JPH04155678A - Servo writer - Google Patents

Abstract

PURPOSE:To obtain an inexpensive and accurate device by detecting an aperiodic component of deflection of a rotary shaft included in a pulse generated from a rotary encoder, and correcting the pulse generated from the encoder based on the component. CONSTITUTION:An edge time difference detector 17 of a pulse corrector 11 inputs a pulse to be output from a rotary encoder 4, and detects an aperiodic component as a pulse time interval based on a reference pulse generated from a reference pulse generator 18. Then, an integrator 19 converts the component into an analog value, and generates a correction pulse based on the analog output from the integrator 19 and a pulse output from the encoder 4 by a correction pulse generator 20. Thus, a servo pattern signal having a small phase deviation between adjacent tracks is obtained even if an expensive rotary encoder is not used, and an inexpensive and accurate function is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a servo writer device that improves the phase accuracy of servo pattern signals between adjacent tracks.

[Prior Art] Magnetic disk drives write and read information while a magnetic head scans a disk-shaped magnetic recording medium that rotates at high speed.In order to increase the density of such magnetic disk drives, servo drives are used. A writer device writes a position control signal for a magnetic head, that is, a servo pattern signal, onto a magnetic recording medium with high precision.

Therefore, in order to increase the density of magnetic disk drives, it is necessary to write servo pattern signals at predetermined positions with high precision and correctly. In particular, in the case of a servo pattern signal characterized in that the synchronization marks of the servo pattern signal on the recording medium are aligned with each other between tracks, 1i
j11! Strict phase alignment of servo pattern signals between tracks is required. This is because if there is a phase shift in the servo pattern signal in such a device, the magnetic disk device will be unable to detect the synchronization mark for recognizing the servo pattern. In a servo writer device, the phases of servo pattern signals between adjacent tracks are precisely aligned.

A block diagram of this conventional servo writer device is shown in FIG. 11, and its configuration is as follows.

The servo writer device has a spindle 32 for rotating a recording medium 31, and the rotation axis of this spindle 32 is coupled in the rotational direction by a highly rigid coupling 33 to a rotary encoder 34 constituting clock signal generation means. By integrating the rotary encoder 34 with the spindle 32, the rotation of the recording medium 31 is transmitted to the rotary encoder 34 with high precision. Also, spindle 3
The rotation shaft of No. 2 is connected to a motor 37 by a pulley 35 that also serves as a flywheel and an elastic belt 36, so that vibrations caused by the rotation of the motor 37 are not transmitted to the rotary encoder 34 or the spindle 32.

A servo pattern signal is written on the recording medium 31 by a magnetic head 38. This magnetic head 38 is attached to a head carriage 39, and the magnetic head 38 and the head carriage 39 are moved 8U forward and backward by a uniaxial stage 40. Further, the rotary encoder 34 is connected to a PLL 41 that constitutes a clock signal generating means. This PLL 41 is connected to a pattern generation circuit 42 that generates a servo pattern signal, and sends a clock signal in which a phase difference caused by uneven rotation of the rotary encoder 34 is adjusted. The pattern generation circuit 42 sends a servo pattern signal to the magnetic head 38 via a read/write circuit 43 constituting a servo pattern signal writing means, and writes the signal onto the recording medium 31. This pattern generation circuit 42 is connected to a microcomputer 44,
Receives a servo pattern signal write command. A microcomputer 44 is connected to the uniaxial stage 40 via a stage controller 45, and controls the position of the magnetic head 38.

Incidentally, in such a servo writer device, the recording medium 3 may be affected even if the rotary encoder 34 itself has eccentricity, as well as when the rotary encoder 34 itself has eccentricity.
If there is eccentricity in the spindle 32 that rotates the rotary encoder 1, vibration of the rotation axis will occur in the rotary encoder 34 through the coupling 33. There are periodic components that synchronize with rotation and aperiodic components that do not synchronize with rotation in such rotational axis shooting, but if there is an aperiodic component in the rotational axis runout of the rotary encoder 34, the servo pattern at the time of writing will change. This causes the 1lJl contact track phase of the signal to shift.

Therefore, in the conventional servo writer device, in order to prevent non-periodic rotational shaft vibration, a highly accurate and expensive spindle or rotary encoder with a small amount of eccentricity is selected and used.

[AM control that the invention aims to solve] However, even if such a high-precision and expensive spindle with a small amount of eccentricity and a rotary encoder are used, it is not possible to eliminate even the slight play that occurs when connecting the rotating shaft of the rotary encoder. It was difficult to improve the phase accuracy of the servo pattern signal.

Furthermore, since a highly accurate and expensive rotary encoder is used, the servo writer device has the disadvantage of being expensive.

This invention solves the above two drawbacks of conventional servo writer devices, and detects the non-periodic component of rotational shaft vibration contained in the pulses generated by the rotary encoder, which causes the phase shift of the servo pattern signal. By correcting the pulses generated by the rotary encoder based on this non-periodic component, it is possible to obtain a servo pattern signal with less phase shift between adjacent tracks without using an expensive rotary encoder, resulting in inexpensive and highly accurate functions. An object of the present invention is to provide a servo writer device having the following features.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a servo writer device that obtains a rotation synchronization clock signal based on pulses generated by a rotary encoder and writes a servo pattern signal on a recording medium. , means for detecting an aperiodic component of the rotational shaft runout of the rotary encoder from pulses generated by the rotary encoder, and means for correcting the pulses generated by the rotary encoder based on the detected aperiodic component of the rotational shaft runout. and a means for obtaining a new rotation synchronization clock signal based on the corrected pulse and writing the servo pattern signal on the recording medium.

[Operation] The servo writer device of the present invention detects the non-periodic component included in the rotational shaft runout of a rotary encoder from the pulses generated by the rotary encoder, and also detects the non-periodic component included in the rotational shaft runout of the rotary encoder based on the detected non-periodic component of the rotational shaft vibration. Correct the pulses generated by the encoder. Then, a new rotation synchronization clock signal is obtained based on this corrected pulse,
Write the servo pattern signal to the recording medium.

[Example] An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a servo writer device.

The servo writer device has a spindle 2 for rotating a recording medium 1, and the rotating shaft of this spindle 2 is coupled in the rotational direction by a highly rigid coupling 3 to a rotary encoder 4 constituting a clock signal generating means. By integrating the rotary encoder 4 with the spindle 2, the rotation of the recording medium 1 is transmitted to the rotary encoder 4 with high precision. Further, the rotating shaft of the spindle 2 is connected to the motor 7 by a pulley 5 that also serves as a flywheel and an elastic belt 6, so that vibrations caused by the rotation of the motor 7 are not transmitted to the rotary encoder 4 or the spindle 2.

A servo pattern signal is written onto the recording medium 1 by a magnetic head 8. This magnetic head 8 is attached to a helad carriage 9, and the magnetic head 8 and head carriage 9
is moved back and forth by a uniaxial stage 10.

Further, the rotary encoder 4 is connected via a pulse correction circuit 11 to a PLLI 2 constituting clock signal generation means.
is connected to. PLLI 2 sends a clock signal to a pattern generation circuit 13 that generates a servo pattern signal. The pattern generation circuit 13 sends a servo pattern signal to the magnetic head 8 via the read/write circuit 14, and writes the same signal onto the recording medium 1.The pattern generation circuit 13 is connected to the microcomputer 15, Receives a write command. The microcomputer 15 is connected to the uniaxial stage 10 via a stage controller 16, and controls the position of the magnetic head 8.

FIG. 2 shows the structure of the rotary encoder 4 used here.

A rotating shaft 42 is supported on a main body 41 of the rotary encoder 4 by a bearing 43 such as a ball bearing.
A rotary slit plate 44 is fixedly attached to 2. A pattern is engraved on this rotating slit plate 44, and when it receives light from a projecting light source 4S provided opposite to this rotating slit plate 44, light corresponding to the pattern is transmitted. The light source 4 for projecting light on this rotating slit plate 44
A fixed slit plate 46 having a multiphase array of slits 46a to 46C is fixed on the opposite side of the 5, and light receiving sensors 4a to 47c are arranged in correspondence with the slits 46a to 46c. It is arranged.

The light transmitted through the rotating rotating slit plate 44 passes through the slits 46a to 46C of each phase of the fixed slit plate 46,
Patterned light for each phase is sent to light receiving sensors 47a to 47c. As a result, the pulse train corresponding to each phase is transmitted to the light receiving sensor 4.
It is output from 7a to 47c. This pulse train is input to the pulse correction circuit 11.

Next, the configuration of the pulse correction circuit 11 will be explained.

The pulse correction circuit 11 includes an edge time difference detection circuit 17 that manually inputs the pulses output from the rotary encoder 4 and detects the aperiodic component as a pulse time interval, and an edge time difference detection circuit 17 that detects the aperiodic component based on the pulse output from the rotary encoder 4. a reference pulse generation circuit 18 that generates a reference pulse that serves as a reference; an integration circuit 19 that converts the aperiodic component detected as a pulse time interval by the edge time difference detection circuit 17 into an analog value; The correction pulse generation circuit 20 generates correction pulses based on the analog values obtained and the pulses output from the rotary encoder 4.

Detection of the non-periodic component of rotation shaft runout in this servo writer device will be explained based on FIGS. 3 to 8.

Figures 3 and 4 show the case where there is no runout of the rotating shaft, and Figures 5 and 6 show the case where there is periodic runout of the rotating shaft.
FIGS. 7 and 8 show cases where there is non-periodic vibration in the rotating shaft.

In FIGS. 3, 5, and 7, symbol C indicates the rotation axis 42 of the rotary encoder 4 when there is no runout in the rotation axis.
It shows the zero rotation center point. On the other hand, the reference numeral in FIG. 5 indicates the rotation center point when periodic runout occurs in the rotating shaft 42, and the reference numeral E in FIG. It shows the center of rotation. or,
The rotary encoder 4 has two phases from the inside of the center of rotation, B
The light receiving sensors 478 to 47c, which have phase and A phase slit patterns and receive light emitted from the projecting light source 45, are located on the line CF.

As shown in FIG. 3, when there is no vibration in the rotating shaft 42, the center of one rotation is at point C, and the light receiving sensor 4 is
Naturally, the relative positional relationship between 7a to 47c and the slit patterns of each phase does not change.

Therefore, the output pulses of each phase also do not vary in relative time. The generation timing between specific pulses at predetermined rotational positions of the A phase and B phase at this time will be explained using FIG. 4. In Figure 4, the rise of a specific pulse of A phase (
The time T=Tn required from a) to rise (b) of the corresponding specific pulse of the B phase is always constant when there is no shaft runout in the rotating shaft 42.

Further, as shown in FIG. 5, if there is periodic vibration in the rotating shaft 42, the center of rotation is 4. (From 6 onwards, the light is periodically turned on. Even in this case, since the light receiving sensors 47a to 47c are on the line CF, originally the light receiving sensors 47a to 47c
The slit pattern of each phase is detected at a predetermined rotational position to be detected, that is, at a position offset from the line DG. In this case, the relative positional relationship between the light receiving sensors 47a to 47c and the slit patterns of each phase changes periodically (for example, the angle θ1 between the A phase and B phase), and the output pulse of each phase also changes periodically. This will result in significant time fluctuations.

At this time, the generation timing between the specific pulses of the A phase and the B phase corresponds to the rising edge (C) of the specific pulse of the A phase, as shown in FIG. The time T required for the rise (d>) of the specific pulse of the B phase is shifted by a time ΔT1 corresponding to the angle θ1, which is TzTn−ΔT1.However, since the shaft runout of the rotating shaft 42 is periodic, No matter how many times you rotate it, CD=-
ΔT1 is also always constant.

However, if there is non-periodic wobbling in the rotating shaft 42 as shown in FIG. 7, the rotation center moves from point C non-periodically to the other point. Even in this case, the timing at which the A-phase light receiving sensor 47c and the B-phase light receiving sensor 47b receive light from their respective slit patterns is relatively shifted by an angle of 02, as in the case where there is periodic vibration described above. It turns out. At this time, the generation timing between the specific pulses of the A phase and the B phase changes from the rising edge (6) of the specific pulse of the A phase to the ratio when there is no shaft vibration in the rotating shaft 42, as shown in FIG. The time T required for the rise (f) of the corresponding B-phase specific pulse deviates by a time ΔT2 corresponding to the angle 02 minutes.

That is, time T=Tn-ΔT2. However, since the shaft runout of the rotating shaft 42 is non-periodic, the distance between CE and the direction of E seen from C change each time it rotates, and the 4-tooth 2
also changes each time. Therefore, the time T will also vary. In this way, when the time T required for the specific pulse to rise varies for each rotation, the range of variation in the time T represents the non-periodic component of the shaft runout.

Next, correction of the aperiodic component in this embodiment will be explained using FIG. 9.

As shown in FIG. 9, an A-phase pulse and a B-phase pulse are output at each rotation of the rotary encoder, such as the first rotation, the second rotation, and so on.

In this FIG. 9, (1) shows the generation timing of the A-phase pulse at a predetermined rotational position of the rotary encoder, (2) shows the generation timing of the B-phase pulse corresponding to a specific pulse of the A-phase, and (3) shows the generation timing of the B-phase pulse corresponding to a specific pulse of the A-phase. ) indicates a reference pulse generated by the reference pulse generation circuit 18 based on the generation timing of this specific pulse of the A phase.

The pulse width δ of the reference pulse in (3) may be determined based on the regular generation timing position of the B-phase pulse corresponding to the A-phase pulse, or may be determined by repeatedly generating both pulses several times. The data may be taken and the average time required for the rise of the B-phase pulse relative to the rise of the A-phase pulse in that case may be set as the reference pulse width δ.

The edge time difference detection circuit 17 compares the falling edge of the reference pulse thus determined and the rising edge of the B-phase pulse. If there is a time difference between the two,
The edge time difference x1 is detected as a non-periodic component (4) and converted into an analog value by an integrating circuit 19.

Next, a position shifted by a fixed time y with respect to the rising edge of the A-phase pulse is set. This position becomes the reference position of the correction pulse, and is the position indicated by the - dotted chain line. A correction pulse is generated from the correction pulse generation circuit 20 using the edge time difference x1 from this reference position. The rise of this correction pulse is shown in (5) of FIG. The correction pulse is started shifted by zwaxl from the reference position. The value of Z has a different sign depending on the appearance of the previous edge time difference x1. For example, when the B-phase pulse overlaps with the reference pulse as in (2) of the first rotation in FIG. If the B-phase pulse does not overlap with the reference pulse and rises with a delay, as in the case of , the edge time difference x
2, a correction pulse is generated a predetermined time Z=ax2 earlier than the reference position as shown in (5). The reference position must be set so that the rising edge of the correction pulse at this time lags behind the rising edge of the B-phase pulse.

This will be explained based on FIG. 10. Figure 10 (2) shows the longest rise time of the aperiodic component in the B-phase pulse (
At this time, based on the edge time difference x 3 shown in Figure 10 (4), a correction pulse is generated a predetermined time z=ax3 earlier than the reference position, but the rising edge (h) of this correction pulse is always (8) The reference position must be determined so that it is slower.

Note that the value of a is set as follows based on FIG.

Since the edge time difference X represents a non-periodic component, Fig. 7 shows the time ΔT2 corresponding to the relative angle of 02 minutes between the A phase and B phase. Therefore, the distance from the rotation axis center to the A phase slit pattern is set as RA. , let T be the rotation period, then let y^ be the circumferential deviation between the original A-phase pulse detection position (on EH) and the actual detection position (on CF), and H
If EG=θ and the distance from the rotation axis center to the B-phase slit pattern is RE, then since θ is minute, the following equation holds approximately.

X^+yA4R^ ・tanθ Next, when y^ is converted to time ΔTA, therefore, if RA and RB are known, the phase shift amount ΔTA of the A phase can be found after all if time ΔT2 is detected. In the same way, ΔT8 in the B phase is also calculated. From these facts, the correction magnification a of each phase is a in the case of the A phase.
=RB/(R^-RB), and if phase B is O! 1-R
＾／(R＾-RB) is a skill.

The correction times calculated as above! A new reference pillow signal is created using the generated correction pulse using la as a reference.

[Effects of the Invention] As described above, the present invention extracts the aperiodic component of the rotary encoder rotation shaft runout, which causes the six-phase deviation of the servo pattern signal, from the pulses emitted by the rotary encoder, and By correcting the pulses generated by the rotary encoder in Amaki, it is possible to obtain a servo pattern signal with no phase shift between adjacent tracks without using an expensive rotary encoder. You can get a writer device.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of the servo writer device of this invention, Fig. 2 is an optical rotor in this embodiment) Structural diagram of the rotary encoder, Fig. 3, Fig. 5, and Fig. 7 is a schematic diagram of the rotary encoder of this invention. 4, 6, and 8 are explanatory diagrams explaining the generation timing between specific pulses of each phase of the rotary encoder. FIG. 11, which is an explanatory diagram of a non-periodic component correction method, is a schematic diagram of a conventional servo writer device. In the figure, 4 is a rotary encoder, 11 is a pulse correction circuit, 13 is a pattern generation circuit, 14 is a read/write circuit, 17 is an edge time difference detection circuit, 18 is a reference pulse generation circuit, 19 is an integration circuit, and 20 is a correction circuit. This is a pulse generation circuit. Patent applicant Konica Co., Ltd. (Kitaji)

Claims (1)

[Claims] In a servo writer device that obtains a rotation synchronized clock signal based on pulses generated by a rotary encoder and writes a servo pattern signal on a recording medium, the pulses generated by the rotary encoder correspond to non-periodic components of the rotation shaft runout of the rotary encoder. means for correcting the pulses generated by the rotary encoder based on the non-periodic component of the detected rotary shaft runout; and means for obtaining a new rotation synchronization clock signal based on the corrected pulses to control the servo A servo writer device comprising means for writing a pattern signal onto a recording medium.