JP4070767B2 - Servo information writing device - Google Patents

Description

  The present invention relates to a servo information writing device for recording servo information for positioning a magnetic head for recording / reproducing data on a magnetic disk of a magnetic disk device.

Servo information is written to each sector position of each track position formed concentrically by magnetic recording on a magnetic disk arranged in a magnetic disk device as a finished product. Used to position the head on the target track.
By the way, when writing servo information on the magnetic disk, the magnetic disk device itself cannot position the magnetic head in a state where the servo information is not written on the magnetic disk.

  Therefore, normally, the magnetic disk device is assembled to some extent, for example, a motor for rotationally driving the spindle is incorporated, the magnetic disk is attached to the spindle, and an arm for supporting the magnetic head is provided to move the magnetic head in the radial direction of the magnetic disk. An internal actuator to be moved is incorporated, and a magnetic head is mounted on the arm. Then, the magnetic disk device is mounted on the servo information writing device while being accessible to the arm, the magnetic disk, and the magnetic head from the outside, and servo information is written by the servo information writing device. Note that the “accessible state from the outside” means, for example, a state in which the magnetic disk device is not sealed in the housing, or a window that can be accessed from the outside with respect to the above components even when the housing is attached to the housing. Say the state of providing.

Accordingly, on the conventional servo information writing device 50 side, as shown in FIGS. 6 and 7, for example, the external actuator 58 for positioning the arm 56 of the internal actuator 54 of the magnetic disk device 52 from the outside, and the current position of the external actuator 58 A position sensor 60 for detecting the position, an external actuator 58 using the position sensor 60 to position the magnetic head 62 supported by the arm 56, and a position for each track position. A pattern generation circuit 66 for generating servo information to be written at a predetermined position in each sector, and a servo head for recording servo information on the magnetic disk 70 via a magnetic head 62 provided in the magnetic disk device 52. 1 recording / reproducing control circuit 68, spindle 72 and magnetic A clock head 74 for recording and reproducing a reference clock synchronized with the rotation of the disk 70, for example, in a clock recording area provided on the outermost periphery of the magnetic disk 70, a second recording / reproducing control circuit 76 thereof, and a driving mechanism 78 thereof. A motor control circuit 82 is provided that drives a spindle motor 80 (also referred to simply as a motor) that rotates the spindle 72 to rotate the spindle 72 at a predetermined rotational speed.
In addition, on the servo information writing device 50 side, a host computer 84 that performs overall control of each component provided in the servo information writing device 50 is also provided.

  In the operation of the servo information writing device 50, first, the motor control circuit 82 is operated to rotate the motor 80, and the magnetic disk 70 is continuously rotated at a predetermined rotational speed. Next, a reference clock is recorded in the clock recording area of the magnetic disk 70 using the clock head 74 and the second recording / reproducing control circuit 76. Next, the external actuator control circuit 64 uses the position sensor 60 to position the external actuator 58 so that the magnetic head 62 supported by the arm 56 is at a desired track position. As an example of the positioning method of the arm 56 of the internal actuator 54 by the external actuator 58, there is a push pin method. In this case, a pin (not shown) attached to the external actuator 58 is pressed against the arm 56 of the internal actuator 54 of the magnetic disk device 52 and moved.

When the magnetic head 62 can be positioned at a track position where servo information is written, servo information is generated from the pattern generation circuit 66 using the reference clock reproduced by the clock head 74 as a clock source. Servo information is output to the magnetic head 62 via the first recording / reproduction control circuit 68, and servo information is recorded on the magnetic disk 70.
In order to generate servo information from the pattern generation circuit 66, the basic clock input to the pattern generation circuit 66 generally requires a signal having a higher frequency than the reference clock reproduced by the clock head 74. Therefore, a PLL circuit (not shown) is provided inside or outside the pattern generation circuit 66, and this PLL circuit is used with the reference clock as a clock source, and a basic clock for servo information generation obtained by multiplying the frequency of the reference clock by an integer is used. Creating.

  The servo information output from the pattern generation circuit 66 must be changed for each sector even within the same track. The servo information is recorded at a predetermined position in the sector, and the recording position of the servo information for each track must be aligned. Therefore, in the pattern generation circuit 66 and the like, a start pulse synchronized with the recording position of the servo information is output based on the reference clock that changes corresponding to the rotation of the magnetic disk 70, and each sector is synchronized with the start pulse. Servo information is output. Since the rotational speed of the magnetic disk 70 is controlled to be a constant rotational speed, when the magnetic disk 70 makes one revolution, the same number of start pulses as the number of sectors are output at equal intervals.

However, the servo information writing apparatus has the following problems.
As described above, in the servo information writing device, it is necessary to record the servo information so that the recording positions between the tracks coincide with each track position of the magnetic disk of the magnetic disk device in units of sectors. Therefore, in the conventional servo information writing device 50, first, the reference clock is recorded in the clock recording area of the magnetic disk using the clock head 74.
When the servo information is recorded at each track position, the reference clock is reproduced via the clock head 74, and a start pulse synchronized with the reference clock is generated based on the reference clock, and the servo for each sector is generated. The information output timing is synchronized with this start pulse. Further, a basic clock for outputting higher-frequency servo information is generated using the reference clock as a clock source, and servo information is generated from the pattern generation circuit 66 using this basic clock as a clock source.

  By the way, the reference clock is used as a clock source for generating a higher frequency basic clock using a PLL circuit. For this reason, it is desirable that the duty of the reference clock is constant. This is because if the duty becomes non-uniform, the PLL circuit does not operate normally at the non-uniform part and the basic clock may not be generated. A case where the duty of the reference clock becomes non-uniform is a case where the writing of the reference clock recording start part and the recording end part by the clock head is not successful. Therefore, conventionally, there has been a problem that the recording operation of the reference clock has to be repeated as many times as necessary until the reference clock is correctly written.

  Therefore, the present invention has been made to solve the above-mentioned problems, and the object of the present invention is that the writing of the reference clock recording start portion and the recording end portion by the clock head is slightly shifted, and the reference clock duty is partially changed. It is an object of the present invention to provide a servo information writing device capable of recording servo information normally even if it is uneven.

  In view of this, according to the first aspect of the present invention, there is provided a magnetic disk device having a magnetic disk mounted on a spindle and a magnetic head for recording / reproducing information on the magnetic disk. In the servo information writing apparatus for recording the servo information at each track position of the magnetic disk by the magnetic head in a state where the recording position of the servo information for each track is made to coincide with each other, the spindle or the magnetic disk A clock head that outputs a reference clock that changes in accordance with rotation; a basic clock generation circuit that generates a basic clock that is higher in frequency than the reference clock and is asynchronous with the reference clock; and As a start pulse in synchronization with the servo information recording position Generating a start pulse generating circuit, synchronizing the start pulse with the basic clock and outputting a synchronization start pulse, and generating the servo information using the basic clock as a clock source in synchronization with the synchronization start pulse And a pattern generating circuit.

  According to this, even if the recording start part and the recording end part of the reference clock by the clock head are slightly shifted, even if the duty of the reference clock is partially non-uniform, pattern generation that generates servo information Since a reference clock or a clock obtained by multiplying the reference clock by an integer by a PLL circuit or the like is not used as a circuit clock source, servo information can be normally recorded. In addition, the reference clock is used for a start pulse that defines the output timing of servo information, and this start pulse is also synchronized with a dedicated clock having a high frequency other than the reference clock used as a clock source for the pattern generation circuit. The servo information writing (recording) position for each track can be matched without deviation.

Preferred embodiments of a servo information writing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
(First embodiment)
First, a servo information writing device having a simplified internal configuration by effectively utilizing the basic functions of the magnetic disk device itself will be described. In addition, the same code | symbol is attached | subjected about the same structure as the structure demonstrated in the prior art example, and detailed description is abbreviate | omitted.

First, the configuration of the servo information writing apparatus 10 of the present embodiment will be described with reference to FIG.
The servo information writing device 10 includes a non-contact position sensor 12 that detects the position of the arm 56 of the internal actuator 54 inside the magnetic disk device 52 in a non-contact manner, and the rotation of the spindle 72 or the magnetic disk 70 inside the magnetic disk device 52. Controls the operation of the clock head 13 that detects and generates a reference clock that changes according to the rotation of the spindle 72 or the magnetic disk 70, and the entire servo information writing device 10 and the magnetic disk device 52 that is mounted on the servo information writing device 10. A host computer 84 is provided.

  Next, the configuration of the magnetic disk device 52 will be described. The difference from the conventional example is that the magnetic disk device 52 to which servo information is recorded in the servo information writing device 10 of the present embodiment has various control circuits and the like as shown in FIG. 1 and FIG. In other words, the magnetic disk device is assembled in the casing 14 together with the internal actuator 54 and assembled in a shape almost similar to a completed body.

  That is, in the magnetic disk device 52, an internal actuator 54 having an arm 56 for supporting the magnetic head 62, an internal actuator control circuit 16 for controlling the internal actuator 54, and a magnetic disk (medium) attached to the spindle 72 are provided. ) 70, a motor (spindle motor) 80 for rotating the spindle 72, a motor control circuit 82 for controlling the rotation of the motor 80, and a recording / reproduction control circuit for recording / reproduction of the magnetic head 62 (first example of the conventional example). 68, a system controller 18 that performs overall control of these components, and a pattern generation circuit 66 that generates servo information are mounted in advance.

Here, the system controller 18 is electrically connected to the host computer 84 provided in the servo information writing device 10 via the external interface unit 20, and receives instructions from the host computer 84 to receive each instruction in the magnetic disk device 52. It has a function of controlling the components by itself and executing a servo information writing operation.
Further, in this embodiment, in order to detect the position of the arm 56 by the non-contact position sensor 12 provided in the servo information writing device 10, the sector-shaped encode scale 20 is attached to the arm 56 as an example. The non-contact position sensor 12 and the internal actuator control circuit 16 are electrically connected via the external interface unit 20.

Further, in order to detect the rotation of the spindle 72 or the magnetic disk 70 without contact with the clock head 13 provided in the servo information writing device 10 and generate a reference clock that changes in accordance with this rotation, the spindle 72 is circular. The encode scale 22 is attached. The clock head 13 and the pattern generation circuit 66 for generating a servo information pattern are electrically connected via the external interface unit 23.
If the pattern generation circuit 66 cannot be stored in the magnetic disk device 52, the pattern generation circuit 66 can be arranged on the servo information writing device 10 side.

  As shown in FIG. 2, the housing 14 of the magnetic disk device 52 includes a non-contact (optical) position sensor 12 and a non-contact (optical) clock head 13 of the servo information writing device 10. A detection window 24 hermetically sealed with a translucent material (transparent glass plate, synthetic resin plate, etc.) so that the encode scales 20 and 22 mounted inside the device 52 can be detected from the outside of the housing 14. Is provided.

In addition to the configuration in which the circular encode scale 22 is attached to the spindle 72 in order to generate the reference clock, for example, the encode scale 22 is placed at a predetermined position on the magnetic disk 70 attached to the tip end side of the spindle 72 most. Alternatively, an encoding pattern that can be detected by a non-contact sensor such as an optical pickup may be recorded in advance by a magneto-optical method.
Further, the clock head 13 may be configured to generate a reference clock by detecting the rotation of the magnetic disk by a laser Doppler method. In this case, the reference clock is generated based on the change in the frequency of the laser beam that is irradiated and reflected on the magnetic disk surface. Accordingly, it is not necessary to attach the spindle 72 and the magnetic disk 70 corresponding to the encode scale 22.

Next, the operation of the servo information writing device 10 will be described with reference to FIG.
First, an instruction to start rotation of the spindle motor 80 is input from the host computer 84 to the system controller 18. In response to this instruction, the system controller 18 operates the motor control circuit 82, rotates the motor 80, and rotates the spindle 72 and the magnetic disk 70 at a predetermined rotational speed (step 100).
Next, a servo lock instruction for the internal actuator 54 is input from the host computer 84 to the system controller 18. In response to this instruction, the system controller 18 issues a servo lock operation instruction to the internal actuator control circuit 16. The internal actuator control circuit 16 detects the position of the arm 56 of the internal actuator 54 via the non-contact position sensor 12, and when the target position of the magnetic head 62 is input from the system controller 18, it automatically reaches this target position. The arm 56 is moved so that the magnetic head 62 is positioned (servo lock state, step 102).

Next, the position of the magnetic head 62 at which servo information writing is started, that is, the so-called format start track position is input from the host computer 84 to the system controller 18. The host computer 84 also inputs the end track position together with the format start track position.
The system controller 18 can automatically generate a target position (target track position) of the magnetic head 62 sequentially at a predetermined track pitch based on the input format start track position and output it to the internal actuator control circuit 16. It has a function.
The system controller 18 first outputs the format start track position input from the host computer 84 to the internal actuator control circuit 16 as the first track position. Thus, the internal actuator control circuit 16 controls the internal actuator 54 while detecting the position of the arm 56 using the non-contact position sensor 12, and moves the magnetic head 62 to the target position (step 104).

Further, the system controller 18 determines whether or not the target position of the magnetic head 62 output to the internal actuator control circuit 16 is the end track position (step 106).
If it is not the end track position, the servo information for one track in the pattern generation circuit 66 is rewritten to servo information corresponding to the target position (target track position) (step 108).
When the servo information has been rewritten, the servo information is written in units of sectors at the track position where the magnetic head 62 is located (step 110). Servo information is output from the pattern generation circuit 66 at equal intervals by the same number as the number of sectors while the magnetic disk 70 rotates once, as in the conventional example. The output servo information is sent to the magnetic head 62 via the recording / reproduction control circuit 68 and recorded on the track of the magnetic disk 70.

When the magnetic head 62 finishes recording servo information at a predetermined track position, the system controller 18 generates the next target position of the magnetic head 62 and outputs it to the internal actuator control circuit 16. As a result, the magnetic head 62 moves to the next target track position (step 112).
The system controller 18 repeats steps 106 to 112 while determining whether the target position of the magnetic head 62 output to the internal actuator control circuit 16 in step 106 is the end track position. Corresponding servo information is recorded at the sector position of the track position.

When the target position of the magnetic head 62 reaches the end track position in step 106, the servo lock operation by the internal actuator control circuit 16 is stopped (step 114).
Further, the motor control circuit 82 is operated to stop the motor 80 and stop the spindle 72 and the magnetic disk 70 (step 116).
This completes the servo information recording operation on the magnetic disk 70.

As described above, the magnetic disk device 52 to which servo information is to be recorded in the servo information writing device 10 includes a magnetic disk device in which various control circuits and the like are incorporated in the housing 14 and is assembled in a shape almost similar to a completed product. The servo information writing device 10 uses the internal actuator control function, the recording / reproducing function for the magnetic disk, and the motor control function of the spindle motor, which are basic functions of the magnetic disk device itself when writing the servo information. Then, the configuration of the servo information writing device 10 can be greatly reduced compared to the conventional configuration, and the device configuration can be simplified. Therefore, the servo information writing device 10 can be reduced in size.
Further, since it is not necessary to record the reference clock on the magnetic disk 70 by the contact type magnetic head type clock head 74 as in the prior art, the servo information writing time can be shortened.

  Further, as described above, non-contact type sensors are used for the position detection sensor of the arm 56 and the rotation detection sensors such as the spindle 72, and the magnetic disk device 52 side detects an airtight structure for these non-contact type sensors. By providing the window 24 in the housing 14, the magnetic disk device 52 is covered with the housing 14, and servo information can be written to the magnetic disk 70 in a completely completed and airtight state. Therefore, a clean room can be achieved in the servo information writing process.

  In the above-described embodiment, the internal actuator control function, which is the basic function of the magnetic disk device itself, the recording / reproducing function for the magnetic disk, and the motor control function of the spindle motor are all used on the servo information writing device 10 side. However, for example, only a part of the basic functions of the magnetic disk device itself may be used on the servo information writing device 10 side. This is because it is not necessary to provide at least the components that perform the basic functions of the used magnetic disk device itself on the servo information writing device 10 side, and the configuration on the servo information writing device 10 side can be simplified accordingly.

For example, the non-contact position sensor 12 is not provided on the servo information writing device 10 side, but the clock head 13 is provided, and the recording / reproduction control for controlling the recording / reproducing operation of the magnetic head 62 incorporated in the magnetic disk device 52 in advance. Servo information can also be recorded on the magnetic disk 70 via the magnetic head 62 using the circuit 68.
The servo information writing device 10 side is not provided with the clock head 13 but the non-contact position sensor 12 is provided, and the position of the arm 56 is detected by using the internal actuator control circuit 16 incorporated in the magnetic disk device 52 in advance. However, the magnetic head 62 can be positioned by controlling the internal actuator 54.
In both of the above examples, the motor control circuit 82 may be built in the magnetic disk device 52 in advance, and the motor control circuit 82 may not be provided on the servo information writing device 10 side using this. It is also possible to provide a motor control circuit 82 on the servo information writing device 10 side so that the motor control circuit 82 is not built in the magnetic disk device 52 in advance.

In addition, since the configuration on the servo information writing device 10 side is significantly smaller than the conventional one as in this embodiment, the servo information writing device 10 is large even if a plurality of magnetic disk devices 52 can be mounted. You don't have to. Therefore, the servo information writing device 10 can be mounted with a plurality of magnetic disk devices 52, and at the same time, servo information is written to the magnetic disks 70 of each magnetic disk device 52 (also referred to as a format of the magnetic disk 70). It is.
Conventionally, after the formatting operation of the magnetic disk device 52 is performed by the servo information writing device 10, various control circuits are further incorporated into the magnetic disk device 52 and covered with a casing, thereby completing the magnetic disk device 52. Thereafter, the magnetic disk device 52 is connected to a self-diagnosis test facility so that the magnetic disk device 52 itself performs a self-diagnosis and performs a final function check.
However, in the present embodiment, the magnetic disk device 52 is assembled to a shape close to a completed body, and then connected to the servo information writing device 10 to record servo information. Therefore, once the servo information is recorded on the magnetic disk 70, the magnetic disk device 52 can continue to perform self-diagnosis while being connected to the servo information writing device 10. Thus, conventionally, it is necessary to provide a servo information writing device and a self-diagnosis test facility separately, but this can be performed by one device, and the equipment cost can be greatly reduced. When the magnetic disk device 52 performs self-diagnosis, after the servo information is recorded on the magnetic disk 70, firmware for self-diagnosis is downloaded from the servo information writing device 10 side to the magnetic disk device 52 side. Like that.

(Second Embodiment)
Subsequently, the reference clock output from the clock head is not directly used as the clock of the pattern generation circuit that outputs servo information, and the servo information is normally recorded even if the duty of the reference clock is partially uneven. A servo information writing apparatus that can be used will be described. In addition, the same code | symbol is attached | subjected about the same structure as the structure demonstrated in the prior art example or 1st Embodiment, and detailed description is abbreviate | omitted.

First, the configuration of the servo information writing device 26 of the present embodiment will be described. The characteristic part of the present embodiment is the configuration of a pattern generation circuit 66 that outputs servo information and its peripheral circuits. Therefore, the overall configuration of the servo information writing device 26 may be the configuration of the first embodiment shown in FIG. 1 or the conventional configuration shown in FIG.
As an example, the overall configuration is the configuration of FIG. 7 in which the servo information writing device 26 writes the reference clock to the magnetic disk 70 using the clock head 74 at the beginning of the servo information recording operation.

  The servo information writing device 26 configured as shown in FIG. 7 has a problem that rotation of the magnetic disk 70, that is, rotation of the motor 80 always has uneven rotation as described above. Therefore, even if the reference clock is accurately written from the clock head 74 in accordance with the rotation of the magnetic disk 70, it is very difficult to accurately write the reference clock recording start portion and recording end portion exactly. In other words, the reference clock reproduced by the clock head 74 always has a non-uniform duty at this joint portion. For this reason, if this reference clock is used as a clock source of a PLL circuit that generates the clock of the pattern generation circuit 66, the PLL circuit may not operate normally at the non-uniform portion and the basic clock may not be generated. It is a point.

  Therefore, in the present embodiment, the servo information writing device 26 side generates a basic clock that is higher in frequency than the reference clock frequency reproduced by the clock head 74 and asynchronous with the reference clock as shown in FIG. A clock generation circuit 28; a start pulse generation circuit 30 that generates a start pulse in synchronization with a recording position of servo information using a reference clock as a clock source; and a synchronization circuit that synchronizes the start pulse with a basic clock and outputs a synchronization start pulse 32 and a pattern generation circuit 66 for generating servo information using a basic clock as a clock source in synchronization with the synchronization start pulse.

  According to this, it is not necessary to generate a basic clock having a high frequency as a clock source for generating servo information using a PLL circuit with the reference clock as a clock source. Therefore, even if the writing start part and the recording end part of the reference clock by the clock head 74 are slightly shifted, servo information can be generated and recorded normally. In addition, the reference clock is used for a start pulse that defines the output timing of servo information, and this start pulse is also synchronized with a dedicated clock having a high frequency other than the reference clock used as a clock source for the pattern generation circuit. There is an effect that the servo information writing (recording) position for each track can be matched without any deviation.

Specifically, the servo information pattern generation operation of this embodiment will be described with reference to FIGS.
The reference clock A (5 MHz as an example) reproduced by the clock head 74 is input to the start pulse generation circuit 30. The start pulse generation circuit 30 generates a start pulse B synchronized with the servo information recording position using the reference clock A as a clock source. appear. The start pulse generating circuit 30 can be configured by a frequency divider circuit as an example. For example, if the rotational speed of the magnetic disk 70 is 100 revolutions / second and the number of sectors per one round of the magnetic disk (one round of the track) is 80, the output frequency of the start pulse B is 80 × 100 = 8 KHz. At this time, the frequency dividing ratio in the frequency dividing circuit is 5M / 100/80 = 625.

In other words, “occurs in synchronization with the recording position of the servo information” here means that the servo information needs to be recorded at the same position in each sector while changing the contents in each sector in one track. This means that each sector is generated so as to coincide with a predetermined position in the sector.
Since the start pulse B is generated by dividing the reference clock A, even if the reference clock A itself has a non-uniform portion of the duty, the divided start pulse B has a uniform portion of the duty. The ratio of the length of the non-uniform portion to the length of is reduced.

The synchronization circuit 32 receives the start pulse B and the basic clock C (1 GHz) of the basic clock generation circuit 28. For example, as shown in FIG. 4, the synchronization circuit 32 can be composed of a D-type flip-flop (DFF) 32a and a synchronous 2-bit counter (first counter) 32b.
The basic clock C is used as a clock for the DFF 32a and the first counter 32b. The start pulse B is used as a reset signal for the first counter 32b and as data for the DFF 32a.
Therefore, the synchronization start pulse E having the same cycle as the start pulse B synchronized with the basic clock C is output from the Q terminal of the DFF 32a.
The first counter 32b performs a counter operation when the start pulse B is valid (for example, valid when high), and the counter value changes like D. The upper bits of the first counter 32b are output from the synchronization circuit 32 as the signal F. That is, it is output as a clock F (250 MHz) obtained by dividing the basic clock C by four.

The pattern generation circuit 66 receives a synchronization start pulse E and a clock F. For example, as shown in FIG. 4, the pattern generation circuit 66 can be composed of an address counter (second counter) 66a and a pattern memory 66b in which servo information patterns are stored.
The clock F becomes the clock of the second counter 66a, and the synchronization start pulse E (8 KHz) is used as its reset signal. Here, since the number of bits of the second counter 66a is 250 MHz / 8 KHz = 31250, 15 bits or more are required. The capacity of the pattern memory 66b needs to be equal to or larger than that of the second counter 66a.
With this configuration, the second counter 66a performs a counter operation when the synchronization start pulse E is valid (eg, valid when high), and the counter value changes like G. Since the output of the second counter 66a is input to the address of the pattern memory 66b, the output of servo information is started for each sector in synchronization with the synchronization start pulse E, and thereafter, the output of the second counter 66a is synchronized with the clock F. Thus, servo information for each sector is output for a predetermined address.
In this example, the address length of the second counter 66a and the pattern memory 66b is set to a depth of one sector. However, the address length of one track may be used.

  The synchronization start pulse E becomes invalid in the middle of the sector, and the count value of the second counter 66a is reset and remains zero, but generally the servo information write position is a short time in the initial portion of each sector. No problem arises. As an example, when the time of one sector is about 100 microseconds, the servo information write position is a short time of about 10 microseconds at the head, so the second counter 66a counts up to the middle position of the sector. It is enough to do.

  In FIG. 4, the basic clock generation circuit 28, the start pulse generation circuit 30, and the synchronization circuit 32 are provided outside the pattern generation circuit 66, but these are all included in the pattern generation circuit 66. 28, a start pulse generation circuit 30, and a synchronization circuit 32 may be provided.

Further, when the servo information writing apparatus has the configuration of the first embodiment shown in FIG. 1 (clock head is non-contact type), the encoder scale 22 which is a base for generating the reference clock in advance is connected to the spindle 72 or the magnetic field. The disc 70 is provided. For this reason, the duty of the reference clock output from the clock head 13 is uniform.
However, in the case of this configuration, the number of reference clocks output when the magnetic disk 70 rotates once is determined. For this reason, depending on the specifications of the magnetic disk 70, for example, even if it is an integral multiple, the servo information clock frequency does not become the problem, so that there is a problem that it cannot be used as the clock source of the pattern generation circuit 66.
Therefore, the servo information writing apparatus according to the present embodiment in which the reference clock output from the clock head 13 is not directly used as the clock source of the pattern generation circuit 66 can be applied to the configuration of the first embodiment shown in FIG. .

  When the clock head 13 is a non-contact type, the resolution of the encode scale 22 is lower than that of a magnetic head type clock head, and the frequency of the reference clock output from the clock head 13 is often low. . In this case, a PLL circuit may be provided at the subsequent stage of the clock head 13 so as to be input to the start pulse generation circuit 30 after the frequency is multiplied by an integer. The PLL circuit also has an effect of absorbing the jitter component of the signal output from the clock head 13.

  The preferred embodiments of the present invention have been described above in various ways. However, the present invention is not limited to the above-described embodiments, and it goes without saying that many modifications can be made without departing from the spirit of the invention. It is.

  According to the servo information writing apparatus of the first aspect of the present invention, the connection between the recording start portion and the recording end portion of the reference clock by the clock head is slightly shifted, and the duty of the reference clock is partially uneven. However, since a reference clock or a clock obtained by multiplying the reference clock by an integer by a PLL circuit or the like is not used as a clock source for a pattern generation circuit that generates servo information, servo information can be normally recorded. In addition, the reference clock is used for a start pulse that defines the output timing of servo information, and this start pulse is also synchronized with a dedicated clock having a high frequency other than the reference clock used as a clock source for the pattern generation circuit. There is an effect that the servo information writing (recording) position for each track can be matched without any deviation.

1 is a block diagram showing a configuration of a first embodiment of a servo information writing device according to the present invention. FIG. 2 is a perspective view showing a relationship between two non-contact sensors provided in the servo information writing device of FIG. 1 and a magnetic disk device. 2 is a flowchart for explaining a data writing operation of the servo information writing device of FIG. 1. It is explanatory drawing explaining the structure of the pattern generation circuit of the characteristic part of the 2nd Embodiment of the servo information writing device based on this invention, and its peripheral circuit. 5 is a timing chart for explaining operations of the pattern generation circuit of FIG. 4 and its peripheral circuits. It is explanatory drawing for demonstrating the structure of an example of the conventional servo information writing apparatus. It is a block diagram which shows the structure of the servo information writing apparatus of FIG.

Explanation of symbols

12 Non-contact position sensor 16 Internal actuator control circuit 52 Magnetic disk device 54 Internal actuator 56 Arm 62 Magnetic head 70 Magnetic disk 72 Spindle

Claims (1)

A magnetic disk device having a magnetic disk attached to a spindle and a magnetic head for recording / reproducing information with respect to the magnetic disk is mounted, and a servo is moved to each track position of the magnetic disk of the magnetic disk device by the magnetic head. In a servo information writing device for recording information in a state where the recording position of servo information for each track is matched for each sector,
A clock head that outputs a reference clock that changes according to the rotation of the spindle or the magnetic disk;
A basic clock generation circuit for generating a basic clock that is higher in frequency than the reference clock and asynchronous with the reference clock;
A start pulse generating circuit for generating a start pulse in synchronization with a recording position of the servo information using the reference clock as a clock source;
A synchronization circuit for synchronizing the start pulse with the basic clock and outputting a synchronization start pulse;
A servo information writing apparatus, comprising: a pattern generation circuit that generates the servo information using the basic clock as a clock source in synchronization with the synchronization start pulse.

Images