JP3788664B2 - Recording / playback device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention is optimal for an optical recording medium using magnetic super-resolution in which an aperture (opening) smaller than the spot area of a light beam is generated on the optical recording medium by applying an external magnetic field. The present invention relates to a recording / reproducing apparatus that performs test write or test read for obtaining a proper recording / reproducing condition.
[0002]
[Prior art]
  In recent years, in order to improve the recording density, a reproducing layer is provided on the recording layer, an opening smaller than the spot area of the light beam (hereinafter referred to as an aperture) is generated in the reproducing layer, and the mark on the recording layer is increased. Optical recording media that are read at a density have been developed. For example, a magneto-optical recording medium disclosed in Japanese Patent Laid-Open No. 3-93056 includes a recording layer for recording a recording mark, a reproducing layer to which the recording mark is transferred by exchange coupling with the recording layer, a recording layer, and a reproducing layer. By having a multilayer structure with a cutting layer that cuts the exchange coupling force with the layer, when reproducing, by applying a reproducing magnetic field and generating a magnetic super-resolution using the high temperature part generated behind the light spot as a mask, High-density recording marks are being played back.
[0003]
  This method is generally called FAD (Front Aperture Detection) because an aperture is generated in front of the light spot. In addition, CAD (Center Aperture Detection) in which an aperture is generated in the center of the light spot, RAD (Rear Aperture Detection) in which an aperture is generated in the center, and the like are known.
[0004]
  In these discs, a portion of the light spot is masked by a high temperature portion in the reproducing layer, so that a recording mark is read out by a portion smaller than the spot area, a so-called aperture. At this time, since the size of the high-temperature portion varies due to changes in the environmental temperature and variations in disk characteristics, the aperture area also varies accordingly. For this reason, it is necessary to control the size of the aperture and perform stable reproduction.
[0005]
  For example, in the test read method disclosed in Japanese Patent Laid-Open No. 8-63817 as a method for controlling the aperture in the CAD system, the short mark and the long mark are reproduced so that the amplitude ratio of the reproduction signal is constant. The size of the aperture was controlled by controlling the amount of reproduction light. Since this method controls the size of the high-temperature portion by controlling the amount of reproduction light, it can be used in the RAD method as well as other FAD methods.
[0006]
  Further, the change in the environmental temperature and the variation in the characteristics of the disc described above are not limited to the time of reproduction, and the size of the recording mark at the time of recording is also changed. As a method for recording a fixed recording mark on a conventional optical recording medium in which magnetic super-resolution does not occur, there is a test write method disclosed in Japanese Patent Laid-Open No. 7-249226. In this method, a test pattern is recorded in advance while changing the recording light quantity, and the recording light quantity is controlled so that a test signal reproduced from the test pattern has an optimum signal level.
[0007]
[Problems to be solved by the invention]
  However, in the above-described conventional configuration, when the above-described test lead is performed on an optical recording medium that generates magnetic super-resolution, if the recording mark is accurately recorded in advance, it can be controlled to an optimum reproduction light amount. When a recording mark having an inaccurate size is recorded due to a change in the environmental temperature described above, there arises a problem that the reproduction light amount is controlled to be incorrect.
[0008]
  For this reason, a method of controlling the recording light amount in advance for an optical recording medium in which magnetic super-resolution is generated by a conventional test light can be considered. However, when the recording state is detected by reproducing the test pattern, the size of the aperture fluctuates due to the above-described change in the environmental temperature, which causes a problem of detecting an erroneous recording state.
[0009]
  In other words, even if a conventional test write is performed on the optical recording medium that produces the above super-resolution, the recording light quantity cannot be optimally controlled, so that a recording mark of an accurate size cannot be recorded. However, there is a problem that the amount of reproduction light cannot be optimally controlled.
[0010]
  The present invention has been made to solve the above-mentioned problems, and its purpose is to perform test writing and test reading without being affected by fluctuations in environmental temperature, etc., and to determine optimum recording conditions and reproduction conditions. An object of the present invention is to provide a recording / reproducing apparatus that can be obtained.
[0011]
[Means for Solving the Problems]
  Of the present inventionThe recording / reproducing apparatus has a recording layer for recording a recording mark, a reproducing layer in which information magnetically recorded on the recording layer is transferred by an exchange coupling force through a cutting layer, and when a light beam is irradiated. While applying an external magnetic field to a magneto-optical recording medium having a multilayer structure of a recording layer and a cutting layer that cuts the exchange coupling force of the reproducing layer in a region where the temperature exceeds a predetermined temperature. Irradiate the playback layer with a light beaminformationIn order to solve the above problems, a recording means for recording information on an optical recording medium, a reproducing means for reproducing information on the optical recording medium, and an optical recording medium A magnetic field applying means for applying an external magnetic field, a reproduction signal detecting means for detecting a signal level of a reproduction signal obtained by reproduction by the reproducing means, and controlling the recording means to record information on the optical recording medium, When the information is reproduced by controlling the reproduction means and the signal level of the reproduction signal is detected by the reproduction signal detection means,In order to be able to reproduce both with and without external magnetic field,And a control means for controlling the magnetic field applying means so that the external magnetic field is selectively applied.
[0012]
  According to the above configuration, the control unit controls the recording unit to record information on the optical recording medium and causes the reproducing unit to reproduce the information. When it is desired to detect the signal level of the reproduction signal during information reproduction, the control means can selectively apply an external magnetic field by controlling the magnetic field application means. The reproduction signal detection means detects the level of the reproduction signal obtained by reproduction.
[0013]
  As a result, when information is read out, that is, during normal reproduction, by applying an external magnetic field, an aperture can be generated in the reproduction layer of the optical recording medium, and high-resolution reproduction can be performed at the same time. By reproducing the information without applying a magnetic field and detecting the level of the reproduced signal by the reproduced signal detecting means, it is possible to reproduce without generating an aperture. The recording state of the recording mark on the optical recording medium can be detected without being affected by disc variations.
[0014]
  Further, for example, the level of a reproduction signal when information is reproduced while applying an external magnetic field and the level of a reproduction signal when information is reproduced without applying an external magnetic field are detected, and these are detected. By comparing, it is possible to accurately detect a change in resolution from the reproduction signal.
[0015]
  The present inventionThe recording and playback devicefurther,A test signal generating means for generating a test signal; and a recording condition setting means for setting a recording condition, wherein the control means controls the recording condition setting means to cause the recording means to set a recording condition, and The test pattern is recorded on the optical recording medium from the test signal generated by the test signal generating means, and the reproducing means is controlled to reproduce the test pattern without applying an external magnetic field. When the reproduction signal level obtained by the above method is detected by the reproduction signal detecting means, the recording condition is controlled based on the level of the reproduction signal to obtain the optimum recording condition.
[0016]
  According to the above configuration, the recording condition is, for example, the amount of light beam irradiated to the optical recording medium during recording, or the magnetic field strength applied to the optical recording medium. The control unit controls the recording condition setting unit to cause the recording unit to set a specific recording condition within, for example, an appropriate range. Then, the recording means is controlled to record the test pattern on the optical recording medium, and the test pattern is reproduced by the reproducing means. During the reproduction, no external magnetic field is applied by the magnetic field applying means. Then, the reproduction signal detection means detects the level of the reproduction signal obtained by this reproduction and transmits it to the control means. Thus, the control means can acquire the level of the reproduction signal corresponding to a plurality of recording conditions within the above range. Then, the control means compares the levels of the acquired reproduction conditions, and determines the recording condition for recording the optimum reproduction signal as the optimum recording condition.
[0017]
  As a result, it is possible to accurately determine the optimum recording condition in the recording / reproducing apparatus that performs reproduction by generating an aperture in the reproducing layer of the optical recording medium without being affected by fluctuations in the environmental temperature or variations in the disc. Therefore, if recording is performed on the optical recording medium using the recording conditions, recording can be performed under optimum conditions. For this reason, it is possible to record information with few errors.
[0018]
  The present inventionThe recording and playback devicefurtherThe test pattern is a pattern for forming a recording mark larger than the spot diameter of the light beam irradiated to the optical recording medium by the reproducing means.
[0019]
  With the above configuration, it is possible to compensate for a decrease in resolution when an external magnetic field is not applied due to a large recording mark, and it is possible to detect a recording state with a high S / N ratio.
[0020]
  The present inventionThe recording and playback deviceA recording layer for recording a recording mark, a reproducing layer in which information magnetically recorded on the recording layer is transferred by an exchange coupling force through the cutting layer, and a predetermined temperature or more when irradiated with a light beam A magneto-optical recording medium having a multilayer structure composed of a recording layer and a cutting layer that cuts the exchange coupling force between the reproducing layer and a reproducing layer while applying an external magnetic field to the magneto-optical recording medium. Information is recorded and reproduced by irradiating a beam.To solve the above problem,Recording means for recording information on an optical recording medium, reproducing means for reproducing information on the optical recording medium, magnetic field applying means for applying an external magnetic field to the optical recording medium, and reproduction by the reproducing means Reproduction signal detection means for detecting the signal level of the reproduced signal, and recording means for recording information on the optical recording medium, controlling the reproduction means to reproduce the information, and detecting the reproduction signal When the signal level of the reproduction signal is detected by the means, the magnetic field is applied so that the external magnetic field is selectively applied so that the reproduction can be performed both in the state where the external magnetic field is applied and in the state where the external magnetic field is not applied during reproduction of the information. Control means for controlling the application means;Playback condition setting means for setting playback conditionsWhenThe control means controls the reproduction condition setting means to cause the reproduction condition to be set in the reproduction means, and controls the reproduction means to apply information recorded on the optical recording medium to an external magnetic field. When the playback signal level is detected by the playback signal detection means, playback conditions are controlled based on the playback signal level. It is characterized by obtaining optimum reproduction conditions.
[0021]
  According to the above configuration, the reproduction condition is, for example, the amount of light beam applied to the optical recording medium during reproduction or the strength of the magnetic field applied to the optical recording medium. The control unit controls the reproduction condition setting unit to cause the reproduction unit to set a specific reproduction condition within a certain appropriate range, for example. Then, the reproducing means is controlled to reproduce information recorded on the optical recording medium in both the state where the external magnetic field is applied and the state where the external magnetic field is not applied. When the level of the reproduction signal obtained by the reproduction is detected by the reproduction signal detection means, the control means analyzes this level and determines whether the obtained reproduction signal is the optimum reproduction signal. To do. If the reproduction signal is not optimal, the reproduction condition is changed and the level of the reproduction signal is acquired and analyzed again. When it is determined that the reproduction signal is optimum, the reproduction condition in this reproduction is determined as the optimum reproduction condition.
[0022]
  As a result, when an external magnetic field is applied to the optical recording medium, that is, when reproducing is performed by generating an aperture smaller than the spot diameter of the light beam on the reproducing layer, and when an external magnetic field is not applied, that is, an aperture is generated in the reproducing layer Since the level of the reproduction signal is detected in both of the cases where the reproduction is performed without performing the reproduction, the change in the resolution can be known by comparing these levels, and the comparison result becomes a predetermined value. Thus, the playback conditions can be optimized.
[0023]
  The present inventionThe recording and playback devicefurther,The reproducing means reproduces a recording mark smaller than the spot diameter of the light beam irradiated to the optical recording medium by the reproducing means, and the control means controls the reproduction condition based on the level of the reproduction signal. It is characterized by that.
[0024]
  With the above configuration, it is possible to greatly change the resolution when an external magnetic field is applied with a small recording mark and when the external magnetic field is not applied, and to control the reproduction light quantity or reproduction magnetic field strength during information reproduction with a high S / N ratio. Can do.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
  An embodiment of the present invention will be described with reference to FIGS. 1 to 13 as follows.
[0026]
  FIG. 1 is a block diagram showing a configuration of a recording / reproducing apparatus (hereinafter referred to as the present apparatus) according to the present embodiment. As shown in FIG. 1, this apparatus includes an optical pickup 2, a feed motor 3, a laser driver 4, a magnetic head 5, a magnetic head driver 6, and a reproduction signal detection circuit 7 as reproduction signal detection means, It comprises a control circuit 8 as a control means, a reproduction condition setting means and a recording condition setting means, and a test signal generation circuit 9 as a test signal generation means, and records on a magneto-optical disk 1 as an optical recording medium. Perform playback. The recording means is composed of an optical pickup 2, a laser driver 4, a magnetic head 5 and a magnetic head driver 6, and the reproducing means is composed of an optical pickup 2 and a laser driver 4. Further, the magnetic head 5 also functions as a magnetic field applying unit.
[0027]
  The optical pickup 2 is for reading information recorded on the magneto-optical disk 1 by irradiating the magneto-optical disk 1 with a light beam b. Further, the optical pickup 2 sends the read information to the reproduction signal detection circuit 7 as a reproduction signal h.
[0028]
  The feed motor 3 is for moving the optical pickup 2 in accordance with an instruction from the control circuit 8 so that a predetermined portion of the magneto-optical disk 1 is irradiated with the light beam b. The laser driver 4 is for controlling the power of the light beam emitted by the optical pickup 2 by transmitting an optical pickup driving signal e to the optical pickup 2 according to an instruction from the control circuit 8.
[0029]
  The magnetic head 5 is for applying a magnetic field to the magneto-optical disk 1 for recording information. The magnetic head driver 6 controls the strength of the magnetic field applied by the magnetic head 5 by transmitting a magnetic head drive signal d to the magnetic head 5 in accordance with an instruction from the control circuit 8.
[0030]
  The reproduction signal detection circuit 7 detects the level of the reproduction signal read by the optical pickup 2 and transmits it to the control circuit 8 as signal level data i. Here, the level of the reproduction signal means the amplitude of the reproduction signal.
[0031]
  The control circuit 8 is for controlling the feed motor 3 by transmitting a movement control signal a to the feed motor 3. The control circuit 8 controls the laser driver 4 by transmitting a light amount control signal g to the laser driver 4. Further, the control circuit 8 controls the magnetic head driver 6 by transmitting a magnetic field control signal f to the magnetic head driver 6.
[0032]
  The test signal generation circuit 9 is for transmitting a test signal for controlling a recording condition to be described later to the laser driver 4 and the magnetic head driver 6 as a test signal c.
[0033]
  For example, as shown in FIG. 2, the magneto-optical disk 1 used in this apparatus has a test write area 11 in which a test pattern is written at the outer periphery of the magneto-optical disk 1, and normal recording information is provided on the inner side. An information recording area 12 for writing is formed.
[0034]
  FIG. 4 is a block diagram showing a configuration for processing the magnetic field control signal f and the light amount control signal g from the control circuit 8 in the magnetic head driver 6 and the laser driver 4 described above. As shown in FIG. 4, the magnetic head driver 6 includes a magnetic head drive circuit 21 and a D / A converter 22, and the laser driver 4 includes an optical pickup drive circuit 23 and a D / A converter 24. ing. Further, the optical pickup 2 includes a semiconductor laser 25 for emitting a light beam b.
[0035]
  The magnetic field control signal f sent from the control circuit 8 is, for example, 8-bit binary data. The D / A converter 22 receives this magnetic field control signal f, converts it into an analog signal, and sends it to the magnetic head drive circuit 21. send. The magnetic head drive circuit 21 sends a magnetic head drive signal d based on the analog signal to the magnetic head 5 to control the magnetic field generated by the magnetic head 5. In this way, the magnetic head driver 6 can accurately control the external magnetic field generated by the magnetic head 5 based on an instruction from the control circuit 8. As a result, the intensity of the external magnetic field can be accurately reduced to a level at which no aperture is generated or turned off based on an instruction from the control circuit 8.
[0036]
  Similarly to the magnetic field control signal f, the light quantity control signal g sent from the control circuit 8 is, for example, 8-bit binary data. The D / A converter 24 receives the light quantity control signal g and receives an analog signal. To the optical pickup driving circuit 23. The optical pickup drive circuit 23 sends an optical pickup drive signal e based on the analog signal to the semiconductor laser 25 provided in the optical pickup 2 to control the light quantity of the light beam b generated by the semiconductor laser 25. In this way, the laser driver 4 can accurately control the light amount of the light beam b generated by the optical pickup 2 based on an instruction from the control circuit 8.
[0037]
  FIG. 5 is a block diagram showing a configuration of the reproduction signal detection circuit 7. As shown in FIG. 5, the reproduction signal detection circuit 7 includes an amplifier 31, a low-pass filter 32, an amplitude detection circuit 33, and an A / D converter 34.
[0038]
  The reproduction signal h sent from the optical pickup 2 is an analog signal, and the amplifier 31 receives this amplification signal h, amplifies it, and sends it to the low-pass filter 32. The low-pass filter 32 improves the S / N ratio of the amplified reproduction signal h and sends it to the amplitude detection circuit 33. The amplitude detection circuit 33 detects the signal level of the reproduction signal h that has been amplified and has an improved S / N ratio, and sends it to the A / D converter 34. The A / D converter 34 converts this signal level into, for example, 8-bit binary data and transmits it to the control circuit 8 as signal level data i. In this way, the reproduction signal detection circuit 7 can transmit an accurate reproduction signal level to the control circuit 8.
[0039]
  A case where the recording information on the magneto-optical disk 1 is read by the apparatus having the above configuration will be described below with reference to FIG. However, at the time of reading, the read characteristics differ between when the external magnetic field is turned on and when the external magnetic field is turned off.
[0040]
  First, FIG. 6A shows a case where the external magnetic field is turned on. The magneto-optical disk 1 has a multilayer structure including a reproducing layer 41, a cutting layer 42, and a recording layer 43, and a pattern magnetically recorded on the recording layer 43 is transferred to the reproducing layer 41 by exchange coupling.
[0041]
  When the information recorded on the magneto-optical disk 1 is read, the reproduction layer 41 of the magneto-optical disk 1 is irradiated with the light spot p. A high temperature portion q (shaded portion in FIG. 6) is generated in front of the light spot p, that is, on the moving direction (x direction in FIG. 6) side of the recording medium. In the region of the high temperature part q, the temperature of the cutting layer 42 rises above the Curie temperature, and the magnetic field of the cutting layer 42 disappears. Accordingly, the exchange coupling between the recording layer 43 and the reproducing layer 41 is broken. The above description exemplifies the case of the FAD method.
[0042]
  At this time, when an external magnetic field Hex is applied to the magneto-optical disk 1 by the magnetic head 5, magnetization is aligned in the direction of the external magnetic field Hex in the reproducing layer 41 of the high temperature portion q. For this reason, the recording mark recorded on the recording layer 43 is masked in the high temperature portion q. Therefore, in this case, the low temperature portion excluding the high temperature portion q from the light spot p becomes the aperture r, and the aperture r becomes the readout region (horizontal line portion in FIG. 6A). When the external magnetic field is turned on, the aperture r is smaller than the light spot p in this way, so that information recorded on the magneto-optical disk 1 with high density can be reproduced. In the present embodiment, only the external magnetic field Hex corresponds to the external magnetic field described in the claims.
[0043]
  On the other hand, when the external magnetic field is turned off, as shown in FIG. 6B, the external magnetic field Hex is not applied even when the magnetic field of the cutting layer 42 disappears due to the high temperature portion q. The same pattern as the recording layer 43 is transferred to 41 by the leakage magnetic field Hlk from the recording layer 43. Therefore, unlike the case where the external magnetic field is turned on, the mask due to the high temperature portion q does not occur, and the entire irradiation region of the light spot p becomes the readout region (the horizontal line portion in FIG. 6B) as it is, and the environmental temperature The recorded mark can be reproduced regardless of the change in the recording level.
[0044]
  In addition to turning off the external magnetic field Hex in FIG. 6B, if the strength is reduced to make it smaller than the leakage magnetic field Hlk, the effect of the mask is lost, and the external magnetic field Hex is substantially turned off. Needless to say, recording marks are transferred.
[0045]
  Now, the recording / reproducing operation of the magneto-optical disk 1 by this apparatus will be described in detail. FIG. 7 is a flowchart showing the recording / reproducing operation. In this apparatus, the recording operation for the magneto-optical disk 1 and the reproducing operation for the information recorded on the magneto-optical disk 1 can be performed separately, but in the following description, the reproducing operation is performed following the recording operation. The operation shall be performed.
[0046]
  First, before the apparatus performs a recording operation on the magneto-optical disk 1, a test light is performed in order to appropriately adjust the light amount of the light beam b applied to the magneto-optical disk 1. Therefore, the optical pickup 2 is moved to the test write area 11 of the magneto-optical disk 1 (S1), and test write is performed while changing the recording conditions such as the recording light quantity and the recording magnetic field intensity (S2). When the test light is finished and the light quantity of the light beam b is adjusted, the optical pickup 2 is moved to the information recording area 12 of the magneto-optical disk 1 (S3), and the optimized recording conditions are used. Information is recorded (S4).
[0047]
  A reproduction operation is performed following the recording operation. Even before the reproduction operation, the information recording area is changed while changing reproduction conditions such as a reproduction light amount and a reproduction magnetic field strength in order to adjust the light amount of the light beam b. The information recorded in (2) is reproduced to perform test read (S5). When the test lead is completed, information is reproduced based on the optimized reproduction condition (S6).
[0048]
  The operation of the test light in FIG. 7 will be described in detail below. The test light records the test pattern in the test write area 11 of the magneto-optical disk 1, reproduces the test pattern and detects the recording state, and determines the optimum recording light quantity and magnetic field intensity based on the detected recording state. It is divided into the process to do.
[0049]
  First, in the test pattern recording process, as shown in FIG. 1, a movement control signal a is output from the control circuit 8 to the feed motor 3, and the optical pickup 2 moves to the test write area 11 of the magneto-optical disk 1 shown in FIG. Moved. A test signal c is generated from the test signal generation circuit 9 and sent to the laser driver 4, and an optical pickup drive signal e is sent to the semiconductor laser in the optical pickup 2. Further, a magnetic field control signal f is sent from the control circuit 8 to the magnetic head driver 6, and the magnetic head driver 6 converts the magnetic field control signal f into a magnetic head drive signal d and sends it to the magnetic head 5. The magnetic head 5 applies an external magnetic field to the magneto-optical disk 1 based on the magnetic head drive signal d. A light amount control signal g is sent from the control circuit 8 to the laser driver 4 to record the test signal c while changing the recording light amount of the light beam b.
[0050]
  Next, in the process of reproducing the test signal c, the external magnetic field is first turned off by the magnetic field control signal f. As a result, the generation of super-resolution during reproduction can be temporarily stopped, and the recorded test pattern can be reproduced without being affected by environmental temperature fluctuations. Next, the test pattern is read out by the optical pickup 2, and the test pattern signal h is sent to the reproduction signal detection circuit 7. The reproduction signal detection circuit 7 detects the signal level data i of the test pattern signal h, sends it to the control circuit 8, and stores it in a memory (not shown).
[0051]
  When the reproduction of the test pattern is completed, the external magnetic field is turned on again by the magnetic field control signal f, the recording light quantity is slightly increased, and the test signal c is recorded again. In this way, while slightly increasing the recording light amount, the test signal c is recorded in a predetermined light amount range, and the recording state at that time is detected. The above-described external magnetic field OFF operation includes a case where the external magnetic field is reduced to a level at which super-resolution does not substantially occur.
[0052]
  Next, in the step of determining the optimum recording light amount, the optimum recording light amount is searched from the recording states stored in the memory, and the recording light amount at this time is determined as the optimum recording light amount.
[0053]
  When the test light is completed, the optical pickup 2 can be moved to the information recording area 12 in FIG. 2, and information can be recorded based on the optimum recording light amount. The recorded information is read at the time of test reading, and optimal reproduction light quantity control can be performed. The test read operation will be described later.
[0054]
  The above operation will be described in more detail mainly using the flowchart of FIG. When the test write is started by the test write operation command, the apparatus turns on the external magnetic field by the magnetic head 5 (S11). Next, an initial value of the recording light quantity is set (S12), and a test pattern is magnetically modulated and recorded in the test write area of the magneto-optical disk 1 (S13). At this time, as shown in FIG.₀A recording mark m1 is recorded in Next, the external magnetic field is turned off (S14), and the track T₀Is reproduced (S15). Thus, the amplitude V of the reproduction signal indicated by the solid line in FIG.₀Is detected (S16).
[0055]
  Note that the external magnetic field that is turned on in S11 is given to write a test pattern on the magneto-optical disk 1. That is, the external magnetic field is controlled by the magnetic head drive signal d sent from the magnetic head drive circuit 21, unlike the external magnetic field Hex given to generate an aperture on the reproduction layer 41 during reproduction.
[0056]
  Subsequently, the external magnetic field is turned on again (S17), and as shown in FIG.₁And then the adjacent track T on the opposite side_-1Is deleted (S18). Then, the external magnetic field is turned off (S19), and as shown in FIG.₀Is reproduced (S20). Thus, the amplitude V of the reproduction signal indicated by the broken line in FIG.₁Is detected (S21). The external magnetic field that is turned on in S17 is provided to erase the test pattern of the magneto-optical disk 1, and the direction and magnitude of the magnetic field are constant, but an aperture is generated on the reproducing layer 41. This is different from the external magnetic field Hex applied for the purpose.
[0057]
  Here, if the recording light quantity is too large, the spot area of the light spot p becomes large, and as shown in FIG. 9C, the recording mark m2 is erased on both sides of the mark compared to the recording mark m1 before erasure. Will be. Therefore, the amplitude V₁Is the amplitude V₀Smaller than Conversely, when the recording light quantity is small, both sides of the recording mark m2 are not erased, so the amplitude V₀And amplitude V₁Is equal to
[0058]
  Playback signal amplitude V₁Is detected, the external magnetic field (similar to the external magnetic field turned on in S11) is turned back on (S22). Next, the amplitude reduction rate V₀-V₁And the amplitude reduction rate V₀-V₁The recording light quantity at this time is stored in the memory (S23), and it is determined whether or not the recording light quantity exceeds a predetermined light quantity range (S24). If the recording light quantity does not exceed the predetermined light quantity range (NO in S24), the recording light quantity is increased by a predetermined change (S25), and the track T₀Recording operation, that is, the process returns to S13. In this way, steps from S13 to S25 are repeated until the recording light quantity exceeds the predetermined light quantity range (YES in S24), and each recording light quantity and the corresponding amplitude reduction rate V are stored in the memory.₀-V₁Is memorized. If the set recording light amount exceeds the light amount range (YES in S24), the optimum recording light amount is selected from the recording light amounts stored in the memory (S26), and the test light is terminated.
[0059]
  Here, the recording light quantity and the amplitude reduction amount V₀-V₁The relationship of the S / N ratio will be described with reference to FIG. When the amount of recording light is low, as described above, the track T₀Since both sides of the upper recording mark are not erased, the amplitude reduction amount V₀-V₁Becomes almost zero and falls within the detection error δV due to noise. However, as the recording light quantity is gradually increased, both sides of the recording mark begin to be erased at a certain recording light quantity, and the amplitude reduction amount V is gradually increased.₀-V₁Begins to increase.
[0060]
  Amplitude reduction amount V₀-V₁Immediately before starting to increase, that is, the amount of amplitude decrease V₀-V₁Recording light quantity P immediately before the detection error δV exceeds_w0Since the spot diameter of the light spot p is substantially equal to the track width, both sides of the recording mark are not erased and the largest recording mark can be recorded. That is, the optimum recording light amount P_w0Then, the S / N ratio of the recording mark can be maximized. Therefore, in S26, the amplitude reduction amount V₀-V₁<ΔV and the highest recording light amount is selected as the optimum recording light amount.
[0061]
  In the flowchart of FIG. 8, the amplitude decrease amount V is determined in step S23.₀-V₁Instead of amplitude V₁, And the amplitude V in step S26₁May be selected as the optimum recording light amount.
[0062]
  In the above description, the track T₁And T_-1Both are erased, but the same effect can be obtained even if only one of them is erased. But track T₁And T_-1If both of these are erased, the amplitude reduction amount V shown in FIG.₀-V₁Increases, and the detection sensitivity can be increased. In the above example, magnetic field modulation recording is shown. However, the present invention is not limited to this, and test writing can be performed by the same operation in the case of optical modulation recording.
[0063]
  Further, in FIGS. 9A and 9C, the recording marks m1 and m2 are reproduced over the entire light spot p with the external magnetic field Hex turned off. Therefore, although the resolution is lowered as compared with the case where information is reproduced by turning on the external magnetic field Hex and generating super-resolution, it is possible to detect a stable recording state that is not affected by fluctuations in the environmental temperature. As for the reduction in resolution, it is possible to compensate for the reduction in S / N ratio due to the reduction in resolution by recording the test pattern so that the size of the recording mark m1 is equal to or larger than the light spot diameter.
[0064]
  The above test light shows an example in which the external magnetic field strength at the time of test pattern recording is fixed and the recording light amount is optimized. However, in addition to this, the recording light amount is fixed, and in S25 of FIG. The external magnetic field intensity may be increased instead of the recording light quantity. Thereby, the external magnetic field strength at the time of recording can be optimized. That is, in FIG. 9, in order to simplify the explanation, the light spot p is shown as a complete circle, and the recording mark is transferred in the region irradiated with the light spot p. The light spot has a temperature distribution such as a Gaussian distribution, and the transfer area of the recording mark is determined by the temperature distribution of the light spot and the external magnetic field intensity. Therefore, even when the recording light quantity is fixed, the size of the recording mark changes if the external magnetic field strength changes, and if the external magnetic field strength continues to increase, the amplitude decrease V₀-V₁An external magnetic field strength is generated so that the value of the current increases from 0 to an increase. For this reason, the optimum value of the external magnetic field strength at the time of recording can be obtained.
[0065]
  Next, the operation of the test lead in FIG. 7 will be described in detail below. At the time of test reading, the reproduction light quantity of the light beam b is first set based on the light quantity control signal g from the control circuit 8. Next, the external magnetic field Hex is turned off to detect the reproduction signal level from the recording mark when super-resolution does not occur. Next, the external magnetic field Hex is turned on to generate super-resolution, and the reproduction signal level is detected. When the reproduction signal level is compared between the ON state and the OFF state of the external magnetic field, the size of the aperture with respect to the light spot area can be measured, so that the amount of reproduction light can be controlled so that the predetermined aperture size is obtained.
[0066]
  The test read operation will be described in more detail mainly using the flowchart of FIG. When the test read is started by the test read operation command, the apparatus first sets an initial value of the reproduction light amount (S31). Next, the external magnetic field Hex is turned off (S32), and the amplitude V of the signal reproduced from the recording mark₀Is detected (S33). At this time, as shown in the left part of FIG. 12A, the recording mark is reproduced by the entire spot of the light spot p, and the amplitude V₀Is obtained from the reproduction signal indicated by the broken line in the left part of FIG.
[0067]
  Next, the external magnetic field Hex is turned back on (S34), and the amplitude V of the signal reproduced from the recording mark₁Is detected (S35). At this time, as shown in the right part of FIG. 12A, the recording mark on the magneto-optical disk 1 is reproduced by the aperture r indicated by the broken line, and the amplitude V₁Is obtained from the reproduction signal indicated by the broken line in the right part of FIG. Since the area of the aperture r is smaller than the spot area of the light spot p, the resolution is increased when the external magnetic field Hex is turned on compared to when it is turned off. For this reason, the amplitude V₁Is the amplitude V obtained when the external magnetic field Hex is turned off.₀Slightly larger than
[0068]
  As mentioned above, the amplitude V₀And V₁Is detected, V₁/ V₀To calculate the V₁/ V₀It is further determined whether or not the current reproduction light quantity is appropriate (S36). If it is determined that the reproduction light amount is not appropriate (NO in S36), the reproduction light amount is increased by a predetermined amount (S37), and the process returns to S32. Thus, steps S32 to S37 are repeated until it is determined that the reproduction light amount is appropriate (YES in S36).
[0069]
  Here, an example of the method for determining the reproduction light amount in S36 will be described. First, with reference to FIG.₁/ V₀I will explain the change. When the reproduction light quantity of the light spot p increases, when the external magnetic field Hex is turned off, the amplitude V of the reproduction signal as shown by the solid line in the left part of FIG.₀Will increase. Next, when the external magnetic field Hex is turned on, the mask region in the high temperature portion is expanded, and the area of the aperture r which is the readout portion is reduced as shown by the solid line in the right portion of FIG. Thus, as the resolution further increases, the amplitude V of the reproduction signal is indicated by a solid line in the right portion of FIG.₁Becomes larger.
[0070]
  Above amplitude V₁The rate of increase is the amplitude V₀Is larger than the increase rate of V.₁/ V₀Will also increase. FIG. 13 shows the reproduction light amount of the light beam b, V₁/ V₀FIG. 3 is a diagram illustrating the relationship between the S / N ratio of a reproduction signal and the reproduction signal. As described above, as the reproduction light quantity of the light beam b increases, V₁/ V₀It grows gradually. Also, the amplitude V of the reproduction signal₁However, when the temperature of the recording layer approaches the Curie point, the S / N ratio increases.₁Begins to decrease and the S / N ratio begins to decrease. Therefore, the reproduction light quantity P that maximizes the S / N ratio due to these trade-offs._r0Exists. V at this time₁/ V₀Is the reference value A, the reproduction error can be minimized by controlling the reproduction light quantity in the test lead so that the reference value A is obtained.
[0071]
  That is, in step S36, V₁/ V₀May be determined that the reproduction light amount is appropriate when becomes a value substantially equal to the reference value A. Specifically, for example, V₁/ V₀Is compared with a preset reference value A and the V₁/ V₀Is set to a suitable reproduction light amount when the value first exceeds the reference value A, or a reference range centering on the reference value A is set in advance.₁/ V₀A method is conceivable in which the reproduction light amount when the value becomes within the reference range is set to an appropriate reproduction light amount.
[0072]
  When an appropriate reproduction light quantity is selected in step S36, the test read is terminated, and the information recorded on the magneto-optical disk 1 is read with the light beam b having the reproduction light quantity.
[0073]
  Note that not only the amount of reproduction light is optimized by the test lead, but when the reproduction magnetic field strength is optimized, the reproduction light amount is constant and the amplitude of the reproduction signal is detected while changing the reproduction magnetic field strength. . That is, even if the reproduction light quantity is constant, if the reproduction magnetic field strength increases, the mask region in the high temperature portion increases due to the influence of the temperature distribution of the light spot p and the reproduction magnetic field strength, and thus the area of the aperture r becomes small. . For this reason, the resolution when the external magnetic field Hex is turned on increases, and the amplitude V₁Therefore, the reproduction magnetic field strength can be optimized.
[0074]
  Further, by reproducing the mark m3 smaller than the light spot p on the test lead, it is possible to detect a change in resolution when the external magnetic field is turned on / off. Note that if the mark m3 is larger than the light spot p, a change in resolution cannot be detected.
[0075]
  As described above, the recording / reproducing apparatus according to the present embodiment sets a specific recording condition, for example, a recording light amount or a recording magnetic field strength, within a certain appropriate range at the time of test writing, and under the recording condition, A test pattern is recorded on the magneto-optical disk 1. When reproducing the test pattern, since the external magnetic field Hex is turned off, the level of the reproduction signal obtained by this reproduction can be detected without being affected by fluctuations in the environmental temperature and disk variations. The level of the reproduction signal is transmitted to the control circuit 8 and stored in the memory.
[0076]
  Then, while changing the recording conditions by a predetermined amount and storing the levels of the reproduction signals corresponding to the plurality of recording conditions in the memory, the control circuit 8 compares the levels of the stored reproduction conditions to determine the optimum level. The recording condition for recording the correct reproduction signal is determined as the optimum recording condition.
[0077]
  As a result, the optimum recording condition in the present apparatus can be accurately obtained without being affected by fluctuations in the environmental temperature and disk variations. Therefore, if recording is performed on the optical recording medium using this recording condition, recording can be performed under optimum conditions, and information with few errors can be recorded.
[0078]
  Further, at this time, if the test pattern is a pattern that forms a recording mark larger than the spot diameter of the light beam b irradiated to the magneto-optical disk 1 by the optical pickup 2, the external magnetic field Hex is caused by the large recording mark. It is possible to compensate for a decrease in resolution when turned off, and to detect a recording state with a high S / N ratio.
[0079]
  The recording / reproducing apparatus according to the present embodiment sets, for example, a specific reproduction condition, for example, a reproduction light amount or a reproduction magnetic field strength within a certain appropriate range at the time of test reading, Information recorded on the magneto-optical disk 1 is reproduced in both the state where the magnetic field Hex is applied and the state where the magnetic field Hex is not applied. By comparing the levels of the reproduced signals obtained by these reproductions, it is possible to detect a change in resolution caused by applying the external magnetic field Hex.
[0080]
  Then, after changing the reproduction condition by a predetermined amount and storing the comparison result of the level of the reproduction signal corresponding to the plurality of reproduction conditions in the memory, the control circuit 8 compares the level of the stored reproduction condition. Therefore, the reproduction condition that obtains the optimum reproduction signal is determined as the optimum reproduction condition.
[0081]
  As a result, the optimum reproduction condition in the present apparatus can be accurately obtained without being affected by fluctuations in the environmental temperature and disk variations. Therefore, if the optical recording medium is reproduced using this reproduction condition, reproduction can be performed under optimum conditions, and information with few errors can be reproduced.
[0082]
  Further, at the time of reproduction, if a recording mark smaller than the spot diameter of the light beam b irradiated to the magneto-optical disk 1 by the optical pickup 2 is reproduced, the reproduction condition is obtained based on the level of the reproduction signal. The resolution between when an external magnetic field is applied and when the external magnetic field is not applied can be greatly changed, and the reproduction light amount or reproduction magnetic field strength during information reproduction can be controlled by a high S / N ratio.
[0083]
  The magneto-optical disk 1 used in this apparatus is not limited to that shown in FIG. 2, but a test write area 11 is provided in a periodic part in the circumferential direction of the disk as shown in FIG. A write-only test pattern may be recorded. In the test lead, a mark smaller than the light spot in the recorded information was reproduced. However, the present invention is not limited to this, and the periodic portion shown in FIG. Alternatively, a test lead pattern including a small mark may be recorded.
[0084]
【The invention's effect】
  The present inventionAs described above, the recording / reproducing apparatus includes a recording unit for recording information on the optical recording medium, a reproducing unit for reproducing information on the optical recording medium, and a magnetic field application for applying an external magnetic field to the optical recording medium. Means, a reproduction signal detection means for detecting the signal level of the reproduction signal obtained by reproduction by the reproduction means, and the recording means to record information on the optical recording medium, and the reproduction means is controlled. Control means for controlling the magnetic field applying means so that the external magnetic field is selectively applied at the time of reproducing the information when reproducing the information and detecting the signal level of the reproduced signal by the reproduced signal detecting means. It is the structure equipped with.
[0085]
  Therefore, when information is read out, that is, during normal reproduction, by applying an external magnetic field, an aperture is generated in the reproduction layer of the optical recording medium, and high-resolution reproduction can be performed at the same time. By reproducing information without applying a magnetic field and detecting the level of the reproduced signal by the reproduced signal detecting means, reproduction can be performed without causing an aperture. In this case, there is an effect that it is possible to detect the recording state of the recording mark on the optical recording medium without being affected by the fluctuation of the environmental temperature and the fluctuation of the disk.
[0086]
  Also, the level of the reproduction signal when information is reproduced while applying an external magnetic field is detected and the level of the reproduction signal when information is reproduced without applying an external magnetic field, and these are compared. As a result, it is possible to accurately detect a change in resolution from the reproduction signal.
[0087]
  The present inventionThe recording and playback devicefurther,A test signal generating means for generating a test signal; and a recording condition setting means for setting a recording condition, wherein the control means controls the recording condition setting means to cause the recording means to set a recording condition, and The test pattern is recorded on the optical recording medium from the test signal generated by the test signal generating means, and the reproducing means is controlled to reproduce the test pattern without applying an external magnetic field. When the reproduction signal level obtained by the above method is detected by the reproduction signal detecting means, the recording condition is controlled based on the level of the reproduction signal to obtain the optimum recording condition.
[0088]
  therefore,aboveIn addition to the effects, it is possible to accurately determine the optimum recording conditions in a recording / reproducing apparatus that performs reproduction by generating an aperture in the reproducing layer of an optical recording medium without being affected by fluctuations in environmental temperature or disc variations. Become. Therefore, if recording is performed on the optical recording medium using this recording condition, there is an effect that recording can be performed under optimum conditions.
[0089]
  In addition, the present inventionAs described above, the recording / reproducing apparatusthe aboveIn addition to the configuration described above, the test pattern is a pattern that forms a recording mark larger than the spot diameter of the light beam irradiated onto the optical recording medium by the reproducing means.
[0090]
  therefore,aboveIn addition to the effect, it is possible to compensate for a decrease in resolution when an external magnetic field is not applied due to a large recording mark, and the recording state can be detected with a high S / N ratio.
[0091]
  The present inventionAs described above, the recording / reproducing apparatus ofRecording means for recording information on an optical recording medium, reproducing means for reproducing information on the optical recording medium, magnetic field applying means for applying an external magnetic field to the optical recording medium, and reproduction by the reproducing means Reproduction signal detection means for detecting the signal level of the reproduced signal, and recording means for recording information on the optical recording medium, controlling the reproduction means to reproduce the information, and detecting the reproduction signal Reproduction signal by means When the signal level is detected, the magnetic field application means is controlled so that the external magnetic field is selectively applied so that the external magnetic field can be reproduced both in the state where the information is reproduced and in the state where the external magnetic field is not applied. Control means toPlayback condition setting means for setting playback conditionsWhenThe control means controls the reproduction condition setting means to cause the reproduction condition to be set in the reproduction means, and controls the reproduction means to apply information recorded on the optical recording medium to an external magnetic field. When the playback signal level is detected by the playback signal detection means, playback conditions are controlled based on the playback signal level. In this configuration, the optimum reproduction condition is obtained.
[0092]
  therefore,aboveIn addition to the effect, when an external magnetic field is applied to the optical recording medium, that is, when reproduction is performed by generating an aperture smaller than the spot diameter of the light beam on the reproducing layer, and when an external magnetic field is not applied, that is, the aperture is applied to the reproducing layer. Since the level of the reproduced signal is detected in both the state where the reproduction is performed without generating the error, the change in the resolution can be known by comparing these levels, and the comparison result is a predetermined value. There is an effect that the reproduction condition can be optimized so as to be a value.
[0093]
  Of the present inventionThe recording / playback deviceaboveIn addition to the configuration, the reproducing means reproduces a recording mark smaller than the spot diameter of the light beam that the reproducing means irradiates the optical recording medium, and the control means reproduces based on the level of the reproduction signal. This is a configuration for controlling the conditions.
[0094]
  therefore,aboveIn addition to the effect, it is possible to greatly change the resolution with and without the application of an external magnetic field with a small recording mark, and to control the reproduction light quantity or reproduction magnetic field strength during information reproduction with a high S / N ratio. There is an effect that can be.
[Brief description of the drawings]
FIG. 1, showing an embodiment of the present invention, is a block diagram showing a configuration of a recording / reproducing apparatus.
FIG. 2 is a perspective view showing a configuration of an optical recording medium used in the recording / reproducing apparatus.
FIG. 3 is a perspective view showing another example of an optical recording medium used in the recording / reproducing apparatus.
FIG. 4 is a block diagram showing a part of the configuration of a magnetic head driver and a laser driver in the recording / reproducing apparatus.
FIG. 5 is a block diagram showing a configuration of a reproduction signal detection circuit in the recording / reproducing apparatus.
6A is an explanatory diagram showing a reproducing operation when an external magnetic field is turned on, and FIG. 6B is an explanatory diagram showing a reproducing operation when an external magnetic field is turned off. FIG.
FIG. 7 is a flowchart showing an operation flow of the recording / reproducing apparatus.
FIG. 8 is a flowchart showing a flow of an operation related to a test write among the operations of the recording / reproducing apparatus.
FIG. 9A is an explanatory view showing a state in which a recording mark is recorded on a track of the optical recording medium shown in FIG. 2, and FIG. 9B shows a track adjacent to the track. FIG. 9C is an explanatory view showing a state where the recording mark is erased, FIG. 9C is an explanatory view showing a state where the recording mark recorded on the track is reproduced, and FIG. 9D is a state where the recording mark is reproduced. It is a graph which shows the signal level data obtained by doing.
10 is a graph showing the relationship between the recording light amount of the light beam, the amplitude reduction amount, and the S / N ratio obtained by controlling the recording conditions by the recording / reproducing apparatus shown in FIG.
FIG. 11 is a flowchart showing a flow of an operation related to a test lead among the operations of the recording / reproducing apparatus.
FIG. 12 (a) is an explanatory view showing a state of reproducing information recorded on the optical recording medium shown in FIG. 2, and FIG. 12 (b) is obtained by the above reproduction. It is a graph which shows signal level data.
13 shows the reproduction light amount of light beam and V obtained by controlling the reproduction condition by the recording / reproducing apparatus shown in FIG.₁/ V₀It is a graph showing the relationship with S / N ratio.
[Explanation of symbols]
  1 Magneto-optical disk (optical recording medium)
  2 Optical pickup (recording / reproducing)
  4 Laser driver (recording / reproducing)
  5 Magnetic head (recording means / magnetic field applying means)
  6 Magnetic head driver (recording means)
  7 Reproduction signal detection circuit (reproduction signal detection means)
  8. Control circuit (control means / reproduction condition setting means / recording condition setting means)
  9 Test signal generation circuit (test signal generation means)
41 Playback layer
42 Cutting layer
43 Recording layer

Claims (4)

A recording layer for recording a recording mark, a reproducing layer in which information magnetically recorded on the recording layer is transferred by an exchange coupling force through the cutting layer, and a predetermined temperature or more when irradiated with a light beam A light beam is applied to the reproducing layer while applying an external magnetic field to the optical recording medium having a multilayer structure of a recording layer and a cutting layer that cuts the exchange coupling force between the recording layer and the reproducing layer. In a recording / reproducing apparatus for recording and reproducing information by irradiation,
Recording means for recording information on an optical recording medium;
Reproducing means for reproducing information of the optical recording medium;
Magnetic field applying means for applying an external magnetic field to the optical recording medium;
Reproduction signal detection means for detecting a signal level of a reproduction signal obtained by reproduction by the reproduction means;
Test signal generating means for generating a test signal;
Recording condition setting means for setting recording conditions;
When the information is recorded on the optical recording medium by controlling the recording means, the information is reproduced by controlling the reproduction means, and the signal level of the reproduction signal is detected by the reproduction signal detection means, Control means for controlling the magnetic field applying means so that the external magnetic field is selectively applied so that the external magnetic field can be reproduced both in a state where the external magnetic field is applied and in a state where the external magnetic field is not applied during information reproduction,
The control means controls the recording condition setting means to set a recording condition in the recording means, and controls the recording means to generate a test pattern from a test signal generated by the test signal generating means on the optical recording medium. Recording, controlling the reproducing means to reproduce the test pattern without applying an external magnetic field, and when the reproduction signal detecting means detects the level of the reproduction signal obtained by this reproduction, A recording / reproducing apparatus for controlling recording conditions based on a level to obtain an optimum recording condition . 2. The recording / reproducing apparatus according to claim 1 , wherein the test pattern is a pattern for forming a recording mark larger than a spot diameter of a light beam irradiated to the optical recording medium by the reproducing means. A recording layer for recording a recording mark, a reproducing layer in which information magnetically recorded on the recording layer is transferred by an exchange coupling force through the cutting layer, and a predetermined temperature or more when irradiated with a light beam A light beam is applied to the reproducing layer while applying an external magnetic field to the optical recording medium having a multilayer structure of a recording layer and a cutting layer that cuts the exchange coupling force between the recording layer and the reproducing layer. In a recording / reproducing apparatus for recording and reproducing information by irradiation,
Recording means for recording information on an optical recording medium;
Reproducing means for reproducing information of the optical recording medium;
Magnetic field applying means for applying an external magnetic field to the optical recording medium;
Reproduction signal detection means for detecting a signal level of a reproduction signal obtained by reproduction by the reproduction means;
When the information is recorded on the optical recording medium by controlling the recording means, the information is reproduced by controlling the reproduction means, and the signal level of the reproduction signal is detected by the reproduction signal detection means, Control means for controlling the magnetic field applying means so that the external magnetic field is selectively applied so that the external magnetic field can be reproduced both in a state where the external magnetic field is applied and in a state where the external magnetic field is not applied during information reproduction;
A playback condition setting means for setting playback conditions is provided,
The control means controls the reproduction condition setting means to cause the reproduction condition to be set in the reproduction means, and controls the reproduction means to apply information recorded on the optical recording medium to an external magnetic field ; When the reproduction signal level is detected by the reproduction signal detecting means, the reproduction condition is controlled based on the reproduction signal level, and the optimum condition is obtained. A recording / reproducing apparatus characterized by obtaining reproduction conditions . The reproducing means reproduces a recording mark smaller than the spot diameter of the light beam with which the reproducing means irradiates the optical recording medium;
4. The recording / reproducing apparatus according to claim 3 , wherein the control means controls the reproduction condition based on the level of the reproduction signal .

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