JP4524978B2 - Optical recording device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical recording apparatus for recording various types of information on a rewritable optical recording medium such as a phase change optical disk, and more particularly to a write strategy function for optimizing the pulse waveform of a write pulse for the optical recording medium. The present invention relates to an optical recording apparatus in which
[0002]
[Prior art]
In recent years, phase-change optical disks have been practically used as writable optical disk systems. In this phase change optical disc, writing can be performed while erasing by controlling the laser power. The basic principle of this phase change optical disc is disclosed in, for example, Japanese Patent Laid-Open No. 56-145530.
On the other hand, in the magneto-optical recording method (MO), when a special medium is not used, since erasing is performed in one pass and writing is performed in one pass, the disk needs to be rotated twice in one writing operation.
[0003]
Hereinafter, the pulse waveform control of the write pulse for the conventional phase change optical recording medium will be described.
First, in order to increase the recording density as much as possible for a given phase change type optical recording medium, it is necessary to obtain an optimal recording shape, and various modifications are devised instead of a simple rectangular wave as a writing pulse. Has been. Such deformation control for the write pulse is called a write strategy.
As a method for realizing the conventional write strategy, for example, as disclosed in Japanese Patent Laid-Open No. 6-251375, a method using a pattern memory is known in order to conform to the pit edge recording method.
For example, Japanese Patent No. 2788637 discloses the necessity and effectiveness of a method for controlling a recording pattern with a combination of three levels of pulses.
[0004]
[Problems to be solved by the invention]
However, there are various difficulties in actually realizing a high-speed, high-precision write strategy, and it is not easy to construct an ideal system.
For example, in the conventional method using the pattern memory, a large number of pattern memories are provided for each pulse waveform, and a pulse pattern is read out from each pattern memory via a gate circuit and synthesized at a later stage. Since the pulse pattern of each waveform is read and synthesized, subtle timing shifts are likely to occur between the pulse waveforms, and in order to obtain a highly accurate waveform, it is necessary to strictly synchronize the entire waveform. Accurate waveform control is difficult.
[0005]
The present invention has been made in view of such a situation, and an object thereof is to provide an optical recording apparatus capable of realizing a high-speed, high-precision write strategy.
[0006]
[Means for Solving the Problems]
To accomplish the above object, and light according to the drive pulse, a light source unit that writes record data to the optical recording medium, as waveform data corresponding to the mark length to be used for recording of the optical recording medium A waveform data memory for storing waveform data including data indicating rising positions and falling positions of a plurality of the drive pulses constituting the waveform data, and rising and falling positions of the drive pulses of the waveform data. A plurality of one cycle of the reference clock signal as a plurality of minute width pulses based on a decoder for outputting a plurality of decoded binary data in parallel and a reference clock signal serving as a reference for output timing of each drive pulse of the waveform data A conversion unit that generates a plurality of minute width pulses to be divided into a plurality of widths, and the conversion unit and the light source unit are connected, Said plurality of minute width pulses generated by the part having a single transmission line and transmitting serially to the light source unit, the conversion unit, the output from the decoder in response to the drive pulse of the waveform data Based on the plurality of parallel binary data, a part of a plurality of minute width pulses in a period corresponding to one period of the reference clock signal is selectively combined, and thereby the waveform A serial signal corresponding to each driving pulse of data is output, and the light source unit emits the driving pulse based on the serial signal input from one transmission path.
[0007]
According to the optical recording apparatus of the present invention, the number of pulse waveform data corresponding to the mark length set for each mark length of data to be recorded on the optical recording medium is stored in advance in the waveform data memory as waveform data, and input Corresponding waveform data is read out by searching in the waveform data memory based on the recorded data, and this waveform data is converted into a serial pulse signal through the decoding means and parallel / serial conversion means and output to the light source driving section. All the waveform data can be set centrally by one waveform data memory and sent to the light source drive unit using one transmission system to generate the optical drive signal.
Therefore, it is possible to easily generate a light source drive signal with no positional deviation for each pulse waveform, and a high-speed and highly accurate write strategy can be realized.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration example of an optical recording apparatus according to an embodiment of the present invention. The optical recording apparatus of this embodiment provides a system suitable for a write strategy for converting into an optical drive signal composed of a pulse train having a subtle width, particularly at three levels according to the recording mark length.
[0009]
First, prior to the description of the optical recording apparatus of this example, the optical drive signal will be described.
FIG. 2 is an explanatory diagram showing a reference clock and a pulse signal for optical driving used in this optical driving device.
First, in this example, 1-7 modulation is used as the light modulation method, 2T to 8T is used as the mark length, and 2T to 8T is used as the space length.
Here, assuming that the reference clock (channel clock) shown in FIG. 2A is, for example, 66 MHz, 1T is 15 nsec.
When recording one mark, a writing pulse having a number and waveform set for each mark length is output, and the laser light source is driven by this writing pulse to control the amount of heat.
[0010]
Further, the laser power of the laser light source used in this example is ternary. That is, there are three levels: an Erase level that hits the space portion, a Cool level that melts the recording layer to create an aromamorphic mark portion, and a Peak level.
Each drive current has a Peak level of MAX 200 mA and a Cool level of about 40 mA, and drives from Cool to Peak with a rise / fall period (Tr / Tf) of 1 nsec.
In addition, for each of these three values of laser power, the light source drive unit that actually performs recording also has an APC that performs feedback control.
[0011]
A write pulse for driving such a laser light source has a waveform as shown in FIG.
That is, the operation of recording a 5T mark is controlled using the timing of a total of 7 pulses including 5 pulses corresponding to 5T and one pulse before and after that, and after the Erase level, the Cool level and Peak level Are written, and the waveform then returns from the Cool level to the Erase level.
The operation of recording the 2T mark is controlled using the timing of a total of four pulses including two pulses corresponding to 2T and one pulse before and after that, and after the Erase level, the Cool level and Peak level One write pulse that repeats the above is output, and then the waveform returns from the Cool level to the Erase level.
[0012]
In the optical recording apparatus of this example, the light source drive signal as described above is generated in a state where the pulse waveform is optimized (write strategy), and waveform data for obtaining the light source drive signal as described above is generated. Based on the waveform data, a pulse signal whose rising edge and falling edge are independently controlled is generated and supplied to the light source driving unit at the subsequent stage.
Note that the target accuracy in the optical recording apparatus of this example is, for example, about 500 psec to 200 psec at the pulse edge timing.
Therefore, in order to satisfy this requirement, the IC is provided with outputs of a total of 8 systems, 4 systems with 1 / 32T accuracy corresponding to 200 pS resolution and 4 systems with 1 / 4T accuracy. Each of the eight systems has a circuit configuration using a RAM having a sufficient capacity for storing 50 kinds of independent parameters, and using a bipolar transistor for high-speed driving.
[0013]
The specific configuration and operation of the optical recording apparatus of this example will be described below with reference to FIG.
As shown in FIG. 1, the optical recording apparatus of this example includes a register unit 10, an address encoder unit 20, a RAM unit (waveform data memory) 30, a decoder (DEC) unit 40, a parallel / serial (P / S) conversion circuit 50, output circuit 60, PLL circuit 70, 16 tap ring oscillator 80, light source driver (LD driver) 90, light source (LD) 100, and the like.
Among these, the parallel / serial (P / S) conversion circuit 50, the output circuit 60, the PLL circuit 70, and the 16 tap ring oscillator 80 shown in the broken line frame A are ultra high speeds that realize the above-described 5 GHz operation for high speed driving. It is a bipolar transistor circuit part, and the other part is a circuit part made of CMOS or the like.
[0014]
Hereinafter, the components of the optical recording apparatus will be described in order.
First, the register unit 10 is a writing unit for registering setting data from the outside to the RAM unit 30 or the like via a serial interface, and is used in a setting mode different from the normal operation.
Particularly in this example, it is necessary to store waveform data as will be described later in the RAM unit 30, and the waveform data is written from the register unit 10 to the RAM unit 30 using a write clock and a write address.
In addition, the address encoder unit 20 inputs recording data (NRZI) during a normal recording operation, accesses the RAM unit 30 according to the mark length or space length indicated by the recording data, and gives the RAM unit 30 a waveform. A data read operation is executed.
A read address and a read clock are sent from the address encoder unit 20 to the RAM unit 30, and the RAM unit 30 searches the storage area based on the read address received from the address encoder unit 20, and extracts the corresponding waveform data from the decoder unit. Output to 40.
[0015]
3 and 4 are explanatory diagrams showing a configuration example of the waveform data stored in the RAM unit 30 in this example, and FIG. 3 shows a data configuration example of the two strategy mode (second mode). Shows an example of the data structure of one strategy mode (first mode).
In the waveform data of this example, 2 to 8 pulse waveform data are assigned to mark lengths from 2T to 8T, and one pulse waveform data is assigned before and after that, so that each mark length is assigned. The waveform data is configured. That is, for example, if the mark length is 2T, the waveform data is composed of four pulse waveform data, and if it is 5T, the waveform data is composed of seven pulse waveform data.
The vertical axis in FIGS. 3 and 4 indicates the mark length from 2T to 8T, and the portion where the waveform indicated by the broken line in FIGS. 3 and 4 is “H” indicates the pulse waveform data with respect to the mark length. Yes.
[0016]
The pulse waveform data for the mark length and the symbols attached to the pulse waveform data before and after the mark length indicate individual setting data set for each pulse waveform data.
For example, two pulse waveform data constituting a 2T mark length are sequentially given the symbols “2TLA2” and “2TTA1”, and the pulse waveform data before and after the two are sequentially given the symbols “2TLA1” and “2TTA2”. It is attached.
The three pulse waveform data constituting the 3T mark length are sequentially given the symbols “3T LA2”, “3T PoLA”, and “3T TA1”, and the pulse waveform data before and after that are sequentially assigned “3T LA1” and “3T”. The symbol “TA2” is attached.
The pulse waveform data distinguished by these symbols has its own setting data.
The same symbol indicates that the pulse waveform data has the same content. In particular, for data having a long mark length, the same data such as “6T CA” and “7T CA” are repeatedly used in the center portion of the mark. It has a structure.
[0017]
Further, each waveform data is composed of a plurality of pulses information corresponding to the mark length to illustrate the case of 5T mark in FIG. 2, the waveform of each pulse, the falling position and the rising position, And polarity data.
Here, the rising position and the falling position of each pulse indicate the rising position and the falling position of each pulse in a period corresponding to one cycle of the reference clock signal (Channel CLK) in FIG.
Each pulse of the LD drive current in FIG. 2B is generated by combining and selecting the timing pulse (Timing Pulse) in FIG. 5 as will be described later , and the reference clock signal (Channel CLK ) Rises and falls at a timing specified by the rising position and the falling position of each pulse of each waveform data in a period corresponding to one cycle.
For this reason, the rising position and the falling position of each pulse in each waveform data are obtained by dividing a period corresponding to one cycle of the reference clock signal (Channel CLK) into n (n is an integer of 2 or more). What is necessary is just to designate the rising timing and falling timing of each pulse.
For example, when a period corresponding to one cycle of the reference clock signal (Channel CLK) is divided into 32 , the rising position or falling position of the pulse signal may be data specifying one bit out of 32 bits. That's fine. Based on this bit designation, the parallel / serial conversion circuit 50 executes the selection process of 32 minute pulses in FIG.
32-bit data can be represented by 5- bit binary data (2 ⁵ ) .
The polarity of the pulse signal is represented by 1-bit binary data.
Therefore, in this case, each pulse waveform data is composed of data of 5 bits + 5 bits + 1 bit.
Such 11-bit waveform data is set for each memory area to which symbols such as “2T LA1” and “2T LA2” are assigned.
[0018]
Also, the 2 strategy mode shown in FIG. 3 and the 1 strategy mode shown in FIG. 4 have different contents for a mark length of 4T or more.
That is, in the one strategy mode shown in FIG. 4, the waveform data is individually set for all mark lengths from 2T to 8T, and the waveform data is stored using a larger memory capacity. .
Since the waveform data is individually set for all mark lengths from 2T to 8T, finer drive control of the LD light source 100 is performed.
On the other hand, in the 2-strategy mode shown in FIG. 3, for the mark length of 5T or more, the waveform data used at the mark length of 4T is used.
That is, the waveform data represented by the symbols “≧ 4T LA1” and “≧ 4T LA2” assigned with a mark length of 4T is used as waveform data with a mark length of 5T or more as it is. That is, the symbol “≧” added to the head of each symbol means that it is commonly used for waveform data of 4T or more.
[0019]
By using such a two-strategy mode shown in FIG. 3, the storage area in the RAM unit 30 can be saved.
In addition, for example, in the case of an optical recording medium having a structure for recording data in both lands and grooves, the optimum light source drive signal may differ between lands and grooves, and it is necessary to set waveform data individually for each. It becomes. Therefore, if the two strategy modes shown in FIG. 3 are used to set different waveform data for the land recording and the groove recording, a storage area equivalent to that for the one strategy mode is used. Therefore, it is possible to perform light source control optimized for both land recording and groove recording.
[0020]
Next, based on the waveform data read from the RAM unit 30, the decoder (DEC) unit 40 converts the pulse data into parallel binary data corresponding to each pulse waveform.
For example, when the resolution can represent the pulse width by 32 bits and the polarity is positive, the bit from the leading bit to the rising bit indicated by the pulse waveform data is “L”, and the bit from the rising bit to the falling bit is “ Outputs a parallel pulse signal such as “H” and “L” from the falling bit to the last bit. Conversely, if the polarity is negative, the bits from the leading bit to the rising bit indicated by the pulse waveform data are A parallel pulse signal such as “H”, “L” from the rising bit to the falling bit, and “H” from the falling bit to the last bit is output.
Up to this point, the operation is the reference clock (channel clock) CLK.
[0021]
Next, the parallel / serial (P / S) conversion circuit 50 converts the parallel binary signal input from the decoder unit 40 into serial data using a minute width pulse of 1/32 wavelength of the reference clock CLK. , Output to the output circuit 60.
The output circuit 60 outputs necessary signal processing such as amplification and impedance matching to the light source driving unit 90 for the serial signal from the parallel / serial conversion circuit 50.
Note that the optical recording apparatus of this example has eight outputs as described above.
This is because, for example, pulse signals having different levels such as the Erase level and Peak level shown in FIG. 2 are separately generated and synthesized by the light source driving unit 90 in the subsequent stage, or in addition to the above-described 32-bit resolution, In order to perform resolution waveform processing, a plurality of systems are prepared in parallel in the configuration after the RAM unit 30, and these are appropriately selected and used.
[0022]
The PLL circuit 70 receives and locks the reference clock CLK and supplies it to each part of the apparatus. Note that the clock CK0 shown in FIG. 1 corresponds to the reference clock CLK.
Further, the 16 tap ring oscillator 80 shifts the phase of the clock controlled by the PLL circuit 70 and synchronized with the reference clock, so that the phase is shifted by 1/32 of the clock width with respect to the reference clock by the 16 tap differential output. 32 types of phase shift clocks CK0 to CK31 are generated and output to the parallel / serial conversion circuit 50.
In the parallel / serial conversion circuit 50, a minute width pulse having a pulse width of 1/32 is generated based on 32 types of phase shift clocks whose phases are shifted by 1/32. Used to convert a parallel signal into a serial signal.
[0023]
FIG. 5 is a timing chart showing processing in the parallel / serial conversion circuit 50 for generating such a minute pulse.
As shown in the figure, the parallel / serial conversion circuit 50 has a clock width of 1/32 with respect to the reference clock by taking the phase difference between two adjacent phase shift clocks among the 32 types of phase shift clocks. 32 micro-width pulses are created.
Then, the 32 minute width pulses generated in this way are combined to form a timing pulse, and the parallel pulse signals “H” and “L” corresponding to the waveform data sent from the decoder unit 40 described above. A serial signal corresponding to the pulse waveform data is output by selectively combining minute width pulses according to the above.
As described above, in this example, it is possible to perform high-speed processing with a minute width pulse generated from the reference clock, and the burden of increasing the clock speed is reduced.
[0024]
Note that the above is an example of the present invention, and specific circuit configurations and numerical values can be modified as appropriate.
Further, the shape of the optical drive signal, the structure of the waveform data, and the like are not limited to the above example, and can be widely applied to various forms.
[0025]
【The invention's effect】
As described above, according to the optical recording apparatus of the present invention, the pulse waveform of the pulse signal set for each mark length of data to be recorded on the optical recording medium is stored in advance in the waveform data memory as waveform data, and input Based on the recorded data, the corresponding waveform data is read out by searching in the waveform data memory, and this waveform data is output to the light source driver through the decoding means and parallel / serial conversion means, so that all waveform data is waveform data It can be set centrally by the memory and sent to the light source drive unit using one transmission system to generate a light drive signal, thereby realizing a high-speed and high-accuracy write strategy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of an optical recording apparatus according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a reference clock and a pulse signal for optical driving used in the optical driving device shown in FIG. 1;
3 is an explanatory diagram showing a configuration example of waveform data stored in a RAM unit of the optical recording apparatus shown in FIG. 1. FIG.
4 is an explanatory diagram showing a configuration example of waveform data stored in a RAM unit of the optical recording apparatus shown in FIG. 1. FIG.
FIG. 5 is a timing chart showing processing for generating a minute width pulse in the parallel / serial conversion circuit of the optical recording apparatus shown in FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Register part, 20 ... Address encoder part, 30 ... RAM part (waveform data memory), 40 ... Decoder (DEC) part, 50 ... Parallel / serial (P / S) conversion circuit, 60 ... Output circuit, 70... PLL circuit, 80... 16 tap ring oscillator, 90... Light source drive unit (LD driver), 100.

Claims (10)

Emits light according to the drive pulse, a light source unit that writes record data to the optical recording medium,
As waveform data corresponding to the mark length used for recording on the optical recording medium, a waveform data memory for storing waveform data including data indicating rising positions and falling positions of the plurality of drive pulses constituting the waveform data;
A decoder for outputting in parallel a plurality of binary data obtained by decoding rising positions and falling positions of the drive pulses of the waveform data;
A conversion unit that generates a plurality of minute width pulses that divide one cycle of the reference clock signal into a plurality of minute width pulses based on a reference clock signal serving as a reference of output timing of each drive pulse of the waveform data;
A single transmission line that connects the conversion unit and the light source unit, and serially transmits the plurality of minute width pulses generated by the conversion unit to the light source unit;
The converter is
From the plurality of minute width pulses in a period corresponding to one period of the reference clock signal, a plurality of binary data output from the decoder corresponding to each drive pulse of the waveform data, A plurality of minute width pulses are selectively combined, thereby outputting a serial signal corresponding to each drive pulse of the waveform data,
The light source unit is
An optical recording apparatus that emits the drive pulse based on the serial signal input from one transmission path. The decoder
n (n is an integer of 2 or more) binary data are output in parallel,
The converter is
The optical recording apparatus according to claim 1, wherein n minute width pulses that divide one period of the reference clock signal into n are generated. The waveform data memory is
As the plurality of waveform data, the mark length is composed of a 2T (T period of the reference clock signal) to 8T, space length is stored as 1-7 modulation method consists of 2T to 8T The optical recording apparatus according to claim 1 or 2. The waveform data memory is
The optical recording apparatus according to any one of claims 1 to 3, wherein waveform data corresponding to all mark lengths used for recording on the optical recording medium is individually stored. The waveform data memory is
Of the plurality of mark lengths used for recording on the optical recording medium, individually storing waveform data corresponding to some mark lengths,
4. The optical recording apparatus according to claim 1, wherein the waveform data corresponding to the remaining mark length is generated from the waveform data corresponding to the partial mark length. 5. The waveform data memory is
The optical recording apparatus according to any one of claims 1 to 5, which stores waveform data for land recording and waveform data for groove recording of the optical recording medium. The optical recording apparatus according to claim 1, further comprising a writing unit for writing waveform data in the waveform data memory. The waveform data memory is
The optical recording device according to any one of claims 1 to 7, wherein data indicating a polarity for each pulse of each waveform data is stored. The waveform data memory, the decoder, and the conversion unit are:
Outputting a plurality of pulse signals for driving one light source unit;
The plurality of pulse signals are:
The optical recording apparatus according to claim 1, wherein the optical recording apparatus is combined by the one transmission path and serially transmitted to the light source unit. The plurality of pulse signals are:
The optical recording apparatus according to claim 9, comprising an erasing pulse signal and a recording pulse signal having different levels.

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