JP2007141406A - Recording waveform generation device, and method of generating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording waveform generation device which suppresses deterioration when recording waveforms are transmitted via a flexible board. <P>SOLUTION: A board 10 is provided with a modulation circuit which modulates recording data for generating a modulation signal, a control circuit for outputting a parameter value showing the shape of the recording waveforms, a recording compensation circuit which changes the modulation signal to a recording waveform signal, a rectangular wave generation circuit which generates a rectangular wave signal. The optical pickup 12 is provided with a driving circuit which changes transmission signal to a driving current for an optical beam, a detection circuit for outputting a detection signal according to the timing of transmission signals of two or more systems; and a laser diode emitting light with prescribed power based on the driving current. The board 10 and the optical pickup 12 are connected by the flexible board 11, and a transmission signal is transmitted from the board to the pickup via the flexible board. The control circuit provided on the board changes the parameter value according to the detection signal output from the detection circuit provided on the pickup. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus for generating a recording waveform of an optical disc and a generation method thereof.

  In recent years, various types of optical disc apparatuses for recording and reproducing data using a light beam have been developed. In particular, CD-R / RW, DVD-RAM, DVD-R / RW, Bluray Disc, and the like have been developed as additional recordable optical disks.

  These optical discs are generally composed of a recording film made of a dye or a phase change material, and have a recording groove (groove track) formed on a spiral, and irradiate the groove track with a light beam. By adjusting the strength of the power, a recording mark is formed and data is recorded. In the case of a dye, a recording mark is formed with a change in optical characteristics due to a chemical change in which the dye is decomposed by heat in a portion where the light beam is strongly irradiated. In the case of a phase change material, the optical characteristics change due to a chemical change that stabilizes in a state where the crystal of the recording layer is dissolved and changes to an amorphous phase (amorphous) when the portion irradiated with the light beam is rapidly cooled. A recording mark is formed.

  In the case of DVD-R / RW, the length of the recording mark is from the shortest 0.40 μm to the longest 1.866 μm, and there are 9 patterns from 3T to 11T and 10 patterns in total, 14T. Here, 1T means a unit time length of a recording mark, and is 38.2 ns (1 / (26.16 MHz)) at the standard speed of DVD-R / RW.

  In order to form the recording marks with good quality, as shown in FIG. 14, the recording film is irradiated with a light beam with a recording waveform obtained by adding a predetermined change to the shape in the recording power direction (vertical direction) and the time axis direction (horizontal direction). To do. This process is called recording compensation. The recording waveform obtained by the recording compensation has a different shape such as a different number of pulses for each recording mark so that the recording mark can be formed optimally. Furthermore, since a minute recording mark having a minimum length of 0.40 μm must be formed at high speed and accurately, it is necessary to adjust the position of the edge of each pulse of the recording waveform with extremely high accuracy. Information indicating the timing of the edge position of each pulse is hereinafter referred to as a recording compensation parameter. In DVD-R, in order to obtain good recording characteristics, it is necessary to adjust the edge of the recording waveform with a resolution of about 1/40 of the unit time length T. In the case of 16 times speed, about 60 ps (38.2 ns ÷ A highly accurate recording waveform generation device having an adjustment resolution of about 16 ÷ 40) is required.

  On the other hand, in the optical disk drive, as shown in FIG. 15, the pickup 12 having the laser light source and the light receiving unit is separated from the main board 10 that performs signal processing, and the pickup 12 and the main board 10 are connected by the flexible board 11. A configuration for exchanging signals is common. At that time, the recording compensation circuit can be roughly divided into two cases, that is, a case where it is mainly provided on the main substrate 10 side and a case where it is provided on the pickup 12 side.

  In the configuration in which the recording compensation circuit is provided on the main substrate 10 side, the modulation data is converted into a recording waveform based on the recording compensation parameter on the main substrate side. Further, as shown in FIG. 3, the recording waveform is converted into a digital signal (hereinafter referred to as a transmission signal) composed of a plurality of signal lines each corresponding to the recording power, and transmitted to the pickup 12 via the flexible substrate 11. . On the pickup side, the drive current of the light beam is generated by turning on / off the outputs of a plurality of current sources using a plurality of transmission signals, and the laser diode is driven using the drive current. The recording film is irradiated with a light beam. The reason why the recording waveform is once converted into a digital signal composed of a plurality of signal lines without directly generating a driving current on the main board 10 is because it is less susceptible to level fluctuations and noise than transmitting as a driving current. is there.

In the configuration in which the recording waveform generating device is provided on the pickup 12 side, as described in Patent Document 1, the modulation data, the reference clock signal, and the recording compensation parameter are transmitted to the pickup via a flexible cable. The pickup side has a storage means for storing the recording compensation parameter, generates a recording waveform based on the recording compensation parameter using the clock obtained by multiplying the reference clock as the operation clock, and converts the recording waveform into a drive current Then, by driving the laser diode using the drive current, the recording film of the optical disc 13 is irradiated with the light beam.
Japanese Patent No. 3528612

  In the configuration in which the recording compensation circuit is provided on the main board side, transmission is performed due to the effect of transmission path loss during transmission from the main board to the pickup via the flexible board, variation in the transmission circuit of the main board and the receiving circuit of the pickup, etc. When the signal deteriorates, an error occurs in the ON / OFF timing of the current source for obtaining the driving current of the light beam, and the light beam may not be irradiated with the original recording waveform.

  Specifically, as shown in FIG. 16, the pulse width of the transmission signal fluctuates, or a skew occurs between a plurality of transmission signal lines as shown in FIG. 17, and the ON / OFF timing of the current source shifts. As a result, a waveform rounding or the like in which the rise time Tr or the fall time Tf of the light emission waveform of the light beam becomes long may occur.

  It is conceivable to reduce the fluctuation and skew of the pulse width at the time of designing the optical disk drive or in the manufacturing process. For example, at design time, impedance matching is strictly performed to match the wiring path length, etc., and in the optical disk drive manufacturing process, the influence of pulse width variation and skew are minimized by observing the light emission waveform. Or make adjustments.

  However, the fluctuation and skew of the above pulse width may change depending on the optical disk drive usage state such as bending of flexible substrate, temperature change, voltage change and aging deterioration, so it is only adjusted at the time of optical disk drive design or manufacturing process. Then there is a problem of insufficient. Further, adjustment in the manufacturing process leads to an increase in manufacturing cost such as an increase in manufacturing tact time and introduction of manufacturing equipment for adjustment.

  On the other hand, in the configuration in which the recording compensation circuit is provided on the pickup side, it is not necessary to transmit a high-speed and high-accuracy signal on the flexible cable, and there is an effect of reducing the influence of signal distortion on the flexible cable. However, it is necessary to have a relatively large and high-frequency recording compensation digital circuit and multiplication circuit on the pickup side, and there is a concern about the influence of noise mixing into the analog circuit on the pickup.

  In addition, when changing the recording waveform shape, it is necessary to sequentially transmit the recording compensation parameters to the pickup via the flexible cable, which causes a problem of time loss associated with changing the recording compensation parameters. It was.

  The object of the present invention is to provide a large-scale circuit on the pickup side, so that the shape of the transmission signal deteriorates due to transmission path loss, transmission circuit, reception circuit variation, voltage change, temperature change, flexible substrate bending, etc. Another object of the present invention is to provide a recording waveform generating apparatus and method for suppressing recording with a recording waveform different from the original recording waveform.

  In order to solve the above problems, in the recording waveform generating apparatus and method of the present invention, in a configuration in which a recording compensation circuit is provided on the main substrate side to generate a recording waveform and transmit it to a pickup, two or more systems with a predetermined period It is most important to detect the deterioration of the transmission signal during transmission of the recording waveform by detecting the rectangular wave signal at the pickup side and to change the shape of the recording waveform to be transmitted so as to cancel the deterioration. Features.

  Specifically, a recording waveform generation device of the present invention is a recording waveform generation device that generates a recording waveform of an optical disc, and includes a modulation circuit that modulates recording data on a substrate to generate a modulation signal, and a shape of the recording waveform. A control circuit that outputs a parameter value to be indicated, a recording compensation circuit that converts the modulated signal into a plurality of recording waveform signals according to the parameter value based on a predetermined rule, and two or more systems of a predetermined period A rectangular wave generation circuit for generating a rectangular wave signal, and a selection circuit for selecting the recording waveform signal and the rectangular wave signal and outputting them as a transmission signal. The pickup uses the transmission signal as a drive current for the light beam. A drive circuit for conversion, a detection circuit for outputting a detection signal corresponding to the timing of each transmission signal, and a laser diode for emitting light at a predetermined power based on the drive current, The board and the pickup are coupled by a flexible substrate, and a transmission signal is transmitted from the substrate to the pickup via the flexible substrate, and the control circuit provided on the substrate is provided by the detection circuit provided on the pickup. The parameter value is changed according to the detection signal output from the circuit.

The recording waveform generation method of the present invention is a method for generating a recording waveform of an optical disc,
(a) has a step for adjusting the recording waveform and (b) a step for recording data,
(a) The step of adjusting the recording waveform includes: (a-1) generating two or more systems of rectangular wave signals having a predetermined period; and (a-2) generating two or more systems of rectangular waves. Comparing the timing of the signal on the pickup and notifying the detection result, and (a-3) converting the detected result into an offset value,
(b) The step for recording data includes (b-1) a step of modulating the recording data, and (b-2) a step of changing a parameter value indicating the shape of the recording waveform according to the offset value. (B-3) a step of converting the recording waveform signal into a plurality of systems according to the parameter value; (b-4) a step of converting the recording waveform signal into a driving current of the light beam; 5) A step of causing the laser diode to emit light with a predetermined power based on the drive current is provided.

  The recording waveform generation apparatus and method of the present invention can detect a change in the recording waveform due to transmission path loss and variations in the transmission circuit and the reception circuit when the recording waveform is transmitted from the main board to the pickup. By changing the shape of the recording waveform to be transmitted according to the above, it is possible to suppress the change of the recording waveform at the time of transmission and to record with a desired recording waveform.

  Hereinafter, the configuration and operation of a recording waveform generation apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of a recording waveform generation apparatus according to an embodiment of the present invention. FIG. 2 is an example of a recording waveform transmitted by the recording waveform generation apparatus according to the embodiment of the present invention.

  As shown in FIG. 1, the recording waveform generation apparatus according to the embodiment of the present invention includes a main substrate 10, a flexible substrate 11, and a pickup 12. The main board 10 includes a modulation circuit 14, a recording compensation circuit 15, a driver circuit 16, a controller 17, a serial I / F 18, a rectangular wave generation circuit 19, and a switcher 20. A pickup 12 includes a receiver circuit 21, a detection circuit. A circuit 22, a drive circuit 23, a laser diode 24, and a serial I / F 25 are included.

  When recording data, a recording waveform is generated on the main board 10, converted into a transmission signal, then transmitted to the pickup 12 via the flexible board 11, and the transmission signal is converted into a drive current in the pickup, and a laser diode. 24 is driven to irradiate the optical disk with the light beam. The spot size on the recording surface of the optical disc 13 is adjusted so that the light beam transmitted from the laser diode 24 inside the pickup 12 can be optimally recorded.

  The modulation circuit 14 performs predetermined modulation on the data to be recorded, and generates a modulation signal (NRZI) indicating a recording mark and a recording space. As an example, the 8/16 modulation method employed in DVD will be described. In 8-16 modulation, an RLL (2, 10) modulation code is generated by converting 8 bits (1 byte) into 16 bits using a predetermined modulation table. RLL is an abbreviation for “Run Length Limited” and means that the number of consecutive “0” s (RUN Length) is limited. That is, in RLL (2, 10), the number of consecutive “0” s following “1” is limited from 2 to 10. Further, in order to obtain frame synchronization during reproduction, a synchronization signal of 2 bytes (32 bits) is given every 91 bytes (1456 bits) of the modulation code. This synchronization signal includes a pattern of “1000000000000000010001” that does not exist in the rear part of RLL (2, 10), and the run length is 13, so that it can be distinguished from other data.

  A modulation signal in which the number of consecutive “0” or “1” is limited to 3 to 11 or 14 (that is, 3T to 11T or 14T) is obtained by performing NRZI conversion on the modulation code thus generated. NRZI is an abbreviation of “Non Return to Zero Invert” and is a method of reversing “0” and “1” every time a modulation code “1” appears when a modulation code is recorded on a disc.

  The recording compensation circuit 15 is a circuit that converts the modulation code into a waveform suitable for recording. As described above, recording on an optical disk causes a chemical change in the recording film due to heat radiated with a light beam, and forms a recording mark having optical characteristics different from those of other portions. Correspondingly, just by irradiating the light beam with a constant power, the recording mark does not have a desired shape due to heat interference or heat accumulation. Therefore, it is necessary to control such that the modulation code is divided into a plurality of pulses to avoid heat accumulation. As an example, FIG. 2 shows a waveform of multi-pulse modulation of DVD-RW. In multi-pulse modulation of DVD-RW, in order to form a recording mark, it is composed of a leading pulse called a top pulse, a plurality of subsequent multi-pulses, and a cooling pulse for cooling. The width of the top pulse is defined as Ttop, the width of the multi-pulse is defined as Tmp, and the width of the cooling pulse is defined as Tcl. The recording power value is defined by Po, Pe, and Pb with reference to the zero level. By precisely controlling these pulse widths and recording power values, thermal interference between recording marks and heat accumulation at the trailing edge of the recording marks can be suppressed, and the heat distribution generated by recording mark formation can be optimized and desired. Recording marks can be formed. Each pulse (top pulse, multi-pulse, cooling pulse, etc.) is generated by a pulse generator composed of a delay line with a predetermined resolution and a multiphase PLL (Phase Locked Loop), and each pulse is synthesized and output. To do. Although it depends on the double speed, in the case of DVD-RW, a resolution of about T / 40 is required.

  In the case of the recording waveform as shown in FIG. 2, since the power level of the light beam to be irradiated has three values of Po, Pe, and Pb, it becomes a four-value signal together with the zero level. Is easily affected by amplitude fluctuations and level fluctuations, and signal transmission is difficult. Therefore, it is transmitted as a digital signal divided into a plurality of systems corresponding to recording powers of Po, Pe, and Pb (hereinafter referred to as a recording waveform transmission signal). It is common. Here, it is converted into a recording waveform transmission signal of three binary signals as shown in FIG.

  The driver circuit 16 converts the three transmission signals into signal levels suitable for transmission and outputs them. A transmission system is not particularly limited as a mode for carrying out the present invention, but it is converted into a signal level of TTL or LVDS (Low Voltage Differential Signaling) composed of two differential signals of one system and transmitted. It is common.

  The flexible substrate 11 connects the main substrate 10 and the pickup 12 and transmits a signal output from the main substrate 10 and the pickup 12.

  The receiver circuit 21 receives a transmission signal having a signal level of TTL or LVDS, and restores the transmission signal to three original transmission signals.

  The drive circuit 23 converts the transmission signal into a drive current for the light beam. As an example, a configuration using a current source and a switch as shown in FIG. 4 will be described. The switches 45 to 48 are turned on / off by transmission signals A, B, C, D and recording gates, and control the four current sources A, B, C, D. The current sources A, B, and C are current sources that generate a drive current for recording, and the current source D is a current source that generates a drive current for reproduction. At the time of recording, the recording gate becomes H, so that the outputs of the current sources A, B, and C are turned on according to the transmission signals A, B, and C. At the time of non-recording, the recording gate becomes L and the output of the current source D is turned on. The total of each output current is output as a drive current.

  The laser diode 24 irradiates the optical disk 12 with a light beam having a light emission power corresponding to the drive current output from the drive circuit 23.

  The modulation circuit 14, the recording compensation circuit 15, the driver circuit 16, the receiver circuit 21, the drive circuit 23, and the laser diode 24 each show a general configuration, and are not limited to the embodiments for carrying out the present invention. Absent.

  The controller 17 stores recording waveform timing information (recording compensation parameter) in an internal memory element (not shown), and outputs it to the recording compensation circuit 15. The recording compensation parameter includes information indicating the rising and falling edges of the recording waveform such as Ttop, Tmp, and Tcl in FIG. Since the values of Ttop, Tmp, and Tcl that can be optimally recorded differ depending on the recording medium, the recording mark length, and the interval between the preceding and succeeding recording marks, it is necessary to store various variations of recording compensation parameters.

  The rectangular wave generation circuit 19 outputs a rectangular wave signal used in a recording waveform adjustment step described later as a rectangular wave transmission signal. Details of the output rectangular wave transmission signal will be described in the recording waveform adjustment procedure described later.

  The switcher 20 selects one of the recording waveform transmission signal output from the recording compensation circuit 15 and the rectangular wave transmission signal output from the rectangular wave generation circuit 19 and outputs it as a transmission signal. A rectangular wave transmission signal is selected when recording waveform adjustment is performed, and a recording waveform transmission signal is selected when normal data recording is performed.

  The detection circuit 22 detects a timing difference between the two systems of transmission signals and outputs it to the serial I / F 25 as timing difference information. Here, the case where it comprises with DFF as shown in FIG. 5 implement | achieved with the simplest structure is demonstrated. The transmission signal A is connected to the OR preceding the D input of the DFF, and the transmission signal B is connected to the clock input. As shown in FIG. 6, when the transmission signals A and B having a predetermined phase difference are transmitted after the DFF is reset once, if the rising edge of the transmission signal B is in the L section of the transmission signal A, the L level signal is When there is a rising edge of the transmission signal B in the H section of the transmission signal A, an H level signal is output. At this time, in order to reduce detection variation, it is better to statistically obtain timing difference information by outputting a plurality of pulses or repeating the same processing. In FIG. 6, three pulses are output.

  The serial I / F 25 on the pickup transmits the detection result of the detection circuit to the serial I / F 18 of the main board 10 via the flexible 11 board. The controller 17 receives the detection result notified to the serial I / F 18, detects the fluctuation amount of the pulse width and the skew amount from the detection result, and changes the recording compensation parameter.

  Next, the operation of the recording waveform generation apparatus according to the embodiment of the present invention will be described. The operation of the recording waveform generating apparatus is roughly divided into (a) recording waveform adjustment step and (b) data recording step, and switching control is performed by the controller 17.

  (a) Recording waveform adjustment step is executed prior to (b) data recording step, and using the test waveform for recording waveform adjustment, distortion of the recording waveform is detected, and the actual recording waveform is actually transmitted A difference from the recorded waveform (hereinafter referred to as an offset value) is derived.

  (b) In the data recording step, data is recorded by using the offset value obtained in (a) so as to reduce the distortion of the recording waveform.

  Hereinafter, (a) the recording waveform adjustment step will be described in detail. In the recording waveform adjustment step, the test waveform for adjusting the recording waveform is used to detect the distortion of the recording waveform, and the difference between the original recording waveform and the actually transmitted recording waveform (hereinafter referred to as offset value) is derived. To do.

  FIG. 7 is a timing chart showing the recording waveform adjustment procedure. As shown in FIG. 3, the recording waveform generated by the recording waveform generating apparatus according to the present embodiment is transmitted on two pulses of transmission signals A and B. Therefore, fluctuations and skews in the pulse width occur in the transmission signals A and B. Therefore, adjustment is performed using the transmission signals A and B as shown in FIG. If the recording waveform to be generated is a pulse waveform transmitted to all of the transmission signals A, B, and C, after adjusting using the transmission signals A and B as shown in FIG. Adjustment may be performed using the transmission signals A and C as shown in FIG.

  Hereinafter, a case where a waveform on a pulse is transmitted to two transmission signals A and B will be described.

  The rectangular wave generation circuit 19 generates rectangular wave transmission signals A and B used for recording waveform adjustment. At this time, it is desirable that at least one of the rectangular wave transmission signals A and B has a width equal to or smaller than the top pulse width Ttop, the multi-pulse width Tmp, and the cooling pulse width Tcl used in the actual recording. The reason why the width is the same or smaller is that the narrower the pulse width, the more conspicuous the influence of pulse width variation and skew.

  The switcher 20 selects a rectangular wave transmission signal from the recording waveform transmission signal output from the recording compensation circuit 15 and the rectangular wave transmission signal output from the rectangular wave generation circuit 19, and outputs it as transmission signals A to C. These transmission signals A to C are input to the detection circuit 22 via the driver circuit 16, the flexible substrate 12, and the receiver circuit 21. In the recording waveform adjustment step, since the original data recording is not performed, the recording gate is set to L, and the output of the current source corresponding to C from the transmission signal A in the drive circuit 23 is cut off. To prevent the drive current from reacting.

  Prior to transmission of the rectangular wave transmission signal, the DFF of the detection circuit 22 issues a reset instruction so that the output of the DFF of the detection circuit 22 becomes L level via the serial I / Fs 18 and 25 from the controller 17. In this state, when the transmission signal A and the transmission signal B are output as shown in FIG. 6A, the detection signal becomes L level, and the rising timing of the transmission signal B is in the L section of the transmission signal A. When it can be detected and output as shown in FIG. 6B, it becomes H level, and it can be detected that the rising timing of the transmission signal B is in the H section of A of the transmission signal. The result is notified to the controller 17 via the serial I / Fs 25 and 18. When the controller 17 receives the notified detection result, the controller 17 holds the result in a memory element (not shown) in the controller 17 and passes through the serial I / Fs 18 and 25 to perform the next measurement, thereby detecting the circuit 22. Instruct the reset to. Next, the transmission signal B is delayed and output with respect to the transmission signal A. The resolution at the time of delaying is desirably the same as or lower than the resolution adjustable by the recording compensation circuit. Then, the same processing as described above is performed, and when the controller 17 receives the result of the detection circuit, the result is held in a memory (not shown) inside the controller 17.

  By repeating the above operation while changing the phase relationship between the transmission signals A and B, a detection result as shown in FIG. 8 is obtained. For example, when a signal having a width W is transmitted as the transmission signal A and a detection result as shown in FIG. 8 is obtained, the change point of L → H on the reception side is the phase difference of the transmission signal B with respect to the transmission signal A. Is the point of P1, and the change point of H → L is the point of phase P2 of the transmission signal B with respect to the transmission signal A. From this detection result, on the pickup side, as a transmission signal having a width of P2-P1 You can see that it was received. That is, W− (P2−P1) becomes the pulse width variation ΔW. Further, since the point at which the phase difference between the transmission signal A and the transmission signal B minus the transmission signal A from the main substrate 10 side is 0 is P1, P1 may be the skew ΔAB of the transmission signal B with respect to the transmission signal A. Recognize.

  When the same processing is performed by transmitting a rectangular wave having a Ttop width, a pulse variation ΔTtop when a Ttop width signal is transmitted can be obtained. When a rectangular wave having a Tmp width is transmitted, a pulse fluctuation amount ΔTmp when a Tmp width signal is transmitted is obtained. When a rectangular wave having a Tcl width is transmitted, a pulse fluctuation amount ΔTcl when a pulse having a Tcl width is transmitted is obtained. 8 is obtained using the transmission signal A and the transmission signal B, the skew ΔAB of the transmission signal B with respect to the transmission signal A is obtained. These values are the difference between the original recording waveform and the actually transmitted recording waveform, and are held in a memory element inside the controller 17 as an offset value.

  Next, (b) the data recording step will be described in detail.

  In the data recording step, using the offset value obtained in the recording waveform adjustment step (a), the recording compensation parameter is corrected so as to reduce the distortion of the recording waveform, and the data is recorded.

  A case where the recording waveform of FIG. 2 is output will be described. When the offset value obtained in the recording waveform adjustment procedure is used to add the offset value to the parameter value so as to cancel the fluctuation of the pulse width in the recording waveform of FIG. 2, the result is as shown in FIG. That is, for Ttop, the offset value ΔTtop is added to make Ttop + ΔTtop the parameter value, for Tmp, the offset value ΔTmp is added to make Tmp + ΔTmp the parameter value, and for Tcl, the offset value ΔTcl is added to make Tcl + ΔTcl the parameter Value. As a result, a recording waveform is generated by adding the pulse fluctuation at the time of transmission, and the pulse width fluctuation is canceled on the pickup 12 side, so that a recording waveform with high accuracy can be obtained.

  Further, the skew can be adjusted with a circuit as shown in FIG. In the circuit of FIG. 10, skew generated between the transmission signals A, B, and C is adjusted with respect to the transmission signals A, B, and C through a variable delay line and the like. As shown in FIG. 3, the recording waveform generated by the recording waveform generating apparatus according to the embodiment transmits a waveform on a pulse to the two transmission signals A and B. Therefore, the skew between the transmission signal A and the transmission signal B is transmitted. Can be adjusted. When ΔAB is positive, the transmission signal B is delayed with respect to the transmission signal A, and when it is negative, it can be said that the transmission signal B with respect to the transmission signal A is advanced. Therefore, when ΔAB is positive, the variable delay line A is set to be delayed by ΔAB. When ΔAB is negative, the variable delay line B is set to be delayed by −ΔAB. As a result, a recording waveform is generated by adding a skew amount at the time of transmission, and the skew amount is canceled on the pickup 12 side, so that a recording waveform with high accuracy can be obtained. This circuit may be incorporated in the recording compensation circuit 15 or in the driver circuit 16.

  In this description, since the waveform on the pulse is transmitted to the two transmission signals A and B, only the skew ΔAB between the transmission signals A and B is corrected. However, depending on the generated recording waveform, the transmission signal A is corrected. , B, and C may be transmitted with a waveform on a pulse. In that case, after obtaining ΔAB using the transmission signals A and B, ΔAC is obtained using the transmission signals A and C, and the following processing is performed.

  When ΔAB is positive, the transmission signal B is delayed with respect to the transmission signal A, and when it is negative, it can be said that the transmission signal B with respect to the transmission signal A is advanced. When ΔAC is positive, the transmission signal C is delayed with respect to the transmission signal A, and when it is negative, the transmission signal C with respect to the transmission signal A is advanced. Therefore, when ΔAB is positive, ΔAC is positive, and ΔAB is smaller than ΔAC, the variable delay line A is set to be delayed by ΔAC, and the variable delay line B is set to be delayed by ΔAC−ΔAB. The skew generated between the transmission signals A, B, and C on the receiving side can be canceled out. Similarly, when ΔAB is positive, ΔAC is positive, and ΔAB is larger than ΔAC, the variable delay line A is set to be delayed by ΔAB, and the variable delay line C is set to be delayed by ΔAB−ΔAC. When ΔAB is negative and ΔAC is positive, the variable delay line A is set to be delayed by ΔAC, and the variable delay line B is set to be delayed by ΔAC−ΔAB. When ΔAB is positive and ΔAC is negative, the variable delay line A is set to be delayed by ΔAB, and the variable delay line C is set to be delayed by ΔAB−ΔAC. When ΔAB is negative and ΔAC is negative, the variable delay line B is set to be delayed by −ΔAB, and the variable delay line C is set to be delayed by −ΔAC. The above is summarized as shown in FIG.

  Comparing the case where the correction using the offset value of the recording compensation parameter is not performed and the case where it is not performed, the case where the correction is not performed, as shown in FIG. 12, the influence of the transmission line loss and the variation of the driver circuit 15 and the receiver circuit 21. In some cases, the reception side may not obtain a desired recording waveform due to fluctuations in the pulse width or skew on the reception side. However, if this is done, as shown in FIG. Since the waveform is generated by adding the amount of skew and the amount of skew, the effect of suppressing fluctuations in pulse width and skew on the receiving side can be obtained. Further, the detection circuit provided in the pickup for realizing this processing may be a DFF and a simple logic circuit, and can be realized relatively easily.

  In this embodiment, the offset value is obtained for each pulse width of Ttop, Tmp, and Tcl. However, in actuality, the pulse width may fluctuate due to interference between preceding and subsequent pulses. In such a case, if the offset value is obtained for each combination of the pulse width and the interval before and after, the pulse fluctuation can be more accurately suppressed. For example, in the case of the recording waveform of FIG. 2, the pulse set by the Tmp parameter is Tmp in the H section and 1T-Tmp in the L section. Therefore, when adjusting, if a rectangular wave transmission signal having an H section of Tmp and an L section of 1T-Tmp is used, the adjustment is performed with a pulse shape closer to a transmission signal actually used. The result will be obtained.

  In order to further improve the adjustment accuracy, the same measurement may be performed a plurality of times to statistically obtain the offset.

  In addition, a timer may be provided in the detection circuit 22 to measure the time between edges between transmission signals and the pulse width. In this case, although the scale of the detection circuit 22 is increased by at least the timer, it is not necessary to perform measurement repeatedly while shifting the phase of the transmission signal B, so that the adjustment time can be shortened.

  The recording waveform generation apparatus and method according to the present invention can also be applied to applications that require high-speed signal transmission using a plurality of transmission signal lines.

The block diagram which shows the structure of the recording waveform generation apparatus in embodiment of this invention Waveform diagram showing a recording waveform transmitted by the recording waveform generation device according to the embodiment of the present invention The wave form diagram which shows the transmission signal transmitted with the recording waveform production | generation apparatus in embodiment of this invention The block diagram which shows the structure of the drive circuit of the recording waveform generation apparatus in embodiment of this invention The figure which shows the structure of the detection circuit of the recording waveform generation apparatus in embodiment of this invention FIG. 4 is a timing chart showing the operation of the detection circuit of the recording waveform generation device according to the embodiment of the present invention. Timing chart showing a recording waveform adjustment procedure of the recording waveform generation device according to the embodiment of the present invention FIG. 4 is a waveform diagram for explaining offset adjustment of a recording waveform of the recording waveform generation device according to the embodiment of the present invention; FIG. 4 is a waveform diagram for explaining offset adjustment of a recording waveform of the recording waveform generation device according to the embodiment of the present invention; The block diagram which shows the structure of the skew adjustment circuit of the recording waveform of the recording waveform generation apparatus in embodiment of this invention The figure for demonstrating the operation | movement of skew adjustment of the recording waveform generation apparatus in embodiment of this invention The waveform diagram which shows the influence at the time of not performing offset adjustment of the recording waveform generation apparatus in embodiment of this invention The waveform diagram which shows the effect at the time of performing offset adjustment of the recording waveform generation apparatus in embodiment of this invention Waveform diagram showing an example of a recording waveform transmitted by a conventional recording waveform generator Block diagram showing the configuration of a conventional general optical disk device Explanatory drawing showing the effect of pulse width fluctuation of transmission signal line Explanatory diagram showing the effect of skew in the transmission signal line

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Main board 11 Flexible board 12 Pickup 13 Optical disk 14 Modulation circuit 15 Recording compensation circuit 16 Driver circuit 17 Controller 18 Serial I / F
19 rectangular wave generation circuit 20 switch 21 receiver circuit 22 detection circuit 23 drive circuit 24 laser diode 25 serial I / F
41, 42, 43, 44 Current sources A, B, C, D
45, 46, 47, 48 Switch 91, 92, 93 Variable delay line

Claims (8)

A recording waveform generation device that generates a recording waveform of an optical disc, a modulation circuit that modulates recording data on a substrate to generate a modulation signal, a control circuit that outputs a parameter value indicating the shape of the recording waveform, and a predetermined rule A recording compensation circuit that converts the modulation signal into a plurality of recording waveform signals according to the parameter value, a rectangular wave generation circuit that generates two or more systems rectangular wave signals of a predetermined period, and A selection circuit for selecting a recording waveform signal and the rectangular wave signal and outputting it as a transmission signal is provided,
The pickup is provided with a drive circuit that converts the transmission signal into a drive current of the light beam, a detection circuit that outputs a detection signal corresponding to the timing of each transmission signal, and a laser diode that emits light with a predetermined power based on the drive current And
The substrate and the pickup are coupled by a flexible substrate, and a transmission signal is transmitted from the substrate to the pickup via the flexible substrate,
The recording waveform generating apparatus, wherein the control circuit provided on the substrate changes a parameter value in accordance with a detection signal output from the detection circuit provided on the pickup. The rectangular wave generating circuit variably outputs one phase of two systems of rectangular wave signals having a predetermined pulse width,
The detection circuit detects whether the rising timing of one of the two types of rectangular wave signals is in the other H section or L section, and outputs a detection signal,
The recording waveform generating apparatus according to claim 1, wherein the control unit changes a parameter value according to a detection signal. The rectangular wave generating circuit simultaneously outputs two types of rectangular wave signals having the same pulse width,
The detection circuit detects a phase difference between two types of rectangular wave signals and outputs a detection signal;
The recording waveform generating apparatus according to claim 1, wherein the control unit changes a parameter value according to a detection signal. 2. The recording waveform generation apparatus according to claim 1, wherein the drive circuit does not change a drive current value according to the transmission signal when the selection circuit selects the rectangular wave signal. A method for generating a recording waveform of an optical disc,
(a) Steps for adjusting the recording waveform
(b) has a step for recording data;
(a) The step of adjusting the recording waveform
(a-1) generating rectangular wave signals of two or more systems with a predetermined period;
(a-2) comparing the timings of the generated rectangular wave signals of two or more systems on the pickup and notifying the detection result;
(a-3) comprising a step of converting the detected result into an offset value;
(b) The steps for recording data are:
(b-1) modulating the recording data;
(b-2) changing the parameter value indicating the shape of the recording waveform according to the offset value;
(b-3) according to the parameter value, the step of converting into a recording waveform signal of a plurality of systems,
(b-4) converting the recording waveform signal into a light beam driving current;
(b-5) A recording waveform generating method comprising a step of causing a laser diode to emit light with a predetermined power based on a drive current. In the rectangular wave generation, one of the two types of rectangular wave signals having a predetermined pulse width is output with the phase varied.
The detection signal indicates whether the rising timing of one of the two types of rectangular wave signals is in the other H section or L section,
6. The recording waveform generation method according to claim 5, wherein a parameter value is changed according to the detection signal. The rectangular wave generation simultaneously outputs two types of rectangular wave signals having the same pulse width,
The detection signal indicates a phase difference between two types of rectangular wave signals;
6. The recording waveform generation method according to claim 5, wherein a parameter value is changed according to the detection signal. 6. The recording waveform generating method according to claim 5, wherein when the rectangular wave signal is selected, a drive current is not output according to the transmission signal.

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