JPH0687324B2 - 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 synchronizer, a device using digital signal processing has been developed as a device capable of high-speed pull-in and highly stable tracking (Japanese Patent Application No. 60-228039 "Data Identification Device" Shimada).

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. 5 is a block diagram of a multiplexing device of a conventional magneto-optical disk recording / reproducing device. In FIG. 5, 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 17 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. 18 is a multiplexing circuit 17
Is an automatic gain control circuit that changes the output levels of the address signal and the data signal, which are the output signals of, according to the output signal level of the clamp circuit 20. 19 is an automatic gain control circuit 18
2 is a waveform equalization circuit that corrects the frequency characteristics of the output signal of. Reference numeral 20 is a clamp circuit which makes the output signal of the waveform equalization circuit 19 a constant level and outputs it to the analog-digital converter 21, and changes the output signal level of the automatic gain control circuit 18. 21 is a data identification device that converts the analog address signal and data signal of the clamp circuit 20 into digital signals
It is an analog-digital converter that outputs to 16. Reference numeral 16 is a data identification device for reproducing a clock from an address signal converted into a digital signal by the analog-digital converter 21 and synchronizing the data signal with the signal to process the digital signal.

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. 2 (a) and 2 (b).

The address signal and the data signal are input to the two input terminals of the multiplexing circuit 17, switched and multiplexed into one signal. 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 signal is shown in FIG. The automatic gain control circuit 18 is a multiplexing circuit
The output of 17 is amplified and the amplification degree is changed according to the output level of the clamp circuit 20. When the output waveform of the waveform equalizing circuit 19 is distorted, the amplification signal is reduced by the feedback signal of the clamp circuit 20 to prevent the distortion. The waveform equalization circuit 19 corrects the frequency characteristics of the analog address signal and the analog data signal. This is shown in FIG. The frequency bands required for the address signal and the data signal input to the data identification circuit 16 are indicated by broken lines. 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 lines, the output waveform is blunted, which adversely affects the data identification of the data identification device 16. Therefore, the waveform equalization circuit 19 eliminates the blunting of the waveform by indicating the frequency characteristic with a chain line. The output signal of the waveform equalization circuit 19 is input to the clamp circuit 20. Clamp circuit 20 is a waveform equalization circuit
The output signal of 19 is clamped at a constant level and output to the analog-digital converter 21. Further, when the signal of the waveform equalizing circuit 19 is distorted, the output signal is fed back so as to reduce the amplification degree of the automatic gain control circuit 18. The analog-digital converter 21 converts the analog address signal and the analog data signal, which are the output signals of the clamp circuit 20, into a digital signal and outputs the digital signal to the data identification device 16. Data identification circuit
At 16, the clock is regenerated from the digital address signal and the data signal is digitally processed in synchronization with the signal. The part enclosed by the broken line is where the digital signal operates, and the other part operates with the analog signal.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional configuration, since the address signal detection circuit 3 and the data signal detection circuit 4 have different DC levels, when the address signal and the data signal are multiplexed by the multiplexing circuit 17, the address The waveform of the signal changes. Further, when the frequency characteristics of the address signal detection circuit 3 and the data signal detection circuit 4 are different from each other, the signal correction of the ares signal and the data signal varies with respect to the frequency characteristics corrected by the waveform equalization circuit 19. Further, since the multiplexer is composed of analog elements such as resistors and capacitors, it has a drawback that it is not suitable for IC.

The present invention solves the above-mentioned problems of the prior art. By performing signal processing of a multiplexer by digital signal processing, the waveform of the address signal does not change even when the address signal and the data signal are multiplexed. Another object of the present invention is to provide a multiplexer for a magneto-optical disk having a structure suitable for IC by configuring most of the elements of the multiplexer with digital elements.

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 that detects a data signal from an electric signal reproduced by photoelectrically converting the reflected light of the magneto-optical disk, and the output of the address signal detection circuit is input to a first terminal. A first automatic gain control circuit for inputting the output of the first digital-analog converter to the second terminal and amplifying the output signal of the address detection circuit according to the output level of the first digital-analog converter; , The output of the data signal detection circuit is input to the first terminal, the output of the second digital-analog converter is input to the second terminal, and the second digital-analog converter is input. A second automatic gain control circuit that amplifies the output of the data signal detection circuit according to the output of the log converter, and a first analog-digital converter that analog-digital converts the signal of the first automatic gain control circuit. An analog-digital converter for converting the signal of the second automatic gain control circuit, a first digital waveform equalizing circuit for correcting the frequency characteristic of the output signal of the first analog-digital converter, and A second digital waveform equalizer circuit for correcting the frequency characteristic of the output signal of the second analog-digital converter; and a second digital waveform equalizer circuit for clamping the output signal of the first digital waveform equalizer circuit, A first digital clamp circuit for outputting to one terminal and an input terminal of the first digital-analog converter, and an output of the second digital waveform equalizing circuit A second digital clamp circuit for clamping the signal and outputting the output to the second input terminal of the digital multiplexing circuit and the input terminal of the second digital-analog converter, and the first input terminal to the first digital terminal. An output signal of the digital clamp circuit is input, and an output signal of the second digital clamp circuit is input to a second input terminal, and a digital multiplexing circuit that switches the address signal and the data signal and outputs the data signal to the data identification circuit is provided. It has a different configuration.

Operation With this configuration, a DC step between the address signal and the data signal does not occur because the address signal and the data signal are analog-to-digital converted and signal correction is performed before the signal is multiplexed before the signal is multiplexed. The waveform does not change, and since there are digital waveform equalization circuits in the two signal correction paths for the address signal and the data signal, the frequency characteristics of the address signal and the data signal do not vary, and most of the device is a digital element. Since it is composed of, the IC can be easily realized.

Example An example 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 is a magneto-optical disk which is recorded, reproduced and erased by this system. 2 is a magneto-optical disk 1
This is an objective lens that transmits the reflected light of. 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 5 designates the output level of the address signal which is the output signal of the address signal detection circuit 3 as a digital signal.
It is an automatic gain control circuit that changes according to the output signal level of the analog converter 9. 6 is a data signal detection circuit 4
Is an automatic gain control circuit that changes the output level of the data signal, which is the output signal of, according to the output signal level of the digital-analog converter 10. 7 is an automatic gain control circuit 5
Is an analog-to-digital converter that converts an analog address signal, which is an output signal of, into a digital signal. Reference numeral 8 denotes an analog-digital converter that converts an analog data signal, which is an output signal of the automatic gain control circuit 6, into a digital signal. Reference numeral 9 denotes a digital-analog converter that digital-analog converts the digital output signal of the digital clamp circuit 1 to change the output signal level of the automatic gain control circuit 5. Reference numeral 10 denotes a digital-analog converter that digital-analog converts the digital output signal of the digital clamp circuit 14 to change the output signal level of the automatic gain control circuit 6. Reference numeral 11 is a digital waveform equalization circuit for correcting the frequency characteristic of the address signal converted into a digital signal. Reference numeral 12 is a digital waveform equalization circuit for correcting the frequency characteristic of the data signal converted into the digital signal. A digital clamp circuit 13 clamps the address signal converted into a digital signal and outputs the signal to the digital multiplexing circuit 15 and the digital-analog converter 9. Reference numeral 14 is a digital clamp circuit that clamps the data signal converted into a digital signal and outputs the signal to the digital multiplexing circuit 15 and the digital-analog converter 10. A digital multiplexing circuit 15 multiplexes the digital address signal of the digital clamp circuit 13 and the digital data signal of the digital clamp circuit 14. Reference numeral 16 is a data identification device for reproducing a clock from a digital address signal and synchronizing the data signal with the signal to process the digital signal. The blocks having the same function among the blocks used in the conventional configuration shown in FIG. 5 are designated by the same reference numerals. The automatic gain control circuits 5 and 6 have the same function as the conventional automatic gain control circuit 18, and the analog-digital converters 7 and 8 have the same function as the analog-digital converter 21.

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 address signal and the data signal output at this time are analog signals, and their waveforms are shown in FIGS. 2 (a) and 2 (b).

The manner in which the waveform is corrected will be described using an address signal as an example. The analog address signal output from the address signal detection circuit 3 is amplified by the automatic gain control circuit 5. The amplification degree at that time is a level at which the address signal is not distorted in the digital clamp circuit 13, and when distorted, the output level of the digital-analog converter 9 for converting the output signal of the digital clamp circuit 13 from digital to analog is kept constant. The gain of the automatic gain control circuit 5 is reduced. The output waveform of the automatic gain control circuit 5 is shown in FIG. The analog address signal is converted into a digital signal by the analog-digital converter 7. In order to make the description of the operation easier to understand, the analog signal waveform will be used in the following description. The frequency characteristic of the digital address signal output of the analog-digital converter 7 is shown by the solid line in FIG. The frequency band required for data identification of the data identification device 16 is shown by a broken line. The digital waveform equalization circuit 11 is a device for identifying the frequency characteristics of the digital address signal output.
Correct the frequency characteristics required for 16. The waveform of the corrected digital address signal is shown in FIG. Digital waveform equalizer circuit for correction signal path of digital data signal
If the frequency characteristic of the address signal detecting circuit 3 and the frequency characteristic of the data signal detecting circuit 4 are different due to the presence of 12, then the frequency characteristic to be corrected by the digital waveform equalizing circuit 11 and the digital waveform equalizing circuit 12 is changed. You can do it.

The corrected digital address signal is clamped at the level of the chain double-dashed line by the digital clamp circuit 13 and output to the digital-analog converter 9 and the digital multiplexing circuit 15. The waveform is shown in FIG. The digital address signal output from the digital clamp circuit 13 is multiplexed with the digital data signal output from the digital clamp circuit 14 into one signal by the digital multiplexing circuit 15 and output to the data identifying device 16. The waveform is shown in FIG.

Further, in the present embodiment, the multiplexing device and the data identification device are described separately, but in the configuration of the automatic gain control circuits 5 and 6 and thereafter, since the processing is performed using the digital signal,
Analog-digital converter 7,8 in the data identification device
Of course, it is possible to add a later system.

As described above, according to the present invention, an address signal detection circuit for photoelectrically converting the reflected light of the magneto-optical disk to reproduce and detecting an address signal from an 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, the output of the address signal detection circuit is input to the first terminal, the output of the first digital-analog converter is input to the second terminal, A first automatic gain control circuit for amplifying an output signal of the address detection circuit according to an output level of the first digital-analog converter, and an output of the data signal detection circuit is input to a first terminal of a second automatic gain control circuit. The output of the second digital-analog converter is input to the terminal and the output of the data signal detection circuit is amplified according to the output of the second digital-analog converter. A gain control circuit and a first analog-analog-digital converting signal of the first automatic gain control circuit.
A digital converter, a second analog-digital converter for analog-digital converting the signal of the second automatic gain control circuit, and a first analog-digital converter for correcting the frequency characteristic of the output signal of the first analog-digital converter One digital waveform equalizer circuit, a second digital waveform equalizer circuit for correcting the frequency characteristic of the output signal of the second analog-digital converter, and an output signal of the first digital waveform equalizer circuit. A first digital clamp circuit for clamping and outputting the output to the first terminal of the digital multiplexing circuit and the input terminal of the first digital-analog converter;
A second digital clamp circuit for clamping the output signal of the second digital waveform equalization circuit and outputting the output to the second input terminal of the digital multiplexing circuit and the input terminal of the second digital-analog converter; , An output signal of the first digital clamp circuit is input to a first input terminal, an output signal of the second digital clamp circuit is input to a second input terminal, and an address signal and a data signal are switched to identify data. By providing a digital multiplexing circuit for outputting to the circuit, the DC of the address signal and the data signal for multiplexing after the analog-digital conversion and signal correction are performed before the address signal and the data signal are multiplexed. No step is generated, the waveform of the address signal does not change, and there are two digital correction paths for the address signal and the data signal. Because of the waveform equalization circuit, the frequency characteristics of the address signal and the data signal do not vary, and because most of the device is composed of digital elements, it is an excellent magneto-optical device that can easily be integrated into an IC. It is possible to realize a multiplexing device of a disk recording / reproducing device.

[Brief description of drawings]

FIG. 1 is a block diagram of a multiplexing circuit of a magneto-optical disk recording / reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform of each part of the multiplexing apparatus of the magneto-optical disk recording / reproducing apparatus of the present embodiment. FIG. 3 is a waveform diagram of each part of this embodiment, FIG. 4 is a frequency characteristic diagram of the digital waveform equalizing circuit of this embodiment, and FIG. 5 is a multiplexing device of a conventional magneto-optical disk recording / reproducing apparatus. It is a block diagram. 1 ... Magneto-optical disk, 2 ... Objective lens, 3 ... Address signal detection circuit, 4 ... Data signal detection circuit, 5 ...
Automatic gain control circuit, 6 ... Automatic gain control circuit, 7,8 ...
Analog-digital converter, 9,10 ... Digital-analog converter, 11,12 ... Digital waveform equalization circuit, 13,
14 ... Digital clamp circuit, 15 ... Digital multiplexing circuit, 16 ... Data identification device.

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, an output of the address signal detection circuit is input to a first terminal, and an output of the first digital-analog converter is input to a second terminal, a first digital-analog A first automatic gain control circuit that amplifies the output signal of the address detection circuit according to the output level of the converter, and an output of the data signal detection circuit is input to a first terminal and a second terminal is connected to a second terminal. A second automatic gain control circuit which receives the output of the digital-analog converter and amplifies the output of the data signal detection circuit according to the output of the second digital-analog converter. A first analog-digital converter for analog-digital converting the signal of the first automatic gain control circuit, and a second analog-digital conversion for analog-digital converting the signal of the second automatic gain control circuit A first digital waveform equalization circuit for correcting the frequency characteristic of the output signal of the first analog-digital converter, and a first digital waveform equalizing circuit for correcting the frequency characteristic of the output signal of the second analog-digital converter. The output signals of the second digital waveform equalizer circuit and the first digital waveform equalizer circuit are clamped, and the output is output to the first terminal of the digital multiplexing circuit and the input terminal of the first digital-analog converter. And a second digital waveform equalizing circuit for clamping the output signals of the second digital waveform equalizing circuit, and the output thereof is a digital multiplexing circuit. A second digital clamp circuit for outputting to a second input terminal and an input terminal of the second digital-analog converter; and an output signal of the first digital clamp circuit to a first input terminal, A multiplexer for a magneto-optical disk recording / reproducing apparatus, comprising: a digital multiplexing circuit for inputting an output signal of the second digital clamp circuit to an input terminal thereof and switching between an address signal and a data signal to output to a data identification circuit.