JP4587073B2 - Laser light emitting element drive control circuit, optical disk apparatus, and laser light emitting element drive control method - Google Patents

Description

  The present invention relates to recording power information, strategy information, a plurality of information to enable optimum recording at a multiple speed selected from a plurality of speeds ranging from a single speed to a high speed for a plurality of types of optical discs. Supplying a laser drive signal generated on the basis of a combination with information on an overshoot waveform associated with at least one double speed from one double speed to a high double speed for each type of optical disc, The present invention relates to a laser light emitting element drive control circuit, an optical disk apparatus, and a laser light emitting element drive control method that enable optimum double speed recording for each of a plurality of types of optical disks.

  Conventionally, when a laser light emitting element is caused to emit light by a pulse signal sequence that is a laser driving signal during recording on an optical disc, parasitic inductance and stray capacitance generated on a circuit line from the output end of the laser driving signal output circuit to the laser light emitting element. Since overshoot and ringing occur at the rise of the laser drive signal waveform due to the components, measures are taken to effectively suppress and absorb high-frequency components generated by parasitic inductance and stray capacitance components by the snubber circuit connected to this circuit line. Yes.

As an invention in which such measures are taken, for example, the one disclosed in Patent Document 1 has been reported. In the invention disclosed in Patent Document 1, a laser light emitting element is driven to emit light by a pulse train (laser drive signal) in order to perform optimum recording on a recording area at the time of recording on an optical disc. In addition, overshoot and ringing occur at the rise of this laser drive signal waveform due to the parasitic inductance of the wiring to the laser light-emitting element, and the laser light-emitting element is driven to emit light using this laser drive signal as it is to record on the optical disc. Doing so will cause recording errors because optimum recording will not be performed. To prevent this inconvenience, a snubber circuit is inserted in parallel with the laser light emitting element to suppress and absorb parasitic inductance and stray capacitance components. Like to do.
JP-A-10-308026

  However, the invention disclosed in Patent Document 1 is optimal for each of the differences in the degree of overshoot that occurs due to the difference in the type of optical disk that occurs at the rise of the laser drive signal for driving the laser light emitting element to emit light. No measures have been taken to shape the laser drive signal waveform, and a system that uses a single snubber circuit in all cases is employed regardless of these various recording forms.

  This has a problem that it is not sufficient when the overshoot waveform is individually adjusted in accordance with the situation of such various recording forms.

  That is, as in the invention disclosed in Patent Document 1, a snubber circuit that absorbs overshoot and ringing is simply inserted on a circuit line extending from the output end of the laser drive signal output circuit to the laser light emitting element. Then, a combination of multiple types of optical discs (a recordable optical disc such as a DVD-R, a repetitive recording type optical disc such as a DVD-RW and a DVD-RAM) and a multiple speed selected from a plurality of double speeds ranging from a single speed to a high speed. Therefore, there is a problem that it is not a general-purpose and optimal snubber circuit.

  The snubber circuit has a feature that can effectively suppress and reduce overshoot and ringing caused by the parasitic inductance component of the wiring according to the set time constant, but it can suppress and absorb or deliberately overshoot. The level at which the recording layer (film) is formed differs depending on the type of optical disk, the recording area, the recording area, the power supplied to the laser light emitting element, and the high speed to low It is essential that the level includes all diversifications such as a large difference in recording speed up to double speed. Therefore, there is a problem that it is difficult to cope with such diversification and many situations with only a single snubber circuit.

  Accordingly, the present invention has been made in view of the above-described problems, and the difference in the material and composition for forming the recording layer (film) of the write once or repetitive recording type optical disk, the difference in the recording area, and the laser light emitting element associated therewith. The recording form is set in advance in the drive circuit, for example, in accordance with the combination of the multiple speeds selected from among the multiple speeds from the 1 × speed to the high speed, The overshoot waveform (overshoot waveform) generated at the rise of the laser drive signal waveform supplied to the laser light emitting element corresponding to the selected recording form is selected from the set recording forms. By uniquely setting (peak level), it is possible to achieve optimum recording capable of high-precision and high-quality recording in any recording format. Laser light emitting element drive control circuit, the optical disk apparatus, and an object thereof is to provide a laser light emitting element drive control method.

In order to solve the above-described problems, the present invention provides a laser light emitting element drive control circuit, an optical disc apparatus, and a laser light emitting element drive control method having the following configurations (1) to ( 3 ).

(1) Information on recording power, strategy information, and information on an overshoot waveform associated with at least one double speed from a single speed to a high speed for each of a plurality of types of optical disks, supplied from the outside. A laser drive signal generated based on the combination with the laser light emitting element, and a laser light emitting element drive control circuit that enables double speed recording on each of the plurality of types of optical discs,
A snubber circuit for shaping a strategy waveform of the laser drive signal supplied to the laser light emitting element;
In the snubber circuit, a resistor and a capacitor are connected in series, a resistance value of the resistor is different, and a plurality of RC series circuits having different capacitance values of the capacitor and a plurality of RC series circuits are based on the combination. Switching means for switching
The laser light emitting element drive control circuit, wherein the plurality of RC series circuits are respectively connected in parallel to the laser light emitting elements via the switching means.

(2) An optical disc apparatus capable of optimum recording using at least one double speed from a single speed to a high double speed for each of a plurality of types of optical disks,
A laser light emitting element that emits laser light toward the optical disc, a drive circuit that supplies a laser driving signal to the laser light emitting element, a device that is connected between the laser light emitting element and the drive circuit, and is supplied to the laser light emitting element A snubber circuit for shaping a strategy waveform of the laser drive signal, and an optical pickup having a light receiving element for receiving a return light from the optical disc and generating a reproduction signal;
The type of the optical disc is discriminated based on the reproduction signal, and one double speed from a preset 1 × speed to a high double speed is discriminated, and the recording power information related to the discriminated double speed and the discriminated double speed are related. A signal control unit for outputting strategy information, and overshoot waveform information related to the discriminated optical disc type and double speed, to the drive circuit;
With
The drive circuit generates the laser drive signal and the control signal based on a combination of the recording power information, the strategy information, and the overshoot waveform information,
In the snubber circuit, a resistor and a capacitor are connected in series, a resistance value of the resistor is different, a plurality of RC series circuits having different capacitance values of the capacitor, and the plurality of RC series circuits are used as the control signal. Switching means for switching based on,
The optical disc apparatus, wherein the plurality of RC series circuits are connected in parallel to the laser light emitting element via the switching unit.

(3) Information on recording power, strategy information, and information on an overshoot waveform associated with at least one double speed from a single speed to a high speed for each of a plurality of types of optical disks, supplied from the outside. A laser drive signal generated based on the combination with the laser light emitting element, and a laser light emitting element drive control method capable of optimum double speed recording for each of the plurality of types of optical discs,
Generating the laser drive signal and the control signal based on the combination;
Selecting one RC series circuit from a plurality of RC series circuits in which a resistor and a capacitor are connected in series based on the control signal, the resistance value of the resistor is different, and the capacitance value of the capacitor is different ; ,
Shaping the strategy waveform of the laser drive signal with the selected RC series circuit;
Supplying a laser drive signal having the shaped strategy waveform to the laser light emitting element;
A laser light emitting element drive control method comprising:

  The present invention having the above-described configuration is a difference in material and composition for forming a recording layer (film) of a write once or repetitive recording type optical disk, a difference in recording area, a difference in power supplied to the laser light emitting element, and a strategy. In accordance with the combination of multiple speeds selected from a plurality of multiple speeds ranging from 1 × speed to high speed, this recording form is set in advance in, for example, the drive circuit, and from this set, Select the currently required recording form, and uniquely set the overshoot waveform (overshoot peak level) generated at the rise of the laser drive signal waveform supplied to the laser light emitting element, corresponding to the selected recording form As a result, the laser light emitting element drive control circuit can realize optimum recording capable of high-precision and high-quality recording in any recording form. Optical disc apparatus, it is possible to provide a laser light emitting element drive control method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, relative arrangements of components and display drawings described in the following embodiments do not limit the scope of the present invention to those unless otherwise specified.

[First Embodiment]
(overall structure)
FIG. 1 is a block diagram showing the main part of a first embodiment of an optical disk apparatus according to the present invention. As shown in FIG. 1, the optical disc apparatus includes a pickup 3 and a front end 12.

  The optical disc 1 is an optical disc such as a DVD-R (Digital Versatile Disc-Recordable), a DVD-RW (Digital Versatile Disc-Rewritable), a DVD-RAM (Digital Versatile Disc-RAM), or a CD (Compact Disc).

The pickup 3 includes a laser light emitting element LD that irradiates the optical disk 1 with laser light during recording and reproduction, a photodetector PD that receives reflected light from the optical disk 1 irradiated with the laser light, a snubber circuit 4, and a drive circuit 5. Have.

  The drive circuit 5 includes an overshoot adjustment circuit 18. The pickup 3 configured as described above irradiates the optical disc 1 with laser light to record data, then optically reads the recorded data, receives it with the photodetector PD, and outputs an RF reproduction output to the outside.

  The signal processing unit 7 generates reproduction data from the RF reproduction signal output from the pickup 3, generates a disc determination signal, and outputs it to the signal control unit 13. The signal control unit 13 includes a disk discrimination control unit 9 and a double speed discrimination control unit 11.

  In particular, the disc discrimination control unit 9 discriminates the type of the optical disc based on the disc discrimination signal supplied from the signal processing unit 7, and the double speed discrimination control unit 11 starts from the 1 × speed preset by the host computer 15. One double speed during high speed is determined.

Power data related to the recording power related to the double speed determined by the double speed determination control unit 11, strategy data related to the determined double speed, and overshoot control data related to the overshoot waveform related to the determined double speed are output to the drive circuit 5.

  The drive circuit 5 described above has at least one multiple speed from the single speed to the high speed for each of the power data relating to the recording power, the strategy data, and the plurality of types of optical discs input from the signal control unit 13. A control signal is output to the snubber circuit or the current mirror circuit based on the combination with the overshoot control data regarding the associated overshoot waveform, and the laser drive signal generated based on the above combination is output to the laser light emitting element LD. And the laser light emitting element LD is driven so as to enable optimum double speed recording for each of a plurality of types of optical disks.

(Overall basic action)
Next, the operation of the disk device of this embodiment will be described with reference to the flowchart shown in FIG.

(1) When controlling by the type of optical disc
The overshoot level varies depending on the recording strategy waveform of DVD-R, RW, and RAM optical disks. Also, with DVD-R, even if the waveform overshoot is large, the recording quality is better if priority is given to the one with the faster rise time. On the other hand, phase change rewritable media such as DVD-RW and DVD-RAM have a disadvantage that data written at the time of erasure is not erased if overshoot is large. Therefore, it is only necessary to select a driving circuit that is optimal for each medium.

(2) When controlling at the recording double speed The influence of the overshoot amount of the recording power differs depending on the double speed number (for example, 16-times speed). That is, in the case of high speed (for example, 16 times speed), since the output is high power, the influence of overshoot on the overall recording power is small, but the recording power at low speed (for example, 1 time) is higher than that at high speed. Since it is low, the influence (ratio) of overshoot becomes large, and in DVD-RW, DVD-RAM, etc., recording quality is adversely affected. Therefore, it is necessary to adjust the overshoot at low speed and high speed. Therefore, an optimum snubber circuit 4 corresponding to the recording speed may be selected.

  Next, the operation of the disk device of this embodiment will be described with reference to the flowchart shown in FIG.

  First, in step S10, the laser light emitting element LD emits laser light and the optical disk 1 is irradiated with the laser light. Then, an optical signal is read from the optical disc 1 by a photodiode PD provided in the pickup 3.

  Next, in step S20, a current signal flowing through the photodiode PD that has received this optical signal is passed through a resistor to be converted into a reproduction signal and output to the signal processing unit 7. The signal processing unit 7 causes the focus error, RF signal level, Detect reflectivity.

  In step S30, the focus error, the RF signal level, and the reflectance detected by the signal processing unit 7 are output to the signal control unit 13, and the disc type control unit 9 discriminates the disc type.

  In step S40, the focus and tracking servo are turned on to read the disc control data. Next, in step S50, the disk information (strategy data, power data) is fed back to the host computer 15 (back end). Next, in step S <b> 60, the host computer 15 transfers recording speed data for each medium to the signal control unit 13.

  Next, in step S70, the signal control unit 13 decodes the disc discrimination data and recording speed data to generate overshoot control data related to the determined double speed, and in step S80, the strategy data related to the determined double speed, the determined double speed. In addition to control signals such as power data relating to the recording power, overshoot control data is output to the drive circuit 5 to control the overshoot adjustment circuit 18.

  Furthermore, a control signal is output to the snubber circuit 4 or the current mirror circuit, and a laser drive signal generated based on the combination of the strategy data, power data, and overshoot control data described above is supplied to the laser light emitting element LD. The laser light emitting element LD is driven so that optimum double speed recording can be performed for each of a plurality of types of optical disks.

(Detailed overall action)
Next, the detailed operation of the disk device of this embodiment will be described.

  When recording is performed by condensing the laser beam on the recording surface of the optical disc 1, when the laser beam is emitted by a pulse signal sequence that is a laser drive signal, the laser beam exists on the circuit line between the drive circuit 5 and the laser light emitting element LD. Due to the parasitic inductance component and the stray capacitance component, overshoot or ringing occurs at the rise of the waveform of the laser drive signal.

  For this reason, in general, measures have been taken to absorb high-frequency components by a snubber circuit, as described above. However, the level of overshoot or ringing can be recorded on a write-once or repetitive recording type optical disc. Difference in material and composition for forming a layer (film), difference in recording area, difference in power supplied to the laser light emitting element, and double speed recording that can be set within a wide speed range from high speed to low speed Depending on the recording mode, which is a variety of combinations, such as the speed of the optical disk (rotation speed of the optical disc), the characteristics of the snubber circuit are optimal for each condition by simply using a snubber circuit having a single time constant. As shown in FIG. 4, overshoot and ringing cannot be effectively generated or suppressed. Was Tsu.

  FIGS. 3A, 3B and 3C are waveform diagrams showing the difference in the recording laser light emission waveform depending on the type of the optical disc 1 (DVD-R, DVD-RW, DVD-RAM). DVD-R is a write-once optical disk using an organic dye film as a recording film. DVD-RW and DVD-RAM are phase change optical disks, respectively. DVD-RW is group recording, and DVD-RAM is This is land group recording, and the areas to be recorded are different.

  For this reason, DVD-R, DVD-RW, and DVD-RAM each have a different method for controlling the heat distribution generated during mark formation when recording a mark (high-speed recording), and FIGS. 3 (A) and 3 (B). , (C) have different optimum recording light emission waveforms.

  That is, in the optimum light emission waveform at the time of DVD-R shown in FIG. 3 (A), the laser power (recording strategy waveform) rises greatly from the reproduction level to the recording level at the time of recording the mark. Becomes larger. As a result, the peak level of overshoot at the time of DVD-R is the highest compared to the peak level of each overshoot at the time of DVD-RW and DVD-RAM, and the fluctuation range of ringing is the largest. The reflectance when the DVD-R recording film is irradiated with laser light from the laser light emitting element LD is a value of 60% or more.

  In the optimum light emission waveform at the time of DVD-RW shown in FIG. 3B, when recording a mark, the laser power is first raised from the reproduction level to the erasure level and then instantaneously raised from this erasure level to the recording level. Therefore, the level variation from the recording level to the recording level is smaller than the variation during DVD-R.

  As a result, the peak level of overshoot at the time of DVD-RW is slightly lower than the peak level of overshoot at the time of DVD-R, and the level is similar to that at the time of DVD-RAM, and the ringing is the same as that at the time of DVD-R. Although it has a fluctuation range, it has a feature that is larger than that of DVD-RAM. The reflectance when the laser light is irradiated from the laser light emitting element LD onto the DVD-RW recording film is a value exceeding 18% and not more than 30%.

  In the light emission waveform in the DVD-RAM shown in FIG. 3C, when recording a mark, the laser power is first raised from the reproduction level to the erasure level and then raised from the erasure level to the recording level. For this reason, the peak level of overshoot at the time of DVD-RAM is the same as the peak level of overshoot at the time of DVD-RW, but the fluctuation range from the peak level of overshoot to the recording level is smaller than that at the time of DVD-RW. There is a characteristic. The reflectance when the DVD-RAM recording film is irradiated with laser light from the laser light emitting element LD is a value of 15% to 25%.

  Therefore, in the present embodiment, as shown in FIG. 4, the types of the optical disc, the type of the laser light emitting element, and the recording speed are diversified, respectively, as will be described later with reference to FIGS. In order to obtain an overshoot waveform or ringing waveform that forms the optimum recording light emission waveform shown in FIG. 18A, an overshoot is formed or damped by the capacitor C and the inductance L in FIG. Thus, the waveform can be controlled.

  Specifically, a plurality of snubber circuits 19a, 19b, 19c that can be connected in parallel with the laser light emitting element LD are provided, and in order to effectively control the overshoot level and ringing in each case, a plurality of snubber circuits 19a, 19b and 19c are configured to be used by being switched by selection switches SW0, SW1 and SW2 by a control signal. As a result, the recording strategy waveform supplied from the drive circuit 5 to the laser light emitting element LD via any of the plurality of snubber circuits 19a, 19b, 19c can be shaped into the optimum recording light emission waveform shown in FIG. Therefore, it is possible to perform recording with high-precision recording quality. Incidentally, at the time of reproduction, since the laser drive signal supplied from the drive circuit 5 to the laser light emitting element LD applies the HFM signal, it may be supplied through without passing through the snubber circuits 19a, 19b, 19c.

  Next, the case of controlling according to the type of the optical disc 1 will be specifically described.

  The peak level of the overshoot differs depending on the recording strategy waveform difference (FIGS. 3A to 3C) in the optical disc 1 such as DVD-R, DVD-RW, DVD-RAM or the like. Also, in DVD-R, recording quality is improved if priority is given to a faster rise time even if the peak level of waveform overshoot is large, whereas in phase change rewritable media such as DVD-RW and DVD-RAM, DVD If the peak level of overshoot is high as in -R, there is a problem that data written at the time of erasure is not erased. Therefore, it is necessary to select the optimum snubber circuit for each optical disc 1 from a plurality of snubber circuits 19a, 19b, 19c.

  That is, as shown in FIG. 1, an optical signal read from the optical disk 1 that has been trial-written prior to the main recording is converted into an electric signal by a photodiode PD provided on the pickup 3, and is converted by an electric circuit of the signal processing unit 7. A focus error and an RF signal level are detected from the reproduction signal and output to the disc discrimination control unit 9. The disc discrimination control unit 9 generates disc discrimination data from the reproduction signal input by the signal processing unit 7.

  Next, a specific description will be given of a case where control is performed at a recording speed of the optical disc 1.

  In the signal control unit 13 that has received a speed control signal corresponding to the recording double speed output from the host computer 13, high-speed recording (for example, 8 × speed, 12 × speed, 16 × speed, etc.) or low double speed recording (for example, 2 × speed, 4 × speed) The influence of the overshoot amount (overshoot peak level) of the recording power differs depending on whether the speed is 6 times or 6 times.

  In other words, in the case of high speed, since it is a high power output, the influence of overshoot on the overall recording power is relatively small. However, at low speed, the recording power is lower than that at high speed, so the effect of overshoot increases. This has a significant adverse effect on the recording quality. Therefore, overshoot must be reduced at low speeds than at high speeds. For this reason, in this embodiment, an optimum snubber circuit corresponding to the recording speed is selected from the plurality of snubber circuits 19a, 19b, 19c.

  That is, as shown in FIG. 1, an optical signal read from the optical disk 1 is converted into an electric signal by a photodiode PD provided on the pickup 3 and reproduced, and a focus error is generated from the reproduced signal by an electric circuit of the signal processing unit 7. The RF signal level is detected and output to the disc discrimination control unit 9. The disc discrimination control unit 9 generates disc discrimination data from the reproduction signal input by the signal processing unit 7. Also, a speed control signal related to the double speed input from the host computer 13 is input to the double speed discrimination control unit 11, and recording speed data is generated from the speed control signal with the double speed indicated in the disc discrimination data as an upper limit.

  Further, the disc discrimination data and the recording speed data are decoded by the double speed discrimination control unit 9 into an overshoot control data format, and an overshoot adjustment circuit 18 provided in the pickup 3 is controlled.

  As described above, according to the present embodiment, the overshoot level and the ringing level vary depending on the diversification of the recording speed, the type of the recording medium, and the type of the laser light emitting element. Since the switching of the snubber circuits 19a, 19b, and 19c can be controlled, it is possible to perform recording with higher precision recording quality under each condition.

(Specific configuration)
Next, the configuration in the case of controlling according to the type of the optical disc 1 will be described more specifically based on FIG.

  FIG. 5 is a circuit diagram of the optical disc apparatus according to the first embodiment. The configuration in FIG. 5 is a case where a serial type drive circuit 5 that serially transfers control data is used, and a control signal for switching the snubber circuit is input to the drive circuit 5 as strategy data, power data, overload It is generated using shoot control data.

  As shown in FIG. 5, in the case of the serial transfer type, the signal control unit 13 forms overshoot control data separately from the strategy data and power data in the recording medium, the laser light emitting element LD, and the recording speed discrimination signal. These are serially transferred to a register (not shown) provided in the drive circuit 5, and a control signal level corresponding to the register value is decoded to obtain a laser drive signal. In addition to the SCLK (serial clock) signal, strategy data, and power data that are the original signals, the signal control unit 13 provided in the front end 12 sends overshoot control data to the overshoot adjustment circuit 18 of the drive circuit 5. Forward to. Then, switches SW0, SW1 and SW2 as selection means for selecting the snubber circuits 19a, 19b and 19c are controlled.

(Specific action)
As shown in FIG. 5, the serial transfer type drive circuit 5 includes a register (not shown) in the drive circuit 5. The signal control unit 13 outputs strategy data, power data, and overshoot control data to the drive circuit 5. In the register, an address for storing the discriminating data of the recording medium, the laser light emitting element and the recording speed is secured and transferred as serial data together with the serial clock SCLK.

  The serial data transferred to the register 17 is decoded so as to correspond to a predetermined control signal level, and a laser control signal is output to the laser light emitting element LD via the LD signal line A.

  For example, when the serial data is 000 (corresponding to DVD-R), it is decoded into 5V, and when it is 001 (corresponding to DVD-RW), it is decoded to output a control signal. When the serial data is 010, it corresponds to DVD-RAM, and when it is 011, it corresponds to 16 × speed (× 16_R).

  Therefore, in FIG. 5, overshoot control data is transferred from the signal control unit 13 provided in the front end 12 to the overshoot adjustment circuit 18 of the drive circuit 5 separately from the SCLK signal and the strategy power data which are the original signals. The switches SW0, SW1, SW2 as selection means for selecting the snubber circuits 19a, 19b, 19c are controlled. It is assumed that the switches SW0, SW1, and SW2 are turned on when the control data output from the overshoot adjustment circuit 18 is at a high level and turned off when the control data is at a low level.

  As described above, according to this embodiment, it is possible to obtain a control signal for selecting a snubber circuit by using a signal input to the drive circuit 5 without newly increasing signal lines.

[Second Embodiment]
FIG. 6 is a circuit diagram showing an optical disc apparatus according to the second embodiment of the present invention, and FIG. 7 is an explanatory diagram showing proper use of the W1 to W3 terminals by the Enable terminal in the second embodiment. In each of the following examples, the same reference numerals are used for the same or corresponding parts as in the above embodiment.

  In the second embodiment, a conventional type drive circuit that transfers control data in parallel is used, and a control signal for switching the snubber circuit is generated using an input control signal of the drive circuit.

  Next, the operation of this embodiment will be described.

  As shown in FIG. 6, Write 1 to 3 (W 1 to 3) in the drive circuit 5 are originally recording pulse terminals, but the Enable terminal of the drive circuit 5 is set to a low level so that the drive circuit 5 does not operate. After that, it is also used as an input terminal for overshoot control data so that no recording pulse is generated.

  Then, the signal control unit 13 provided in the front end 12 outputs overshoot control data to the W1 to W3 terminals, and applies a single pulse that changes from Low to High level to the OSCEN terminal (originally a high-frequency superposition switch). At this time, when a high level Enable signal is input from the output terminal of the inverter INV1 to the Enable terminals of the D latch circuits 21 to 23, the signal becomes valid, and each of the overshoot control data input to the D latch circuits 21 to 23 is obtained. Bit data is latched and held and sent to the switches SW0, SW1 and SW2.

  Further, when the signal control unit 13 sets the Enable terminal of the drive circuit 5 to the high level, the inputs of the D latch circuits 21 to 23 become invalid, and only W1 to W3 sent to the drive circuit 5 become valid. The W1 to W3 terminals can be used as original recording pulse output terminals.

  Therefore, according to the present embodiment, when there is no signal input to the terminal before recording from the signal control unit 13 provided in the front end 12 separately from the original signal, the Enable terminal is set to Low and the W1 to W3 terminals are set. The overshoot control data is latched and held by the D latch circuits 21 to 23, and the snubber circuits 19a, 19b, 19c can be selected by controlling the switches SW0, SW1, SW2. Each operation is summarized as shown in FIG.

  As described above, according to this embodiment, it is possible to obtain a control signal using a signal input to the drive circuit 5 without newly increasing signal lines.

[Third Embodiment]
FIG. 8 is a circuit diagram showing an optical disk device according to the third embodiment of the present invention, and FIG. 9 is an explanatory diagram showing the relationship between a control signal voltage and a switch to be turned on in the third embodiment. That is, FIG. 8 shows a circuit for switching a snubber circuit by ternary control using one overshoot control signal B as an example of a snubber circuit switching circuit by multi-value control.

  In FIG. 8, depending on the type of recording medium, the type of laser, and the recording speed, at least one of the power data relating to the recording power, the strategy data, and the plurality of types of optical disks from the 1 × speed to the high speed. The overshoot control data generated based on the combination with the information on the overshoot waveform associated with the double speed is input to the D / A converter 25 of the signal control unit 13 provided in the front end 12 and converted into an analog signal. The overshoot control signal B that is converted and output from the D / A converter 25 is input to the + input terminals of the two comparators Comp1 and Comp2.

  As shown in FIG. 9, when the overshoot control signal B is between min level and level 1, only the switch SW0 is turned on, and when the overshoot control signal B is between level 1 and level 2, the switch SW1 is turned on. Only when the overshoot control signal B is between the levels 2 and max, only the switch SW2 is turned on, and only one snubber is always provided by the control signal from the snubber circuits 19a, 19b, 19c. The circuit can be selected.

  When the overshoot control signal B is between the min level and the level 1, the two comparators Comp1 and Comp2 shown in FIG. 8 compare with the voltages of the level 1 and level 2, respectively, and the low level is output, respectively. When only the output becomes high level, only the switch SW0 is turned on, and the snubber circuit 19a is selected and connected in parallel to the laser light emitting element.

  Similarly, when the overshoot control signal B is level 1 to level 2 and level 2 to max, the voltages are compared with the voltages of level 1 and level 2, and only the switches SW1 and SW2 are turned on in accordance with the output. Thus, only one snubber circuit 19b or 19c is selected.

  Therefore, in the present embodiment, when the D / A conversion is performed by the D / A converter 25 of the signal control unit 13 provided in the front end 12, when the overshoot control signal B is between the min level and the level 1, When only the switch SW0 is ON and the overshoot control signal B is between level 1 and level 2, only the switch SW1 is ON, and when the overshoot control signal B is between level 2 and max level, the switch SW2 Only one snubber circuit can be always selected by the overshoot control signal B.

  As described above, according to the present embodiment, a plurality of overshoot control snubber circuits 19a, 19b, and 19c are controlled in multiple values by a multi-value control signal depending on the type of recording medium, the type of laser light emitting element, and the recording speed. It can be switched by line.

[Fourth Embodiment]
FIG. 10 is a circuit diagram showing an optical disc apparatus according to the fourth embodiment of the present invention. FIG. 10 shows a circuit for switching the snubber circuit by ternary control by sending digital data directly from the front end side as an example of switching the snubber circuit using multi-value control as in FIG.

  In FIG. 10, in the fourth embodiment, the snubber circuits 19a, 19b, and 19c are selected from the D / A converter 27 provided in the drive circuit 5 depending on the type of recording medium, the type of laser, and the recording speed. The level overshoot control signal B is input to the + input terminals of the two comparators Comp1 and Comp2. Other configurations and operations are the same as those of the third embodiment, and thus description thereof is omitted.

[Fifth Embodiment]
FIG. 11 is a circuit diagram showing an optical disc apparatus according to the fifth embodiment of the present invention, which is a system in which an overshoot control signal from the front end side is D / A by a drive circuit. FIG. 12 is a diagram illustrating the ON resistance characteristics of the transistor when the overshoot control voltage B is input as the base input voltage in the fifth embodiment.

  As shown in FIG. 11, in the present embodiment, a snubber circuit 19 is formed by connecting a capacitor C4 and an emitter e-collector c of a transistor Tr in series, and connecting a capacitor C in parallel to one end of the capacitor C4 and the emitter e. Is connected in parallel with the laser light emitting element LD, receives the reflected light from the optical disk 1, determines the type of the optical disk 1 based on the reflectance and the disk data, and according to the determined type result The voltage of the overshoot control signal B is applied from the D / A converter 29 to the base b of the transistor Tr provided in the snubber circuit 19 via the resistor R. When D / A conversion is performed by the drive circuit 5, in addition to the original control line, overshoot control data is supplied from the signal control unit 13 provided in the front end 12 to the D / A converter 29 provided in the drive circuit 5. Have been transferred to.

  That is, in FIG. 11, as an example of the switching circuit of the snubber circuit in the multi-value control, the impedance is varied by inputting the overshoot control signal B to the base b of the transistor Tr through the resistor R, and the characteristics of the snubber circuit. The circuit which controls is shown.

  In FIG. 11, in order to change the characteristics of the snubber circuit 19 depending on the type of recording medium, the type of laser light emitting element, and the recording speed, an overshoot control signal B output from the D / A converter 29 is a resistor R. To be input to the base b of the transistor Tr. The overshoot control signal B is an overshoot control signal B output from the D / A converters 25 and 27 provided in the signal control unit shown in FIG.

  As shown in FIG. 12, by changing the voltage of the overshoot control signal B, the base current flowing between the base b and the emitter e of the transistor Tr via the resistor R changes. By changing the base current, the ON resistance between the collector c and the emitter e of the transistor Tr can be changed, and as a result, the resistance component of the snubber circuit 19 can be varied.

  As described above, according to the present embodiment, by changing the characteristics of the snubber circuit 19 using the overshoot control signal B, the overshoot and the types of the recording medium, the laser light emitting element, and the recording speed are different. Ringing can be suppressed, and recording can be performed with higher accuracy in each condition.

[Sixth Embodiment]
FIG. 13 is a circuit diagram showing an optical disc apparatus according to the sixth embodiment of the present invention. In FIG. 13, overshooting is performed to change the characteristics of the snubber circuit 19 from the D / A converter 31 of the signal control unit 13 provided in the front end 12 depending on the type of recording medium, the type of laser, and the recording speed. A control signal B is input.

  That is, when D / A conversion is performed by the D / A converter 31 of the signal control unit 13 provided in the front end 12 as in the present embodiment, the overshoot control signal is directly applied from the front end 12 to the base resistance R of the transistor Tr. B is input, and the ON resistance between the collector c and the emitter e of the transistor Tr is controlled. Other configurations and operations are the same as those in the fifth embodiment, and thus description thereof is omitted.

[Seventh Embodiment]
FIG. 14 is a circuit diagram showing an optical disc apparatus according to the sixth embodiment of the present invention, and FIG. 15 is a waveform diagram showing a state in which overshoot or ringing occurs in the laser drive waveform. In this embodiment, the same reference numerals are used for the same or corresponding parts as those in the second embodiment shown in FIG.

  In the seventh embodiment, a conventional type drive circuit is used, and overshoot control drive is performed by time difference control on a differential circuit composed of a pair of transistors.

  The signal control unit 13 provided in the front end 12 sets the Enable terminal to Low when there is no signal input to the terminal before recording, and outputs the overshoot control data to the drive circuit 5 of the laser light emitting element LD. To do. In the overshoot adjustment circuit 18, overshoot control data input from the signal control unit 13 is held in the D latches 21, 22, and 23, and a delay amount suitable for reproduction or recording of the optical disc is determined according to this data in the delay circuits DYa, DYb and DYc are set.

  For example, the delay circuit DYa is configured to delay and output the input signal by t1 when the data output from the D latch 21 is at a high level, and output the input signal by delaying by t2 when the data is at a low level. Has been.

  Further, the strategy data (Write Level) output from the signal control unit 13 is held in the D latch 43, and a current amount suitable for reproduction or recording of the optical disc 1 according to this data is provided in the current mirror circuit. It is set in the converter 45a.

  The current mirror circuit 41 is connected in series with the laser light emitting element LD, divides the transmission data into two systems, operates on / off with only one transmission data through the delay circuit DYa, and turns on / off according to the other transmission data Along with a differential circuit composed of a pair of operating transistors Tr13 and Tr14, a plurality of current mirror elements Tr11 and Tr12 that supply current to the pair of switch elements are provided. That is, the current mirror circuit 41 inputs the respective overshoot control data latched and held in the D latches 21, 22, and 23, and the strategy data W1set, W2set, and W3set latched and held in the D latch 43, respectively. Thus, the transistor Tr13 includes current mirror circuits 41a, 41b, and 41c that drive the laser light emitting element LD, and is provided in each of the current mirror circuits 41a, 41b, and 41c with respect to the cathode of one laser light emitting element LD. Are connected in common.

  The configuration of the current mirror circuit 41a will be described on behalf of these drive circuits.

  As shown in FIG. 14, a delay circuit DYa is provided between the inverting amplifier G1 and the amplifier G2 of the current mirror circuit 41a. The drain of the N-channel MOS transistor Tr12 is commonly connected to the sources of the N-channel MOS transistors Tr13 and Tr14, and these transistors Tr13 and Tr14 are configured to be switched by transmission data SD including the strategy waveform W1. The transistors Tr13 and Tr14 formed of N-channel MOS transistors constitute a switch for switching the drive current path in accordance with the transmission data SD, and operate in a linear region. The transistors Tr11 and Tr12 constitute a current mirror circuit for amplifying the output current of the D / A converter 45a to a current necessary for driving the laser light emitting element LD.

  Here, the operation of the current mirror circuit 41 shown in FIG. 14 will be described. For simplification of description, the operation of the current mirror circuit 41a will be specifically described.

The strategy data W1set output from the signal control unit 13 provided in the front end 12 is latched and held in the D latch 43, and the data output from the D latch 43 is stored in each D / D provided in the current mirror circuit 41a. Set to A converter 45a. Needless to say, the current setting data W1set latched and held by the D latch 43 is a plurality of bits, and the analog voltage output from the D / A converter 45a can be arbitrarily set within a predetermined range.

  In the D / A converter 45a, a voltage corresponding to the strategy data (voltage that determines the current value) ED is output, and a set current I corresponding to this voltage flows between the drain and source of the transistor Tr11. A mirror current of I flows between the drain and source of Tr12.

  When the signal control unit 13 provided in the front end 12 sets the Enable terminal to High, and the power data W1 output from the signal control unit 13 at this time is input as transmission data SD to the amplifier G2 and the delay device DYa. Depending on the logic value, one of the transistors Tr14 or Tr13 is turned on in a complementary manner.

  However, when the transistors Tr13 and Tr14 are switched, there is a period in which both transistors become high resistance, the transistor Tr12 cannot maintain a constant current, and the potential at the point B temporarily decreases as shown in FIG.

  During the time until the voltage at the point B becomes the original potential, a current for charging up the parasitic capacitance at the point B flows transiently through the laser light emitting element LD and the transistor Tr13.

  This transient current becomes an overshoot for the current waveform and appears as an overshoot of the optical waveform.

  Therefore, by adjusting the delay amount by the delay circuit Dya provided between the amplifier G2 and the inverting amplifier G1, the time for the potential at the point B to be lowered can be adjusted, and the overshoot level can be adjusted.

  The delay time td of the delay circuit DYa is controlled by overshoot control data obtained from information on the type of optical disk and recording speed. The overshoot control data W1 output from the signal control unit 13 provided in the front end 12 is set in the D latch 21, and the overshoot control data W1 set in the D latch 21 corresponds to the delay time td of the delay circuit DYa. Therefore, the optimum overshoot amount can be set and high-quality recording becomes possible.

  As described above, although there are various overshoot levels and ringing levels depending on the diversification of recording speed, the type of recording medium, and the type of laser light emitting element, the overshoot time and ringing time are individually determined in each case. Therefore, it is possible to perform recording with higher recording quality under each condition.

(Explanation of effect)
Next, the overall effect of each embodiment described above will be described. 16 to 18 show strategy waveforms when the overshoot is optimized for each recording medium in the DVD-R, DVD-RW, and DVD-RAM and when the overshoot is not optimized.

  FIG. 16A shows a case where the overshoot is optimized in the DVD-R, and the jitter value is 9%. FIG. 16B shows a case where the overshoot is not optimized, and the jitter value is 13%. When comparing FIG. 16A and FIG. 16B, the recording quality can be improved by providing an overshoot and increasing the rise time as shown in FIG. 16A.

  FIG. 17A shows a case where overshoot is optimized in DVD-RW, and FIG. 17B shows a case where overshoot is not optimized. 18A shows a case where overshoot is optimized in the DVD-RAM, and FIG. 17B shows a case where overshoot is not optimized. As shown in FIGS. 17A and 18A, by optimizing the overshoot, the recording quality at the time of disc rewriting can be improved.

  If the overshoot is large, problems such as data remaining when the disc is rewritten occur. Therefore, in the case of a rewritable recording medium, reducing the overshoot suppresses a decrease in recording quality when rewriting. It is done.

  Furthermore, as shown in FIG. 19, it can be seen that when the overshoot is individually adjusted, the jitter value with respect to the number of repeated recordings is suppressed as compared with the case where the individual adjustment is not performed, and the repetition characteristics are improved.

  As described above, according to each embodiment, there are various overshoot levels and ringing levels depending on the diversification of recording speed, the type of recording medium, and the type of laser light emitting element. Since the switching of the snubber circuit or the change of the constant can be controlled, it is possible to perform recording with higher accuracy recording quality under each condition than in the past.

  Further, according to each embodiment, the control signal for switching the snubber circuit is used by time-sharing the power data bus line input to the drive circuit 5, without newly increasing the signal line, A control signal can be obtained using a signal input to the drive circuit 5, and an increase in cost due to an increase in circuit scale or a circuit change can be suppressed.

1 is a block diagram illustrating an overall configuration of an optical disc device according to a first embodiment of the present invention. 3 is a flowchart for explaining the operation of the optical disc device according to the first embodiment of the present invention. (A), (B), (C) is a waveform diagram showing the difference in recording light emission waveform depending on the type of recording medium. It is a circuit diagram showing a plurality of snubber circuits of this embodiment. 1 is a circuit diagram showing an optical disc device in a first embodiment. FIG. It is a circuit diagram which shows the optical disk apparatus in 2nd Embodiment of this invention. It is explanatory drawing which shows the proper use by the Enable terminal of W1-W3 terminal in 2nd Embodiment. It is a circuit diagram which shows the optical disk apparatus in 3rd Embodiment of this invention. It is explanatory drawing which shows the relationship between the voltage level of a control signal, and the switch which should be turned ON in 3rd Embodiment. It is a circuit diagram which shows the optical disk apparatus in 4th Embodiment of this invention. It is a circuit diagram which shows the optical disk apparatus in 5th Embodiment of this invention. It is a figure which shows the ON resistance characteristic of the transistor with respect to the control voltage B in 5th Embodiment. It is a circuit diagram which shows the optical disk apparatus in 6th Embodiment of this invention. It is a circuit diagram which shows the optical disk apparatus in 7th Embodiment of this invention. It is a wave form diagram which shows the state which the overshoot and ringing generate | occur | produced in the laser drive waveform. (A) is a waveform diagram showing a case where the overshoot is optimized in the DVD-R, and (B) is a waveform diagram showing a case where the overshoot is not optimized. (A) is a waveform diagram showing a case where overshoot is optimized in DVD-RW, and (B) is a waveform diagram showing a case where overshoot is not optimized. (A) is a waveform diagram showing a case where the overshoot is optimized in the DVD-RAM, and (B) is a waveform diagram showing a case where the overshoot is not optimized. It is a figure which shows the jitter value with respect to the frequency | count of repeated recording.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 3 Pickup 5, 41 Drive circuit 7 Signal processing part 9 Disc discrimination control part 11 Double speed discrimination control part 13 Signal control part 15 Host computer 17 Register 19, 19a, 19b, 19c Snubber circuit 29 D / A converter 43 D latch 45 D / A converter DYa delay circuit

Claims (3)

A combination of information relating to recording power, strategy information, and information relating to an overshoot waveform corresponding to at least one double speed from a single speed to a high speed for each of a plurality of types of optical discs. A laser light emitting element drive control circuit that supplies a laser driving signal generated based on the laser light emitting element to enable double speed recording on each of the plurality of types of optical discs,
A snubber circuit for shaping a strategy waveform of the laser drive signal supplied to the laser light emitting element;
In the snubber circuit, a resistor and a capacitor are connected in series, a resistance value of the resistor is different, and a plurality of RC series circuits having different capacitance values of the capacitor and a plurality of RC series circuits are based on the combination. Switching means for switching
The laser light emitting element drive control circuit, wherein the plurality of RC series circuits are respectively connected in parallel to the laser light emitting elements via the switching means. An optical disc apparatus capable of optimal recording using at least one double speed between a single speed and a high speed for each of a plurality of types of optical disks,
A laser light emitting element that emits laser light toward the optical disc, a drive circuit that supplies a laser driving signal to the laser light emitting element, a device that is connected between the laser light emitting element and the drive circuit, and is supplied to the laser light emitting element A snubber circuit for shaping a strategy waveform of the laser drive signal, and an optical pickup having a light receiving element for receiving a return light from the optical disc and generating a reproduction signal;
The type of the optical disc is discriminated based on the reproduction signal, and one double speed from a preset 1 × speed to a high double speed is discriminated, and the recording power information related to the discriminated double speed and the discriminated double speed are related. A signal control unit for outputting strategy information, and overshoot waveform information related to the discriminated optical disc type and double speed, to the drive circuit;
With
The drive circuit generates the laser drive signal and the control signal based on a combination of the recording power information, the strategy information, and the overshoot waveform information,
In the snubber circuit, a resistor and a capacitor are connected in series, a resistance value of the resistor is different, a plurality of RC series circuits having different capacitance values of the capacitor, and the plurality of RC series circuits are used as the control signal. Switching means for switching based on,
The optical disc apparatus, wherein the plurality of RC series circuits are connected in parallel to the laser light emitting element via the switching unit. A combination of information relating to recording power, strategy information, and information relating to an overshoot waveform corresponding to at least one double speed from a single speed to a high speed for each of a plurality of types of optical discs. A laser drive signal generated based on the laser light emitting element, and a laser light emitting element drive control method that enables optimum double speed recording for each of the plurality of types of optical discs,
Generating the laser drive signal and the control signal based on the combination;
Selecting one RC series circuit from a plurality of RC series circuits in which a resistor and a capacitor are connected in series based on the control signal, the resistance value of the resistor is different, and the capacitance value of the capacitor is different ; ,
Shaping the strategy waveform of the laser drive signal with the selected RC series circuit;
Supplying a laser drive signal having the shaped strategy waveform to the laser light emitting element;
A laser light emitting element drive control method comprising:

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