JP4185530B2 - Magnetic recording / reproducing apparatus and control method thereof, magnetic recording medium, and stamper for manufacturing magnetic recording medium - Google Patents

Description

  The present invention relates to a magnetic recording / reproducing apparatus including a magnetic recording medium such as a discrete track medium or a patterned medium, a control method thereof, a magnetic recording medium, and a magnetic recording medium manufacturing stamper.

  Conventionally, a magnetic recording / reproducing apparatus including a magnetic recording medium on which position information used for magnetic head positioning control is recorded is widely known.

  FIG. 19 shows an example of a magnetic recording medium provided in such a conventionally known magnetic recording / reproducing apparatus.

  In the magnetic recording medium 100 shown in FIG. 19, a plurality of servo regions 102 are radially formed at predetermined intervals by a concavo-convex pattern formed of a magnetic layer. As shown in an enlarged view in FIG. 20, the servo area 102 includes a preamble section 104, a servo mark section 106, an address section 108 in which address information is recorded, and a burst section 110 in which position information is recorded. Servo information including it is recorded. In the figure, reference numeral 112 denotes a data track for recording user data.

  In the burst portion 110 of the servo area 102, burst patterns including four types of burst signal groups 110A, 110B, 110C, and 110D are formed as position information. The burst signal groups 110A and 110B are arranged as a pair of position information so as to equally straddle the center line of the data track 112, while the burst signal groups 110C and 110D have a burst signal as a pair of position information. The groups 110A and 110B are arranged at positions shifted by a half track pitch.

  FIG. 21 shows an enlarged view of the burst signal group 110A. The other burst signal groups 110B, 110C, and 110D have the same structure.

  As shown in FIG. 21, the burst signal group 110A (110B, 110C, 110D) includes a plurality of protrusions (generally 10 parts in the circumferential direction) made of a magnetic layer (magnetic material) in the circumferential direction. About 30 pieces). The circumferential length of the convex portion is BL1, the circumferential length of the concave portion is BL2, and the radial width of the convex portion is BW1. In general, in the magnetic recording / reproducing apparatus, since the magnetic recording medium 100 is rotated at a constant angular velocity, the circumferential length BL1 of the convex portion and the circumferential length BL2 of the concave portion vary depending on the radial position in the magnetic recording medium 100, and The concavo-convex pattern is formed so that the circumferential length BL1 of the convex portion and the circumferential length BL2 of the concave portion become longer from the peripheral portion toward the outer peripheral portion.

  The burst pattern of the burst unit 110 is configured by arranging a plurality of burst signal groups (110A, 110B, 110C, 110D) in the radial direction at intervals of a width BW2, as shown in FIG.

  Such a burst pattern is reproduced by, for example, a position control circuit 130 as shown in FIG. The position control circuit 130 includes an amplifier 116 that amplifies the reproduction signal read by the magnetic head 114, a differentiator 118 that differentiates the reproduction signal, a zero-cross detector 120, and a comparator 122 that generates a predetermined gate pulse signal. A peak detector 124 that detects the maximum output (peak output) of the reproduction signal and generates a position control signal, a sample hold device 126 that holds the position control signal, and a differential amplifier circuit 128. Thus, the circuit is used for position control of a so-called peak detect method.

  The zero-cross detector 120 is a circuit that generates a predetermined signal while the magnitude of the signal differentiated by the differentiator 118 is 0. For example, the maximum value of the reproduction output read by the magnetic head 114 (peak value) ) Is generated, a predetermined signal is generated.

  The comparator 122 is configured to output a gate pulse signal when the reproduction output is greater than a certain fixed output. Since the zero cross detector 120 generates a predetermined signal even when the reproduction output is 0, an unnecessary signal generated from the zero cross detector 120 is removed by the gate pulse signal.

  After the burst pattern recorded on the magnetic recording medium 100 is read by the magnetic head 114, the reproduction signal of the burst pattern is amplified by the amplifier 116 and input to the differentiator 118. The reproduction signal differentiated by the differentiator 118 passes through the zero cross detector 120 and is then input to the peak detector 124. Thereafter, the peak detector 124 detects a position where both the gate pulse signal from the comparator 122 and the signal from the zero cross detector 120 exist, and the reproduction output from the amplifier 116 at that position becomes the maximum output (peak output). . This maximum output is output to the sample hold unit 126 as a position control signal. Then, the output difference between the position control signal of the burst signal group 110A and the position control signal of the burst signal group 110B held by the sample hold device 126, or the position control of the position control signal of the burst signal group 110C and the burst signal group 110D. Position information of the magnetic head 114 is obtained by obtaining the output difference from the signal by the differential amplifier circuit 128, and positioning (tracking) control of the magnetic head 114 is performed (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2003-323772

  However, in a magnetic recording medium in which a burst pattern (position information) is recorded by an uneven pattern formed by a magnetic layer, such as a discrete track medium or a patterned medium, the magnetization signal of the uneven pattern has a unidirectional polarity. Since it is recorded, the reproduction signal of the concavo-convex pattern has a waveform as shown in FIG. In FIG. 24, the blacked out portion schematically shows the plane of the convex portion of the concave / convex pattern, and the reproduction signal waveform of the concave / convex pattern is an example in the case where the magnetic layer is a perpendicular magnetic recording layer. .

  As described above, the magnetic recording medium in which the burst pattern is recorded by the concavo-convex pattern formed by the magnetic layer is different from the conventional continuous film medium in which the magnetization signal of the burst pattern is recorded with the polarity in two directions. Since the output of the position control signal used for the magnetic head positioning control is about half, there is a limit to the improvement of the magnetic head positioning accuracy.

  Moreover, since the position control signal is greatly affected by the shape of the concavo-convex pattern and placement errors, it is necessary to process the concavo-convex pattern with high accuracy in order to obtain an accurate position control signal. There is also a problem that increases.

  The present invention has been made to solve such problems, and while reducing the manufacturing burden and the manufacturing cost, at the same time increasing the output of the position control signal and controlling the positioning of the magnetic head. Provides a magnetic recording / reproducing apparatus and a control method therefor, as well as a magnetic recording medium used therein and a magnetic recording medium manufacturing stamper used for manufacturing the magnetic recording medium For the purpose.

  The inventor of the present invention can reduce the manufacturing burden and the manufacturing cost, and at the same time, increase the output of the position control signal and perform the magnetic head positioning control with high accuracy as follows. A reproducing apparatus and its control method, magnetic recording medium, and magnetic recording medium manufacturing stamper have been found.

  That is, the above-described object can be achieved by the following present invention.

  (1) Position information is recorded by a plurality of burst signal groups, and each burst signal group includes a magnetic recording medium including only one concave portion and one convex portion of a concave-convex pattern formed of a magnetic layer; A magnetic recording / reproducing apparatus comprising: signal integrating means for integrating the area of each reproduction signal corresponding to each burst signal group.

  (2) The signal integration means includes an extraction means for extracting a part of each reproduction signal by removing a signal at an end of each reproduction signal corresponding to each burst signal group, and each reproduction signal after extraction. The magnetic recording / reproducing apparatus according to (1), characterized by comprising integration means for integrating the area.

  (3) The extraction means generates a gate pulse signal having a pulse width smaller than the pulse width of each reproduction signal corresponding to each burst signal group, and extracts a part of each reproduction signal by the gate pulse signal. The magnetic recording / reproducing apparatus according to (2), which is configured as described above.

  (4) Position information is recorded by a plurality of burst signal groups, and each burst signal group includes a magnetic recording medium including only one concave portion and one convex portion of a concave-convex pattern formed of a magnetic layer; A plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal are generated for each reproduction signal corresponding to each burst signal group, and a plurality of portions of each reproduction signal are generated by the plurality of gate pulse signals. And a signal extracting means for extracting the magnetic recording and reproducing apparatus.

  (5) Position information is recorded by a plurality of burst signal groups, and each burst signal group is included in each of the burst signal groups, and a magnetic recording medium composed of concave and convex portions of a concavo-convex pattern formed by a magnetic layer. A plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal is generated for each reproduction signal corresponding to one of the two concave portions and the one convex portion, and the respective gate pulse signals are used to generate the respective gate pulse signals. And a signal extraction means for extracting a plurality of portions of the reproduction signal.

  (6) A plurality of burst signal groups are recorded on the magnetic recording medium, and each burst signal group is in position information including only one concave portion or one convex portion of the concave / convex pattern formed by the magnetic layer. A method of controlling a magnetic recording / reproducing apparatus, wherein a position control signal is generated by area integration of each reproduction signal corresponding to each burst signal group, and positioning control of the magnetic head is performed based on the position control signal.

  (7) When the reproduction signal corresponding to each burst signal group is area-integrated, a signal at the end of each reproduction signal corresponding to each burst signal group is removed to extract a part of each reproduction signal. The method for controlling a magnetic recording / reproducing apparatus according to (6), wherein the area of each reproduced signal after extraction is integrated.

  (8) A gate pulse signal having a pulse width smaller than a pulse width of each reproduction signal corresponding to each burst signal group is generated, and a part of each reproduction signal is extracted by the gate pulse signal. The method for controlling a magnetic recording / reproducing apparatus according to (7) above.

  (9) Recording on a magnetic recording medium by a plurality of burst signal groups, each burst signal group in position information consisting of only one concave portion and one convex portion of the concave-convex pattern formed by the magnetic layer For each reproduction signal corresponding to each burst signal group, a plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal are generated, and a plurality of each reproduction signal is generated by the plurality of gate pulse signals. A method for controlling a magnetic recording / reproducing apparatus, comprising: extracting a portion and performing positioning control of a magnetic head using the extracted portion.

  (10) A plurality of burst signal groups are recorded on the magnetic recording medium, and each burst signal group is included in each burst signal group in position information including concave and convex portions of the concave and convex pattern formed by the magnetic layer. A plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal are generated for each reproduction signal corresponding to one of one concave portion and one convex portion, and the plurality of gate pulse signals A method for controlling a magnetic recording / reproducing apparatus, comprising: extracting a plurality of portions of each reproduction signal and performing positioning control of a magnetic head using the extracted portions.

  (11) Position information is recorded by a plurality of burst signal groups, and each burst signal group includes only one of a concave portion and a convex portion of a concave / convex pattern formed of a magnetic layer. Magnetic recording medium.

  (12) A stamper for manufacturing a magnetic recording medium, wherein a concavo-convex pattern corresponding to the concavo-convex shape of the concavo-convex pattern in the magnetic recording medium according to (11) is formed.

  The magnetic recording / reproducing apparatus and the control method thereof according to the present invention can reduce the manufacturing burden and the manufacturing cost, and at the same time, increase the output of the position control signal and perform the magnetic head positioning control with high accuracy. It has an excellent effect of being able to.

  In addition, the magnetic recording medium according to the present invention can reduce the manufacturing burden and the manufacturing cost, increase the output of the position control signal, and perform the magnetic head positioning control with high accuracy. It has an excellent effect that it can be provided.

  Furthermore, the magnetic recording medium manufacturing stamper according to the present invention has an excellent effect that a magnetic recording medium capable of reducing the manufacturing burden and the manufacturing cost can be manufactured.

  In the magnetic recording / reproducing apparatus according to the present invention, position information is recorded by a plurality of burst signal groups, and each burst signal group is a magnetic composed of only one concave portion and one convex portion of a concave / convex pattern formed by a magnetic layer. This problem is solved by including a recording medium and signal integration means for integrating each reproduction signal corresponding to each burst signal group.

  In the magnetic recording / reproducing apparatus according to the present invention, position information is recorded by a plurality of burst signal groups, and each burst signal group is one of one concave portion and one convex portion of the concave / convex pattern formed by the magnetic layer. A plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal for each reproduction signal corresponding to each burst signal group, and the plurality of gate pulse signals The present invention solves the same problem as described above by including signal extraction means for extracting a plurality of portions of each reproduction signal.

  In the magnetic recording / reproducing apparatus according to the present invention, position information is recorded by a plurality of burst signal groups. Each burst signal group includes a magnetic recording medium including concave and convex portions of concave and convex patterns formed by a magnetic layer, Generating a plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal for each reproduction signal corresponding to one of the one concave portion and one convex portion included in the burst signal group; And a signal extraction means for extracting a plurality of portions of each reproduction signal by the gate pulse signal.

  The “position information” in the present invention refers to information used for magnetic head positioning (tracking) control, and generally corresponds to a burst pattern recorded in a burst portion of a servo area.

  Further, the “reproduced signal” in the present invention includes a signal obtained by amplifying this signal in addition to a signal output when the magnetization signal of the concavo-convex pattern is reproduced by the magnetic head.

  The “reproduction signal corresponding to the burst signal group” in the present invention refers to a reproduction signal generated based on the concave portion or the convex portion constituting the burst signal group among the above-mentioned “reproduction signals”. In addition to a reproduction signal generated only by a group, a reproduction signal generated by a burst signal group and another concave portion or convex portion is also included.

  In addition, the “concave shape corresponding to the concave / convex shape of the concave / convex pattern on the magnetic recording medium” in the present invention refers to the concave / convex shape opposite to the concave / convex shape of the concave / convex pattern on the magnetic recording medium and the concave / convex pattern on the magnetic recording medium. Suppose that it uses both the uneven | corrugated shape and the uneven | corrugated shape in which an uneven | corrugated positional relationship corresponds to the meaning included.

  Hereinafter, with reference to the drawings, a magnetic recording / reproducing apparatus and control method thereof according to Example 1 of the present invention, a magnetic recording medium, a magnetic recording medium manufacturing stamper, and a magnetic recording / reproducing apparatus according to Example 2 and a control method thereof will be described. explain.

  A magnetic recording / reproducing apparatus (not shown) according to the first embodiment includes a magnetic recording medium 2 having a disk shape as shown in FIG. 1, and a plurality of servo areas 4 are provided on the magnetic recording medium 2. And user data areas 6 are formed alternately in the circumferential direction.

  In the servo area 4, as shown in an enlarged view in FIG. 2, a burst pattern (position information) is recorded in which a plurality of burst signal groups 8A (8B, 8C, 8D) are arranged in the radial direction. The arrangement of the burst signal group itself is the same as the arrangement of the burst signal group in the burst pattern of the conventional magnetic recording medium 100 described above. Note that reference numeral 112 in the figure indicates a data track for recording user data.

  FIG. 3 is an enlarged view of a part of the burst pattern formed in the servo region 4 (the whole burst signal group 8A and a part of the burst signal group 8B), and corresponds to FIG. It is. FIG. 3 shows the entire burst signal group 8A and only a part of the burst signal group 8B, but the other burst signal groups 8C and 8D have the same structure except for the radial position. is there. In the following description, reference numeral 8 denotes four types of burst signal groups 8A, 8B, 8C, and 8D.

Each burst signal group 8 in the burst pattern of the magnetic recording medium 2 is constituted by one concave portion or one convex portion (a convex portion in the first embodiment). For example, as shown in FIG. 4, the concavo-convex pattern is formed by providing a convex portion 152 made of a magnetic layer on a substrate 150 made of a glass substrate, an underlayer, a soft magnetic layer, an orientation layer, or the like. The recess 154 may be filled with a filler made of SiO ₂ or the like.

  On the other hand, a plurality of substantially concentric recording tracks are formed in the user data area 6 by convex portions of a predetermined concave / convex pattern formed of a magnetic layer, and each of these recording tracks is substantially concentric by concave portions of the concave / convex pattern. The plurality of formed grooves are magnetically separated. In the user data area 6, user data is recorded as magnetization information.

  The concave / convex pattern of the magnetic recording medium 2 is formed (recorded) on the magnetic recording medium 2 by the following procedure using a magnetic recording medium manufacturing stamper 30 as shown in FIG. The The magnetic recording medium manufacturing stamper 30 is previously formed with a concavo-convex concavo-convex pattern corresponding to the concavo-convex shape of the magnetic recording medium 2, and the convex portion of the magnetic recording medium manufacturing stamper 30 is magnetic. Corresponding to the concave portions of the recording medium 2, the concave portions of the magnetic recording medium manufacturing stamper 30 correspond to the convex portions of the magnetic recording medium 2.

  First, a starting workpiece for the workpiece 32 shown in FIG. 5A is prepared. The processing starting body of the workpiece 32 is, for example, a plate-like body 32A formed by forming an underlayer, a soft magnetic layer, an orientation layer, a continuous recording layer, and a mask layer in this order on a glass substrate by a sputtering method. Further, it can be obtained by applying the resist layer 32B by spin coating.

  Next, as shown in FIG. 5B, using the magnetic recording medium manufacturing stamper 30, an uneven pattern is formed on the resist layer 32B of the processing starting body of the workpiece 32 by, for example, a nano-imprint method. To do. Then, after removing the resist layer 32B at the bottom of the recess, the mask layer and the continuous recording layer of the plate-like body 32A are removed by, for example, etching, and the unevenness as shown in FIG. Form a pattern.

  The burst signal group 8 of the magnetic recording medium 2 is reproduced by a magnetic recording / reproducing apparatus described below.

  FIG. 6 shows a block diagram of the position control circuit 10 provided in the magnetic recording / reproducing apparatus (not shown) according to Embodiment 1 of the present invention, and corresponds to the conventional position control circuit 130 shown in FIG. To do. The configuration of the magnetic recording / reproducing apparatus according to the first embodiment is the same as that of the conventional magnetic recording / reproducing apparatus except for the magnetic recording medium 2 and the position control circuit 10. A reference numeral is attached and a description thereof is omitted (the same applies to the following embodiments).

  Hereinafter, the position control circuit 10 which is a characteristic part of the present invention will be described in detail.

  As shown in FIG. 6, the position control circuit 10 removes a signal at the end of each reproduction signal corresponding to each burst signal group 8 recorded on the magnetic recording medium 2 by the amplifier 116 and removes one of the reproduction signals. A gate circuit (extraction means) 12 for extracting a part, an integrator (integration means) 14 for area integration of a signal extracted by the gate circuit 12, a sample hold unit 126, and a differential amplifier circuit 128. (The gate circuit 12 and the integrator 14 constitute a signal integration means).

  The gate circuit 12 detects a servo mark indicating the start position of the burst pattern, and generates a gate pulse signal S2 as shown in FIG. 7 using the servo mark as a reference. 7 shows the plane of the burst signal group 8 in the magnetic recording medium 2 of the magnetic reproduction recording apparatus according to the first embodiment, the reproduction signal S1, the gate pulse signal S2, and the position control signal S3 corresponding to the burst signal group 8. Are respectively schematically shown.

  The gate pulse signal S2 is composed of a gate pulse composed of a rectangular wave. The pulse width W2 of the gate pulse signal is set to be smaller than the pulse width W1 of each reproduction signal S1 corresponding to each burst signal group 8, and each gate pulse signal S2 corresponds to each burst signal group 8. It is used for extracting a part of each reproduction signal S1 corresponding to each burst signal group 8 by removing the signal at the end from each reproduction signal S1. The pulse width of each reproduction signal corresponding to each burst signal group is obtained by dividing "the circumferential length of the convex portion (or concave portion) constituting each burst signal group" by "the peripheral velocity of the magnetic recording medium". It is a value.

  Next, the operation of the magnetic reproduction recording apparatus according to the first embodiment will be described.

  The reproduction signal S 1 corresponding to the burst signal group 8 read by the magnetic head 114 is amplified by the amplifier 116 and then input to the integrator 14 via the gate circuit 12. Each reproduction signal S1 input to the integrator 14 is area-integrated by the integrator 14 during a period in which each gate pulse signal S2 generated for each reproduction signal S1 by the gate circuit 12 is output. The signal after the area integration is output to the sample hold device 126 as a position control signal S3. Then, the output difference between the position control signal S3 of the burst signal group 8A and the position control signal S3 of the burst signal group 8B held by the sample hold unit 126, or the position control signal S3 and burst signal group 8D of the burst signal group 8C. The position information of the magnetic head 114 is obtained by obtaining the output difference with the position control signal S3 by the differential amplifier circuit 128, and the positioning (tracking) control of the magnetic head 114 is performed.

  According to the magnetic recording / reproducing apparatus according to the first embodiment, a burst signal group including one concave portion or one convex portion of a predetermined concave / convex pattern formed of a magnetic layer (in the first embodiment, a burst signal including convex portions). A magnetic recording medium 2 on which position information is recorded by the group 8), and signal integration means (gate circuit 12 and integrator 14 in the first embodiment) for area integration of each reproduction signal S1 corresponding to each burst signal group 8. Therefore, it is possible to increase the output of the position control signal and perform highly accurate positioning control.

  In addition, according to the control method of the magnetic recording / reproducing apparatus according to the first embodiment, a burst signal group consisting of one concave portion or one convex portion of a predetermined concave / convex pattern formed of a magnetic layer (in the first embodiment, a convex signal). A position control signal is generated by integrating the area of each reproduction signal S1 corresponding to each burst signal group 8 in the position information recorded on the magnetic recording medium 2 by the burst signal group 8) composed of parts, Since the positioning control of the magnetic head is performed based on this, as in the magnetic recording / reproducing apparatus according to the first embodiment, the output of the position control signal can be increased and the positioning control with high accuracy can be performed.

  Furthermore, the signal integration means removes the signal at the end of each reproduction signal S1 corresponding to each burst signal group 8 and extracts a part of each reproduction signal S1 (gate circuit 12 in the first embodiment). And integration means (integrator 14 in the present embodiment 1) for integrating the areas of the respective reproduced signals after extraction, so that each reproduced signal caused by variations in the shape and arrangement of each burst signal group is included. Noise can be removed and the position control signal can be stabilized. In particular, the extraction means generates a gate pulse signal having a pulse width W2 smaller than the pulse width W1 of each reproduction signal S1 corresponding to each burst signal group 8, and extracts a part of each reproduction signal by this gate pulse signal. Thus, the noise of each reproduction signal can be easily removed while having a simple structure.

  Further, according to the magnetic recording medium 2 according to the first embodiment, position information is recorded by a plurality of burst signal groups, and each burst signal group has one concave portion and one convex portion of the concave / convex pattern formed by the magnetic layer. (In this embodiment, the burst signal group 8 is composed of one convex portion), the manufacturing burden and manufacturing cost can be reduced, the output of the position control signal is increased, and the magnetic head It is possible to provide a magnetic recording / reproducing apparatus (for example, a magnetic recording / reproducing apparatus according to the first embodiment) that can perform the positioning control of the above with high accuracy. In addition, compared to conventional magnetic recording media in which a burst signal group is configured by convex portions and concave portions, the area of the signal output portion in each burst signal group is increased, the output can be increased, and the convex portion The number of the burst signal groups is small, and variations in the shape and arrangement of each burst signal group can be reduced.

  Furthermore, according to the magnetic recording medium manufacturing stamper 30 according to the first embodiment, a magnetic recording medium (for example, the magnetic recording medium 2 according to the first embodiment) capable of reducing manufacturing burden and manufacturing cost is manufactured. Can do.

  The inventor of the present invention measured the output of the position control signal using the magnetic recording / reproducing apparatus according to Example 1 and the conventional magnetic recording / reproducing apparatus.

  In this experiment, the circumferential length of the burst signal group 8 (BL1 in FIG. 3) is 8 μm, the circumferential interval of the burst signal group 8 (BL3 in FIG. 3) is 1 μm, and the burst signal group The radial width of 8 (BW1 in FIG. 3) and the radial interval of the burst signal group 8 (BW2 in FIG. 3) were 200 nm. Note that the circumferential length of the burst signal group 8 and the circumferential interval of the burst signal group 8 are values at a radial position of 20 mm on the 2.5-inch disk, respectively. The track pitch of the data track was 200 nm (127 kTPI), and the width of the data track was 120 nm.

Further, the recording layer (magnetic layer) is a perpendicular magnetic recording layer having a thickness of 15 nm. The convex portion of the burst signal group 8 is formed by the perpendicular magnetic recording layer, and the perpendicular magnetic recording layer is magnetized to generate a servo signal magnetic field. The process for generating was performed. Specifically, after setting the disk surface between the magnetic poles of the electromagnet generating a DC magnetic field of 1.2 × 10 ⁶ A / m so that the disk surface is parallel to the magnetic pole surface, the perpendicular magnetic recording layer in the servo area is bundled. And recorded servo information. When the magnetic characteristics of the perpendicular magnetic recording layer were measured using a sample vibration type magnetometer (VSM), the saturation magnetization Bs was 0.44 T and the residual saturation magnetization Br was 0.43 T.

  Using such a magnetic recording medium, the disk is rotated at a disk rotational speed of 4200 rpm, the magnetic head is levitated by 11 nm in the vicinity of a radial position of 20 mm of a 2.5 inch disk, and a signal is recorded on the data track by a magnetic head having a write width of 200 nm. Then, a burst pattern was reproduced with a GMR magnetic head having a read width of 120 nm, and the output of the position control signal of Example 1 and the conventional magnetic recording / reproducing apparatus was measured.

  The measurement results are shown in FIG. FIG. 8 is a graph showing the relationship between the magnetic head position and the output of the position control signal of the burst signal group 8A. The solid line indicates the output of the magnetic recording / reproducing apparatus according to the first embodiment, and the dotted line indicates the conventional one. The output of the magnetic recording / reproducing apparatus is shown. The magnetic head position on the horizontal axis indicates the distance between the left end of the burst signal group 8A and the right end of the magnetic head, as shown in FIG. Further, the output value on the vertical axis was normalized by setting the output value at the magnetic head position of 160 nm in Example 1 to 1.

  As shown in FIG. 8, in the magnetic recording / reproducing apparatus according to the first embodiment, the conventional magnetic recording / reproducing apparatus, which is a comparative example, in all the ranges in which data is collected (the magnetic head position is in the range of 60 to 160 nm). It can be seen that the output of the position control signal is larger than in FIG.

  Further, the inventor of the present invention measured a position error signal (PES: Position Error Signal) with respect to the magnetic head position by using the magnetic recording / reproducing apparatus according to the first embodiment and the conventional magnetic recording / reproducing apparatus.

  More specifically, as shown in FIG. 10, when burst signal groups 8A, 8B, 8C, and 8D as position information are formed on a magnetic recording medium and the magnetic head is moved, burst signal group 8A is formed. And 8B, and the position error signal Scd obtained by the burst signal groups 8C and 8D were measured, respectively. Here, the position error signal Sab is given by (Sa−Sb) / (Sa + Sb) where Sa is the position control signal output of the burst signal group 8A and Sb is the position control signal output of the burst signal group 8B. . The position error signal Scd is given by (Sc−Sd) / (Sc + Sd) where Sc is the position control signal output of the burst signal group 8C and Sd is the position control signal output of the burst signal group 8D.

  The graph of FIG. 10 shows the relationship between the magnetic head position and the position error signals Sab and Scd in Example 1 and the comparative example. In the graph of FIG. 10, an upward right line (magnetic head position 10 nm to 110 nm) indicates the position error signal Sab, and a downward right line (magnetic head position 110 nm to 210 nm) indicates the position error signal Scd. . Also, the solid line indicates the position error signals Sab and Scd of the magnetic recording / reproducing apparatus according to the first embodiment, and the dotted line (almost coincides with the solid line) indicates the position error signals Sab and Scd of the conventional magnetic recording / reproducing apparatus. Show.

  As shown in the graph of FIG. 10, it was confirmed that the position error signal of the magnetic recording / reproducing apparatus according to the first embodiment maintains the same linearity as the position error signal of the conventional magnetic recording / reproducing apparatus. It was.

  Thus, according to the magnetic recording / reproducing apparatus and the control method thereof according to the first embodiment, the output of the position control signal is increased and the positioning control with high accuracy is performed while maintaining the linearity of the position error signal. Can do.

The inventor of the present invention uses the magnetic recording / reproducing apparatus according to the first embodiment and the conventional magnetic recording / reproducing apparatus, and the number of track address reading errors per track for 10 tracks and the bit of user data. The error rate was also measured. As a result, in the conventional magnetic recording / reproducing apparatus, the number of track address reading errors for each track is 0 to 15 (average of 3.5 for one track), and the bit error rate for each track is 2.6 × 10 ⁻⁶ to 1. Whereas it was 0.0 × 10 ⁻⁷ , the number of track address reading errors in the magnetic recording / reproducing apparatus of Example 1 was 0 for all 10 tracks, and the bit error rate was 1.0 × 10 for all 10 tracks. ^-7 or less.

  As described above, the number of track address reading errors for each track and the bit error rate for each track can be reduced as compared with the conventional magnetic recording / reproducing apparatus, while maintaining the linearity of the position error signal. This is considered to be because the output of the position control signal was increased and the noise of the reproduction signal due to the variation in the shape and arrangement of the burst signal group could be removed.

  FIG. 11 is a block diagram of the position control circuit 20 provided in the magnetic recording / reproducing apparatus (not shown) according to the second embodiment of the invention.

  The magnetic recording / reproducing apparatus according to the second embodiment includes a position control circuit 20 instead of the position control circuit 10 of the first embodiment. Other configurations are the same as those of the first embodiment.

  In this position control circuit 20, a gate circuit 22 (extraction means) is disposed between the amplifier 116 and the differentiator 118 in the conventional position control circuit 130 shown in FIG.

  The gate circuit 22 detects a servo mark indicating the start position of the burst pattern, and generates a plurality of gate pulse signals S4 as shown in FIG. 12 for each burst signal group 8 with reference to the servo mark. These gate pulse signals S4 correspond to a pattern of a plurality of convex portions or a plurality of concave portions constituting a burst signal group in the conventional magnetic recording medium 100. 12 shows a plane of one burst signal group 8 in the magnetic recording medium 2 of the magnetic reproduction recording apparatus according to the second embodiment, a reproduction signal S1 corresponding to one burst signal group 8, a gate pulse signal S4, and The signal S5 generated by the reproduction signal S1 and the gate pulse signal S4 is schematically shown.

  In the magnetic reproduction recording apparatus according to the second embodiment, the gate circuit 22 generates a plurality of gate pulse signals S4 for one pulse of each reproduction signal S1. Then, a plurality of portions of the reproduction signal S1 corresponding to one burst signal group 8 are extracted by the plurality of gate pulse signals S4 to generate a signal S5.

  The reproduction signal S1 corresponding to each burst signal group 8 read by the magnetic head 114 is amplified by the amplifier 116, and then the gate circuit only during a period in which each gate pulse signal S4 generated by the gate circuit 22 is output. 22 and extracted as signal S5.

  The signal S5 extracted by the gate circuit 22 is input to the differentiator 118. The reproduction signal differentiated by the differentiator 118 passes through the zero cross detector 120 and is then input to the peak detector 124. Thereafter, the peak detector 124 detects a position where both the gate pulse signal from the comparator 122 and the signal from the zero cross detector 120 exist, and the reproduction output from the amplifier 116 at that position becomes the maximum output (peak output). . This maximum output is output to the sample hold unit 126 as a position control signal. Then, the output difference of the position control signal between the burst signal group 8A and the burst signal group 8B held by the sample hold unit 126 or the output difference of the position control signal between the burst signal group 8C and the burst signal group 8D is differentiated. The position information of the magnetic head 114 is acquired by the amplifier circuit 128 and the positioning control of the magnetic head 114 is performed.

  In the magnetic recording / reproducing apparatus according to the second embodiment, position information is recorded by a plurality of burst signal groups (burst signal group 8 including convex portions in the second embodiment), and each burst signal group is formed of a magnetic layer. A magnetic recording medium 2 composed of only one concave portion or one convex portion of the concavo-convex pattern to be formed (in this embodiment, the burst signal group 8 is composed of one convex portion) and each burst signal group 8 Signal extraction means for generating a plurality of gate pulse signals S4 having a pulse width W3 smaller than the corresponding pulse width W1 of each reproduction signal S1, and extracting a plurality of portions of each reproduction signal S1 by using the plurality of gate pulse signals S4 Since the second embodiment includes the gate circuit 22, the manufacturing load and the manufacturing cost can be reduced, and at the same time, the position control circuit 20. Most of the can be constructed using components of a conventional position control circuit 130, as compared to the magnetic recording reproducing apparatus according to the first embodiment, it is possible to shorten the cost and development time.

  Furthermore, it is possible to remove noise in the reproduction signal due to variations in the shape and arrangement of burst signal groups, and to stabilize the position control signal.

  In addition, according to the control method of the magnetic recording / reproducing apparatus according to the second embodiment, the burst signal group (this book) composed of only one concave portion or one convex portion of the predetermined concave-convex pattern formed of the magnetic layer. In Example 2, the pulse width W3 is smaller than the pulse width W1 of each reproduction signal S1 corresponding to each burst signal group in the position information recorded on the magnetic recording medium 2 by the burst signal group 8) consisting of one convex portion. Since the plurality of gate pulse signals S4 are generated and the magnetic head positioning control is performed using the reproduction signal S5 extracted by the plurality of gate pulse signals S4, similarly to the magnetic recording / reproducing apparatus according to the second embodiment. While it is possible to reduce the manufacturing burden and manufacturing cost, it is possible to simultaneously reduce the cost and shorten the development period.

  The inventor of the present invention measured the output of the position control signal using the magnetic recording / reproducing apparatus according to the second embodiment and the conventional magnetic recording / reproducing apparatus under the same conditions as in the first embodiment.

  The measurement results are shown in FIG. FIG. 13 is a graph showing the relationship between the magnetic head position and the output of the position control signal of the burst signal group 8A. The solid line represents the output of the magnetic recording / reproducing apparatus according to the second embodiment, and the dotted line represents the conventional technique. The output of the magnetic recording / reproducing apparatus is shown. Furthermore, the output value on the vertical axis was normalized with the output value at 160 nm of the magnetic head position of Example 2 set to 1.

  As shown in FIG. 13, in the magnetic recording / reproducing apparatus according to the second embodiment, the conventional magnetic recording / reproducing apparatus, which is a comparative example, in all the ranges in which data is collected (the magnetic head position is in the range of 60 to 160 nm). It can be seen that the reproduction output of the position control signal is larger than that of FIG.

  This is because although the demagnetizing field is generated on the side wall of the convex part or the concave part of the magnetic layer, each burst signal group 8 is constituted by one convex part, so that the influence of the demagnetizing field on the side wall is reduced. Conceivable.

  Further, the inventors of the present invention measured the position error signal with respect to the magnetic head position using the magnetic recording / reproducing apparatus according to the second embodiment and the conventional magnetic recording / reproducing apparatus.

  As a result, as shown in the graph of FIG. 14, the position error signal of the magnetic recording / reproducing apparatus according to the second embodiment maintains linearity that is the same as the position error signal of the conventional magnetic recording / reproducing apparatus. Was confirmed. In FIG. 14, the solid line represents the position error signal of the magnetic recording / reproducing apparatus according to the second embodiment, and the dotted line (almost coincident with the solid line) represents the position error signal of the conventional magnetic recording / reproducing apparatus.

Further, the inventor of the present invention uses the magnetic recording / reproducing apparatus according to the second embodiment and the conventional magnetic recording / reproducing apparatus, and the number of track address reading errors per track for 10 tracks and the bit of user data. The error rate was also measured. As a result, in the conventional magnetic recording / reproducing apparatus, the number of track address reading errors for each track is 0 to 15 (average of 3.5 for one track), and the bit error rate for each track is 2.6 × 10 ⁻⁶ to 1. Whereas it was 0.0 × 10 ⁻⁷ , the number of track address reading errors in the magnetic recording / reproducing apparatus of Example 2 was 0 for all 10 tracks, and the bit error rate was 1.0 × 10 for all 10 tracks. ^-7 or less.

  As described above, the number of track address reading errors for each track and the bit error rate for each track can be reduced as compared with the conventional magnetic recording / reproducing apparatus, while maintaining the linearity of the position error signal. This is considered to be because the output of the position control signal was increased and the noise of the reproduction signal due to the variation in the shape and arrangement of the burst signal group could be removed.

  FIG. 25 shows a plane of one burst signal group in a magnetic recording medium of a magnetic recording / reproducing apparatus (not shown) according to Embodiment 3 of the present invention, a reproduction signal S1 corresponding to one burst signal group, a gate pulse signal S4, The signal S5 generated by the reproduction signal S1 and the gate pulse signal S4 is schematically shown.

  The magnetic recording / reproducing apparatus according to the third embodiment has a configuration in which each burst signal group includes two convex portions and one concave portion. Other configurations are the same as those of the second embodiment.

  In the magnetic reproduction recording apparatus according to the third embodiment, each reproduction corresponding to one of the one concave portion and the convex portion (one convex portion in the third embodiment) included in each burst signal group is performed by the gate circuit 22. For each signal S1, a plurality of gate pulse signals S4 are generated for one pulse of each reproduction signal S1. Then, a plurality of portions of the reproduction signal S1 corresponding to one of one concave portion and convex portion are extracted by the gate pulse signal S4, and a signal S5 is generated.

  Therefore, the third embodiment can reduce the manufacturing burden and the manufacturing cost similarly to the second embodiment, but at the same time, most of the position control circuit 20 is configured using the components of the conventional position control circuit 130. Compared with the magnetic recording / reproducing apparatus according to the first embodiment, the cost can be reduced and the development period can be shortened.

  Furthermore, it is possible to remove noise in the reproduction signal due to variations in the shape and arrangement of burst signal groups, and to stabilize the position control signal.

  Each burst signal group is not composed of only one convex portion or one concave portion, but a magnetic recording medium in which each burst signal group is composed of about 10 to 30 convex portions or concave portions. By reducing the number of convex portions and concave portions, the area of the portion that outputs a signal in each burst signal group can be increased, and the output can be increased. The number of recesses is small, and variations in the shape and arrangement of each burst signal group can be reduced.

  The magnetic recording / reproducing apparatus and the control method thereof according to the present invention are not limited to the magnetic recording / reproducing apparatus and the control method thereof according to Example 1-3.

  Therefore, for example, the position control circuit 10 in the first embodiment includes the gate circuit 12, but the present invention is not limited to this. For example, the position information burst signal group may vary in shape and arrangement. When there is little noise in the reproduced signal due to it, the gate circuit 12 may not be provided. That is, the signal integration means according to the present invention may be any means that integrates the reproduction signal corresponding to the burst signal group.

  In the first embodiment, a part of the reproduction signal S1 is extracted by one gate pulse signal S2, but a part of the reproduction signal S1 may be extracted by a plurality of gate pulse signals.

  Further, the “concavo-convex pattern” according to the present invention is not limited to the configuration of the concavo-convex pattern shown in the first embodiment, and is formed on the substrate 42 like the concavo-convex pattern 40 shown in FIG. The magnetic layer 44 may be laminated so as to cover the concavo-convex pattern, and the concavo-convex pattern may be formed with the magnetic layer 44 including not only the convex portion 40A but also the bottom of the concave portion 40B, or the concavo-convex pattern 50 shown in FIG. As described above, the concave / convex pattern may be formed by the magnetic layer 52 including not only the convex portion 50A but also the bottom of the concave portion 50B.

  In addition, the “burst signal group” according to the present invention is not limited to the configuration of the burst signal group shown in the embodiment 1-3, and as shown in FIG. 17, the convexity shown in FIG. The portion (black-filled portion in FIG. 3) may be constituted by a concave portion (a white portion in FIG. 17) of the concavo-convex pattern. In this case, since the portion that was a concave portion in FIG. 3 is constituted by a convex portion made of a magnetic layer, the reproduction signal of the burst pattern (uneven pattern) has a waveform as shown in FIG. If the extraction means according to the present invention removes the edge signal from the reproduction signal corresponding to the burst signal group consisting of the concave portions and extracts a part of the reproduction signal, the same effect as in the first embodiment can be obtained. it can. The same applies to the second embodiment.

  Furthermore, in Example 1-3, as an example of the magnetic recording medium, concentric recording tracks are formed by convex portions formed of a magnetic layer, and each recording track has a plurality of concentric grooves. Although a discrete track medium having a user data area magnetically separated by (concave part of concave / convex pattern) is applied, the present invention is not limited to this.

  Therefore, for example, the projections formed by dividing the magnetic layer into meshes or dots (each recording track is magnetically separated into its circumferential direction) are isolated in islands (islands). The present invention can also be applied to so-called patterned media. In addition, the magnetic layer in the user data area may be formed by a continuous magnetic layer in which an uneven pattern is not formed.

  Further, four types of burst signal groups 8A, 8B, 8C, and 8D are formed as position information on the magnetic recording medium. However, the present invention is not limited to this, and for example, only a pair of burst signal groups 8A and 8B. May be formed. The arrangement of the burst signal group with respect to the data track is not particularly limited. For example, the burst signal groups 8A and 8B as a pair of position information and the burst signal groups 8C and 8D are shifted from each other by 1/3 track pitch. It may be arranged at a different position.

  The present invention can be applied to a magnetic recording / reproducing apparatus including a magnetic recording medium such as a discrete track medium and a patterned medium, a control method thereof, a magnetic recording medium, and a magnetic recording medium manufacturing stamper.

1 is a schematic plan view of a magnetic recording medium in a magnetic recording / reproducing apparatus according to Embodiment 1 of the present invention. Magnified partial enlarged view showing the periphery of a burst pattern in a servo area of a magnetic recording medium in the magnetic recording / reproducing apparatus. Partially enlarged view schematically showing a part of a burst pattern in a servo area of a magnetic recording medium in the magnetic recording / reproducing apparatus. Schematic side sectional view showing an example of a magnetic recording medium in the magnetic recording / reproducing apparatus The figure which showed typically the formation procedure of the uneven | corrugated pattern of the magnetic recording medium in the magnetic recording / reproducing apparatus Block diagram of position control circuit in the same magnetic recording / reproducing apparatus Schematic diagram schematically showing a plane of a burst signal group, a reproduction signal corresponding to the burst signal group, a gate pulse signal, and a position control signal in the magnetic recording medium of the magnetic recording / reproducing apparatus. Graph showing the relationship between magnetic head position and position control signal output in the same magnetic recording / reproducing apparatus The figure for demonstrating the definition of the magnetic head position in each graph The figure which showed typically the positional relationship of the data track in the magnetic recording medium of the magnetic recording / reproducing apparatus based on Example 1 of this invention, a burst signal group, and a magnetic head, The position of a magnetic head and the position error signal in the figure Graph showing the relationship FIG. 5 is a block diagram of a position control circuit in a magnetic recording / reproducing apparatus according to Embodiment 2 of the present invention. Schematic diagram schematically showing a plane of a burst signal group, a reproduction signal corresponding to the burst signal group, a gate pulse signal, and a signal generated by the reproduction signal and the gate pulse signal in the magnetic recording medium of the magnetic recording / reproducing apparatus. Figure Graph showing the relationship between magnetic head position and position control signal output in the same magnetic recording / reproducing apparatus The figure which showed typically the positional relationship of the data track in the magnetic recording medium of the magnetic recording / reproducing apparatus based on Example 2 of this invention, a burst signal group, and a magnetic head, The position of a magnetic head and the position error signal in the figure Graph showing the relationship Schematic side sectional view showing a second example of the uneven pattern in the servo area of the magnetic recording medium according to the present invention Schematic side sectional view showing a third example of the concave-convex pattern in the servo area of the magnetic recording medium according to the present invention Schematic plan view showing another example of the burst signal group in the servo area of the magnetic recording medium according to the present invention The figure which showed the reproduction signal waveform of the concavo-convex pattern in the magnetic recording medium typically Schematic plan view of a magnetic recording medium in a conventional magnetic recording / reproducing apparatus Magnified partial enlarged view showing the vicinity of the servo area of the magnetic recording medium in the magnetic recording / reproducing apparatus. A partially enlarged view schematically showing a burst signal group in a servo area of a magnetic recording medium in the magnetic recording / reproducing apparatus. Partially enlarged view schematically showing a part of a burst pattern in a servo area of a magnetic recording medium in the magnetic recording / reproducing apparatus. Block diagram of position control circuit in the same magnetic recording / reproducing apparatus The figure which showed typically the plane of the burst signal group of the magnetic recording medium in the same magnetic recording and reproducing device, and the reproduction signal of the concavo-convex pattern The burst signal group plane in the magnetic recording medium of the magnetic recording / reproducing apparatus according to the third embodiment of the present invention, the reproduction signal corresponding to the burst signal group, the gate pulse signal, and the reproduction signal and the gate pulse signal are generated. Schematic diagram showing the signal schematically

Explanation of symbols

DESCRIPTION OF SYMBOLS 2,100 ... Magnetic recording medium 4,102 ... Servo area 8 ... Burst signal group 10, 20, 130 ... Position control circuit 12, 22 ... Gate circuit 14 ... Integrator 30 ... Magnetic recording medium manufacturing stamper 32 ... Workpiece DESCRIPTION OF SYMBOLS 110 ... Burst part 110A, 110B, 110C, 110D ... Burst signal group 114 ... Magnetic head 116 ... Amplifier 118 ... Differentiator 120 ... Zero cross detector 122 ... Comparator 124 ... Peak detector 126 ... Sample hold device 128 ... Differential amplifier circuit

Claims (4)

Position information is recorded by a plurality of burst signal groups, and each burst signal group includes a magnetic recording medium including only one concave portion or one convex portion of a concave-convex pattern formed of a magnetic layer, and each burst A plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal are generated for each reproduction signal corresponding to the signal group, and a plurality of portions of each reproduction signal are extracted by the plurality of gate pulse signals. And a signal extraction means for extracting a plurality of portions of the reproduction signal more than the number of either the concave portion or the convex portion forming the burst signal group to be reproduced. A magnetic recording / reproducing apparatus. Position information is recorded by a plurality of burst signal groups, each burst signal group is a magnetic recording medium composed of concave and convex portions of a concave-convex pattern formed by a magnetic layer, one concave portion included in each burst signal group, and A plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal is generated for each reproduction signal corresponding to one of the one convex portions, and the reproduction signal is generated by the plurality of gate pulse signals. Signal extraction means for extracting a plurality of portions and extracting a plurality of portions of the reproduction signal more than any one of the concave portions and the convex portions forming the burst signal group to be reproduced; A magnetic recording / reproducing apparatus comprising: Each burst signal recorded on a magnetic recording medium by a plurality of burst signal groups, each burst signal group in position information consisting of only one concave portion and one convex portion of a concave-convex pattern formed of a magnetic layer For each reproduction signal corresponding to the signal group, a plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal are generated, and a plurality of portions of each reproduction signal are extracted by the plurality of gate pulse signals. Then, a plurality of portions of the reproduction signal are extracted more than the number of either the concave portion or the convex portion forming the burst signal group to be reproduced, and the magnetic head is positioned using the extracted portions. A control method of a magnetic recording / reproducing apparatus, characterized by performing control. A plurality of burst signal groups are recorded on the magnetic recording medium, and each burst signal group includes one concave portion included in each burst signal group in position information including concave portions and convex portions of a concave-convex pattern formed by a magnetic layer. And a plurality of gate pulse signals having a pulse width smaller than the pulse width of each reproduction signal for each reproduction signal corresponding to one of the convex portions, and each reproduction signal is generated by the plurality of gate pulse signals. Extracting a plurality of portions of the signal, extracting a plurality of portions of the reproduction signal more than the number of either the concave portion or the convex portion forming the burst signal group to be reproduced; A control method for a magnetic recording / reproducing apparatus, wherein the magnetic head positioning control is performed using