level when the light source is in a non-light emitting state. By determining the amount of offset injection from the offset injecting means so that both have the same value compared with the non-light emitting detection level output from the value detecting means, there is no offset based on the electric circuit system in the non-light emitting state. Was adjusted as follows. According to an eleventh aspect of the recording light amount control device according to the present invention, in the recording light amount control device of the tenth aspect, the offset removal uses a sample-and-hold method as a method of detecting a reflected light signal level value detection system. The operation is performed in both the state of the peak detecting means and the state of the average value detecting means using the low-pass filter, the respective offset injection amounts are held, and the offset amount corresponding to the detection method is set. According to a twelfth aspect of the recording light amount control device according to the present invention, in the recording light amount control device according to the tenth or eleventh aspect, the offset removal is performed by changing a signal amplification factor of an electric circuit of a reflected light signal level value detection system. Perform with the maximum. According to a thirteenth aspect of the recording light quantity control device according to the present invention, in the recording light quantity control device according to any one of the tenth, eleventh, and twelfth aspects, the power source of the light quantity control device is turned on for removing the offset. Thereafter, the information is stored and executed only once before the information is recorded, and the offset amount is set according to the detection means. According to a fourteenth aspect of the present invention, in the recording light amount control device according to any one of the eighth to thirteenth aspects, the information recording is performed after detecting the reflected light signal level value before the information recording. According to the pre-reflected light signal level value, an offset amount that does not saturate the reflected light signal level is injected into the same phase as the reflected light signal level by the offset injection means, so that the apparent value of the reflected light signal level detection system is obtained. The dynamic range above was increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a block diagram showing a configuration of a recording light amount control device according to the present invention.
Is an optical disk, 2 is an objective lens, 3 is a pickup, 4
Is a semiconductor laser, 5 is a half mirror, 6 is a photodetector, 7 is an RF amplifier, 8 is a low-pass filter (LPF),
9 is a sample / hold circuit (S / H circuit), 10 is a sample pulse generation circuit, 11 is a signal switching circuit (selector), 12 is a gain switch, 13 is a CPU, 14
Denotes a RAM, 15 denotes a ROM, 16 denotes a laser control circuit, and 17 denotes an optical disk encoder. In each of the claims, the light source light emitting means means the semiconductor laser 4, and the reflected light signal level value detecting means before information recording and the reflected light signal level value detecting means after information recording are the RF amplifier 7, the low-pass filter 8, It comprises a hold circuit 9, a sample pulse generation circuit 10, a signal switching circuit 11, and a gain switching device 12. Further, the reference level value record holding means is R
AM14, the comparison means means the CPU 13, and the drive current adjustment means means a laser control circuit. Further, the signal gain switching means means the gain switching device 12, and the gain selection means means the CPU 13. In the recording light amount control device thus configured, a laser beam is emitted from the semiconductor laser 4 in the pickup 3 onto the recording film of the optical disc 1 with an output corresponding to the drive current, and the laser beam is collected through the objective lens 2. The light is emitted to record, reproduce and erase information. The reflected light from the optical disk 1 is reflected by the half mirror 5, irradiates the photodetector 6, and detected. Such a pickup has a known configuration, and the pickup 3 is provided with another optical detector called a front photodetector for detecting the power from the optical disk. The illustration is omitted because it is not directly related to the configuration.

When recording information on an optical disk, a CPU
The optical disk encoder 17 generates a recording pulse corresponding to a predetermined recording speed in accordance with a command from 13, and the laser control circuit 16 supplies a current set to a predetermined light emission output to the semiconductor laser 4. The RF amplifier 7 amplifies the reflected light signal photoelectrically converted by the optical detector 6, and the output is supplied to a low-pass filter 8 and a sample and hold circuit 9. The sample-and-hold circuit 9 receives the ROPCsamp supplied from the sampling pulse generation circuit 10.
The reflected light signal is sampled by le and the level is held. When the recording medium is a CD-R, the sampling pulse ROPCsample has a recording power level P as shown in FIG.
2 to be generated. Also, when using three values of P3, P2, and P1 as the laser beam output, the sampling pulse ROPCsample is generated at a timing corresponding to the P2 level as shown in FIG.
On the other hand, the low pass filter 8 detects a low pass component of the monitor signal, that is, an average value. In the example of the light emission waveform (Power) shown in FIGS. 2 and 4, the average output is near the Pave level, so that the output of the low-pass filter means 8 corresponds to this level.
The Pave level is such that the average duty of the mark and the space (erase mark) is constant, and the laser beam output P
3, Even when the timings at which P2 and P1 occur, that is, the modulation timings, are known, they cannot be unconditionally determined. This is because the reflected light during recording changes greatly as shown in the reflected light output in FIGS. 2 and 4, and the behavior of this change indicates the difference in the recorded light emission output and the difference in the media (for example, This is because there is a large difference between the cyanine-based recording film and the phthalocyanine-based recording film). In the selector 11, the selection command HS (select High S
peed), the output of the sample and hold circuit 9 or the output of the low-pass filter means 8 is selected. When the recording speed on the disc is low, the output of the sample and hold means 9 is selected by setting HS = 0, and when the recording speed on the disc is high, HS = 0.
= 1 and the output of the low-pass filter means 8 is selected. That is, at high speed, the average value means of the reflected light signal is used without using the sample and hold means 9.

[0010] Generally, the running OPC is a method in which a monitor signal at the time of normal OPC performed before information recording is stored in the RAM 14.
And the recorded monitor signal level and the monitor signal level detected during the running OPC are stored in the CPU.
13 to calculate an optimum laser beam output at any time based on a predetermined calculation program stored in the ROM 15 so that the two become equal.
Set. Here, a case is considered where the output to be recorded is set in a wide range from a low output to a high output in the laser control circuit 16. At this time, the reflected light signal level when recording with low output is small, and the reflected light level when recording with high output is large. In such a case, in order to detect a signal level with a wide dynamic range,
The detection sensitivity cannot be increased. That is, high-precision running OPC cannot be performed. Therefore, in the gain switch 12, when the signal level of the reflected light amount is sufficiently smaller than the detection level, the detection sensitivity can be increased by increasing the gain by the Gain Selector signal and increasing the signal level. Also, consider the case where the recording medium changes. In a write-once optical disc such as a CD-R, an optical disk using a dye called a cyanine-based optical disk and an optical disk using a dye called a phthalocyanine-based optical disk generally need to write the same information as pits. It is well known that different laser outputs and required pulse widths are different. That is, when writing on an optical disk using a dye called a cyanine-based dye, it is necessary to increase the laser output, and accordingly, the signal level of the reflected light output from the optical disk increases. Therefore, similarly to the above, it is necessary to detect a signal level having a wide dynamic range, and the detection sensitivity cannot be increased. That is, high-precision running OPC cannot be performed. Therefore, the detection sensitivity can be increased by setting the gain by the gain switch 12 so that the optimum dynamic range is obtained depending on the recording medium.

Next, the laser output P2 or P3 to be recorded
Consider the case where it fluctuates depending on the media and environment used. The factors that change the laser output P2 or P3 to be recorded vary over a wide range, such as the ambient temperature and the sensitivity of the media. Naturally, when the laser output greatly changes, the signal level of the reflected light output also changes. Then, similarly to the above, it is necessary to detect a signal level having a wide dynamic range, and the detection sensitivity cannot be increased. That is, high-precision running OPC cannot be performed. Therefore, the laser output P to be recorded
When 2 or P3 is determined, the detection sensitivity can be increased by setting the gain with the gain switch 12 so that the gain is high when the output is low and low when the output is high. Further, in this case, since the gain can be set before detecting the reflected light signal level value before information recording, the reflected light signal level value before information recording is detected again after the gain is switched. There is also a merit that it is possible to operate at high speed without having to perform the operation.
Next, the detection method when detecting the reflected light detection level value will be considered in the case where the output of the sample and hold circuit 9 is selected and the case where the output of the low-pass filter 8 which is the average value of the reflected light signal is selected. Generally, it is known in principle that the reflected light detection level value output from the sample and hold circuit 9 is larger than the level value output from the low-pass filter 8 which is the average value of the reflected light signal. Therefore, the detection means of the reflected light detection level value sets the gain by the gain switch 12 so that the gain is low when the sample and hold circuit 9 is used and the gain is high when the low pass filter 8 is output. Sensitivity can be increased. Further, in this case, since the gain can be set before detecting the reflected light signal level before information recording, the reflected light signal level before information recording is detected again after the gain is switched. There is also a merit that it is possible to operate at high speed without having to perform the operation. In the above description, the gain setting of the gain switch 12 is set according to the reflected light detection level value. However, the gain setting may be determined according to the digital modulation speed of the light source and the medium of the optical disk on which information is to be recorded. Good.

In an optical disk recording light amount control device,
The laser output to be set and controlled is a laser output P at the time of reproduction in the case of a write-once optical disc such as a general CD-R.
1. As described above, there is a laser output P2 larger than the recording P1 and a laser output P3 larger than the laser output P2. Among these, the level of the current value IP1 supplied to the semiconductor laser 4 for obtaining the laser output P1 at the time of reproduction preferably holds the laser current IP1 required when the laser emits light at the laser output P1 at the time of reproduction. Then, it is preferable to give it in the OPC before the information recording and the running OPC during the information recording.
Means for controlling the laser output during reproduction with the constant output P1 is not shown, but a known output control means may be used. For example, a monitor signal of the laser output P1 is compared with a reference level, amplified, and amplified. It is also possible to provide the semiconductor laser 4 from the laser control circuit 16 as IP1.
The level of the laser current IP1 for obtaining the laser output P1 is stored in a suitable storage means (the laser current value IP by an A / D converter).
After the value of 1 is digitized, it is held in a latch circuit, and when data of the laser current value IP1 is required, the data held in the latch circuit is returned to analog by a D / A converter. However, the details of these storage means are well-known techniques, and therefore illustration and description thereof are omitted.

Next, the case where the laser output level P3 is used will be described. The laser output P3 level is calculated by calculating the laser efficiency (current to power ratio) from the current equivalent level IP2 for generating the laser output P2 level, and calculating the IP3 from the efficiency.
Can be generated by calculating For example, the procedure of the efficiency calculation is as follows. Laser is P2
Laser current value IP required when emitting light at level
2, and the laser current value IP1 required when emitting light at the P1 level, the efficiency can be obtained as follows. Efficiency = (P2-P1) / (IP2-IP1) FIG. 3 shows the light emission outputs P1, P2 and the laser currents IP1, IP2.
This is an example of a current-output characteristic showing the relationship with the above, and the efficiency can be obtained from the above-mentioned relationship as is clear from FIG. Therefore, the laser current value IP3 required to cause the laser to emit light at the P3 level can be calculated as follows. IP3 = IP1 + (P3-P1) / Efficiency FIG. 5 shows the emission outputs P1, P2, P3 and the laser current IP1,
It is an example of the current vs. output characteristics of the laser showing the relationship between IP2 and IP3. Therefore, by estimating and calculating the laser output fluctuations of the laser currents IP2 and IP3 from the signals monitored during the actual writing, not only IP2 but also IP2 is calculated.
3. Running OPC can be performed accurately, including 3.

Next, another embodiment of the recording light amount control apparatus for an optical disk according to the present invention will be described with reference to FIG.
The difference between the embodiment shown in FIG. 6 and the embodiment shown in FIG. 1 is that an offset injection circuit (offset injection means) 18 is provided, and the output from the offset injection circuit 18 is supplied to the gain switch 12. . That is, as described above, the running OPC is performed by a normal OP performed before information recording.
The monitor signal at the time of C is stored in the RAM 14 or the like, and the recorded monitor signal level is compared with the reflected signal level detected during the running OPC by the CPU 13, and a predetermined arithmetic program stored in the ROM 15 is set so that the two become equal. Calculate the optimal laser beam output at any time based on the
Although the laser control circuit 16 is set, an offset voltage based on an electric circuit may be generated in the signal level detection system having such a configuration. Due to this electrical offset, the dynamic range of the signal to be detected may be narrowed, or if the offset is too large, the signal may exceed the dynamic range, making detection impossible. Therefore, before the reflected light signal is output as the monitor signal, for example, immediately after the power is turned on, the monitor signal is measured by the CPU 13, and the offset voltage is injected from the offset injection circuit 18 so as to become a certain known reference voltage. Thus, the signal detected by the CPU 13 can be in a state where there is no electrical offset. (Hereinafter referred to as offset removal) Also, as in the present embodiment, there are two electric circuits (LPF and S / H circuits) for detecting a reflected signal from the optical disk.
In some cases, the offset amount often differs due to the difference between the circuit configurations. Therefore, by performing the above-described offset removal in each of the detection systems, the electrical offset can be removed more accurately. When the above-described offset removal is performed, it is preferable that the gain of the gain switching 12 be maximized. That is, since the offset removal is performed near the reference voltage, there is no fear that the signal is saturated even if the gain is maximized. Further, since the sensitivity of the detection system can be maximized by maximizing the gain, more accurate offset removal can be performed. Further, after detecting the monitor signal at the time of the normal OPC performed before the information recording, the offset injection circuit 18 sets an offset amount that does not saturate the reflected light signal level according to the detected reflected light signal level value. By injecting the signal level into the same phase as the signal level, the apparent dynamic range for detecting the reflected light signal level value can be increased.

FIG. 7 shows a flow of the offset removal described above. First, the gain of the gain switching circuit 12 is maximized (step S1), and a reference voltage at that time is measured.
The measured voltage Vref is stored (held) in the RAM 14 or the like (step S2). Thereafter, the detection means of the reflected light detection level value is set to the sample and hold circuit 9 (step S5).
3) Measure the reflected light signal when there is no signal (step S)
4) Compared with Vref stored in step S2, the first offset removal amount (ROPC_O
FS_1) is stored in the RAM 14 or the like (step S5).
After that, the detecting means of the reflected light detection level value is switched to the low-pass filter 8 which becomes the average value of the reflected light (step S6),
The reflected light signal at the time of no signal is measured (Step S7), and compared with the Vref stored in Step S2, the second offset removal amount (ROPC_OFS_2) of the running OPC is stored in the RAM 14 or the like (Step S8). Since the offset amount held by such a flow is set according to the detection system of the reflected signal, the offset can be accurately removed for each detection system.

[0016]

As described above, according to the first aspect of the present invention,
In the described recording light amount control device, when recording information,
An optical disc on which information to be digitally modulated is recorded using at least two light levels, a predetermined first light level P1 and a second light level P2 larger than the first light level at which pits can be formed. Running OPC
In, since the gain selection can be switched so that the detection sensitivity is maximized at the signal level of the monitor signal,
High-precision running OPC becomes possible. The recording light amount control device according to claim 2, wherein the information is digitally modulated by at least three light amount levels: a first light amount level P1, a second light amount level P2 larger than P1, and a third light amount level P3 larger than P2. In the running OPC of the optical disc for recording the signal, the gain selection can be switched so that the detection sensitivity of the signal level of the monitor signal is maximized, so that the running OPC with high accuracy can be performed. In the recording light amount control device according to the third aspect, when the reflected light signal level value before information recording is detected, the gain is switched according to the detected reflected light signal level value. Running OPC is possible. In the recording light amount control device according to the fourth aspect, since the gain switching command is determined based on the digital modulation speed of the light source, high-precision running OPC is possible regardless of the recording speed. Since the gain switching can be set before detecting the reflected light signal level value before information recording, high-speed processing can be performed. 6. The recording light amount control device according to claim 5, wherein the gain switching command is determined based on the type of the recording medium.
C becomes possible, and gain switching can be set before detecting the reflected light signal level value before information recording, so that high-speed processing can be performed. In the recording light amount control device according to the sixth aspect, since the gain switching command is determined based on the magnitude of the second light amount level, it is possible to perform high-precision and high-speed running OPC. In the recording light amount control device according to claim 7, since the gain switching command is determined based on the reflected light level value detection method, high-precision and high-speed processing is performed regardless of the reflected light level value detection method. OPC becomes possible.

In the recording light quantity control device according to the present invention, when recording information, at least a predetermined first light quantity level P1 and a second light quantity level larger than the first light quantity level at which pits can be formed. In the running OPC of an optical disc for recording digitally modulated information using the two light amount levels of the light amount level P2, the signal level of the monitor signal can be set to a state without an electrical offset caused by an electric circuit. Accurate running OPC becomes possible. 10. The recording light quantity control device according to claim 9, wherein at least the first light quantity level P1, the second light quantity level P2 larger than P1, and the third light quantity level P larger than P2.
In the running OPC of an optical disc for recording information that is digitally modulated at the three light intensity levels, the signal level of the monitor signal can be set to a state without an electric offset caused by an electric circuit, so that high-precision running is performed. OPC becomes possible. 11. The recording light amount control device according to claim 10, wherein the offset is removed by the offset injecting means. The comparison means outputs a predetermined reference level and the reflected light signal level value output from the reflected light signal level detecting means when the light source emits no light. In comparison with the light emission detection level, the offset injection amount from the offset injection means is determined so that both have the same value, that is, since the offset based on the electric circuit system is adjusted so that there is no offset in the non-emission state, The absolute value of the reflected light level can be measured accurately, and highly accurate running OPC can be performed. Claim 1
In the recording light amount control device according to the first aspect, the offset removal may be performed both when the reflected light signal level value detection system detects the peak by the sample and hold detection means and when the average value detection means by the low-pass filter. In each state, the offset injection amount is held and the offset amount corresponding to the detection method is set, so that the offset can be removed accurately regardless of the reflected light signal level value detection means. Running OPC becomes possible.

According to a twelfth aspect of the present invention, there is provided a recording light amount control device.
Since the offset removal is performed in a state where the signal amplification factor of the electric circuit of the reflected light signal level detection system is maximized, the offset can be removed in a highly accurate state, and the offset can be removed accurately. Therefore, high-precision running OPC becomes possible. 14. The recording light amount control device according to claim 13, wherein the offset removal is performed only once after the power supply of the light amount control device is turned on and before recording information, and the offset amount is removed according to the detection unit. Therefore, every time the information is recorded, the offset can be easily and accurately removed simply by setting the offset without performing the offset removal, and high-precision running OPC can be performed. In the recording light amount control device according to claim 14, after detecting the reflected light signal level value before information recording, an offset amount that does not saturate the reflected light signal level according to the reflected light signal level value before information recording, Since the apparent dynamic range of the reflected light signal level value detection system is increased by injecting the reflected light signal level into the same phase as the reflected light signal level by the offset injection means, more accurate running OPC becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a recording light amount control device according to the present invention.

FIG. 2 is a waveform diagram showing a relationship among a recording pattern, a semiconductor laser emission output, a reflected light output, and an ROPCsample output.

FIG. 3 is a diagram illustrating a relationship between a light emission power and a laser drive current value.

FIG. 4 is a waveform diagram showing a relationship among a recording pattern, a semiconductor laser emission output, a reflected light output, and an ROPCsample output.

FIG. 5 is a diagram showing a relationship between a light emission power and a laser drive current value.

FIG. 6 is a block diagram showing another configuration of the recording light amount control device according to the present invention.

FIG. 7 is a diagram showing a flow of offset removal.

[Explanation of symbols]

1 optical disk, 2 objective lens, 3 pickup,
4 semiconductor laser, 5 half mirror, 6 photo detector, 7 RF amplifier, 8 low-pass filter (LPF),
9 sample and hold circuit (S / H circuit), 10 sample pulse generation circuit, 11 signal switching circuit (selector), 12 gain switch, 13 CPU, 14
RAM, 15 ROM, 16 laser control circuit, 17 optical disk encoder, 18 offset injection circuit

Claims (14)

[Claims] 1. A light source emitting means for causing a light source to emit light at a first light amount level value and a second light amount level value larger than the first light amount level value when information is recorded, and information recording on a recording medium. A light emitted from the light source before irradiating the recording medium and detecting a signal level value of the reflected light before the information recording; and a reflected light signal level value before the information recording. Means for recording and holding the signal level value detected as a reference level value, and a signal level of reflected light from the recording medium with respect to light emitted from the light source after information recording on the recording medium is started. A reflected light signal level value detecting means for detecting a value after the information recording is started, a signal level value detected by the reflected light signal level value detecting means after the information recording is started, and the reference level value recording. The information recording apparatus comprising: a comparing unit that compares the reference level value recorded and held in the holding unit; and a driving current adjusting unit that adjusts a driving current that causes the light source to emit light based on a comparison result by the comparing unit. Signal gain switching means for changing the signal gain of the reflected light signal level value of both the pre-reflected light signal level value detecting means and the reflected light signal level value detecting means after the start of information recording in at least two stages; A recording light amount control device for an optical disk, comprising: gain selection means for selecting a gain of a switching means based on a selection command. 2. A light source for causing a light source to emit light based on a first light quantity level value, a second light quantity level value larger than the first light quantity level value, and a third light quantity level value larger than the second light quantity level value. Light emitting means, and irradiating the recording medium with light emitted from the light source before recording information on the recording medium,
A reflected light signal level value detecting means for detecting the signal level value of the reflected light, and a reference level for recording and holding the signal level value detected by the reflected light signal level value detecting means before the information recording as a reference level value Value record holding means, and information recording start reflected light signal level value detection means for detecting a signal level value of reflected light from the recording medium with respect to light emitted from the light source after information recording on the recording medium is started, Comparing means for comparing the signal level value detected by the reflected light signal level value detecting means after the start of the information recording with the reference level value recorded and held in the reference level value recording and holding means; A drive current adjusting means for adjusting a drive current for causing the light source to emit light, based on the information signal. A signal gain switching means for changing the signal gains of both reflected light signal level values of the reflected light signal level value detection means at least in two stages, and a gain of the signal gain switching means is selected based on a selection command. Gain selection means, wherein the drive current adjustment means emits light at the second reference level value based on a comparison result of the comparison means when the light source emits light at the second light quantity level value. While adjusting the drive current of the light source, the light source is set to the third light level based on an efficiency value obtained based on a relationship between the value corresponding to the second light level and the value corresponding to the drive current. A recording light amount control device for an optical disk, comprising: means for adjusting a drive current for causing light emission based on the control signal. 3. The recording light amount control device according to claim 1, wherein the gain switching instruction is performed in accordance with a detected reflected light signal level value when the reflected light signal level value before information recording is detected. A recording light amount control device for an optical disk, characterized in that the gain is switched by a switch. 4. The recording light amount control device according to claim 1, wherein the gain switching command is determined based on a digital modulation speed of the light source. Light intensity control device. 5. The recording light amount of an optical disk according to claim 1, wherein the gain switching command is determined based on a type of the recording medium. Control device. 6. The recording light amount control device according to claim 1, wherein the gain switching command is determined based on the magnitude of the second light amount level at which information is to be recorded. A recording light amount control device for an optical disk, characterized by comprising: 7. The recording light amount control device according to claim 1, wherein the gain switching command is used, and the second light amount level detecting method for recording information uses a sample-and-hold method. A recording light amount control device for an optical disc, characterized in that it is determined based on whether a peak is detected or an average value is detected using a low-pass filter. 8. A light source emitting means for causing a light source to emit light at a first light amount level value and a second light amount level value larger than the first light amount level value when recording information, and recording information on a recording medium. A light emitted from the light source before irradiating the recording medium and detecting a signal level value of the reflected light before the information recording; and a reflected light signal level value before the information recording. Means for recording and holding the signal level value detected as a reference level value, and a signal level of reflected light from the recording medium with respect to light emitted from the light source after information recording on the recording medium is started. A reflected light signal level value detecting means for detecting a value after the information recording is started, a signal level value detected by the reflected light signal level value detecting means after the information recording is started, and the reference level value recording. A comparison unit that compares the reference level value recorded and held in the holding unit; and a drive current adjustment unit that adjusts a drive current that causes the light source to emit light based on a result of the comparison by the comparison unit. Offset injection for giving an arbitrary signal amount offset to both reflected light signal level values when the light source is not emitting light by the reflected light signal level value detecting means and the reflected light signal level value detecting means after the start of information recording. A recording light amount control device for an optical disk, characterized by comprising means. 9. A light source for emitting light based on a first light amount level value, a second light amount level value larger than the first light amount level value, and a third light amount level value larger than the second light amount level value. Light emitting means, and irradiating the recording medium with light emitted from the light source before recording information on the recording medium,
A reflected light signal level value detecting means for detecting the signal level value of the reflected light, and a reference level for recording and holding the signal level value detected by the reflected light signal level value detecting means before the information recording as a reference level value Value record holding means, and information recording start reflected light signal level value detection means for detecting a signal level value of reflected light from the recording medium with respect to light emitted from the light source after information recording on the recording medium is started, Comparing means for comparing the signal level value detected by the reflected light signal level value detecting means after the start of the information recording with the reference level value recorded and held in the reference level value recording and holding means; And a drive current adjusting means for adjusting a drive current for causing the light source to emit light based on the second light amount level value. A drive current of the light source is adjusted so as to emit light at the second reference level value based on a comparison result of the comparison means when the light is emitted, and a value corresponding to the second light amount level value and the drive current are adjusted. Means for adjusting a drive current for causing the light source to emit light based on the third light amount level value based on an efficiency value obtained based on a relationship with the corresponding value, wherein the reflected light signal level value before information recording is provided. The detecting means and the reflected light signal level value detecting means after the start of information recording, wherein the reflected light signal level value when the light source is not emitting light has an offset injection means for giving an offset of an arbitrary signal amount to both reflected light signal level values. Characteristic optical disk recording light amount control device. 10. The recording light amount control device according to claim 8, wherein the offset removal by the offset injection unit is performed by the comparison unit by using a predetermined reference level and a reflected light signal level value when the light source emits no light. In comparison with the non-light emission detection level output from the detection means, the offset injection amount from the offset injection means is determined so that both have the same value, so that there is no offset based on the electric circuit system in the no light emission state. A recording light amount control device for an optical disk, characterized in that the device is adjusted to: 11. The recording light amount control device according to claim 10, wherein the offset removal is performed by using a low-pass filter when a reflected light signal level value detection system detects a peak using a sample and hold method. A recording light amount control device for an optical disk, wherein the control is performed in both states at the time of the average value detecting means, each offset injection amount is held, and an offset amount corresponding to a detection method is set. 12. The recording light amount control device according to claim 10, wherein the offset removal is performed in a state in which a signal amplification factor of an electric circuit of a reflected light signal level detection system is maximized. An optical disk recording light amount control device. 13. The recording light amount control device according to claim 10, wherein the offset removal is performed only once after the light amount control device is turned on and before information is recorded. A recording light amount control device for an optical disk, wherein an offset amount is set in accordance with a detection means. 14. The recording light amount control device according to claim 8, wherein after detecting the reflected light signal level value before information recording, the reflected light is changed according to the reflected light signal level value before information recording. The apparent dynamic range of the reflected light signal level value detection system is increased by injecting an offset amount that does not saturate the signal level into the same phase as the reflected light signal level by the offset injection means. An optical disk recording light amount control device.