JP2738304B2 - Signal processing method and apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk drive, and in particular, when performing sector management of information, detects a header signal and a data signal by separate light detecting means. In addition, the present invention relates to a technique suitable for processing by a common signal processing system. 2. Description of the Related Art An example of a magneto-optical information recording / reproducing apparatus for performing recording, erasing, and reproducing by a magneto-optical effect by a thermomagnetic effect is disclosed in IEICE technical report CPM83-53, pp13.
~ 19. This apparatus uses a medium in which data is recorded by a magnetization signal, and address information is recorded by a phase signal of concave and convex pits. However, no reference is made to the details of the reproduction signal detection system. SUMMARY OF THE INVENTION An object of the present invention is to provide a magneto-optical disk drive in which header information given as phase information and data information given as magnetization information are detected by separate detecting means. The present invention provides a technique suitable for processing as a series of information. That is, after the header signal and the data signal having different detection principles are detected by separate detection systems, the two signals are shared by a common signal processing system in order to simplify the circuit and reduce the cost. Processing is preferred. Therefore, structurally,
Outputs from the two signal processing systems are both input to a common signal processing system. However, these two signals are physically separated on the medium, and in principle, when the header signal is detected, the data signal is not detected, and the data signal is detected. In this case, the header signal should not be detected when the signal is detected. However, when the signals from the two detection systems are input to the signal processing system at the same time, the signal from one detection system becomes the noise component of the signal from the other detection system. There was a problem that. The present invention solves such a problem and provides a technique suitable for processing signals from two detection systems having different signal detection principles by a common signal processing system. In order to achieve the above object, a magneto-optical disk drive according to the present invention comprises a means for irradiating a recording medium with a laser beam, a method for irradiating the recording medium with a light quantity of the laser beam returning from the recording medium. A first detection system for detecting a change, a second detection unit for detecting a change in the deflection surface of the laser beam returning from the recording medium, and a switch unit to which the outputs of the first and second detection systems are input And a signal processing system for processing the output from the switch means. Preferably, based on a command from a higher-level device, a means for switching the switch means so that a signal of the first detection system is input to the signal processing system, and a timing based on the signal of the first detection system. 2
Means for switching the switch means so that the signal of the detection system is input to the signal processing system. Further, the information processing method according to the present invention is directed to a recording medium in which a header area in which a header signal is formed by uneven pits and a data area in which a data signal is recorded magneto-optically exist alternately. An information processing method for irradiating a laser beam, detecting returning light, and reproducing a signal, wherein a header signal and a data signal are detected by separate detection systems, and then both signals are switched to a common signal. Preferably, after reproducing the header signal, the signal is switched to input the data signal to the signal processing system.
After the reproduction of the data signal is completed, the signal is switched so that the header signal is input to the signal processing system. According to the above arrangement, one of the two detection means (for detecting a header signal and for detecting a data signal) can always be operated so that only one of them is input to the signal processing system. Therefore, there is no interference between signals, and signal processing with little noise can be performed. A more preferred configuration will be described below. [0010] The timing of the switching operation of the switch is obtained from the header information detecting side before entering the switching section, or the header information is always set on the side passing through the switching circuit before entering the access operation. By performing the switching operation at the timing from the detection of the sector mark after the end of the access, it is possible to provide an information sector management system capable of reliably performing the switching process even at the time of access. In the present invention, the header portion of the magneto-optical disk is of a concavo-convex type. Reproduction of the header portion detects a change in the amount of reflected light. The data section reproduces the direction of perpendicular magnetization using the magneto-optical effect. On the other hand, on the device side, a detection system for reading the header part and a detection system for reading the data part are separately provided, and an output signal from each detection system is selected by a switching circuit corresponding to the header area and the data area. In this way, it is handled as a series of information. The switching circuit is activated by directly inputting a signal detected by the detection system for reading the header section to the sector mark detection circuit and performing the timing from the mark recognition time. In the header section, management information is provided as uneven pits for the purpose of managing the transfer of information in units of sectors. The header section includes a sector mark for recognizing the start of the sector, a track number indicating the address of the sector, a sector number, a clock synchronization signal, an error correction signal, and the like. On the other hand, the range of the data part is between the header area and the next header area. In the present invention, the detection system for reading the header and the detection system for reading the data are separately provided. It is necessary to select a signal from a certain detection system. When different signals such as a phase signal and a magnetization signal are detected by separate detection systems and handled as a series of information, it is necessary to switch both signals by some method and then combine them. . There are several methods for controlling the switching operation as described below. For example, an encoder signal (pattern) for controlling rotation is provided on a disk, and the encoder signal is detected. Here, if the number and position of the encoder pattern correspond to each sector on the disk, the header area and the data area are recognized based on the timing from the edge of the encoder signal, and the detection signal from each separate photodetector is detected. The switch circuit can be operated to switch and combine. However, in this method, conditions such as that the encoder pattern and the position of each sector accurately correspond to each other, and that the operation of the timing generation circuit is stably performed without being affected by the temperature characteristics and the like, are strict, and the conditions are strict. is not. As another method, a sector mark is detected from a signal after a switch circuit for switching synthesis,
Means for switching between the header area and the data area based on the timing from the mark detection can be considered. This method is to perform its own switching operation at a timing according to its own signal. Indeed, when a certain track is constantly reproduced, the switching operation is performed normally. However, when the irradiation light amount to the disk increases, such as during recording or erasing, or when access to another track is performed. Sometimes, since the sector mark and the header signal cannot be detected, if the changeover switch is in the data area having no address information and the above processing is performed, a signal for returning the changeover switch to the header area is obtained. Therefore, a malfunction occurs, and the subsequent processing cannot be continued. Therefore, the light detection signal on the header detection side before entering the changeover switch is directly input to the sector mark detection circuit, and the changeover switch is operated at the timing from the mark detection signal. Therefore, even if the switch is located on the data area side after the access to the other track is completed, the normal switching operation is surely returned, so that the above-mentioned disadvantage can be solved, which is preferable. As another method, when entering the access process, the access must be made after the changeover switch is forcibly set so that the light detection signal on the header detection side passes therethrough. Thus, the switching operation is performed again in accordance with the header area and the data area. In this case, the detection of the sector mark is performed after the switching circuit, and the processing can be normally continued even if the switching switch is operated according to the timing from the mark detection signal. The present invention will be described below with reference to examples. First, a first embodiment will be described. FIG. 1 is a diagram showing a schematic configuration of a magneto-optical disk drive according to the present invention, in which a magneto-optical head for a magneto-optical disk and a part of a signal detection and processing system are shown. The light beam emitted from the semiconductor laser 1 is converted into a parallel beam by the collimating lens 2, and the light intensity distribution of the cross section is converted into a circular beam by the triangular prism 3. After passing through the beam splitter 4, the aperture lens 5 narrows the spot as a minute spot on the disk 6 having a recording film (perpendicular magnetization film). The electromagnetic coil 7 records,
A magnetic field for erasing is applied. Information is reproduced by detecting the Kerr rotation of the reflected light. The reflected light from the disk 6 passes through the aperture lens 5 again, is reflected by the beam splitter 4, is further reflected by the beam splitter 8, passes through the analyzer 9, passes through the lens, and passes through the photodetector. 10, the magnetization information and the header information are detected. It is convenient to provide the header information in advance in the form of concave and convex pits when the disc is created. That is, the header information is information such as a sector mark for recognizing the start position of each sector, a clocking signal, a track number, and a sector number necessary for data decoding, and generally needs to be changed by the user. This is because it does not. The light transmitted through the beam splitter 8 is split by a beam splitter 11, one of which is guided to an automatic focus control photodetector 12, and the other to a tracking control photodetector 13. For example, the light reflected by the beam splitter 11 passes through an astigmatism optical system including a spherical lens and a cylindrical lens, is partially shielded by a knife edge, and is guided to a photodetector 12 for detecting a defocus. On the other hand, the light transmitted through the beam splitter 11 is guided to a two-segment photodetector 13 for detecting track deviation via a spherical lens. The signal received by the photodetector 13 is a signal modulated in accordance with the amount of reflected light from the disk 6. That is, the header information provided on the disk 6 in the form of irregularities can be detected not only by the photodetector 10 but also by the photodetector 13. The signal light to the photodetector 13 has an advantage that it is not easily affected by the retardation of the disk 6 and the polarization due to the magnetization distribution because it does not pass through the analyzer. Therefore, it is better to use the signal of the photodetector 13 for reproducing the header information. Of course, since the magnetization information detects the rotation of the polarization plane, it is better to use the signal on the photodetector 10 side. Incidentally, a laser irradiation optical system, a magnetization signal detecting system,
The header signal detection system and the electromagnetic coil constitute a magneto-optical head, and the magneto-optical head includes a feed motor (not shown).
The disc 6 can be moved to any radial position on the disc 6. Here, the structure of the header information will be described in some detail. FIG. 2 shows a configuration example of the header information. In order to carry out the present invention, the configuration and the order are not necessarily as shown in FIG. 2, but it is convenient to provide only the sector mark at the sector head position. Further, the number of bits of each component may be arbitrary. Next, a sector mark detection circuit system will be described.
A processing method for switching the signal to the detection circuit system and switching and combining the magnetization information and the header information will be described. In FIG. 1, a signal received by a photodetector 13 for detecting a header signal is amplified to an appropriate level by an amplifier 14, and then the level is adjusted to match a level between a sector mark detection circuit 15 and a magnetization signal. The signal is branched to the variable gain amplifier 16. When the sector mark is recognized by the sector mark detection circuit 15, the timing generation circuit 17 for determining the data portion range (the range from the header portion to the beginning of the next sector) provides a switching signal 18 for the header portion and the data portion. Is generated. On the other hand, a magneto-optical signal (data signal) received by the photodetector 10 for detecting a magnetization signal is amplified by an amplifier 19 and then sent to a switch circuit 20 for switching between a header section and a data section. Thereafter, the signal is processed by the level slice circuit 21 and sent to the next processing system as a digital signal. The above is an example of the configuration for embodying the present invention, but the timing generator 17 and the switch circuit 20 will be described briefly. Since the sector mark detection circuit 15 is a known circuit and does not require any particular change in the present embodiment, the description thereof will be omitted. FIG. 3 shows an example of the switch circuit 20. The signal amplified by the header signal side amplifier 16 and the magnetization signal side amplifier 19 is
After the DC cut in each of the resistors 1202, the resistance 20
3, 204 and 205, 206, the signal is centered on the midpoint potential V / 2.
208. The opening and closing of the diode switch is performed by a digital level signal from the timing generation circuit 17. When the signal from the timing generation circuit 17 is at "L" level, the base of the transistor switch 210 is turned on by the inverter 209 because it is at high level, and the diode switch 207 is opened. On the other hand, since the base of the transistor switch 211 is at a low level, the diode switch 208 is closed. Therefore, only the header signal is transmitted to the next stage. Conversely, when the signal from the timing generation circuit 17 is at "H" level, the diode switch 207 closes and the diode switch 2
Since 08 is opened, only the data signal is transmitted to the next stage.
The signal selected by the diode switch passes through the buffer circuit 212 and is sent to the level slice circuit 21. The buffer circuit 212 has a purpose of reducing output impedance and stably transmitting a signal, and an emitter follower circuit has been described as an example. However, another circuit having the same effect may be used. In FIG. 3, the timing generation circuit 17
Is for defining the range of the data portion by a counter in response to the generation of the sector mark detection signal. That is, by counting a certain number of clocks, for example, an "L" level digital gate signal is generated for the header portion and an "H" level digital gate signal is generated for the data portion. Of course, conversely, even when the "H" level is output in the header section and the "L" level is output in the data section, the same operation can be performed by reversing the operation of the switch circuit 20. . FIG. 4 shows the switching signal 18 generated by the timing generation circuit 17 and the switching of the header section and data section signals. The switch circuit 20 shown in this embodiment
Has shown the configuration example by the diode switches 207 and 208, but a high-speed analog switch may be used. However,
The time required for the switching must be selected in consideration of the data transfer speed. For example, if the transfer speed is on the order of hundreds of kilobytes per second, the switching speed must be less than 100 nanoseconds. The selection of the switching time is determined experimentally, and is ultimately determined by checking with an actual signal processing circuit. Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram showing processing after the photodetector. The configuration before the photodetectors 10 and 13 in FIG. 1 is the same as in the second embodiment, and is therefore omitted. In FIG. 5, the magnetization information of the data area received by the photodetector 10 is amplified by the amplifier 19. On the other hand, the phase information of the header area received by the photodetector 13 is amplified by the amplifier 14, and then the variable gain amplifier 16 performs level matching with the magnetization information. After both signals are selected by the switch circuit 20, one of them is processed by the level slice circuit 21 and digitized.
The other is branched to a sector mark detection circuit 15. When a sector mark in the header is detected, the timing generation circuit 17 outputs a gate signal 18 for switching between the header area and the data area. On the other hand, since the access operation command is to be issued from the host controller (control unit), the time from when the access command signal 23 is issued to the end of the access operation is always determined by the switch control circuit 22 by the light detection. Table 13
The signal from the side passes through the switch circuit 20 so that the detection signal is input to the level slice circuit 21 and the sector mark detection circuit 15 at the subsequent stage. Then, when the access command signal 23 stops, the switch circuit 20 is returned to operate again by the gate signal 18 from the timing generation circuit 17. Here, the access command signal 23 which is not provided in the first embodiment but is added to the second embodiment is provided.
And a time chart for the gate signal 18, the switching signal 24, and the input / output signal of the switch circuit 20. FIG. 6 is a time chart showing the operation of the second embodiment. In FIG. 6, access command 2
When there is no 3, the signal is at the "H" level. When the access command 23 is "H", the gate circuit 18 generates an "L" level signal in the header area and an "H" level signal in the data area by the timing circuit 17 from the sector mark detection signal. A switching operation is performed. Here, a case where the access command 23 is generated will be considered. At this time, the access command 23 changes from “H” to “L”. At the same time, regardless of the state of the gate signal 18, the switching signal 24 is forcibly dropped to "L". Therefore, the switch circuit 20 is selected such that only the signal on the header part reading photodetector side always passes through the switch circuit 20. When the first sector mark is detected after the access operation is completed and the access command 23 returns to the "H" level, the normal switching operation before the access is repeated again. FIG. 7 is a diagram showing a configuration example of the switch control circuit 22. In FIG. 7, reference numeral 30 denotes a delay circuit using a counter or the like. When the sector mark detection signal 25 is input, a detection signal 31 delayed by the time until the beginning of the data area following the header area is output. . Since the delay detection signal 31 is input to the reset (R) terminal of the flip-flop 33 via the inverter 32, the −Q output 34 of the flip-flop 33 becomes “H”.
Level. Therefore, when a sector mark is detected, one input 34 of the AND circuit 35 is
Is at the “H” level, the gate signal 18 is output as the switching signal 24 as it is. If the access operation starts, the access command signal 23 goes low and the inverter 3
6 is applied to the trigger (T) input of the flip-flop 33. Here, D of the flip-flop 33
Since the input and the set (S) input are pulled up to the “H” level (V _OH ), the −Q output of the flip-flop 33 is driven by the rise of the T input.
It becomes “L” level. Therefore, even if the level of the gate signal 18 is "H" level, the switching signal 24
Is forcibly set to the “L” level, so that the signal on the header part detection side is set to pass through the switch circuit 20. When the sector mark detection signal 25 is detected after the access operation is completed, the operation returns to the normal switching operation corresponding to the header area and the data area. Note that the flip-flop 3 shown in the present embodiment is
3 uses a D-type flip-flop,
Other types of flip-flops may be used. Also, it is determined whether or not to insert the inverters 32 and 36 in consideration of the operation of the flip-flop to be used. FIG. 8 shows the logic operation of the switch control circuit 22 of FIG. 7 corresponding to the above description. According to the above-described embodiment, a magneto-optical disk in which the header portion is provided on the disk in the form of concave and convex pits and the data portion is recorded in the magnetization direction is provided with a photodetector dedicated to reading the header portion. In the case where the data section read-only photodetector is handled by a separate magneto-optical disk file device, the timing of switching and synthesizing the signals from both detectors is determined by the signal from the header section read-only photodetector. The effect of enabling the information sector management to be performed stably and reliably because the switching operation continues promptly even when reading of the header section is interrupted by an access operation or the like, and the operation is resumed by directly taking the information. There is. The switching timing is determined by the sector mark detected from the signal after the changeover switch. Only during access, the changeover switch is forcibly set so that the signal from the header read-only photodetector always passes. However, a similar effect can be obtained by returning to the normal switching operation at the end of the access. According to the present invention, in a magneto-optical disk drive, particularly when performing sector management of information, a header signal and a data signal are detected by separate light detecting means, and a common signal processing system is used. And can be processed stably.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a configuration example of a magneto-optical disk device according to the present invention. FIG. 2 is a conceptual diagram showing an example of an information configuration of a header section. FIG. 3 is a configuration diagram of a switching circuit between a header section and a data section. FIG. 4 is a timing chart showing an input signal and an output signal to a switching circuit and a switching operation. FIG. 5 is a block diagram showing a second embodiment of the present invention. FIG. 6 is a timing chart showing a signal switching / combining operation according to the configuration of FIG. 5; FIG. 7 is a block diagram illustrating a configuration example of a switch control circuit. FIG. 8 is a timing chart showing the operation of FIG. 7; [Description of Signs] 1 ... Semiconductor laser, 6 ... Disk, 9 ... Analyzer, 10 ...
Photodetector for magnetization signal, 13 ... Detector for header signal, 1
5: Sector mark detection circuit, 17: Timing generation circuit, 18: Switching signal, 20: Switch circuit, 207, 2
08 ... Diode switch.

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Claims (1)

(57) [Claims] Preformatted signals are formed as uneven pits
Preformat area and the data in which the data signal was recorded.
-Optical disk with data areas alternately arranged along tracks
A signal processing device for performing signal processing on a semiconductor laser
The laser light from the semiconductor laser onto the optical disc.
The optical system that irradiates as a light spot and the optical disk
Photodetector that detects the reflected light and forms a photoelectric conversion signal
And tracking the light spot based on the photoelectric conversion signal.
Tracking control means for performing the above-mentioned photoelectric conversion
Automatic focus control of the light spot based on the signal
Focus control means; and
Preformat signal detection means for detecting a mat signal
And data for detecting the data signal from the photoelectric conversion signal.
Data signal detection means and the preformat signal detection means.
The output of the stage and the output of the data signal detecting means are input
Switch means and signal processing connected to the switch means
Circuit and a specific circuit located in the preformat area.
Mark detecting means for detecting a mark.
The switch means is switched by the output of the output means.
Switching between the preformat signal and the data signal
Signal processing device for input to the signal processing circuit. 2. Preformatted signals are formed as uneven pits
Preformat area and the data in which the data signal was recorded.
-Optical disk with data areas alternately arranged along tracks
A signal processing method for signal processing a semiconductor laser
The laser light from the semiconductor laser onto the optical disc.
The optical system that irradiates as a light spot and the optical disk
Photodetector that detects the reflected light and forms a photoelectric conversion signal
And tracking the light spot based on the photoelectric conversion signal.
Tracking control means for performing the above-mentioned photoelectric conversion
Automatic focus control of the light spot based on the signal
Focus control means; and
Preformat signal detection means for detecting a mat signal
And data for detecting the data signal from the photoelectric conversion signal.
Data signal detection means and the preformat signal detection means.
The output of the stage and the output of the data signal detecting means are input
Switch means, signal processing, which is connected to the switch means
Using an optical disk device having a circuit,
The switch means is switched between the packet area and the data area.
Switch between the preformat signal and data signal
And a signal processing method for inputting the signal to the signal processing circuit.