JPH01256024A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To securely detect reproducing data by providing a recording synchronization circuit for outputting a recording signal ahead of time of the timing for an original recording beforehand in consideration of a delay due to a recording and reproducing system at the time of recording. CONSTITUTION:In the recording synchronization circuit 15, a recording fundamental clock advanced in phase more than a fundamental clock 12 is produced based on a reference pulse 13 and the fundamental clock 12, and the recording signal is synchronized by this recording fundamental clock. That is, the delay time of the recording and reproducing system is taken into consideration, and hence the recording is performed in synchronization with the time prior to the timing for the original recording beforehand. Consequently, a regenerative signal 8 is synchronized with the fundamental clock 12 which high accuracy and enough ability. By this method, the reproducing data can securely be detected so as to promote the reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical recording and reproducing apparatus in which recording and reproduction are performed in synchronization with a basic clock obtained from an optical disc.

2. Description of the Related Art In recent years, optical discs have been actively developed as large-capacity recording media. There are two types of optical discs: a pregroup method and a sample servo tracking method (hereinafter referred to as the sample servo method). Compared to the pregroup method, the sample servo method completely separates the data area and the servo area in time and space, so there is no interference between the data signal and the servo signal. Therefore, the servo characteristics do not change and are stable.

The conventional sample servo system will be described below with reference to the drawings. FIG. 6 is a block diagram of the configuration of a conventional sample servo type optical disc device. In FIG. 6, 19 is a laser diode, 20 is an optical head, 2
1 is a photodiode, 22 is an actuator, and constitutes a pickup 23. 24 is the beam spot,
25 is an optical disc. 26 is a playback signal, 27 is a synchronization signal detection circuit, 28 is a synchronization signal, 29 is a phase-locked loop (hereinafter referred to as PLL), 30 is a basic clock circuit, 31 is a servo circuit, 32 is a recording synchronization circuit, 33 is a laser A diode modulation circuit, 34 is a data detection circuit.

The operation of the sample servo type optical disc device configured as described above will be described below.

The light output from the laser diode 19 is transmitted to the optical head 2
0 is irradiated onto the optical disk 26 by the shear actuator 22 as a beam spot 24.

The light reflected on the optical disk 25 is directed back to the actuator 2.
2. It passes through the optical head 2o and reaches the photodiode 21. Photodiode 21 outputs a reproduction signal 26. The synchronization signal detection circuit 2γ detects the synchronization signal 28 from the reproduced signal 26. The frequency of the synchronization signal 26 is usually about 45K.
It is Hz.

The PLL 29 generates a basic clock 3o from this synchronization signal 28. The frequency of the basic clock 3o is usually the synchronization signal 28
It is approximately several hundred times larger than that of the previous year. The servo circuit 31 has a basic clock 3o
The actuator 22 is controlled so that the beam spot 24 is always on the track on the optical disk 25. The data detection circuit 34 samples the reproduction signal 26 in synchronization with the basic clock 3o and outputs reproduction data.

A recording synchronization circuit 32 synchronizes recording data with a basic clock 30. The laser diode modulation circuit 33 controls the output of the laser diode 19 according to this synchronized recording signal, and performs recording on the optical disc 26.

Recording and reproduction are performed in the conventional sample servo type optical disk device as described above.

Problems to be Solved by the Invention However, in the above configuration, since the basic clock 3o is synchronized with the recording signal before recording is performed, the laser diode modulation circuit 33, the pickup 23, the optical disc 26, Since there is a delay time caused by the response speed of the recording/reproducing system such as the data detection circuit 34, when a recorded signal is reproduced, the reproduced signal 26 cannot be synchronized with the basic clock 30, and the data will not be reproduced correctly. There was a danger that

FIG. 6 shows the relationship among the basic clock, recording signal, reproduction signal, and reproduction data in a conventional sample servo type optical disk device. As shown in (m), when the delay of the recording/reproducing system with respect to the recording signal P3 is T5, the reproduced signal becomes PQ. At this time, if point d is sampled by the basic clock, since the voltage at point d is higher than the threshold voltage Vth, the presence of a recording signal is detected and e is output as reproduced data. but,(
As shown in the figure, when the delay of the recording/reproducing system with respect to the recording signal P4 is T4, the reproduced signal becomes P4', and point f is sampled with the basic clock. Since the voltage at one point is lower than the threshold voltage vth, the presence of a recording signal is not detected, and g is output as reproduced data, resulting in a data detection error.

As described above, conventional sample servo type optical disk devices have the problem that if there is a large delay in the recording/reproducing system, the detection of recorded data cannot be synchronized with the basic clock, resulting in a data detection error. Ta.

In view of the above points, the present invention provides an optical system that allows the playback signal to be synchronized with the basic clock with high precision and with sufficient margin, and to ensure the detection of playback data, even in recording and playback systems with large delays due to recording and playback. The present invention provides a recording/playback device.

Means for Solving the Problems In order to solve the above problems, an optical recording and reproducing apparatus of the present invention includes a pickup for recording and reproducing information on an optical disk, and a device for obtaining a synchronization signal from a reproduction signal obtained from the pickup. a synchronous signal detection circuit, a phase-locked loop that generates a basic clock and a reference pulse from the synchronous signal, a synchronous circuit that synchronizes with the basic clock when recording information on an optical disk, and a laser diode in the pickup. a laser diode modulation circuit that controls the output of the reproducing signal; a data detecting circuit that detects information from the reproduced signal; and a data detecting circuit that detects information from the reproduced signal; The present invention is characterized in that it includes a recording synchronization circuit that outputs a recording signal at a time earlier than the timing at which recording should originally occur.

Effect of the Invention With the above-described configuration, the present invention takes into consideration the delay time of the recording/reproducing system during recording, and records in advance in synchronization with a time earlier than the timing at which it should originally be recorded, so that the reproduced signal is at a high level with respect to the basic clock. This allows synchronization to be achieved with precision and margin. Therefore, detection of reproduced data is performed reliably and reliability is improved.

Furthermore, since the delay time of the recording/reproducing system only needs to be constant, there is greater tolerance for the delay time, making it easier to design the laser diode modulation circuit, which accounts for most of the delay time, and reducing costs. It will become a reality.

Embodiment Hereinafter, an embodiment of the optical recording/reproducing apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an optical recording/reproducing apparatus in an embodiment of the present invention. In FIG. 1, 1 is a laser diode, 2 is an optical head, 3 is a photodiode, and 4 is an actuator, which constitute a big amplifier 5. 6 is a beam spot, and 7 is an optical disk. 8
is a reproduction signal, 9 is a synchronization signal detection circuit, 10 is a synchronization signal,
11 is a PLL, 12 is a basic clock, 13 is a reference pulse, 14 is a servo circuit, 15 is a recording synchronization circuit, 16 is a laser diode modulation circuit, and 17 is a data detection circuit.

The operation of the optical recording/reproducing apparatus configured as above will be explained. The light output from the laser diode 1 passes through the optical head 2 and is irradiated onto the optical disk 6 as a beam spot 5 by the actuator 4 . The light reflected on the optical disk e passes through the actuator 4 and the optical head 2 again and reaches the photodiode 3. The photodiode 3 outputs a reproduction signal 8. A synchronization signal detection circuit 9 detects a synchronization signal 1o from the reproduced signal 8.

The frequency of the synchronization signal 10 is typically about 45KH2.

The PLL 11 generates a basic clock 12 and a reference pulse 132 from this synchronization signal 10. The frequency of the basic clock 12 is usually about several hundred times that of the synchronization signal.

Further, the reference pulse 13 serves as a reference for the basic clock 12, and is usually about three times the basic clock 12.

The servo circuit 14 samples the reproduced signal 8 in synchronization with the basic clock 12 and controls the actuator 4 so that the beam spot 6 is always on the track on the optical disk 6. The recording synchronization circuit 16 uses the reference pulse 13
and basic clock 12, a recording basic clock whose phase is more advanced than that of basic clock 12 is created, and the recording signal is synchronized with this recording basic clock. FIG. 2 shows the recording synchronization circuit 15 with reference pulse 13 and basic clock 1.
FIG. 2 is a configuration diagram for generating a recording basic clock from .2.

18 is a shift register. The shift register 18 is
The basic clock a is taken in at the rising edge of the reference pulse b and is sequentially output to each output of the shift register 18. FIG. 3 shows each input/output signal of the shift register 18. Here, the reference pulse a has a frequency three times that of the basic clock b. When the output C of the second stage of the shift register 18 is selected as the recording basic clock, a pulse P1' that is delayed by 2 reference pulse clocks by -1 with respect to the basic clock a is output as the output basic clock C for recording. . Since the reference pulse a has a frequency three times that of the basic clock b, the basic clock for recording (7) H/L/,,X P
C. The phase of the next pulse P2 of the basic clock b is advanced by T when the reference pulse is 2 clocks. Therefore, the pulse P of the basic clock b
When recording in synchronization with 2, the basic recording clock 7-c
If recording is performed in synchronization with the pulse P', the recording will be performed at a time earlier by a time T corresponding to two clocks of the reference pulse.

The recording signal output from the recording synchronization circuit 15 configured as described above is sent to the laser diode modulation circuit 16 which controls the output of the laser diode 1, and is recorded on the film on the optical disc 7. Next, let's talk about playback. The data detection circuit 17 samples the reproduced signal 8 in synchronization with the basic clock 12 and outputs reproduced data. FIG. 4 shows how signals change during recording and reproduction.

When recording is performed using a recording signal synchronized with a basic recording clock whose phase is advanced by a time T1 with respect to the basic clock, a reproduced signal appears delayed by a delay time T2 of the recording/reproducing system. At this time, if T1 is set to the same time as T2, the 0 point of the reproduced signal will be sampled by the basic clock. The 0 point is the peak of the reproduced signal, and is sampled under the best conditions for the threshold voltage Vth. Therefore, the reproduced data f can be reliably obtained.

In the above embodiment, a shift register was used as the basic clock for recording, but any device having the function of delaying the basic clock may be used, for example, a delay line may be used.

Further, in the above embodiment, the recording basic clock is generated within the recording synchronization circuit, but the PLL may be provided with this function and output two clocks, the basic clock and the recording basic clock.

Further, in the above embodiment, the timing of the recording data is determined by the recording synchronization circuit, but any circuit may be used as long as it has the function of outputting the recording signal at a timing earlier than the basic clock. For example, it is also possible to obtain a recording signal by storing recording data in a -H memory and reading it out at a time earlier than the timing at which data is originally read from the memory during recording.

Furthermore, in the embodiment described above, the recording signal is output after being shifted by a predetermined time before the basic clock, but the recording signal may be provided with a function of changing this time so as to be optimal for each recording. For example, it is also possible to use a learning function that performs trial recording immediately before recording, determines the delay time of the recording/reproducing system from the reproduced signal, and performs recording.

Effects of the Invention As is clear from the above description, the present invention includes a pickup for recording and reproducing information on an optical disk, a synchronization signal detection circuit for obtaining a synchronization signal from a reproduced signal obtained from the pickup, and a synchronization signal detecting circuit for obtaining a synchronization signal from the reproduction signal obtained from the pickup. A PLL that generates a basic clock and a reference pulse, a recording synchronization circuit that synchronizes with the basic clock when recording information on an optical disk, and a laser diode modulation circuit that controls the output of a laser diode in the pickup. , a data detection circuit that detects information from the reproduced signal; and a data detection circuit that detects information from the reproduced signal, and a time that is earlier than the original timing to record in advance, taking into account the delay caused by the recording and reproduction system during recording, so that the reproduced signal is synchronized with the basic clock. By providing a recording synchronization circuit that outputs a recording signal to the base clock, the reproduced signal can be synchronized with the basic clock with high accuracy and with sufficient margin, and the excellent effect that the reproduction data can be reliably detected can be obtained.

As a result, since the delay time of the recording/reproduction system only needs to be constant, there is greater tolerance for the delay time of the recording/reproduction system, and in particular, it becomes easier to design the laser diode modulation circuit, which accounts for most of the delay time. , it is possible to achieve the effect of realizing cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an optical recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a recording synchronization circuit that generates a basic clock for recording from a reference pulse and a basic clock, and FIG. Figure 3 is a waveform diagram showing each input/output signal of the shift register, Figure 4 is a waveform diagram showing signal changes during recording and reproduction, Figure 6 is a block diagram of the configuration of a conventional sample servo type optical disc device, FIG. 6 is a waveform diagram showing the relationship among the basic clock, recording signal, reproduction signal, and reproduction data in a conventional sample servo type optical disk device. 1...Laser diode, 2...Optical head, 3...Photodiode, 4...
...Actuator, 6...Pickup, 6
...Beam spot, 7...Optical disc, 8...Reproduction signal, 9...Synchronization signal detection circuit, 1o...Synchronization signal, 11・・・・・・
PLL. 12... Basic clock, 13... Reference pulse, 14... Servo circuit, 16...
- Recording synchronization circuit, 16... Laser diode modulation circuit, 17... Data detection circuit, 18...
...Shift register. Name of agent: Patent attorney Toshio Nakao and 1 other person1-
Laser diode Figure 2 R Figure 4 19- Ray? 'diode? O-Previous Rad 21...-Huo)-Tie Auto Figure 6 <A+

Claims (1)

[Claims] A pickup for recording and reproducing information on an optical disc, a synchronization signal detection circuit for obtaining a synchronization signal from a reproduction signal obtained from the pickup, a phase-locked loop for generating a basic clock and a reference pulse from the synchronization signal, and an optical disc. a recording synchronization circuit that synchronizes with the basic clock when recording information on the pickup; a laser diode modulation circuit that controls the output of a laser diode in the pickup; and a data detection circuit that detects information from the reproduction signal. , taking into account the delay caused by the recording and reproducing system during recording so that the reproduced signal is synchronized with the basic clock,
An optical recording/reproducing device comprising: a recording synchronization circuit that outputs a recording signal at a time earlier than the timing at which it should originally be recorded.