JPH0687325B2 - Multiplexer for magneto-optical disk recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplexing device of a recording / reproducing device for a magneto-optical disk.

2. Description of the Related Art In recent years, a magneto-optical disk device has been actively developed as a large-capacity data file device capable of high-density recording, erasing, and reproduction. For a data identification device of a reproduction signal, a phase synchronization that reproduces a clock in the reproduction signal. The device is being developed. As this phase synchronization device, a device using digital signal processing has been developed as a device capable of high-speed pull-in and highly stable tracking (for example, Japanese Patent Application No. 60-228039).

The multiplexing device switches the address signal and the data signal of the reproduced signal into one signal and outputs the signal to the data identification device. A multiplexing device of a conventional magneto-optical disk recording / reproducing device will be described below.

FIG. 6 is a block diagram of a multiplexing device of a conventional magneto-optical disk recording / reproducing device. In FIG. 6, 1
Is a magneto-optical disk recorded and reproduced by this system. Reference numeral 2 is an objective lens that allows the reflected light of the magneto-optical disk 1 to pass through. An address signal detection circuit 3 photoelectrically converts the reflected light of the magneto-optical disk 1 into an electric signal and detects an address signal from the electric signal. A data signal detection circuit 4 photoelectrically converts the reflected light of the magneto-optical disk 1 into an electric signal and detects a data signal from the signal. Reference numeral 8 is a multiplexing circuit for switching and outputting the address signal which is the output signal of the address signal detection circuit 3 and the data signal which is the output signal of the data signal detection circuit 4. 9 is a multiplexing circuit 8
Is a control signal input terminal to which a control signal for controlling is input. An automatic gain control circuit 10 changes the output levels of the address signal and the data signal, which are the output signals of the multiplexing circuit 8, in accordance with the output signal level of the clamp circuit 12. 11
Is a waveform equalization circuit that corrects the frequency characteristics of the output signal of the automatic gain control circuit 10. A reference numeral 12 clamps the output signal of the waveform equalizing circuit 11 to a constant level and outputs it to the analog-digital converter 14 of the data discriminating device 13, and also an automatic gain control circuit.
It is a clamp circuit that changes the output signal level of 10.
13 is an analog-digital converter 14 and a data identification circuit
The data identification device is composed of 15. Reference numeral 14 denotes an analog-digital converter which converts the analog address signal and data signal of the clamp circuit 12 into digital signals and outputs the digital signals to the data identification circuit 15. Reference numeral 15 is a data identification device for reproducing a clock from an address signal converted into a digital signal by the analog-digital converter 15 and synchronizing a data signal with the signal to perform digital signal processing.

The operation of the multiplexing device of the magneto-optical disk recording / reproducing device configured as described above will be described below.

First, the laser light incident on the magneto-optical disk 1 is deflected and reflected by the surface of the magneto-optical disk and enters the objective lens 2.
The reflected light that has passed through the objective lens 2 is an address signal detection circuit 3
And is incident on the data signal detection circuit 4. The address signal detection circuit 3 photoelectrically converts the reflected light into an electric signal and outputs the address signal. The data signal detection circuit 4 photoelectrically converts the reflected light into an electric signal and outputs the data signal.
The address signal and the data signal output at this time are analog signals, and their waveforms are shown in FIGS. 2B and 2C.

Since the address signal is a reproduction signal from the intensity modulated laser light, it can only swing to one side with respect to the DC reference level.
The frequency characteristics are also good. Since the data signal is a reproduction signal from the laser light that has been rotated by the deflection, it swings to both sides with respect to the DC reference level, but the frequency characteristic is poor.

The address signal and the data signal are input to the two input terminals of the multiplexing circuit 8, switched by the control signal from the control signal input terminal 9 and multiplexed into one signal. The signal at the control signal input terminal 9 is shown in FIG. When the control signal has the logical value "1", the address signal is output, and the logical value "0"
When, the data signal is output. At this time, since the DC levels of the address signal and the data signal are different, the waveform of the address signal changes. The waveform of the signal is shown in FIG. The automatic gain control circuit 10 amplifies the output of the multiplexing circuit 8 and changes the amplification degree according to the output level of the clapping circuit 12. When the output waveform of the waveform equalizing circuit 11 is distorted, the amplification degree is reduced by the feedback signal of the clamp circuit 12 to prevent the distortion. The waveform equalization circuit 11 corrects the frequency characteristics of the analog address signal and the analog data signal. This is shown in FIG. A frequency band required for the address signal and the data signal input to the data identification circuit 15 is indicated by a broken line. However, since the frequency bands of the output signals of the address signal detection circuit 3 and the data signal detection circuit 4 are as shown by the solid line, the output waveform is rounded and the data discrimination of the data discrimination circuit 18 is adversely affected. Therefore, the waveform equalization circuit 11 eliminates the blunting of the waveform by indicating the frequency characteristic with a chain line. The output signal of the waveform equalization circuit 11 is input to the clamp circuit 12.
The clamp circuit 12 clamps the output signal of the waveform equalization circuit 11 at a constant level and outputs it to the analog-digital converter 14. Further, when the signal of the waveform equalizing circuit 11 is distorted, the output signal is fed back so as to reduce the amplification degree of the automatic gain control circuit 10. The analog-digital converter 14 converts the analog address signal and the analog data signal, which are the output signals of the clamp circuit 12, into a digital signal and outputs the digital signal to the data identification circuit 15. The data identification circuit 15 reproduces a clock from the digital address signal and processes the data signal as a digital signal in synchronization with the clock. The part enclosed by the broken line in the figure is the place where the digital signal is operating, and the other part is operating the analog signal.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above conventional configuration, when the address signal detection circuit 3 and the data signal detection circuit 4 have different DC bells, the address signal and the data signal are multiplexed by the multiplexing circuit. Has the drawback that the waveform changes, and that the signal correction of the address signal and the data signal varies with respect to the frequency characteristic corrected by the waveform equalization circuit 11 when the frequency characteristics of the address signal and the data signal differ. Had.

The present invention solves the above-mentioned problems of the prior art, in which a DC signal is added to the address signal before the address signal and the data signal are multiplexed.
By adding levels, the waveform of the address signal does not change even when the address signal and the data signal are multiplexed, and the waveform of the data signal is equalized before the address signal and the data signal are multiplexed. A magneto-optical disk recording / reproducing apparatus in which the frequency characteristics of the address signal and the data signal are corrected after being multiplexed to eliminate the variation in the frequency characteristics of the address signal and the data signal, thereby facilitating the reproduction of the clock signal of the data identification circuit It is an object of the present invention to provide a multiplexer of the above.

Means for Solving the Problems To achieve this object, a multiplexing device of a magneto-optical disk recording / reproducing apparatus of the present invention detects an address signal from an electric signal reproduced by photoelectrically converting reflected light of a magneto-optical disk. An address signal detection circuit, a data signal detection circuit for detecting a data signal from an electric signal reproduced by photoelectrically converting the reflected light of the magneto-optical disk, and an output of the address signal detection circuit based on a control signal. A first multiplexing circuit that switches between an output signal of a DC level adding circuit that adds a DC level to the output signal of the address signal detection circuit, and a first waveform that corrects the frequency characteristic of the output signal of the data signal detection circuit. An equalizer circuit, and a second multiplexer circuit that switches between the output of the first multiplexer circuit and the output of the first waveform equalizer circuit based on the control signal. An automatic gain control circuit that controls the gain of the output of the second multiplexing circuit, a second waveform equalization circuit that corrects the frequency characteristics of the signal of the automatic gain control circuit, and an output of the waveform equalization circuit It has a configuration including a clamp circuit that clamps a signal and outputs the output to the automatic gain control circuit and the data identification device.

Function With this configuration, the DC level of the address signal and the data signal is changed before the address signal and the data signal are multiplexed, because the DC level is added to the address signal before the address signal and the data signal are multiplexed. In addition, a waveform equalization circuit that corrects the frequency characteristic of the data signal is provided before the address signal and the data signal are multiplexed, and the frequency characteristic of the address signal and the data signal is corrected after the waveform equalization circuit is multiplexed. Even when the frequency characteristics of the data signal vary, the frequency characteristics of the address signal and the data signal can be made the same so that the data identification of the data identification device can be facilitated.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a multiplexer of a magneto-optical disk recording / reproducing apparatus according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes recording / reproducing by this system.
It is a magneto-optical disk that is erased. Reference numeral 2 is an objective lens that allows the reflected light of the magneto-optical disk 1 to pass through. An address signal detection circuit 3 photoelectrically converts the reflected light of the magneto-optical disk into an electric signal and detects the address signal from the electric signal. A data signal detection circuit 4 photoelectrically converts the reflected light of the magneto-optical disk 1 into an electric signal and detects a data signal from the signal. Reference numeral 5 is a DC level adding circuit for adding a DC level to the address signal output from the address signal detecting circuit 3. Reference numeral 6 is a waveform equalization circuit for correcting the frequency characteristic of the data signal which is the output signal of the data signal detection circuit 4. Reference numeral 7 is a multiplexing circuit for switching the signals of the address signal detecting circuit 3 and the DC level adding circuit 5 with a control signal input from a control signal input terminal 9. 8 is a multiplexing circuit 7
Is a multiplexing circuit that multiplexes the address signal to which the DC level is added, which is the output signal of, and the data signal, the frequency characteristic of which is corrected by the waveform equalizing circuit 6, by the control signal of the control signal input terminal 9. Reference numeral 9 is a control signal input terminal for inputting a control signal for controlling the multiplexing circuit 7 and the multiplexing circuit 8. Ten
Is an automatic gain control circuit that changes the output levels of the multiplexed address signal and data signal which are the output signals of the multiplexing circuit 8 according to the output signal of the clamp circuit 12. Reference numeral 11 is a waveform equalization circuit that corrects the frequency characteristic of the output signal of the automatic gain control circuit. Reference numeral 12 is a clamp circuit that clamps the output signal of the waveform equalization circuit 11 to a constant level and outputs it to the automatic gain control circuit 10 and the analog-digital converter 14 of the data discriminating device 13. 13 is an analog-digital converter 14
And a data identification circuit 15 including a data identification circuit 15. Reference numeral 14 is an analog-digital converter for analog-digital converting the output signal of the clamp circuit 12. 15
Is a data identification circuit for reproducing a clock from a digital address signal and synchronizing a data signal with the signal to process the digital signal. It is to be noted that, of the conventional constituent blocks shown in FIG. 6, those having the same function are designated by the same reference numerals.

The operation of the multiplexing device of the magneto-optical disk recording / reproducing device configured as described above will be described below.

First, the laser light incident on the magneto-optical disk 1 is deflected and reflected by the surface of the magneto-optical disk 1 and enters the objective lens 2. The reflected light that has passed through the objective lens 2 enters the address signal detection circuit 3 and the data signal detection circuit 4. The address signal detection circuit 3 photoelectrically converts the reflected light into an electric signal and outputs the address signal. The data signal detection circuit 4 photoelectrically converts the reflected light into an electric signal and outputs the data signal. The waveforms of the address signal and the data signal output at this time are shown in FIGS. 2 (b) and (c). The address signal output from the address signal detection circuit 3 is multiplexed with the DC level of the DC level adding circuit 5 by the multiplexing circuit 7 controlled by the signal input to the control signal input terminal 9, and output to the multiplexing circuit 8. To be done. The signal at the control signal input terminal 9 is shown in FIG. The multiplexing circuit 7 outputs an address signal when the logical value of the control signal is "1", and when the logical value of the control signal is "0"
The DC level of the DC level adding circuit 5 is output. The waveform is shown in FIG. As shown in the figure, the address signal which is the output signal of the multiplexing circuit 7 is a signal in which the DC level shown by the broken line is added to the DC reference level. The frequency characteristic of the data signal output from the data signal detection circuit 4 is corrected by the waveform equalization circuit 6. The multiplexer circuit 8 outputs signals from the multiplexer circuit 7 and the waveform equalizer circuit 6 to a control signal input terminal 9
The output is switched to the automatic gain control circuit 10 according to the control signal. The multiplexing circuit 8 outputs an address signal when the logical value of the control signal is "1", and outputs a data signal when the logical value of the control signal is "0". The waveform is shown in FIG. The signal multiplexed by the multiplexing circuit 8 is amplified by the automatic gain control circuit 10. Waveforms of the multiplexed address signal and data signal of the multiplexing circuit 8 are shown in FIG. 3 (a) with the time axis enlarged. The amplification factor of the automatic gain control circuit 10 is a level at which the signal is not distorted in the clamp circuit 12, and when the signal is distorted, the amplification factor is reduced. The output waveform of the moving gain control circuit 10 is shown in FIG. The waveform equalization circuit 11 is an automatic gain control circuit 10
The frequency characteristic of the output signal of is corrected and output to the clamp circuit 12. The waveform equalizing circuit 6 and the waveform equalizing circuit 11 are shown in FIG. FIG. 4A shows the address signal detection circuit 3
Is the frequency characteristic of the address signal which is the output signal of
Is the frequency characteristic of the data signal which is the output signal of the data signal detection circuit 4. The data signal is first subjected to correction of frequency characteristics by the waveform equalization circuit 6. The frequency characteristic of the waveform equalizing circuit 6 is shown in FIG. Waveform equalization circuit 11 corrects the frequency characteristics of the multiplexed address signal and data signal. The frequency characteristic of the waveform equalizing circuit 11 is shown in FIG. As a result, the data signal undergoes waveform equalization by 2
This is the same as receiving the waveform equalization of the frequency characteristic shown in FIG. 4 (b). As a result, the waveform equalization circuit
Of the 11 output signals, the address signal becomes the signal having the frequency characteristic shown in FIG. 4 (c) and the data signal is shown in FIG. 4 (c).
Since the signal has the frequency characteristic of, the frequency characteristics of the address signal and the data signal are the same, and the data identification circuit
15 data can be easily identified. The address signal and data signal corrected as described above are shown in FIG.
The third address signal and the third data signal are generated by the clamp circuit 12.
It is output to the analog-digital converter 14 of the data discriminating device 13 clamped to the level shown by the chain double-dashed line in FIG. The data identification circuit 15 reproduces a clock from the address signal and digitally processes the data signal in synchronization with the signal. The part enclosed by the broken line in FIG. 1 is where the digital signal operates, and the other part operates with the analog signal.

As described above, in the present invention, an address signal detection circuit for photoelectrically converting the reflected light of the magneto-optical disk to detect an address signal from the reproduced electric signal, and photoelectrically converting the reflected light of the magneto-optical disk. A data signal detection circuit for detecting a data signal from the reproduced electric signal; an output signal of the address signal detection circuit based on a control signal; and an output signal of a DC level addition circuit for adding a DC level to the output signal of the address signal detection circuit. A first multiplex circuit for switching the output signal of the data signal detection circuit, a first waveform equalization circuit for correcting the frequency characteristic of the output signal of the data signal detection circuit, and an output of the first multiplex circuit based on the control signal A second multiplexing circuit that switches to one of the outputs of one waveform equalizing circuit, and the output of the second multiplexing circuit is input and the output of the clamp circuit is output to the second terminal. An automatic gain control circuit for controlling the gain of the signal, a second waveform equalization circuit for correcting the frequency characteristic of the signal of the automatic gain control circuit, an output signal of the waveform equalization circuit is clamped, and its output is By providing the gain control circuit and the clamp circuit for outputting to the data discriminating device, the address signal can be converted to the address signal before multiplexing the address signal and the data signal.
Since a DC level difference between the address signal and the data signal does not occur because the DC level is added and multiplexed, the waveform of the address signal does not change, and a waveform equalization circuit that corrects the frequency characteristics of the data signal before multiplexing is provided. Since there is a waveform equalization circuit that corrects the frequency characteristics of the address signal and the data signal after being provided and multiplexed, there is no variation in the frequency characteristics of the address signal and the data signal, and the data identification circuit facilitates data identification. It is possible to realize an excellent multiplexing device of a magneto-optical disk recording / reproducing device capable of doing so.

[Brief description of drawings]

FIG. 1 is a block diagram of a multiplexing device of a magneto-optical disk recording / reproducing device according to an embodiment of the present invention, and FIG. 2 is each part of the multiplexing device of an embodiment of the present invention and a conventional magneto-optical disk recording / reproducing device. Waveform diagram of FIG. 3, FIG. 3 is a waveform diagram of each part of the present embodiment, FIG. 4 is a frequency characteristic diagram of the waveform equalizing circuit of the present embodiment, and FIG. 5 is a frequency characteristic diagram of a conventional waveform equalizing circuit. , Sixth
FIG. 1 is a block diagram of a multiplexing device of a conventional magneto-optical disk recording / reproducing device. 1 ... Magneto-optical disk, 2 ... Objective lens, 3 ... Address signal detection circuit, 4 ... Data signal detection circuit, 5 ...
DC level addition circuit, 6,11 ... Waveform equalization circuit, 7,8 ... Multiplexing circuit, 9 ... Control signal input terminal, 10 ... Automatic gain control circuit, 12 ... Clamp circuit, 13 ... Data Identification device,
14 …… Analog-digital converter, 15 …… Data identification circuit.

Claims (1)

[Claims] 1. An address signal detection circuit for detecting an address signal from an electric signal reproduced by photoelectrically converting the reflected light of a magneto-optical disk, and data from an electric signal reproduced by photoelectrically converting the reflected light of the magneto-optical disk. A data signal detection circuit for detecting a signal and a control signal for switching between the output of the address signal detection circuit and the output signal of the DC level addition circuit for adding a DC level to the output signal of the address signal detection circuit. A first multiplexing circuit, a first waveform equalizing circuit for correcting the frequency characteristic of the output signal of the data signal detecting circuit, an output of the first multiplexing circuit based on the control signal, and A second multiplexing circuit that switches to one of the outputs of the first waveform equalizing circuit; an automatic gain control circuit that controls the gain of the output of the second multiplexing circuit; A second waveform equalizer circuit for correcting the frequency characteristic of the signal and a clamp circuit for clamping the output signal of the waveform equalizer circuit and outputting the output to the automatic gain control circuit and the data identification device are provided. Multiplexing device for magneto-optical disk recording / reproducing device.