JPH0531232B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to a rotating recording medium reproducing apparatus, particularly a tracking device for a rotating recording medium reproducing apparatus that reproduces information signals such as video signals recorded on a rotating magnetic recording medium such as a magnetic disk. Regarding.

Background technology Recently, imaging devices such as solid-state imaging devices and image pickup tubes,
In combination with a recording device that uses a magnetic disk, which is inexpensive and has a relatively large storage capacity, as a recording medium, the subject is still photographed purely electronically and recorded on a rotating disk, and the images are reproduced using a separate television system or printer. An electronic still camera system has been developed.

In the rotating magnetic recording media used in electronic still camera systems, for example, a small disk with a diameter of about 50 mm has a track pitch of about 100 μm, that is, a track width of about 50 to 60 μm, and a guard band width of about 50 to 40 μm. 50 tracks are recorded. In a recording or reproducing device, this magnetic disk rotates at a constant speed of, for example, 3600 revolutions per minute.
Video signals are recorded or reproduced in units of fields or frames.

Recording media used for such magnetic recording, especially magnetic disks, are prone to tracking defects due to compatibility, eccentricity, thermal expansion, etc. There is a problem in that crosstalk occurs when multiple tracks are scanned.

In order to avoid this problem, there is a method in which the magnetic head for information recording records a tracking signal by applying tracking servo, and the reproducing head applies tracking servo using this tracking signal. However, it is not practical to provide a tracking servo mechanism that requires precise control to a small, lightweight recording device such as a camera.

Therefore, one method is to use the guard band method or FM azimuth method as the recording method, and to prevent some tracking failures during playback, to prevent the playback head from scanning the adjacent track, or to prevent the signal of the adjacent track even if it scans. There is a way to compensate by not picking it up.

Along with this, a so-called mountain climbing method is also used. This means that the recording head moves at a predetermined track pitch using a stepping motor without applying a tracking servo, and the reproducing head detects the envelope of the output signal of each track and identifies the optimal track from its peak position. The tracking servo is applied by

The head position showing the peak from the envelope is
The determination is made by moving the magnetic head a predetermined pitch, reading the envelope value at that position, and comparing it with the envelope value detected at the previous head position.

Digital processing systems are generally advantageously applied to perform this comparison. for that,
The video signal detected by the reproduction magnetic head is subjected to envelope detection, and the envelope output is converted into a digital value by an analog-to-digital converter and input to a digital processing system.
In order to eliminate false detections due to system disturbances such as noise, it is advantageous to subject only envelope levels exceeding a predetermined threshold to this comparison operation.

However, such hill-climbing control performs tracking by detecting the peak position of the envelope at an arbitrary or predetermined rotational phase angle of the magnetic disk. If the center of rotation of the magnetic disk is shifted from the center of the recorded track circle, the playback head may not always be on-track correctly as the magnetic disk rotates, and may deviate from the position where the envelope peaks as the disk rotates. be. Therefore, the information on the recorded track may not be properly reproduced.

Purpose The present invention overcomes the drawbacks of the prior art and
An object of the present invention is to provide a rotating recording body tracking device that can perform tracking effectively even if the tracks recorded on the rotating recording body are eccentric when tracking is performed from signals recorded on the rotating recording body. do.

DISCLOSURE OF THE INVENTION According to the present invention, there is provided a reproducing head that reads signals from a plurality of tracks formed on a rotary recording medium that rotates steadily at a predetermined rotational speed with a locus in which the starting and ending ends of recording coincide; A head support means for movably supporting the rotating recording medium, an envelope detection means for detecting the envelope of the signal read by the playback head, and a head support means are controlled to position the playback head at a desired position on the track. The rotating recording body tracking device includes a position detecting means for detecting the position of the reproducing head on the rotating recording body, and a phase detecting means for detecting the rotational phase of the rotating recording body. , the head supporting means is controlled to move the reproducing head, and the position detecting means detects when the envelope detecting means detects the peak of the envelope at a plurality of predetermined phase angles of the rotation of the rotary recording medium for one track. Detects the position of the playback head,
The control means determines the average position of the plurality of detected positions, and controls the head support means to move the reproducing head to the average position.

In addition, in this specification, "a plurality of tracks formed by trajectories whose recording start and end coincide with each other" means
For example, in a magnetic disk, a large number of tracks are formed concentrically around the rotation axis, and in a magnetic drum, a large number of tracks are formed in parallel in the circumferential direction. It means something recorded so as to form one track without changing its relative position.

DESCRIPTION OF EMBODIMENTS Next, embodiments of a rotating recording medium tracking device according to the present invention will be described in detail with reference to the accompanying drawings.

In the apparatus of this embodiment shown in FIG. 1, a rotating recording medium 10 such as a magnetic disk is removably mounted on a spindle 14 driven by a spindle motor 12. In this embodiment, the magnetic disk 10 has a magnetic recording material sheet with a diameter of about 50 mm, and a plurality of recording tracks, for example 50 recording tracks, are recorded concentrically on the recording surface 16 at a pitch of, for example, about 100 μm. In this embodiment, the signal recorded on the recording track is a video signal, which may be, for example, a color video signal in which a luminance signal and a chroma signal are FM-modulated. For example, a field video signal forming one field of an image is recorded onto one track by raster scanning.

The spindle motor 12 has a frequency generator 18 that generates an alternating frequency signal and a servo circuit 20.
The disk 10 is servo-controlled so that it rotates at a predetermined rotational speed, for example, 3600 rpm. The servo circuit 20 is connected to a control section 22 that controls the entire apparatus, and controls the steady rotation of the disk 10 in response to a reference clock of a predetermined frequency generated by a reference generator 58.

Phase detector 28 and servo circuit 20 are responsive to a reference clock generated by reference generator 58. In this embodiment, the servo circuit 20 includes a magnetic disk 1.
A reference signal of 60 Hz, which is the same as the field frequency of the raster scan video signal recorded at 0, and a high speed clock of, for example, 3.58 MHz, are supplied to the phase detection section 28.

A phase generator 24 is disposed at a predetermined position near the recording surface 16 of the disk 10, and this is connected to an amplifier 26.
It is connected as an output 60 to the servo circuit 20, phase detection section 28, and control section 22 via. As a result, the timing mark disposed at a predetermined position on the core 30 is detected, and the timing pulse is detected.
PG is formed.

A magnetic transducer or magnetic head 32 is disposed above the recording surface 16 and is indicated by dotted line 34.
As conceptually shown in FIG. This support mechanism 36 is driven by a head motor 38 to move the head 32 in both radial directions along the recording surface 16 as shown by arrow R, so that any track on the recording surface 16 can be selected. It is composed of

The head support mechanism 36 includes a peak position detection section 40.
is connected to the head 32 from the head support mechanism 36.
A signal corresponding to the position on the recording surface 16 of is applied to its input 42. This will be explained in detail later.

The magnetic head 32 may have a magnetic recording function, but in this embodiment, it has a playback function of detecting a video signal from a track already recorded on the recording surface 16 and converting it into a corresponding electric signal. Things are exemplified. As mentioned above, in this embodiment, the disk 10 rotates at a constant speed of 3600 revolutions/minute, so 1
One track of video signals, that is, one field of FM modulated video signals, is reproduced from the magnetic head 32 every 1/60 second of rotation. By demodulating this, it becomes compatible with standard color television systems such as the NTSC system.

The reproduction output 44 of the magnetic head 32 is connected to the preamplifier 4.
6 to a video signal output terminal 48 and an envelope detection circuit 50. A device that uses this video signal is connected to the video signal output terminal 48.

The envelope detection circuit 50 is a detection circuit that detects the envelope of the FM modulated video signal recorded on the track of the recording surface 16 and outputs a voltage corresponding to the envelope to the output 52. Output 52 is a comparison circuit 54
The output 56 of the latter is connected to the peak position detection section 40.

The comparison circuit 54 is a circuit that compares the input 52 from the envelope detection circuit 50 with a predetermined reference voltage, and outputs a corresponding signal to the output 56 when the former exceeds the latter. This reference voltage is set to correspond to an envelope value sufficient to determine that a video signal is recorded on the recording surface 16 of the magnetic disk 10.

The phase detector 28 receives an input 6 from the phase detector 24.
This is a functional unit that detects the rotation angle, that is, the phase, of the magnetic disk 10 from the reference position, that is, the position where the signal PG is generated, based on the signal PG obtained at 0 and the reference signal obtained from the reference generator 58 at the input 62.

The peak position detection section 40 is connected to the head support mechanism 36.
Based on the position information of the head 32 inputted from the head 32, the envelope value inputted from the comparison circuit 54, and the rotational phase information of the magnetic disk 10 from the phase detection section 28, the head 3 indicating the peak of the envelope is determined.
This is a functional unit that detects the second position, that is, the peak position.

The apparatus also includes a track position calculating section 64, which is a functional section that calculates an optimal track position from the peak position detected by the peak position detecting section 40 by a predetermined calculation.

These functional units 28, 40, and 64 are controlled by a control unit 22, and these functional units, including the control unit 22, are advantageously configured by a processing system such as a microprocessor. In that case, it goes without saying that an appropriate interface circuit such as an analog-to-digital conversion circuit, a digital-to-analog conversion circuit, or an amplifier circuit is interposed between these functional units and other circuit elements.

An operation unit 66 is connected to the control unit 22 for inputting instructions from an operator and displaying the status of the system. Control unit 2 in response to instruction input from operation unit 66
2 controls and supervises the entire device.

The operation unit 66 can, for example, start or stop the device, set a desired track position, provide track selection instructions for phasing the magnetic head 32 to that position, and move the head 32 in the forward direction of track numbers (for example, from the outer track to the inner track). A forward direction transfer instruction to cause the head 32 to be transferred in the opposite direction, a reverse direction transfer instruction to cause the head 32 to be transferred in the opposite direction, etc. are input.

A storage unit 68 is also connected to the control unit 22,
This is used as a storage area to hold data for calculating track positions, various calculations, and controls.

The head motor 38 is a DC motor in this embodiment, and is supplied with electric power from the motor drive circuit 71, and its rotation is controlled by the control section 22. Thereby, the control section 22 can move the head 32 in the direction of the arrow R by a predetermined unit length.

As conceptually shown in FIG. 2, the head support mechanism 36 includes a carriage 100 that is transported in the radial direction R of the recording surface 16 of the magnetic disk 10 by a head motor 38. A support part 102 is fixed to the carriage 100, and an arm 1 is attached to the support part 102.
04 is rotatably supported around a shaft 106. A head mount 108 is fixed to one end of the arm 104, and a magnetic head 32 is attached to the latter. The other end 110 of arm 104
is a fixed spring 1 with a carriage 100 at one end.
12 in the direction of arrow A.

A piezoelectric element 116 is disposed on the side of the end 110 of the arm 104 between it and the main surface 112 of the carriage 100, as shown. Piezoelectric element 1
16 is electrically connected to the output 122 of the amplifier 120 of the head vibration circuit 70. The piezoelectric element 116 has a function of generating a corresponding mechanical strain by being supplied with a driving voltage from the amplifier 120, thereby causing the arm 104 to rotate a certain amount around the fulcrum 106.

Amplifier 120 is a variable gain amplifier whose gain can be controlled by control input 126 , and signal input 124 is connected to power supply 13 via switch 128 .
0 is connected. In this embodiment, the power source 130 is advantageously used as a power source that generates a sine wave signal with a frequency of 60 Hz, that is, substantially equal to the field frequency of the video signal recorded on the magnetic disk 10. The switch 128 is a normally open switch element, and its opening/closing is controlled by the control unit 22 as conceptually indicated by a dotted line 132. Control input 1
26, a signal for setting the gain of the amplifier 120 is also input from the control section 22 through a digital-to-analog converter (DAC) 134.

The output shaft 144 of the head motor 38 is provided with a head position detector 14 of the photointerrupter type, for example.
0 is connected. In this detector 140, a slit plate 142 having an optical slit 146 is fixed to an output shaft 144. A light source including a light emitting element 148 such as a light emitting diode is disposed on one side of the slit plate 142.
A photodetector element 150, such as a photodiode, is disposed on the opposite side of the photodetector 2. An output 42 of the photodetection element 150 is connected to the peak position detection section 40. As a result, as the slit plate 142 rotates, light from the light emitting element 148 enters the light detecting element 150 each time the slit 146 passes through the position of the optical axis 152 from the light emitting element 148 to the light detecting element 150. , whereby a signal is output to the output 52 from the photodetector element 150. The peak position detection section 40 uses this signal to detect the position of the head 32.

In this embodiment, tracking is performed as follows. The magnetic head 32 is connected to the magnetic disk 10.
in one radial direction, for example inward R1 (Fig. 2)
The peak position of the envelope of a certain track is detected. For example, as shown in FIG. 3, when the head 32 is transferred from the outside to the inside of the magnetic disk 10, if the envelope is read at a specific position θ1 at a certain rotation angle, or phase θ, of the magnetic disk 10. , its peak is detected. Therefore, the head position r1 at this time is stored. Note that the phase angle θ is based on a predetermined position, for example, the position where the signal PG is detected, and the phase angle θ1 at which envelope detection is performed first is the position where the signal PG is detected.
It may be substantially the same as the PG generation position.

Next, the detection phase of the envelope peak is advanced or delayed by 90 degrees from this phase angle θ1 to increase the phase angle θ1.
2, the head 32 is further moved in the same direction or in the opposite direction while detecting the envelope. In this way, as shown in FIG.
When transporting, envelope peaks are detected at four phase angles.

For example, if envelope peaks are detected at four phase angles θ1 to θ4, their head positions r
1 to r4, and basically the magnetic head 32 is moved to the position indicated by the average value.
Thereafter, signals are reproduced from the magnetic disk 10 by the magnetic head 32 centering on this position. When reproducing a signal, static tracking may be performed with the head 32 basically fixed at this head position, or a so-called dynamic tracking method may be used in which the position of the head 32 is moved depending on the degree of eccentricity. You may also perform a king.

As can be seen from FIG. 3, if the rotation center of the magnetic disk 10 is eccentric with respect to the center of the recording track circle, the positions r1 to r4 of the envelope peaks detected at the four phase angles θ1 to θ4 will have a 180° phase. Those with different values are paired with respect to the center position of the track. Therefore, by finding the median value for each of these pairs, ie, r1 and r3, and r2 and r4, and calculating the track position from this, a track position r0 at which the envelope can be sensed on the average can be obtained. That is, r0=[(r1+r3)/2-(r2+r4)/2]/2+(r2+
r4)/2=(r1+r2+r3+r4)/4 If the magnetic head 32 is located at this position r0, even if the track is eccentric, the head 3
2 can always read a recorded signal at a position relatively close to its envelope peak.

In this example, envelope peaks were detected at four phase angles, but generally the number of envelope peak reading phase angles may be two or a larger number n. That is, the envelope peaks are read at n positions with substantially equal phase intervals per revolution of the magnetic disk 10,
The same result can be obtained by simply averaging the n head positions detected for them. This number n
is preferably an even number.

Referring to the flowcharts in FIGS. 4A to 4C,
An example of the operation of dynamic tracking in this device will be explained. This operational flow is mainly executed by each functional section such as the control section 22, phase detection section 28, peak position detection section 40, and track position calculation section 64.

When tracking is instructed by the operation unit 66, the control unit 22 initializes related registers, counters, etc. (200), and then controls the motor drive circuit 7.
1 to move the head 32 by one unit length, for example in the forward direction R1, to a position close to a designated track (202). When the phase generator 24 detects the signal PG from the magnetic disk 10 rotating steadily at a predetermined speed (204), the envelope begins to peak at a phase advanced by a predetermined phase angle (206). It goes without saying that this predetermined phase angle may be 0, that is, the same timing as the generation of the signal PG.

When an envelope exceeding a predetermined reference value is detected in the comparison circuit 54 (208), information indicating the position r1 of the head 32 at that time is taken from the head support mechanism 36 into the peak position detection section 40, and Information indicating the rotational phase angle θ1 of the disk 10 is taken in from the phase detection section 28. These data are temporarily stored in the storage unit 68 (210) and constantly updated until the peak of the envelope is detected at the phase angle θ1 (212).

When a peak is detected, the peak position detection unit 40
In this embodiment, the envelope reading phase is advanced or delayed by 90 degrees from the phase θ1 (214), and similar detection is performed (220 to 230). At this time, even if the magnetic head 32 is moved in the same direction as before, that is, in the forward direction R1 in this example, and the same envelope peak detection is performed a predetermined number of times, for example, twice,
If an envelope greater than the reference value is not detected (252), the transport direction of the head 32 is reversed, that is, in this example, it is set to the reverse direction opposite to the forward direction R1 (254), and the same operation is repeated.

In this way, envelope peaks are detected one after another at four positions θ1 to θ4 whose phases are shifted by 90° in this embodiment. When the envelope peak detection is completed at a position where the reading phase of the envelope peak is advanced or delayed by 270 degrees from the initial state (250), the track position calculation unit 64 calculates the detected positions r1 to r4 of the head 32. A simple average is taken and this is taken as the position r0 of that track.

In addition, in this embodiment, dynamic tracking is performed in the range of the determined positions r1 to r4, so
The difference r4-r2 between the outer peak position r4 and the inner peak position r2 shown in FIG. 3 is determined, and this is taken as the amplitude of the vibration of the head 32 (232).

Next, the control unit 22 controls the motor drive circuit 71 to move the head 32 so that the head 32 is located at the inner peak position r2 (234). this is,
This is because the arm 104 of the head support mechanism 36 is biased by a spring 112 so that the head 32 is always located inside the disk 10, and the head 32 is configured to vibrate outward from this. . The amplitude value calculated in step 232 is set in the head vibration circuit 70 (236).

Therefore, when a time corresponding to the phase angle θ2 has elapsed since the next signal PG is generated 238 (240), the control section 22 activates the head vibration circuit 70 (242).
The magnetic head 32 then vibrates in the direction of arrow B shown in FIG. As a result, as the magnetic disk 10 rotates, the position of the head 32 changes so as to follow the envelope peak 170 (FIG. 3) of the track, that is, in synchronization with this, and the dynamic tracking is properly performed. It is done.

As described above, in this embodiment, while moving the reproducing head in the radial direction of the disk, the peaks of the envelope of the signal recorded on the rotating recording medium are detected at four phase angles that differ by 90 degrees. Since the playback head is moved to these average positions and dynamic tracking is performed within the range of these positions, effective tracking can be performed even if there is eccentricity in the tracks recorded on the rotating recording medium. . In other words, in this embodiment, if the signal detection capability of the playback head is able to accurately detect a signal by covering half of the track, then the head is stationary at the average position of the plurality of positions determined. Even when tracking is performed, it can sufficiently cope with an eccentricity of about 10 to 15 μm on both sides of a track width of 50 to 60 μm, and even if the eccentricity becomes large, it can be adequately coped with by dynamic tracking. can. For example, in a conventional rotating recording medium on which tracking information is recorded, an information area of approximately 10 μm is formed on both sides of the track, so if this and eccentricity are taken into account, there is a maximum error of 40 μm between the playback head and the track. In this case, the playback head and the
There is only an intersection of 10 to 20 .mu.m between the tracks of m, that is, the amount of intersection is less than half of the track, making it difficult to perform static tracking. In this embodiment, static tracking can be performed even when the eccentricity is larger than the maximum eccentricity when static tracking is performed using a rotating recording medium on which tracking information is recorded, and furthermore, it is possible to perform static tracking according to phase detection. By performing dynamic tracking while maintaining synchronization, accurate tracking can be performed even when the amount of eccentricity increases.

Note that the embodiments described here are for explaining the present invention, and the present invention is not necessarily limited thereto, and modifications and variations that can be made by those skilled in the art without departing from the spirit of the present invention. Modifications are within the scope of this invention. For example, although dynamic tracking is performed in this embodiment, it is not necessarily necessary to perform dynamic tracking, and stationary tracking may also be used. In the case of stationary tracking, the head support mechanism 34 may not be provided with a vibration mechanism, and the head may be moved to a position corresponding to the above-mentioned average value r0 and fixedly tracked there. Further, the number of reading positions of the envelope peaks to be averaged may be any number greater than or equal to 2.

Effects The rotating recording body tracking device according to the present invention reads a signal while moving the reproducing head in the radial direction of the rotating recording body on which tracking information is not recorded, and detects the peak of the strength of this signal. Tracking is performed by detecting one track at a plurality of predetermined phase angles and moving the reproduction head to the average position. As a result, the reproducing head can be positioned approximately at the midpoint of the eccentricity of the track recorded eccentrically on the rotating recording medium, and a signal of approximately uniform strength can be reproduced from the entire circumference of the track. Therefore, this device can omit a mechanism for detecting tracking information and a mechanism for correcting eccentricity, making the device smaller and lighter, and it is also possible to effectively use signals recorded from eccentric rotating recording bodies. It has an excellent effect that can be reproduced. Particularly when performing dynamic tracking, the head is vibrated in a range smaller than the eccentric width of the track, so the amplitude of vibration of the head is minimized, which is effective in preventing damage to the head support system and reducing noise. It is.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an embodiment of a rotating recording medium tracking device according to the present invention, and FIG.
FIG. 1 is a schematic diagram conceptually showing the magnetic head support mechanism and its related parts in the embodiment shown in FIG. 4C and 4C are flowcharts showing an example of the tracking operation flow in the same embodiment. Explanation of symbols of main parts, 10...Magnetic disk, 22...Control unit, 28...Phase detection unit, 32
... Magnetic head, 36 ... Head support mechanism, 38
...Head motor, 40...Peak position detection section,
50... Envelope detection circuit, 54... Comparison circuit, 64... Track position calculation unit, 70... Head vibration circuit, 116... Piezoelectric element, 120... Variable gain amplifier, 130... Power supply.

Claims (1)

[Scope of Claims] 1. A playback head that reads signals from a plurality of tracks formed on a rotary recording body that rotates steadily at a predetermined rotational speed with a trajectory in which the start and end of recording coincide; A rotary recording body comprising: a head support means for movably supporting the rotary recording body along a radial direction; and a control means for controlling the head support means and moving the reproduction head to a desired position among the tracks. In the tracking device, the device receives a signal read by the reproduction head,
Signal detection means for detecting the strength of a signal that changes depending on the relative distance between the reproduction head and the track; Position detection means for detecting the radial position of the reproduction head on the rotating recording body. , phase detection means for detecting the rotational phase of the rotary recording medium, and the position detection means detects the rotational phase for one track when the reproducing head is being transported under the control of the control means. The position of the reproducing head is detected when the signal detection means detects a signal peak at a plurality of predetermined phase angles of the rotation of the recording medium, and the control means detects the position of the reproduction head at a plurality of predetermined positions of the track. A rotating recording medium tracking device characterized in that an average position is determined, and the head supporting means is controlled to transport the reproducing head to the average position. 2. In the device according to claim 1,
An FM modulated signal is recorded on the rotating recording body, and the signal detection means detects the envelope of the FM signal read by the reproduction head to detect the strength of the signal. A rotating recording body tracking device. 3. The apparatus according to claim 1, wherein the head supporting means includes a vibrating means for vibrating the reproducing head in a direction parallel to the transport direction thereof, and the control means controls the vibrating means, The reproducing head is vibrated in synchronization with the rotation of the rotary recording body within a range of the plurality of detected positions based on the average position of the plurality of positions detected by the position detecting means. Rotating recording body tracking device. 4. In the device according to claim 1,
A rotating recording body tracking device, wherein the rotating recording body includes a magnetic disk. 5. In the device according to claim 4,
A rotating recording medium tracking device, wherein the plurality of phase angles are spaced apart from each other by substantially 90 degrees in the rotational direction of the magnetic disk.