JPH0536079A - Disk device - Google Patents

Abstract

PURPOSE:To prevent a direction in which data are absent from being binarized even at the time of the intrusion of a noise due to media or the like by serially connecting two diodes, in a circuit which binarizes data by the potential difference of input diodes. CONSTITUTION:A binary circuit 42(45) is constituted of a comparator 42a, resistances R31 and R32, diodes D5-D7, and capacitor C5. At that time, the light part of a data signal is easy to be affected by the influence of the noise of the return light of a laser beam, or the noise of a disk. Then, the rectification of the light direction is operated by enlarging the potential difference, and widening a margin to the noise by serially connecting the two diodes D6 and D7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device such as a magneto-optical disk device for reproducing data recorded on a magneto-optical disk.

[0002]

2. Description of the Related Art As is well known, for example, data (information) is recorded on a magneto-optical disk or is recorded on a magneto-optical disk by a laser beam and magnetism output from a semiconductor laser oscillator (light source) in an optical head. Magneto-optical disk devices for reading (reproducing) existing data have been developed.

Now, such a magneto-optical disk device is provided with a signal processing circuit for processing a data signal obtained by the optical head. Then, in the signal processing circuit, the data signal is binarized by using the binarization circuit and further demodulated by the demodulation circuit to reproduce the data (convert it to a video signal).

However, in the above-described binarization circuit, in the case where the binarization process is performed by the potential difference of the input diode, a lot of noise components such as media noise and return light noise are included in the direction in which there is no data. Therefore, there is a drawback that the bright part of the data is likely to be affected.

[0005]

As described above, in the prior art, in the case of a binarizing circuit which binarizes a data signal by the potential difference of the input diode, noise of the medium or return of laser light to a bright portion of the data. It had a drawback that it was easily affected by optical noise. So, this invention
It is an object of the present invention to provide a disk device that can obtain stable output and can achieve stable control and high performance.

[0006]

In order to achieve the above-mentioned object, in the disc apparatus of the present invention, in which the information recorded on the disc is reproduced by using the focused light, the information from the light source is The signal processing circuit comprises: an optical head that obtains an information signal by detecting the light from the disk when the light is focused and emitted; and a signal processing circuit that processes the information signal obtained by the optical head. To 2
It has a reference synthesized from the information signal to be digitized, and is connected in series so that the difference between the two signals becomes larger with respect to the direction of the potential appearing when the light amount of the light source is large than the direction of the potential appearing when the light amount is small. A / consisting of two rectifying elements
The D conversion means is provided.

[0007]

According to the present invention, since the margin for noise in binarization can be widened by the above-mentioned means, the noise of the medium or the returning light noise of the laser beam affects the bright portion of the data. Can be prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an optical disc device according to the present invention.

This disk device is different from the disk 1 composed of an optical disk or a magneto-optical disk, for example.
Data is recorded / reproduced (or erased) by using focused light. The disk 1 is rotated by a motor 2 at a constant speed, for example. The motor 2 is controlled by a motor control circuit 18.

On the surface of the disc 1, spiral grooves (recording tracks) are formed. Also, disk 1
, A plurality of sectors are assigned with the reference mark as a reference. This sector is designed to be used as an address reference.

On the disk 1, variable-length data (information) is recorded over a plurality of blocks. For example, 300,000 blocks are formed on 36000 tracks on one disk. ing.

The recording capacity of one block on the disk 1 is constant, and the number of sectors corresponding to one block decreases, for example, from the inner side to the outer side. At the start position of the block, a block header (header portion) including a block number, a track number, a sector number, etc. is recorded at the time of manufacturing the disc 1, for example. After this header part, there is a data part in which data is recorded.

If each block on the disk 1 does not end at the sector switching position, a block gap is provided so that each block always starts at the sector switching position.

Recording / reproducing (erasing) of data on the disk 1 is performed by an optical head 3 provided below the disk 1. This optical head 3
The linear motor 31 is fixed to a drive coil 13 that constitutes a movable portion. The drive coil 13 is connected to the linear motor control circuit 17.

A linear motor position detector 26 is connected to the linear motor control circuit 17. The linear motor position detector 26 outputs a position signal by detecting the optical scale 25 provided on the optical head 3.

The fixed portion of the linear motor 31 is provided with a permanent magnet (not shown). When the drive coil 13 is excited by the linear motor control circuit 17, the optical head 3 is moved in the radial direction of the disk 1.

Although the disk 1 uses a recording film for forming pits by punching holes,
It is also possible to use a recording film or a multi-layer recording film that utilizes phase change.

A recording / reproducing magnetic field generating means 35 composed of an electromagnet or a permanent magnet is arranged across the disk 1 at a portion facing the optical head 3. The recording / reproducing magnetic field generating means 35 is capable of reversing the polarity of the generated magnetic field according to a signal corresponding to writing or erasing of a pit to be recorded. The recording / reproducing magnetic field generating means 35 can also be provided on the optical head 3 side.

An objective lens 6 is held on the optical head 3 by a wire or a leaf spring (not shown). The objective lens 6 is moved in the focusing direction (optical axis direction of the lens 6) by the drive coil 5, and is movable in the tracking direction (direction orthogonal to the optical axis of the lens 6) by the drive coil 4.

On the side of the objective lens 6, there is provided a reflection plate 6a composed of a mirror or the like that moves together with the objective lens 6. Two detectors 70 and 71 fixed to the main body of the optical head 3 are provided side by side at opposite positions of the reflection plate 6a. Each of the detectors 70 and 71 includes an LED (light emitting diode) as a light emitting element and a phototransistor as a light receiving element.

These detectors 70 and 71 are provided with a light shield plate 6a.
The electric signal corresponding to the position of is output to the lens sensor processing circuit 72 as a position detection circuit. The lens sensor processing circuit 72 obtains a difference signal between the detection signals from the detectors 70 and 71, and outputs the difference signal as an electric signal of a level corresponding to the moving position of the objective lens 6, that is, a position signal. Is.

Further, the lens sensor processing circuit 72 obtains the sum signal of the detection signals from the detectors 70 and 71, and adjusts the light emission amount of the LEDs in the detectors 70 and 71 by this sum signal. ..

Laser light generated by a laser diode 9 as a semiconductor laser oscillator driven by the laser control circuit 14 is applied to the disk 1 through a collimator lens 11a, a half prism 11b and an objective lens 6. The reflected light from the disc 1 is transmitted through the objective lens 6 and the half prism 11b to the half prism 11
led to c. One of the light beams split by the half prism 11c is guided to a photodetector 8 as a pair of tracking position sensors via a condenser lens 10. This photodetector 8 has two photodiodes 8a,
8b.

On the other hand, the other light split by the half prism 11c is a condenser lens 11d and a knife edge 1.
It is guided to the photodetector 7 as a pair of focus position sensors via 2. The photodetector 7 is composed of two photodiodes 7a and 7b.

A photodiode PD for monitoring is provided near the laser diode 9 as a light emission amount detecting device for detecting the light emission amount of the laser diode 9. A monitor current as a detection signal from the photodiode PD is supplied to the laser control circuit 14.

The photodiode 8a of the photodetector 8,
8b is connected to the preamplifier circuit 36, and the photodiodes 7a and 7b of the photodetector 7 are connected to the preamplifier circuit 3
Connected to 7.

The preamplifier circuit 36 outputs a voltage signal corresponding to a data signal as header data or recording data for the write-once disc 1 according to a detection current from the photodiodes 8a and 8b, and a signal relating to a laser light tracking point. That is, the tracking signal (track difference signal) is output.

The preamplifier circuit 37 outputs a voltage signal corresponding to a data signal as recording data for a rewritable disc (magneto-optical disc) 1 by detecting currents from the photodiodes 7a and 7b, and at the same time focuses the laser beam. A signal related to a point, that is, a focusing signal (focus difference signal) is output.

The tracking signal from the preamplifier circuit 36 is supplied to the tracking control circuit 16. The track difference signal output from the tracking control circuit 16 is supplied to the linear motor control circuit 17 and the drive coil 4 in the tracking direction.

The focusing signal from the preamplifier circuit 37 is supplied to the focusing control circuit 15. The output signal of the focusing control circuit 15 is supplied to the driving coil 5 in the focusing direction, and the laser light is controlled so that the laser beam is always just focused on the disc 1.

The data signal (voltage value) from the preamplifier circuit 36 reflects the unevenness of the pits (header data or recording data) recorded on the disk (write-once optical disk) 1. This data signal is supplied to the video signal processing circuit 19 to reproduce address data (track number, sector number, etc.) as header data and image data in the video signal processing circuit 19.

The data signal (voltage value) from the preamplifier circuit 37 reflects the unevenness of the pits (recording data) recorded on the disk (rewritable magneto-optical disk) 1. This data signal is supplied to the video signal processing circuit 19, and in this video signal processing circuit 19, the image data is demodulated and reproduced.

The laser control circuit 14 causes the laser diode 9 to generate a laser beam corresponding to the reproduction light amount according to the switching signal from the CPU 23. Also, in the state where the laser light of this reproduction light amount is generated,
By driving the laser diode 9 in accordance with the recording pulse (original signal) supplied from the recording signal generation circuit 34, the laser light of the recording light amount is generated. The laser control circuit 14 includes a photodiode PD
The output light amount (reproduction light amount) of the laser diode 9 is controlled by the monitor current from the.

The recording signal generating circuit 34 modulates the recording data supplied from the magneto-optical disk control device 33 as an external device, which is provided in the preceding stage of the laser control circuit 14, through the interface circuit 32 into a recording pulse. It is a modulation circuit for.

The video signal (demodulated signal) processed by the video signal processing circuit 19 is the interface circuit 32.
After being subjected to error correction processing and the like, the data is output to the magneto-optical disk controller 33.

Further, this disk device has a focusing control circuit 15 and a tracking control circuit 1, respectively.
6. A D / A converter 22 used for exchanging information between the linear motor control circuit 17 and the CPU 23 is provided.

Further, the tracking control circuit 16 is
The objective lens 6 can be moved according to a track jump signal supplied from the CPU 23 via the D / A converter 22 to move the laser beam by one track.

The laser control circuit 14, the focusing control circuit 15, the tracking control circuit 16, the linear motor control circuit 17, the motor control circuit 18, the video signal processing circuit 19, the recording signal generating circuit 34 and the like are connected via a bus line 20. And is controlled by the CPU 23. The CPU 23 is adapted to perform a predetermined operation according to a program stored in the memory 24. FIG. 2 shows the configuration of the preamplifier circuit 36 described above.

The preamplifier circuit 36 outputs a voltage signal corresponding to a data signal or a header signal by using the currents from the photodiodes 8a and 8b forming the photodetector 8 and a voltage signal as a tracking signal. For example, the high speed amplifier 51, the low speed amplifiers 52 and 53, the differential amplifier 54, the resistors R1 to R12,
And capacitors C1 and C2.

That is, when the signals from the cathodes of the photodiodes 8a and 8b are supplied to the inverting input terminal of the high speed amplifier 51, the current flowing through the photodiodes 8a and 8b is converted into a voltage by the resistor R1.
A resistor R3 is provided on the non-inverting input end side of the high speed amplifier 51.
The potential determined by R4 is supplied. Therefore, the inverting input terminal side has the same potential. On the other hand, the anode sides of the photodiodes 8a and 8b are current / voltage converted by the low speed amplifiers 52 and 53 in order to generate a tracking signal.

Here, the power supply voltage V is applied to the preamplifier circuit 36.
By applying REF as a bias, the voltage on the non-inverting input terminal side of the high speed amplifier 51 can be increased up to about 10V. Therefore, by applying a bias of 4V to the photodiodes 8a and 8b, it becomes possible to perform processing such that the output of the high speed amplifier 51 is centered at 6V. For this reason,
The voltage on the non-inverting input terminal side of the high-speed amplifier 51 can be increased, the photodiodes 8a and 8b are reverse-biased, and the signal band can be widened.

The low-speed amplifier 52 is connected to the anode side of the photodiode 8a via a bypass means composed of the capacitor C1 and the resistor R5, and the anode side of the photodiode 8b is connected to the capacitor C2 and the resistor R8. The low-speed amplifier 53 is connected via the configured bypass means. Therefore, the photodiode 8
Even if a high-speed signal tries to flow in a and 8b, there is no path, and by passing only the high band to the capacitors C1 and C2 by the capacitor C1 and the resistor R5 and the capacitor C2 and the resistor R8, the high-speed current flows to the photodiodes 8a and 8b. Flows. As a result, the photodiodes 8a and 8b
A high-speed data signal can be taken out by the cathode side of, that is, the high-speed amplifier 51. That is, the capacitors C1 and C2
Thus, the impedance for high frequencies is lowered so that a high band signal flows through the photodiodes 8a and 8b.

The preamplifier circuit 37 is used for the photodetector 7
The voltage signals corresponding to the magneto-optical data signals are output using the currents from the photodiodes 7a and 7b that configure the above, and the voltage signal as the focusing signal is output. Is becoming FIG. 3 shows the configuration of the video signal processing circuit 19 described above.

The video signal processing circuit 19 demodulates a data signal from the preamplifier circuit 36, a header signal, or a voltage signal corresponding to the magneto-optical data signal from the preamplifier circuit 37 into a reproduction signal. Header signal processing circuit 41, binarization circuits 42, 45,
It is composed of a demodulation circuit 43, a magneto-optical data signal processing circuit 44, and a reference voltage circuit 90.

The data / header signal processing circuit 41 is capable of accurately treating the small dust adhering to the disc 1 and the scratches even when the amplitude of the data signal becomes small and the pit tip portion largely changes in level. For binarization, the peak of the pit tip is detected and the input signal is fed back to make the output pit tip level uniform.

Further, the data / header signal processing circuit 41
Is for processing the header signal or the data signal supplied from the high-speed amplifier 51 in the preamplifier circuit 36, and by applying band control to the feedback loop in addition to peak detection, it is suitable for the number of revolutions and the density. This is to allow feedback.

That is, the data / header signal processing circuit 4
As shown in FIG. 4, 1 includes a level conversion circuit 56, a detection circuit 57, an auto bias control circuit 58, and changeover switches SW1 and SW2.

The level conversion circuit 56 performs level conversion on the header signal or the data signal supplied from the high speed amplifier 51 in the preamplifier circuit 36, and is composed of, for example, an amplifier 56a, resistors R21 to R24, and a diode D1. Has been done.

The detection circuit 57 performs peak detection of the signal supplied from the level conversion circuit 56, and has resistors R25, R26 and diodes D2, D3, for example.
It is composed of D4.

The auto bias control circuit 58 is
The bias of the level conversion circuit 56 is controlled according to the peak detection signal from the detection circuit 57, and is composed of, for example, an amplifier 58a, resistors R27 to R29, a capacitor C3, and a band control capacitor C4.

Further, the automatic bias control circuit 5
Reference numeral 8 denotes a circuit for feeding back the level detection for the output signal to the input, and the feedback signal has a band in which the time constant of the peak detection and the time constant of the filter (composed of the capacitor C4) at the time of feedback are combined. Feedback control is performed. The changeover switch SW1 is a switch which is changed over by a header / data changeover signal from the CPU 23. The changeover switch SW2 is for recording / recording from the CPU 23.
It is a switch that is switched by a reproduction switching signal.

The automatic bias control circuit 5
In Fig. 8, there is a gap of about several pits between the header part and the data part, so that the response in the header part affects the next data part unless it is performed as early as possible. Therefore, the peak detection time of the data section and the peak detection time of the header section are switched by the changeover switch SW1 to improve the response to the header section. The peak detection time here is switched by changing the time constant of the level detection.

That is, the response speed of the header portion and the data portion is switched so that the response of the auto bias control circuit 58 is fast at the tip of the pit and slow at the return without the pit.

Further, the automatic bias control circuit 5
The bias in 8 is applied from + 12V and GND, which makes it unnecessary to generate the bias voltage VBias. In this case, since the power supply is directly turned on without considering the movement of VBias with respect to the power supply fluctuation, the whole can move according to the power supply, and the circuit can be simplified.

By the way, there is a signal called a sector mark at the beginning of the header portion, which has a larger amplitude than the header portion. For this reason, in order to respond to this, the time constant of peak detection is changed in the data part with respect to charging / discharging, but it is switched when the header part is entered to make the charging / discharging time the same, and Diodes D3 and D4 for this rectifying action
The two are connected in series to have a potential difference (0.7 V) to improve the response to the first sector mark of the header section. As a result, the diode forward bias can be increased and the response to the first sector mark in the header section can be improved.

Similarly for a magneto-optical (MO) signal,
The magneto-optical data signal processing circuit 44 is used to perform signal processing. At this time, the header section is processed by a separate system (data and header signal processing circuit 41), but the influence of the header section also appears on the magneto-optical signal (ideally, it does not appear at all, but the mounting error of the optical head 3). The header signal appears in the operation detection signal, etc.). Since the S / N of the header signal is larger, even a small error is at a level that cannot be ignored as compared with the magneto-optical signal.

Therefore, in order to prevent the binarization of the head portion when the magneto-optical signal comes in, it is difficult to binarize the header portion, and the bias is switched to a negligible level so as to have a fixed bias.

The magneto-optical data signal processing circuit 44 processes the magneto-optical data signal supplied from the high speed amplifier 51 in the preamplifier circuit 37. By applying band control to the feedback loop in addition to peak detection. ,
It is designed so that appropriate feedback can be performed according to the number of revolutions and the density.

That is, the magneto-optical data signal processing circuit 44
As shown in FIG. 5, for example, is composed of an adder circuit 61, a level conversion circuit 62, a detection circuit 63, an auto bias control circuit 64, and a changeover switch SW3.

The adder circuit 61 adds the header signal supplied from the high-speed amplifier 51 in the preamplifier circuit 36 and the magneto-optical signal supplied from the high-speed amplifier 51 in the preamplifier circuit 37, so that the header signal is converted from the magneto-optical signal. It outputs a magneto-optical data signal excluding the influence of the parts, and is composed of, for example, resistors R41 to R44 and a differential amplifier 61a.

The level conversion circuit 62 performs level conversion on the magneto-optical data signal supplied from the differential amplifier 61a in the adder circuit 61, and for example, the amplifier 62.
a, resistors R45 to R48, and a diode D8.

The detection circuit 63 performs peak detection of the signal supplied from the level conversion circuit 62, and is composed of, for example, resistors R49 and R50 and a diode D9.

The auto bias control circuit 64 is
The bias of the level conversion circuit 62 is controlled according to the peak detection signal from the detection circuit 63, and is composed of, for example, an amplifier 64a, resistors R51 to R53, R54, a capacitor C6, and a band control capacitor C7. ..

This automatic bias control circuit 64
Is a circuit that feeds back the level detection for the output signal to the input, and the feedback signal is in a band in which the time constant of the peak detection and the time constant of the filter (composed of the capacitor C7) at the time of feedback are combined. The feedback control is performed. The changeover switch SW3 is a switch which is changed over by a header / data changeover signal from the CPU 23.

This automatic bias control circuit 64
In the above, in the case where the detection signal for the header section is input, a signal that causes binarization is input, so that the binarization circuit 45 in the subsequent stage operates and affects the next data section. Will end up. Therefore, detection is performed in the data section, but not in the header section, and is switched by the changeover switch SW3 so as to provide feedback of the fixed bias (VR).

Further, the automatic bias control circuit 6
The bias in 4 is applied from + 12V and GND, which makes it unnecessary to generate the bias voltage VBias. In this case, since the power supply is directly turned on without considering the movement of VBias with respect to the power supply fluctuation, the whole can move according to the power supply, and the circuit can be simplified. FIG. 6 shows the configuration of the binarization circuit 42 described above.

The binarization circuit 42 binarizes the data, the data signal supplied from the header signal processing circuit 41, or the header signal. For example, the comparator 42.
a, resistors R31, R32, diodes D5, D6, D
7 and a capacitor C5.

That is, the binarization circuit 42 binarizes the signal rectified by the diodes D5, D6 and D7. The bright portion of the data signal is likely to be affected by the return light noise of the laser light and the noise of the disk (media) 1. Therefore, for rectification in the bright direction, the two diodes D6 and D7 are used to increase the potential difference and widen the margin for noise. This makes it possible to prevent binarization even if a large amount of noise components are included in the direction in which there is no data.

Further, feedback (positive feedback) is applied by the capacitor C5 so that the rectified signal (contrast of binarization) changes in the opposite direction to the changing direction of the data signal for a short period immediately after binarization. The margin for valuation spreads,
Data cracking can be prevented. The binarization circuit 45 binarizes the data signal supplied from the magneto-optical data signal processing circuit 44, and has the same configuration as the binarization circuit 42. The demodulation circuit 43 is a binarization circuit 4
The demodulated signal obtained by demodulating the binarized signal supplied from Nos. 2 and 45 is output as a reproduced signal.

The reference voltage circuit 90 generates a reference voltage VR used in each circuit in the video signal processing circuit 19, and as shown in FIG. 7, an amplifier 90a and a resistor R are used.
61 to R66.

That is, once the resistance value is sufficiently smaller than the resistance value of the voltage dividing circuit composed of the resistors R63 and R64.
If the VR voltage is generated by the voltage dividing circuit including the resistors R65 and R66 and only the changed amount is supplied from the amplifier 90a, the amplifier 90a with a small output current can be used, which is inexpensive and compact. A sufficient reference voltage VR can be generated by the amplifier 90a. As mentioned above, 2
It is possible to widen the margin for noise when digitizing.

That is, in a binarization circuit which performs binarization by a signal rectified by a diode, two diodes are used for rectification in a light direction to increase the potential difference. This makes it possible to prevent binarization even if noise due to media or the like is introduced. Therefore, it is possible to prevent the noise of the medium and the return light noise of the laser beam from affecting the bright portion of the data, and it is possible to take out a stable binary output. The present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the spirit of the invention.

[0073]

As described above in detail, according to the present invention, it is possible to provide a disk device capable of obtaining a stable output and stabilizing control and high performance.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an outline of a disk device according to an embodiment of the present invention.

FIG. 2 is a diagram similarly showing a circuit configuration of a preamplifier circuit.

FIG. 3 is a diagram similarly showing a peripheral circuit configuration related to video signal processing.

FIG. 4 is a diagram showing a circuit configuration of a data / header signal processing circuit.

FIG. 5 is a diagram similarly showing a circuit configuration of a magneto-optical data signal processing circuit.

FIG. 6 is a diagram showing a circuit configuration of a binarizing circuit.

FIG. 7 is a diagram similarly showing a circuit configuration of a reference voltage circuit.

[Explanation of symbols]

1 ... Disk, 3 ... Optical head, 6 ... Objective lens, 7,
8 ... Photodetector, 7a, 7b, 8a, 8b ... Photodiode, 9 ... Laser diode, 14 ... Laser control circuit,
15 ... Focusing control circuit, 16 ... Tracking control circuit, 17 ... Linear motor control circuit, 19 ... Video signal processing circuit (signal processing circuit), 23 ... CPU, 33 ... Magneto-optical disk control device, 34 ... Recording signal creating circuit, Three
6, 37 ... Preamplifier circuit, 41 ... Data, header signal processing circuit, 42, 45 ... Binarization circuit (A / D conversion means), 42a ... Comparator, 43 ... Demodulation circuit, 44 ... Magneto-optical data signal processing circuit , R31, R32 ... Resistance, C5 ... Capacitor, D5-D7 ... Diode (rectifying element), 90
… Reference voltage circuit.

Claims (1)

Claim: What is claimed is: 1. A disk device for reproducing information recorded on a disk using focused light, wherein the light from the disk is detected when the light from the light source is focused and irradiated. An optical head that obtains an information signal by doing so, and a signal processing circuit that processes the information signal obtained by this optical head, wherein the signal processing circuit has a reference synthesized from the information signal to be binarized, An A / D conversion unit composed of two rectifying elements connected in series so that the two signal differences are larger than the direction of the potential appearing when the amount of light of the light source is large with respect to the direction of the potential appearing when the amount of light is small. A disk device characterized by being provided.