JP2005203030A - Optical disk device - Google Patents

Abstract

When monitoring a high recording power and a low reproduction power with one monitor light receiving element 21, the output voltage for the low reproduction power is very small, and a control error becomes large due to an offset, a temperature drift, or the like. Provided is an optical disc device for solving the problem.
In an optical disc apparatus that causes a laser light source to emit light at a first light amount level and a second light amount level that is greater than the first light amount level, the laser light source corresponds to each of the first light amount level and the second light amount level. Provided is at least two current-voltage conversion means 22 and 42 for converting the output signal current of the light-receiving element for monitoring into a voltage.
[Selection] Figure 9

Description

  The present invention relates to an optical disc apparatus that records and reproduces information with respect to an optical disc using a laser beam.

In recent years, in the optical disk apparatus, the recording power has been increased with an increase in recording speed, the difference between the recording power and the reproduction power has been increased, and the emission power control range of the semiconductor laser has been widened. It is difficult to control both of them accurately.
Therefore, in the optical disc apparatus described in Patent Document 1, the gain of the semiconductor laser drive system is changed according to the recording speed, and thereby, the high recording power and the low recording power are controlled with high accuracy in the semiconductor laser drive system.

JP 2002-230771

  In the optical disk device described in Patent Document 1, the gain of the semiconductor laser drive system is changed according to the recording speed, and thereby the high recording power and the low recording power are controlled with high accuracy in the semiconductor laser drive system. When monitoring high recording power and low reproduction power with a single monitor light receiving element, the output voltage for the low reproduction power becomes very small, and control errors may occur due to offset, temperature drift, etc. It gets bigger.

For example, if the reproduction power is 0.7mW with respect to the recording power of 80mW, the output range is possible if the 0-5V power amplifier is used for the current / voltage converter that converts the output current of the light receiving element for monitoring into voltage. Is approximately 1 to 4 V, and the reference voltage corresponding to the reproduction power is 2.5 V, the dynamic range is 1.5 V. If the output voltage of the current / voltage converter is 1.5 V at a recording power of 80 mW, the output voltage of the current / voltage converter is about 13 mV at a reproduction power of 0.7 mW. At this time, if 1 mV of temperature drift occurs, the reproduction power will be shifted by about 8% due to temperature drift.
An object of the present invention is to provide an optical disc apparatus capable of reducing a control error of laser light source emission power.

  In order to achieve the above object, the invention according to claim 1 is directed to a laser light source for irradiating a laser beam for recording / reproducing data on / from an optical disc, and a light receiving element for monitoring for monitoring the light output of the laser light source. And a control means for controlling an output light amount of the laser light source using an output signal of the monitor light receiving element, and the laser light source has a second light amount level higher than the first light amount level and the second light amount level. In an optical disc apparatus that emits light at a light amount level, at least two current voltages that are provided corresponding to each of the first light amount level and the second light amount level and that convert an output signal current of the light receiving element for monitoring into a voltage. A conversion means is provided.

  According to a second aspect of the present invention, there is provided a laser light source for irradiating a laser beam for recording and reproducing data on an optical disc, a monitor light receiving element for monitoring the light output of the laser light source, and the monitor light receiving element Control means for controlling the output light amount of the laser light source using the output signal of the first light amount level, which is the light amount level of the light source laser during reproduction for reproducing data from the optical disc, and the optical disc In an optical disc apparatus that records and reproduces data to and from the optical disc by using a light amount between a second light amount level that is a light amount level of the light source laser at the time of recording for recording data and that is larger than the first light amount level. , Provided corresponding to each of the first light quantity level and the second light quantity level, and output signal power of the monitor light receiving element. The those having at least two current-voltage conversion means for converting into a voltage.

  According to a third aspect of the present invention, in the optical disc apparatus according to the first or second aspect, the optical disk apparatus has a plurality of laser light sources having different wavelengths, and the at least two current-voltage conversion means are provided for each of the laser light sources.

  According to a fourth aspect of the present invention, in the optical disc apparatus according to the first, second, or third aspect, each of the current-voltage conversion units includes a gain adjustment unit that performs gain adjustment independently.

  According to a fifth aspect of the present invention, in the optical disk device according to the first, second, or third aspect, a relational expression of an output voltage with respect to the light amount level of each of the at least two current-voltage conversion means is stored in a nonvolatile memory element. Is.

  According to the present invention, the control error of the laser light source emission power can be reduced.

FIG. 1 shows a schematic configuration of an optical disc apparatus according to Embodiment 1 of the present invention.
The optical disk 1 is rotationally driven by a spindle motor 2, and the spindle motor 2 is controlled by a motor driver 3 and servo means 4 so that the optical disk 1 rotates at a constant linear velocity (CLV) or a constant rotational speed (CAV).

  The optical pickup device 5 includes a semiconductor laser (hereinafter referred to as LD) as a laser light source, an optical system, a focusing actuator, a tracking actuator, a light receiver, a position sensor, and the like, and laser light from the LD is passed through the optical system to the optical disk 1. Focus on the recording surface. The optical pickup device 5 is provided so as to be movable in a sledge (in the radial direction of the optical disc 1) by a seek motor (not shown). These focusing actuators, tracking actuators, and seek motors are mounted on the optical disk 1 by a motor driver 3 and servo means 4 based on signals from a light receiver or position sensor that receives reflected light from the recording surface of the optical disk 1 through an optical system. The laser beam spot is controlled to be positioned at a target location on the optical disc 1.

  At the time of data reproduction, the reproduction signal obtained by the optical pickup device 5 is amplified by the read amplifier 6 and subjected to equalizer processing and binarization processing, and then EFM demodulated by the CD decoder 7. The EFM signal is data obtained by modulating 8-bit data into 14-bit data so that it can be easily reproduced or recorded optically. The EFM demodulated data undergoes deinterleaving (reordering processing) and error correction processing. Is called. The data from the CD decoder 7 is subjected to an error correction process for improving the reliability of the data by the CD-ROM decoder 8.

  The data from the CD-ROM decoder 8 is temporarily stored in the buffer RAM 10 by the buffer manager 9 and transferred to the host via the interface 11 when it is prepared as sector data. When the data is music data, the data from the CD decoder 7 is converted into an analog audio signal by the D / A converter 12 and extracted.

  On the other hand, at the time of data recording, data sent from the host is received by the interface 11, and the data is temporarily stored in the buffer RAM 10 by the buffer manager 9. Data recording is started when a certain amount of data is accumulated in the buffer RAM 10, but before that, the laser beam spot is positioned at the writing start point of the optical disc 1. The writing start point is obtained by an ATIP (Absolute Time In Pre-groove) signal which is a wobble signal that is preliminarily carved by meandering tracks (pre-grooves) on the optical disk 1. The ATIP signal is time information indicating an absolute address on the optical disc 1, and is extracted from the data from the read amplifier 6 by the ATIP decoder 13, and an ATIP signal error is detected and an ATIP signal detection error rate is measured.

  Further, the synchronization signal generated from the data from the read amplifier 6 by the ATIP decoder 13 is input to the CD encoder 14 so that the data can be written at an accurate position. When data recording is performed, data is read from the buffer RAM 10, and after the error correction code is added and interleaved (rearranged) by the CD-ROM encoder 15 and the CD encoder 14, the data is EFM-modulated, and the laser control circuit. 16, recording is performed on the optical disc 1 via the optical pickup device 5.

  This optical disk apparatus includes a microcomputer 20 including a CPU 17, a ROM 18, and a RAM 19 for controlling the operation of each unit described above.

Here, before explaining the LD light emission power control method of the first embodiment, a general conventional LD light emission power control method will be explained.
Data recording in an optical disc apparatus is performed by irradiating a recording film on an optical disc, such as a CD-R (Compact Disc Recordable), with a strong laser beam as a light beam from the LD in the optical pickup device, and by the thermal reaction, the optical disc This is done by making holes (pits) in the recording film. For data recording in an optical disk device, in CD-RW (Compact Disc ReWritable), the recording film of the CD-RW is irradiated with a strong laser beam from the LD in the optical pickup device as a light beam to change the crystal state of the recording film. Is done by.

  On the other hand, the data written on the optical disk can read the amount of reflected light obtained by irradiating the recording film of the optical disk with a weak laser beam emitted from the LD as a light beam. By the way, as described above, data recording on the optical disk is performed by opening a pit on the optical disk with a light beam from the LD. At this time, the laser light emission power (the laser light emitted from the LD by the CD-R drive device) 2) is as shown in FIG. In FIG. 2, a first power P1 and a second power P2 higher than the first power P1 are repeatedly emitted from the LD. This P2 is the recording power, and the pit is where the P2 level laser beam is irradiated on the optical disk. Further, P1 is the reproduction power, and the place where the laser beam of the P1 level is irradiated on the optical disk becomes a space as it is.

In the CD-R, a recording power waveform may be generated with three values P1, P2, and P3 by providing a P3 level of P3> P2, and the pit edge is sharpened by positioning the P3 level at the head of the pit. ing. In addition, in a phase change type rewritable optical disc such as CD-RW, the LD emission power is also provided with three values. By repeating P3 and P1 at high speed, the recording film is made amorphous (non-crystalline), and P2 is The recording film is crystallized by sustaining it, and this corresponds to the information data. Prior to time t _{write started} in FIG. 2 is a light emission waveform of the LD in a case where after the emission waveform, time t _{write start} LD at the time of reproducing data from the optical disk to record data on the optical disk. As described above, at the time of reproduction (reading) for reproducing data on the optical disc, the LD emits light with low power and DC emission, and generally P1 is about 1 mW. On the other hand, the power of the laser beam emitted by the LD during recording (writing) is high, and P2 is generally several mW to several tens mW. At the time of recording, pits can be formed on the optical disc by repeating the light emission of P1 and P2.

  By the way, in recent years, in the optical disc apparatus, both the reproduction speed and the recording speed tend to increase. Some playback speeds are 52x, and some recording speeds are 52x. For example, when data is recorded on a CD-R at 52 times speed, the recording power may be about 80 times the reproducing power. In addition, since the emission power of LD changes due to its own temperature rise due to its own oscillation (especially when the emission power is high, the temperature rise time is shortened), the optical receiver uses a monitor light-receiving element in the LD. By controlling the current that drives the LD while monitoring the optical output, the light emission power of the LD is kept constant.

  FIG. 3 shows a configuration example of a digital LD light emission power control method for controlling the light emission power of the LD to a constant light emission power in the conventional optical disk apparatus. Constant power control (hereinafter referred to as APC) for controlling the light emission power of the LD to a constant light emission power is performed by digital control. In FIG. 3, laser light incident on a photodiode (hereinafter referred to as PD) 21 as a light receiving element for monitoring from the LD in the optical pickup device is output in the form of a current proportional to the incident light amount by photoelectric conversion in the LD 21. . However, the laser light amount monitor by the PD 21 monitors a part of the laser light from the LD 38 in the optical pickup device, and most of the laser light from the LD 38 is irradiated to the recording film of the optical disk.

  The current output from the PD 21 is converted into a voltage by a current / voltage (I / V) converter 22, output as a voltage value, and amplified by an amplifier 24. In the output voltage of the I / V converter 22, V (P1) corresponds to the light level P1, and V (P2) corresponds to the light level P2. Since the output voltage of the I / V converter 22 at the time of recording is a signal in which V (P1) and V (P2) change alternately unlike at the time of reproduction, the output voltage of the amplifier 24 is a sample hold (S / H) circuit. 25 and 26 separate into V (P1) and V (P2).

  The sample signal 1 in the S / H circuit 25 is a signal that always turns on the switch 25a in the S / H circuit 25 at the time of reproduction, and at the time of recording, the period during which the P1 laser beam is emitted or shorter than that. The switch 25a in the S / H circuit 25 is turned on only during the period, and the switch 25a in the S / H circuit 25 is turned off during the period when the P2 laser beam is emitted, and the capacitor in the S / H circuit 25 is turned on. 25b is a signal for extracting only the voltage Vs (P1) corresponding to P1 and outputting it through the amplifier 25c.

  On the other hand, the sample signal 2 in the S / H circuit 26 is a signal that always turns off the switch 26a in the S / H circuit 26 during reproduction, and during recording, a period during which the laser beam is emitted at P2 or a period shorter than that. Only the switch 26a in the S / H circuit 26 is turned on. During recording, the switch 26a in the S / H circuit 26 is turned off during the period in which the laser beam is emitted at P1, and the capacitor 26b in the S / H circuit 26 is turned off. Thus, only the voltage Vs (P2) corresponding to P2 is extracted and output through the amplifier 26c.

  The Vs (P1) and Vs (P2) separated from the output voltage of the amplifier 24 by the S / H circuit 25 and the S / H circuit 26 are input to the comparator 27 and the comparator 28. The comparator 27 compares the output value Vs (P1) of the S / H circuit 25 with the reference voltage 1 (hereinafter referred to as Vref1). Similarly, the comparator 28 compares the output value Vs (P2) of the S / H circuit 26 with the reference voltage 2. (Hereinafter referred to as Vref2). The comparators 27 and 28 output signals indicating only whether the input signal is larger or smaller than Vref1 and Vref2, that is, binary values (digital values), and these values are read by the CPU 29.

  Data is sent from the CPU 29 to the D / A converters 30 and 31 that convert the digital values into analog values, and the D / A converters 30 and 31 output a voltage proportional to the data input from the CPU 29. The V / I converter 32 converts the output voltage of the D / A converter 30 into a current, and outputs a current proportional to the output voltage of the D / A converter 30. Similarly, data is also sent from the CPU 29 to the D / A converter 31, and the V / I converter 33 converts the output voltage of the D / A converter 31 into a current, which is proportional to the output voltage of the D / A converter 31. Output current.

  The output currents of the V / I converters 32 and 33 are amplified by the current amplifiers 34 and 35, respectively. At the time of reproduction, the LDON signal is turned on and the switch 36 is turned on, whereby the output current of the current amplifier 34 is changed to the switch 36, The current flows through the current adder 37 to the LD 38 in the optical pickup device, and the LD 38 emits light at P1. At the time of recording, when the write pulse superimposed signal is turned on and the switch 39 is turned on, the output current of the current amplifier 35 is added to the output current of the current amplifier 34 by the current adder 37 and flows to the LD 38. LD38 emits light at P2.

  By the way, at the start of reproduction, the CPU 29 first outputs 0 to the D / A converters 30 and 31. As a result, the current corresponding to the recording power of the LD 38 starts from zero. Then, the CPU 29 gradually increases the data output to the D / A converter 30 until the output signal of the comparator 27 is inverted (that is, Vs (P1) becomes larger than Vref1). After that, the CPU 29 constantly changes the data output to the D / A converter 30 so that the output signal of the comparator 27 always repeats inversion (that is, Vs (P1) = Vref1). Thereby, the reproduction power emitted from the LD 38 is maintained at a constant level. This is shown in FIG.

  Similarly, FIG. 5 shows a state from the start of recording until the recording power level (light emission power of the LD 38) is kept constant. In FIG. 5, the CPU 29 sets the output voltages of the D / A converters 30 and 31 to 0 when the reproduction light emission starts. Next, when the recording light emission of the LD 38 is started, the CPU 29 increases the data output to the D / A converter 31 by one or a predetermined value. Along with this, the current proportional to the output voltage of the D / A converter 31 is superimposed on the current proportional to the output voltage of the D / A converter 30 as the current of the recording power, and the light emission power of the LD 38 increases. The output voltage of the S / H circuit 26 is also increased by one or a predetermined value. Then, when the output voltage of the S / H circuit 26 eventually exceeds Vref2, the output signal of the comparator 28 is inverted. When the output signal of the comparator 28 is inverted, the CPU 29 moves the data to be sent to the D / A converter 31 in the reverse direction.

  As a result, the current of the LD 38 decreases, and the output signal of the comparator 28 is inverted. When the output signal of the comparator 28 is inverted, the CPU 29 operates the data to the D / A converter 31 during recording, such as moving the data sent to the D / A converter 31 in the reverse direction before that, and always operates the S / S. The operation is performed so that the output voltage of the H circuit 26 and Vref2 cross each other. As a result, a constant P2 laser beam is emitted from the LD 38. Here, the APC control unit 40 is from the I / V converter 22 to the D / A converters 30 and 31, and the LD driver unit as drive current supply means is from the V / I converters 32 and 33 to the current adder 37. 41.

  With the feedback loop configured as described above, laser light having a constant power determined by Vref1 and Vref2 is output from the LD 38. The constant power control is performed by the CPU 29, the D / A converters 30, 31 and the like. This is the digital control used. However, the constant power control is not limited to such digital control, but the signals from the S / H circuits 25 and 26 are input to an error amplifier or the like and compared with Vref1 and Vref2 by the error amplifier or the like, and the S / H circuit. This can also be done by outputting to the V / I converters 32 and 33 a voltage such that the error amplifier corrects the deviation when the signals from 25 and 26 are deviated from Vref1 and Vref2. Thus, the analog operation and the digital control are the same operations in that the LD light emission power is monitored and the drive current to the LD 38 is controlled so that the levels such as P1 and P2 are compared with the reference voltage to become the reference voltage. .

  By the way, the relationship between the reference voltages Vref1 and Vref2 of the comparators 27 and 28 and P1 and P2 is adjusted by the I / V converter 22 by the volume in the manufacturing process or the like. FIG. 6 shows an example of LD driving current versus light emission power characteristics. As can be seen from FIG. 6, the light emission power and the LD drive current of the LD are linear functions above a certain threshold value (hereinafter referred to as Ith). Of course, the slope of the linear function LD light emission power vs. LD drive current characteristics varies somewhat depending on the LD, but if there is a slope in the relationship between the LD drive current and the LD light emission power, the LD drive current is set. It can be seen that the light emission power is also related to the set voltage of the / A converters 30 and 31.

  Further, since the set voltage values of the D / A converters 30 and 31 are originally determined by the reference voltages of the comparators 27 and 28, the reference voltages of the comparators 27 and 28 and the LD emission power are linear functions with a certain slope. It can be said that there is a relationship. Therefore, if this inclination is obtained in advance, the LD emission power can be obtained from the reference voltage of the comparators 27 and 28. Actually, the constant power control is facilitated by storing the slope and intercept of the linear function relationship in a memory or the like. In addition, the above slope changes with temperature depending on the characteristics of the LD, or Ith shifts. However, since the CPU 29 changes the LD drive current across the output voltages of the comparators 27 and 28, the LD emission power is kept constant. Can be controlled. Controlling the light emission power of the LD to be constant is called Auto Power Control (hereinafter referred to as APC).

  However, in recent years, in the optical disc apparatus, the recording power has been increased with the increase in recording speed, the difference between the recording power and the reproduction power has been increased, and the LD emission power control range has been widened. It is difficult to control both of them accurately. Therefore, in the prior art (described in Patent Document 1), the gain of the LD driving system is changed according to the recording speed, and thereby, the high recording power and the low reproducing power are controlled with high accuracy in the LD driving system. However, when the monitor system monitors high recording power and low reproduction power with a single light receiving element for monitoring, the output voltage for the low reproduction power becomes very small, and the control error of LD emission power due to offset, temperature drift, etc. It gets bigger.

  For example, when the reproducing power is 0.7 mW with respect to the recording power 80 mW, if an amplifier of 0 to 5 V power supply is used for the I / V converter 22, the output possible range is about 1 to 4 V, and the reference of the comparator 27 If the voltage is 2.5V, the dynamic range is 1.5V. If the output voltage of the I / V converter 22 is 1.5 V at a recording power of 80 mW, the output of the I / V converter 22 is about 13 mV at a reproduction power of 0.7 mW. At this time, if a temperature drift of 1 mV occurs, the reproduction power shifts by about 8%.

  FIG. 7 shows an LD light emission power control method in the first embodiment. In this LD light emission power control method, the I / V converter 42 is added and the amplifier 24 is omitted in the conventional LD light emission power control method. The I / V converters 22 and 42 are composed of amplifiers 22a and 41a with volumes 22b and 42b as gain adjusting means, and gains are adjusted by the volumes 22b and 42b. PD 21, I / V converters 22 and 42, V / I converters 32 and 33, current amplifiers 34 and 35, switches 37 and 39, and current adder 37 are provided in optical pickup device 5, and S / H circuit 25 26 to D / A converters 30 and 31 are provided on a main board on which a laser control circuit 16, a CPU 17 and a circuit for processing a reproduction signal are attached. The LD 38 is the LD in the optical pickup device 5, and the PD 21 receives a part of the laser light emitted from the LD 38 and outputs a current proportional to the amount of light. The I / V converters 22 and 42 convert the current output from the PD 21 into voltages, and output the voltages to the S / H circuits 25 and 26. The CPU 29 may be shared by the CPU 17.

  During reproduction, the output voltage of the I / V converter 22 is set to Vs (P1) corresponding to the reproduction power P1, and during recording, the output voltage of the I / V converter 44 is set to Vs (P2) corresponding to P2. This is as described in the conventional LD light emission power control method. In the conventional LD light emission power control method, since the high recording power and the low reproduction power are passed through the same I / V converter 22, the output voltage Vs (P1) of the I / V converter 22 is as described above when the reproduction power is low. This is a very small value of about 13 mV, making it more susceptible to drift and the like, and increasing the control error of the LD emission power. However, in the first embodiment, the I / V converter 22 can ignore the input current with respect to the high recording power and can set the input current with respect to Vs (P1) so as not to be affected by drift or the like. Can be controlled independently, and the reproduction power control error can be reduced.

  As described above, in the first embodiment, each of P1 and P2 is used in the optical disc apparatus that causes the LD 38 as the laser light source to emit light at the first light amount level P1 and the second light amount level P2 that is larger than the first light amount level P1. And I / V converters 22 and 42 as two current-voltage conversion means for converting the output signal current of the PD 21 as a monitor light receiving element into a voltage, so that both P1 and P2 have a control error. Can be reduced, and LD light emission power control can be performed with high accuracy.

  FIG. 8 shows a configuration of Embodiment 2 of the present invention. The optical disk device 50 of the second embodiment includes a spindle motor 52 for rotating the optical disk 51, an optical pickup device 53, a laser control circuit 54, an encoder 55, a motor driver 56, a reproduction signal processing circuit 57, a servo controller 58, a buffer. A RAM 59, a buffer manager 60, an interface 61, a ROM 62, a flash memory 63 as a storage means, a CPU 64, a RAM 65, and the like are provided. In addition, the arrow in FIG. 8 shows the flow of a typical signal and information, and does not represent all the connection relationships of the blocks 52 to 65.

  The optical pickup device 53 operates when a DVD is set as the optical disc 51 and emits a laser beam having a wavelength of 650 nm. When the CD is set as the optical disc 51, the optical pickup device 53 emits a laser beam having a wavelength of 780 nm. The second LD, an optical system that guides the light beam emitted from each LD to the recording surface of the optical disc 51, and guides the return light beam reflected by the recording surface to a predetermined light receiving position. The optical receiver is configured to include a light receiver that receives a return light beam from the recording surface, a drive system (a focusing actuator, a tracking actuator, and a seek motor (not shown)). Then, the light receiver outputs a current (current signal) corresponding to the amount of received light to the reproduction signal processing circuit 57.

  The reproduction signal processing circuit 57 converts a current signal, which is an output signal of the optical pickup device 53, into a voltage signal corresponding to the type of the optical disc 51, and a wobble signal, a reproduction signal, and a servo signal (focus error) based on the voltage signal. Signal, track error signal). Then, the reproduction signal processing circuit 57 extracts address information, a synchronization signal, and the like from the wobble signal. The address information extracted here is output to the CPU 64, and the synchronization signal is output to the encoder 55.

  Further, the reproduction signal processing circuit 57 performs error correction processing or the like on the reproduction signal and then stores it in the buffer RAM 59 via the buffer manager 60. The servo signal is output from the reproduction signal processing circuit 57 to the servo controller 58. The reproduction signal processing circuit 57 sets servo parameters (for example, a signal level adjustment gain) corresponding to the type of the optical disc 51 according to an instruction from the CPU 64.

  The servo controller 58 generates a control signal for controlling the optical pickup device 53 based on the servo signal and outputs it to the motor driver 51. The buffer manager 60 manages input / output of data to / from the buffer RAM 59, and notifies the CPU 64 when the amount of data stored in the buffer RAM 59 reaches a predetermined value. The motor driver 56 controls the optical pickup device 53 and the spindle motor 52 based on a control signal from the servo controller 58 and an instruction from the CPU 64.

  Based on an instruction from the CPU 64, the encoder 55 takes out the data stored in the buffer RAM 59 via the buffer manager 60, adds an error correction code, and creates write data to the optical disk 51. Then, the encoder 55 outputs write data to the laser control circuit 54 in synchronization with the synchronization signal from the reproduction signal processing circuit 57 based on an instruction from the CPU 64.

  The laser control circuit 54 controls the laser light output of the optical pickup device 53 based on the write data from the encoder 55. Note that the laser control circuit 54 controls one of the first LD and the second LD based on an instruction from the CPU 64. The interface 61 is a bidirectional communication interface with a host (for example, a personal computer) 66 and conforms to standard interfaces such as ATAPI (AT Attachment Packet Interface) and SCSI (Small Computer System Interface).

  The ROM 62 stores a program written in a code readable by the CPU 64. The flash memory 63 is a non-volatile memory that can be written to and read from the CPU 64 and retains recorded contents even when the power is turned off. The CPU 64 controls the operation of each unit according to the program stored in the ROM 62 and temporarily stores data necessary for control in the RAM 65.

  Further, the CPU 64 outputs a signal for selecting one of the above circuits when the circuit system is divided into a CD circuit system and a DVD circuit system. When the optical disk device 50 is turned on, the program stored in the ROM 62 is loaded into the main memory of the CPU 64. The CPU 29 may be shared by the CPU 64. As an example, the optical disk device 50 can access a CD-ROM, CD-R, CD-RW, DVD-ROM, DVD + RW, and DVD + R.

FIG. 9 shows an LD light emission power control method in the second embodiment. In this LD light emission power control system, an LD light emission power control unit for CD and an LD light emission power control unit for DVD are provided. The LD light emission power control unit for CD includes the LD light emission power control PD 21 in the first embodiment, I / V converters 22 and 42, S / H circuits 25 and 26, comparators 27 and 28, CPU 29, and a D / A converter. 30, 31, V / I converter 32, current amplifier 34 and 35, switches 36, 39, PD 21 _1, I / V converter ₂₂ 1 of the same monitor light-receiving element and a current adder 37, 42 ₁ , S / H circuits 25 ₁ , 26 ₁ , comparators 27 ₁ , 28 ₁ , CPU 29 ₁ , D / A converters 30 ₁ , 31 ₁ , V / I converters 32 ₁ , 33 ₁ , current amplifiers 34 ₁ , 35 ₁ , The switches 36 ₁ and 39 ₁ and the current adder 37 ₁ operate in the same manner as the LD light emission power control method in the first embodiment. The PD 21 ₁ photoelectrically converts the laser light incident from the second LD in the optical pickup device 53 and outputs a current proportional to the amount of light, and the output current of the current adder 37 ₁ is the above-mentioned in the optical pickup device 53. Supplied to the second LD.

The LD light emission power control unit for DVD includes the LD light emission power control PD 21 in the first embodiment, the I / V converters 22 and 42, the S / H circuits 25 and 26, the comparators 27 and 28, the CPU 29, and the D / A converter. 30, 31, V / I converter 32, current amplifier 34 and 35, switches 36, 39, PD 21 _2, I / V converter ₂₂ 2 as a light receiving element for the same monitor as the current adder 37, 42 ₂ , S / H circuits 25 ₂ and 26 ₂ , comparators 27 ₂ and 28 ₂ , CPU 29 ₂ , D / A converters 30 ₂ and 31 ₂ , V / I converters 32 ₂ and 33 ₂ , current amplifiers 34 ₂ and 35 ₂ , switch ₃₆ 2, 39 _2, is constituted by a current adder 37 ₂ operates similarly to LD emission power control method in the first embodiment. PD 21 ₂ is the laser light incident from the first LD in the optical pickup device 53 photoelectrically converts and outputs a current proportional to the amount, the current adder 37 and _second output currents above in the optical pickup device 53 Supplied to the first LD. I / V converter _{22 1,} 42 _1, 22 2, 42 ₂ Volume ₂₂ 1 _b of the gain adjustment unit, 42 1 _b, 22 2 b, 42 ₂ b with amplifier 22 ₁ a, 42 ₁ a, 22 ₂ a and 42 ₂ a, and the gain is adjusted by the volumes 22 ₁ b, 42 ₁ b, 22 ₂ b, and 42 ₂ b.

I / V converters 22 ₁ , 42 ₁ , 22 ₂ , and 42 ₂ are I / V converters corresponding to high recording power and low reproduction power of CD, and high recording power and low reproduction power of DVD, respectively. since the relative power can be set the I / V converters _{22 1,} 42 _1, 22 2, 42 ₂ of the output voltage to less susceptible value the influence of drift such as can reduce its control error at all power.

Thus, in the second embodiment, current I / V converter ₂₂ 1 of the voltage converting means _{42 1,} 22 2, 42 ₂ so provided for each laser light source, different laser light sources each power every wavelength Therefore, the control error can be reduced and the light emission power of the laser light source can be controlled with high accuracy.

In Embodiments 1, 2, I / V converters 22,42,22 _{1, 42 1,} 22 2, 42 ₂ volumes _22b, at 42b, ₂₂ 1 b, 42 1 _b, 22 2 b, 42 ₂ b The gain adjustment is performed independently, and the I / V converters 22, 22 ₁ and 22 ₂ output the output Vs (P1) corresponding only to the low reproduction power P1 with the volumes 22b, 22 ₁ b and 22 ₂ b. The I / V converters 42, 42 ₁ and 42 ₂ adjust the output Vs (P2) corresponding only to the high recording power P2 with the volumes 42b, 42 ₁ b and 42 ₂ b. Since the I / V converters 22, 42, 22 ₁ , 42 ₁ , 22 ₂ , and 42 ₂ set independent output values for the respective powers of P 1 and P _{2 and} are not affected by each other, the control error of each power Can be reduced.

As described above, in the first and second embodiments, the I / V converters 22, 42, 22 ₁ , 42 ₁ , 22 ₂ , and 42 ₂ as the current / voltage conversion means perform gain adjustment independently. Since it has the volumes 22b, 42b, 22 ₁ b, 42 ₁ b, 22 ₂ b, 42 ₂ b as means, the current-voltage conversion means is independent of each light emitting power (recording power and reproducing power) of the LD. The output voltage can be adjusted, the control error of each light emission power can be reduced, and the laser light source light emission power control can be performed with high accuracy.

  FIG. 10 shows an LD light emission power control method in Embodiment 3 of the present invention. In the third embodiment, the LD light emission power control method is the same as the LD light emission power control method of the first embodiment, but the EEPROM 67 is provided as a nonvolatile memory element. The EEPROM 67 corresponds to the low reproduction power P1 and the P1. A relational expression between the output Vs (P1) of the I / V converter 22 and a relational expression between the high recording power P2 and the output Vs (P2) of the I / V converter 422 corresponding to the P2 are stored in advance. In the I / V converters 22 and 42, fixed resistors 22c and 42c are used instead of the volumes 22b and 42b. The CPU 29 obtains Vref1 and Vref2 from the above two relational expressions stored in the EEPROM 67, gives them to the comparators 27 and 28, and performs the same operation as in the first embodiment. Since P1 and P2 have the above independent relational expressions, they are controlled independently without being influenced by each other, and the control error can be reduced.

As described above, in the third embodiment, the relational expression of the output voltage with respect to the respective light quantity levels P1 and P2 of the I / V converters 22 and 42 as the current-voltage conversion means is stored in the EEPROM 67 as the nonvolatile storage element. Therefore, each light emission power (recording power and reproduction power) of the LD can be controlled independently, the control error can be reduced, and the laser light source light emission power control can be performed with high accuracy.
The present invention can also be applied to an optical disc apparatus having an LD light emission power control system that performs the above-described constant power control of analog control.

It is a block diagram which shows schematic structure of Embodiment 1 of this invention. It is a figure which shows the mode of the light quantity of the laser beam radiate | emitted from LD by CD-R drive apparatus. It is a block diagram which shows the structural example of the digital LD light emission power control system in the conventional optical disk apparatus. It is a wave form diagram which shows the output voltage of the S / H circuit in the digital LD light emission power control system, and the output signal of a comparator. FIG. 6 is a waveform diagram showing a state from the start of recording until the recording power level is kept constant by the digital LD light emission power control method. It is a characteristic view which shows the example of the drive current versus light emission power characteristic of LD. It is a block diagram which shows the LD light emission power control system of the said Embodiment 1. FIG. It is a block diagram which shows schematic structure of Embodiment 2 of this invention. It is a block diagram which shows the LD light emission power control system in Embodiment 2. It is a block diagram which shows the LD light emission power control system in Embodiment 3 of this invention.

Explanation of symbols

21, 21 ₁ , PD21 ₂ PD
22, 42, 22 ₁ , 42 ₁ , 22 ₂ , 42 ₂ I / V converter 25, 26, 25 ₁ , 26 ₁ , 25 ₂ , 26 ₂ S / H circuit 27, 28, 27 ₁ , 28 ₁ , 27 ₂ , 28 ₂ Comparator 29, 29 ₁ , 29 ₂ CPU
30, 31, 30 ₁ , 31 ₁ , 30 ₂ , 31 ₂ D / A converter 32, 33, 32 ₁ , 33 ₁ , 32 ₂ , 33 ₂ V / I converters 34, 35, 34 ₁ , 35 ₁ , 34 ₂ , 35 ₂ Current amplifier 36, 39, 36 ₁ , 39 ₁ , 36 ₂ , 39 ₂ Switch 37, 37 ₁ , 37 ₂ Current adder 38, 38 ₁ , 38 ₂ LD
67 EEPROM

Claims (5)

  A laser light source for irradiating a laser beam for recording / reproducing data on an optical disk, a monitor light receiving element for monitoring the light output of the laser light source, and an output signal of the monitor light receiving element And an optical disk apparatus that emits the laser light source at a first light amount level and a second light amount level that is greater than the first light amount level. And at least two current-voltage converting means provided corresponding to each of the second light quantity level and converting the output signal current of the light-receiving element for monitoring into a voltage.   A laser light source for irradiating a laser beam for recording / reproducing data on an optical disk, a monitor light receiving element for monitoring the light output of the laser light source, and an output signal of the monitor light receiving element Control means for controlling the output light quantity of the light source, and a first light quantity level that is a light quantity level of the light source laser at the time of reproduction for reproducing data from the optical disk, and the recording at the time of recording data on the optical disk In an optical disc apparatus that records and reproduces data to and from the optical disc using a light amount between a second light amount level that is a light amount level of a light source laser and that is larger than the first light amount level, A small amount is provided corresponding to each of the second light quantity levels, and converts the output signal current of the light receiving element for monitoring into a voltage. Both the optical disk apparatus characterized by comprising two current-voltage conversion means.   3. The optical disc apparatus according to claim 1, further comprising: a plurality of laser light sources having different wavelengths, and the at least two current-voltage conversion units provided for each of the laser light sources.   4. The optical disk apparatus according to claim 1, wherein each of the current-voltage conversion means has gain adjustment means for performing gain adjustment independently. 4. The optical disc apparatus according to claim 1, wherein a relational expression of an output voltage with respect to the light amount level of each of the at least two current-voltage conversion means is stored in a nonvolatile storage element.

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