JPH0474780B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to an optical memory device that records, reproduces, or erases information by irradiating a recording medium with a light beam such as a laser beam.

<Prior Art> The prior art will be explained using a magneto-optical disk memory device as an example of an optical memory device. A magneto-optical disk memory device is an optical memory device that uses a magnetic film as a recording medium with an axis of easy magnetization perpendicular to the film surface, and performs recording, reproduction, or erasing by irradiating the film with a laser beam, and has attracted particular attention in recent years. ing.

The recording and reproducing method of the magneto-optical disk memory device will be explained below.

When recording in a magneto-optical disk memory device, first, a laser beam focused to a diameter of about 1 μm is intensity-modulated according to a recording signal and irradiated onto the magnetic film surface. At that time, the temperature of the magnetic film locally increases. Since the coercive force decreases in the area where the temperature has increased, when an auxiliary magnetic field in the opposite direction to the magnetization is applied from the outside at the same time as the laser beam irradiation, the direction of magnetization is reversed and information is recorded.

Also, during reproduction, the surface of the magnetic film recorded in the above manner is irradiated with linearly polarized laser light of a weaker intensity than during recording. Then, the reflected light causes a tilt in the plane of polarization due to the magneto-optical effect (Kerr effect) of the magnetic film. Information is reproduced by detecting this slope with an analyzer and converting it into the intensity of light, which is then detected with a photodetector.

Next, a data string of a reproduced signal in a general recordable optical memory device will be explained. As shown in FIG. 8, the data string of this reproduced signal is composed of a synchronizing signal section A including a sector mark indicating the starting point of a sector and an address section, and an actual data section B consisting of information.

This data string is reproduced by the information reproducing apparatus shown in FIG.

That is, first, the signal 10 detected by the reproduction head 1
1 is amplified via an amplifier 2 and a reproduced signal 102 is output. Furthermore, the signal 103 obtained via the waveform processing circuit 3 is sent to the comparator 5 and the comparison voltage detection circuit 6.
The data signal 105 is guided by the comparator 5 and compared with a comparison voltage 104, and a digital data signal 105 is output.

Next, a conventional recording, reproducing, and erasing timing control method will be explained using FIG. 9. The synchronization signal and actual data shown in FIG. 8 are reproduced by the information reproducing device 42 (shown in FIG. 7). Among these, the synchronization signal is subjected to synchronization detection in a synchronization detection circuit 43, and a synchronization detection signal 131 obtained by the circuit 43 is guided to a timing control circuit 44. The timing control circuit 44 uses the synchronization detection signal 131 as a reference to determine the recording timing signal 13.
2 and an erase timing signal 134 are sent to the information recording/erasing device 41, and a reproduction timing signal 133 is sent to the information reproducing device 42. However, this method has a problem in that when an error occurs in the synchronization detection signal 131, the reliability of the recording, reproducing, and erasing timing signals is lost.

<Object of the Invention> An object of the present invention is to provide an optical memory device that is reliable in controlling the timing of information, recording, reproduction, and erasing in view of the problems of the prior art described above.

<Example> Examples of the optical memory device according to the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a diagram showing an information reproducing device of a magneto-optical disk memory device, Fig. 2 is a diagram showing a recording area detection circuit when a peak hold circuit is used, and Fig. 3 is a diagram showing a recording area when a low-pass filter is used. FIG. 4 is a diagram showing the waveforms in FIG. 2, FIG. 5 is a diagram showing the waveforms in FIG. 3, and FIG. 6 is a diagram showing timing control for recording, playback, and erasing. be.

In addition, Fig. 1, Fig. 2, Fig. 3, Fig. 4, and Fig. 5
The same reference numerals shown in the figures represent the same thing.

In FIG. 1, a reproduction signal 101 of a data string detected by a reproduction head 1 is amplified by an amplifier 2,
This signal 102 is guided to the waveform processing circuit 3 and recording area detection circuit 6. The output signal 103 of the waveform processing circuit 3 is transmitted to the comparator 5 and the comparison voltage detection circuit 4.
is compared with the comparison voltage 104 in the comparator 5, and the digital data signal 105 is
is detected.

On the other hand, the recording area detection circuit 6 outputs a recording area detection signal 106 from the input reproduction signal 102. Here, the recording area refers to an area where the information signal is actually recorded, and here, the recording area of the synchronization signal section A and the recording area of the actual data section B are respectively detected. Note that the output signal 103 of the waveform processing circuit 3 may be input to the recording area detection circuit 6 instead of the reproduction signal 102.

Next, two specific examples of the recording area detection circuit 6 will be described. FIG. 2 is a diagram showing a recording area detection circuit using a peak hold circuit, and FIG. 3 is a diagram showing a recording area detection circuit using a low-pass filter.

First, an example of the recording area detection circuit 6 shown in FIG. 2 will be explained.

In FIG. 2, the reproduced signal 102 amplified by the amplifier 2 (see FIG. 1) is passed through the buffer 11 to the 2
input into two peak hold circuits. One side has a diode 12, a capacitor 13, and an operational amplifier 14.
The other is a positive peak hold circuit composed of a diode 15, a capacitor 16, and an operational amplifier 17. The outputs of these two peak hold circuits are input to a differential circuit composed of resistors 18, 19, 20, 21 and an operational amplifier 22, and as a result, an amplitude detection signal 113 is obtained. That is, this circuit is an amplitude detection circuit for detecting the amplitude level from the reproduced signal 102. Amplitude detection signal 113
In the comparator 24, the constant voltage V ₀ is connected to the variable resistor 2
It is compared with a comparison voltage 114 divided by 3, and a recording area detection signal 106 is output. Note that the amplitude detection signal 113 may be smoothed through a low-pass filter and guided to the comparator 24.

FIG. 4 shows signal waveforms at each part shown in FIG. 2. As shown in the figure, a reproduced signal 102 with a large amplitude is obtained only in the recording area where recording has already been performed. An amplitude detection signal 113 obtained from this reproduced signal 102 is compared with a comparison voltage 114, and a recording area detection signal 106 is output. This recording area detection signal 106 is at a high level for a period corresponding to the discharge time of the peak hold circuit in addition to the recording area, but it almost coincides with the recording area.

Next, the example shown in FIG. 3 will be described. In FIG. 3, a signal 102 amplified by amplifier 2 (see FIG. 1)
is smoothed through a buffer 31 and a low-pass filter 32, and this smoothed signal 121 is guided to a comparator 34. Comparison voltage signal 1 obtained by dividing constant voltage V ₀ by variable resistor 33 in comparator 34
22, a recording area detection signal 106 is output.

FIG. 5 shows signal waveforms at each part shown in FIG. 3. The reproduced signal 102 is passed through a low pass filter 32.
Comparison voltage 122 for signal 121 smoothed by
When compared, a recording area detection signal 106 is obtained. This recording area detection signal 106 is delayed by the transient response time of the low-pass filter 32 with respect to the recording area, but almost coincides with the recording area.

Although the two embodiments described above use DC amplifiers, the example shown in FIG. 2 can be applied to those using AC amplifiers in exactly the same way. Also,
Although an AC amplifier can also be used in the example of FIG. 3, in this case only the starting position of the recording area can be detected.

Furthermore, in the example shown in Figure 2, the amplitude level is detected using a peak hold circuit, but if a DC amplifier is used, the output of the peak hold circuit or the signal detected by using it to detect the envelope can be compared. The recording area can also be detected by inputting the signal to the device 24 (however, if an AC amplifier is used, only the starting position of the recording area can be detected).

That is, the recording area detection signal described above is a timing signal that accurately indicates the recording area or the starting position of the recording area.

Next, timing control of recording, reproduction, and erasure will be explained using FIG. 6.

Synchronization detection is performed in the synchronization detection circuit 43 using the synchronization signal part of the signal 105 reproduced by the information reproduction device 42, and the synchronization detection signal 131 is guided to the timing control circuit 44. The recording area detection signal 106 of the synchronization signal portion and the actual data portion detected by the information reproducing device 42 is also guided to the timing control circuit 44.

As shown above, in addition to the synchronization detection signal 131, by adding timing control using the recording area detection signal 106 representing the actual recording area or the beginning of the recording area, the conventional synchronization detection signal 13
It is possible to improve reliability compared to control using only 1. Further, even if an error occurs in the synchronization detection signal 131, timing control can be performed using the recording area detection signal.

In the above embodiments, a magneto-optical disk memory device was used as an example of the optical memory device.
The present invention is not limited to this, but can also be applied to optical memory devices such as optical disk memory devices and optical cards that allow additional recording or rewriting.

<Effects of the Invention> According to the present invention, by providing a recording area detection circuit, accurate recording, playback, and erasing timing can be obtained even if a synchronization detection error occurs, and a reliable optical memory device is provided. can do.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an information reproducing device for a magneto-optical memory device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a recording area detection circuit using a peak hold circuit, and FIG. 3 is a circuit diagram showing a recording area detection circuit using a peak hold circuit. A circuit diagram showing the recording area detection circuit when used, Fig. 4 is a signal waveform diagram showing the waveform in Fig. 2, Fig. 5 is a signal waveform diagram shown in Fig. 3, and Fig. 6 shows recording, reproduction, and erasing. FIG. 7 is a block diagram showing a conventional information reproducing apparatus, FIG. 8 is an explanatory diagram of a data string, and FIG. 9 is an explanatory diagram showing timing control of recording, reproduction, and erasing. In the figure, 1: reproduction head, 2: amplifier, 3: waveform processing circuit, 4: comparison voltage detection circuit, 5: comparator.
6: recording area detection circuit, 11: buffer, 12:
Diode, 13: Capacitor, 14: Operational amplifier, 15: Diode, 16: Capacitor, 1
7: Operational amplifier, 18, 19, 20, 21: Resistor, 22: Operational amplifier, 23: Variable resistor, 24:
Comparator, 31: Buffer, 32: Low-pass filter, 33: Variable resistor, 34: Comparator, 41: Information recording/erasing device, 42: Information reproducing device, 43: Synchronization detection circuit, 44: Timing control circuit.

Claims (1)

[Scope of Claims] 1. An optical memory device that records, reproduces, or erases information by irradiating a recording medium with a light beam such as a laser beam, comprising: a digital data signal detection circuit that detects a digital data signal from a reproduced signal; a recording area detection circuit that detects a recording area detection signal representing an area in which information has been recorded from a reproduction signal; a synchronization detection circuit that detects a synchronization detection signal indicating a starting point of an information block from the digital data signal; 1. An optical memory device comprising: a timing control circuit that controls timing of recording, reproduction, or erasing using a recording area detection signal. 2. The recording area detection circuit includes a peak hold circuit that detects a peak level of a reproduced signal, and a comparator that compares the output of the peak hold circuit with a comparison voltage and outputs the comparison result as a recording area detection signal. An optical memory device according to claim 1, characterized in that: 3. A first peak hold circuit in which the recording area detection circuit detects a peak level in the positive direction of the reproduction signal; a second peak hold circuit in which the recording area detection circuit detects a peak level in the negative direction of the reproduction signal; and a differential amplifier that detects the amplitude level of the reproduced signal from the output of the second peak hold circuit; and comparing the output of the differential amplifier and a comparison voltage,
The optical memory device according to claim 1, further comprising a comparator that outputs the comparison result as a recording area detection signal. 4. The recording area detection circuit includes a low-pass filter that smoothes the reproduced signal, and a comparator that compares the output of the low-pass filter with a comparison voltage and outputs the comparison result as a recording area detection signal. An optical memory device according to claim 1, characterized in that: