JPH08115521A - Optical recording/reproducing system - Google Patents

Abstract

PURPOSE: To provide an optimum recording power by setting the constant of a waveform equalizing circuit according to the ratio between amplitudes of regenerative signals of the shortest mark and a sufficiently long mark. CONSTITUTION: In the optical recording/reproducing system, test write is performed previously to recording of recording information, and for setting optimum light power at a recording time, the recording of a recording mark pattern for test writing constituted of combination between the shortest mark 2T supplied from a recording control circuit 12 and the mark 8T sufficiently longer than the shortest mark is performed on an optical disk 10 through an optical head 11. Then, after the test write data are read out from the optical disk 10 through the optical head 11, they are supplied to an amplitude comparison circuit 14 through an amplifier 13. A focus offset setting circuit 15, to which a comparison output A/B outputted from the amplitude comparison circuit 14 is supplied, sets a focus offset corresponding to the comparison output A/B value to supply it to the optical head 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus for recording and reproducing digital information on an optical recording medium such as an optical disk, and more particularly, it can increase the margin in mark edge recording to improve reliability. The present invention relates to an optical recording / reproducing system.

[0002]

2. Description of the Related Art Conventionally, so-called mark position recording has been performed in an optical disk device so that the center position of a recording mark has information. That is, in this mark position recording, a laser beam is pulsed to form a recording mark corresponding to "1" of the information bit, and at the time of reading, the center of the mark, that is, the peak position of the reproduction signal is "1". ", And the others are set to" 0 ".

On the other hand, in recent years, mark edge recording in which information is provided at the edge of the recording mark has been put into practical use in order to improve the recording density. In this mark edge recording method, since the information bit "1" corresponds to the edge portion of the recording mark, twice the information can be recorded with the same mark length as in the mark position recording described above.

However, the problem of mark edge recording is
This is because the length of the mark tends to fluctuate, and if the length of the mark fluctuates, the position of the edge shifts, making it impossible to read information accurately.

In this case, the length of the mark varies depending on the optical power during recording, and the optimal optical power during recording varies depending on the sensitivity of the optical recording medium and temperature change. For this purpose, for example, JP-A-4-61028 and JP-A-4-61028.
As shown in Japanese Patent No. 137224, it is necessary to perform trial writing frequently and control so that recording can always be performed with an optimum optical power.

[0006]

However, such mark edge recording is not only sensitive to the fluctuation of the optical power at the time of recording, but also the recording density is reduced, so that the jitter becomes relatively large and the recording / reproducing of There is a problem that the margin becomes small.

In particular, when defocus occurs, not only the power becomes insufficient because the optical power density at the time of recording decreases, but also the resolution at the time of reproducing decreases, and reading errors easily occur.

In this case, defocusing occurs due to various factors such as the difference in the substrate thickness of the optical disk, temperature change, and secular change. Therefore, suppressing this is a very important technique for mark edge recording.

Therefore, the present invention has been made in view of the above points, and not only controls the optical power at the time of recording to an optimum state by a simple method, but also checks the state of the focus offset. Optical recording / reproducing system that can improve the reliability by increasing the margin in mark edge recording by preventing defocusing or adjusting the waveform equalization during reproduction optimally. The purpose is to

[0010]

According to the present invention, in order to solve the above-mentioned problems, an apparatus for recording and reproducing digital information on an optical recording medium, wherein information of "1" and "0" is recorded. In a recording / reproducing apparatus represented by the position of the edge of a mark, a signal of a pattern consisting of a combination of a shortest mark and a mark sufficiently longer than that is trial-written before recording information, and the amplitude and DC component of the reproduction signal of each mark are recorded. There is provided an optical recording / reproducing system characterized by obtaining the optimum recording power and focus offset from the above.

Further, according to the present invention, there is provided an optical recording / reproducing system characterized in that the constant of the waveform equalizing circuit is set according to the ratio of the reproduction signal amplitudes of the shortest mark and the sufficiently long mark. It

Further, according to the present invention, there is provided an apparatus for recording and reproducing digital information on an optical recording medium, the apparatus comprising "1",
In a recording / reproducing apparatus in which information of "0" is represented by the position of the edge of a recording mark, two beams, front and rear, are irradiated on the same track of the optical recording medium, and recording is performed by the front beam, and then by the rear beam. The optical recording / reproducing is characterized in that the reproduction is performed and the focus offset is adjusted by detecting the amplitude or DC component of the reproduced signal immediately after recording, and the power is adjusted by judging whether or not the power is optimum. A scheme is provided.

[0013]

According to one aspect of the present invention, the amplitude of the reproduction signal of the shortest recorded mark and the amplitude of the reproduction signal of a sufficiently long mark are compared and electrically offset so that the difference between them is minimized. Is adjusted so that defocus does not occur, and the recording power is adjusted so that the DC components of both are equal. Further, the waveform equalization circuit is controlled so as to perform the most appropriate waveform equalization based on the ratio of the amplitudes of the both.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows a recording mark pattern of trial writing applied to the present invention and a reproduction waveform thereof.

That is, in mark edge recording of 1-7 modulation, the shortest mark is 2T and the longest mark is 8T.
Here, T is the period of the channel clock, so 2T
As shown in FIG. 1, the repeated reproduction signal has a smaller amplitude than that of 8T due to the limitation of the resolution of the optical system.

Here, assuming that the respective amplitude voltages are A and B, A / B represents the resolution of the reproducing system. Further, whether or not the recording is optimally performed with the optical power can be known by observing the amplitude center of the reproduction signal of each mark, that is, the difference between the DC components.

For example, if the recording is performed with the optimum optical power, the lengths between the marks become equal,
At this time, the DC component 1 of the reproduction signal of 2T coincides with the center of the saturation level between the mark portion and the mark portion, so that the DC component of 8T
Matches component V2.

Therefore, by comparing the reproduction amplitude voltages A and B of 2T and 8T and detecting the point where A / B has the maximum resolution, the optimum focus state without defocus can be obtained.

Further, the DC of each of the reproduction signals of 2T and 8T described above.
By comparing the components V1 and V2 and detecting the substantially coincident point where V1 = V2, the optimum optical power at the time of recording can be set.

FIG. 2 shows the essential points of the optical recording / reproducing system of the first embodiment according to the present invention for performing the optimum optical power setting during recording and the optimum focus control without defocus based on the above principle. It is a block diagram which shows the structure of a part.

That is, at the time of recording, the recording information from the recording control circuit 12 is recorded on the optical disk 10 via the optical head (PU) 11. Also, when reproducing, the optical head 11
The reproduction signal read from the optical disk 10 via the amplifier is supplied to the binarization circuit 21 via the amplifier 13 and the waveform equalization circuit 20, and the binarized reproduction signal is supplied to a reproduction signal processing system (not shown). Supplied.

In this optical recording / reproducing method, trial writing is performed prior to the recording of the record information to set the optimum optical power at the time of the recording, as shown in FIG. The recording mark pattern for trial writing, which is a combination of the shortest mark (2T) and the mark (8T) sufficiently longer than that, is recorded on the optical disk 10 via the optical head 11.

The test write data is read from the optical disk 10 via the optical head 11 and then supplied to the amplitude comparison circuit 14 via the amplifier 13. The focus offset setting circuit 15 to which the comparison output A / B output from the amplitude comparison circuit 14 is supplied sets a focus offset corresponding to the comparison output A / B value and supplies the focus offset to the optical head 11.

Further, the maximum resolution detecting circuit 16 which receives the output of the amplitude comparing circuit 14 detects that the comparison output A / B becomes maximum, and the focus offset setting circuit 1
5 is instructed to fix the focus offset at that time as the optimum focus state thereafter.

After fixing the optimum focus offset in this way, the optical power is changed to perform the test writing as described above, and the test writing data is reproduced for each optical power.

The reproduced signal of the trial writing data is the amplifier 1
Is supplied to the DC component comparison circuit 17 via
Based on the output of the component comparison circuit 17, the recording power setting circuit 18 until the match (V1−V2 ≦ V, V is a predetermined value close to 0) between V1 and V2 is detected by the match detection circuit 19.
Command the optical head 11 to change the optical power.

Then, the coincidence detection circuit 19 is operated by the V1.
The optical power at the time when the coincidence between V2 and V2 is detected is the optimum power for recording, and the recording power setting circuit 18 is instructed to fix the optical power value at that time.

FIG. 3 is a flow chart showing the operations of the optimum focus offset control and the optimum optical power setting during recording by the above optical recording / reproducing system.
First, recording is performed at a predetermined location on the optical disc 10 with the above-described recording mark pattern (step S1). Then, it is reproduced and the above A / B is measured (step S2).

Next, an offset voltage is applied to the focus and A / B is measured again (steps S3 and S4). At this time, as shown in FIG. 6, A / B changes according to the defocus amount.

Therefore, by finding the point where A / B becomes maximum while changing the offset voltage, the in-focus state can be obtained (step S5). Then, after fixing the focus offset in the optimum state, the recording power is changed to perform the trial writing, and the optimum power is determined by matching V1 and V2 (V1−V2 ≦ V) (steps S6 to S10). ).

According to the present embodiment, the trial writing allows the optimum focusing state to be always set, and the optimum recording power can be set. Further, in addition to the present embodiment, the waveform equalization circuit 20 in the reproducing circuit can be optimally set.

That is, normally, the waveform equalizer circuit 20 has a function of electrically increasing the gain of a high frequency in order to supplement the resolution of the optical system, but the resolution of the optical system is not uniform, so It is possible to further improve the performance of the reproducing system by readjusting the frequency and gain of the waveform equalizing circuit 20 according to the final result of A / B.

Next, a second embodiment of the present invention will be described. In this embodiment, as shown in FIG. 4, a two-beam optical system is used as the optical head 11 of FIG. 2, and a spot for recording and a spot for reproducing are irradiated on the same track of the optical disc so that reproduction is performed immediately after recording. To do.

In this case, the head portion of the sector is the VFO area, and the 2T signal of the shortest mark is recorded in the 1-7 modulation format. Therefore, if the DC component of the 2T signal coincides with the center of the saturation level between the mark portion and the mark portion, it means that the recording was performed with the optimum power.

Therefore, for example, as shown in FIGS. 4 and 5, a 8T repetitive signal is recorded at the head of the VFO, and the power component is corrected in real time so that the DC component of the reproduced signal becomes equal to the DC component of the 2T signal. I do.

Although the length of this VFO is standardized to 20 bytes or more, the distance between the recording spot and the reproducing spot is about 10 μm. This is at most 2
Since this corresponds to ~ 3 bytes, it can be sufficiently processed in the VFO area.

Also in the second embodiment, it is possible to adjust the focus offset before setting the power, as in the first embodiment. Further, in order to obtain the reference of the DC component, the DC component of the reproduced signal of the data part of the immediately preceding sector may be used as shown in FIG. 5, instead of using the head portion of the VFO.

In this case, there is no need to record a special signal in the VFO section, which is advantageous in terms of compatibility. Thus, the RAW (Read After) using two beams as in the present embodiment is performed.
By applying the present invention to an apparatus that performs write, it is possible to control the recording power and the focused state accurately in real time without performing trial writing.

According to the present invention, in addition to the above-mentioned claims, the optical recording is characterized in that, during the trial writing, the optimum focus offset is obtained, and then the trial writing is performed again to determine the optimum power. A playback method is provided.

Further, according to the present invention, the above adjustment is performed in the VFO portion at the head of the recorded information in the sector, a sufficiently long mark is recorded before the VFO signal, and the reproduced signal and V
There is provided an optical recording / reproducing system characterized by using a reproduction signal of FO.

Further, according to the present invention, the above adjustment is performed in the VFO portion at the head of the recorded information in the sector, and the reproduced signal of the VFO portion and the reproduced signal of the rear portion of the information of the immediately preceding sector are used. An optical recording / reproducing system is provided.

[0042]

As described in detail above, according to the present invention,
When performing mark edge recording, not only it is possible to control to the optimum recording power, but it is also possible to control the focus offset to achieve the optimum in-focus state and expand the margin in recording and reproduction. Thus, it is possible to provide an optical recording / reproducing system capable of improving reliability.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the principle of the first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a main part of the first embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the first embodiment of the present invention.

FIG. 4 is a diagram for explaining the principle of the second embodiment of the present invention.

FIG. 5 is a diagram for explaining the principle of the second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a defocus amount and a reproduction amplitude value ratio (A / B).

[Explanation of symbols]

10 ... Optical disc, 11 ... Optical head (PU), 12 ...
Recording control circuit, 13 ... Amplifier, 14 ... Amplitude comparison circuit, 1
5 ... Focus offset setting circuit, 16 ... Maximum resolution detection circuit, 17 ... DC component comparison circuit, 18 ... Recording power setting circuit, 19 ... Match detection circuit, 20 ... Waveform equalization circuit,
21 ... Binarization circuit.

Claims (3)

[Claims] 1. A recording / reproducing apparatus for recording and reproducing digital information on an optical recording medium, wherein the information of "1" and "0" is represented by the position of the edge of a recording mark. An optical system characterized in that a signal of a pattern composed of a combination of a shortest mark and a mark sufficiently longer than that is trial-written, and an optimum recording power and focus offset are obtained from the amplitude and DC component of the reproduction signal of each mark. Recording / playback method. 2. The optical recording / reproducing system according to claim 1, wherein the constant of the waveform equalizing circuit is set according to the ratio of the reproduction signal amplitudes of the shortest mark and the sufficiently long mark. 3. A recording / reproducing apparatus for recording and reproducing digital information on an optical recording medium, wherein the information of "1" and "0" is represented by the position of the edge of a recording mark. The optical recording medium is irradiated on the same track, recording is performed by the front beam, and then reproduction is performed by the rear beam, and the focus offset adjustment is performed by detecting the amplitude or DC component of the reproduction signal immediately after recording. An optical recording / reproducing system characterized in that the power is adjusted while determining whether the power is optimum or not.