JPS62134872A - Tracking device for rotary recording body - Google Patents

Abstract

PURPOSE:To remove the influence of eccentricity of a rotary recording body by detecting the envelopes of signals which are read at plural kinds of phase angles and performing tracking to the average position of head positions when the peaks of the envelopes are detected. CONSTITUTION:When a phase generator 24 generates a signal PG from a magnetic disk 10 which rotates steadily, the peak of an envelope is found. When the peak is detected, a peak position detection part 40 advances or delays an envelope readout phase by 90 deg. and performs similar detection. When the peaks of envelopes are detected at 90 deg. out-of-phase positions, a track position calculation part 64 averages of detected positions of a head 32 simply and regards it as a track position. Then, a control part 22 controls a head support mechanism 36 to move the head 32 to the track position calculated by the calculation part 64. Consequently, even if the disk 10 has eccentricity, the disk is tracked properly.

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 ART Recently, imaging devices such as solid-state image sensors and image pickup tubes are combined with recording devices that use magnetic disks, which are inexpensive and have a relatively large storage capacity, as recording media to take still photographs of objects using purely electronic means, such as rotating disks. An electronic still camera system has been developed in which images are recorded on the camera and the images are played back using a separate television system or printer.

In a rotating magnetic recording medium used in an electronic still camera system, for example, a small disk with a diameter of about 50 mm has a track pitch of about 100 m, that is, a track width of about 50 to 80 gm, and a guard band width of about 50 mm. 50 tracks are recorded at ~40 gm. In a recording or reproducing apparatus, this magnetic disk rotates at a constant speed of, for example, 3,800 revolutions per minute, and 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 failures 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 a magnetic head for recording information records a tracking signal by applying tracking servo, and a reproducing head uses this tracking signal to apply tracking servo. 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 adopt 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 from 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.

In this system, the recording head is moved at a predetermined track pitch by a stepping motor without applying tracking servo, and the playback head detects the envelope of the output signal of each track and identifies the optimal track from its peak position. It is something that multiplies.

The head position at which the envelope peaks is determined by moving the magnetic head a predetermined pitch, reading the envelope value at that position, and comparing this with the envelope value detected at the previous position. Ru.

Digital processing systems are generally advantageously applied to perform this comparison. To this end, the video signal detected by the reproducing 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. There is. Therefore, the information on the recording track may not be properly reproduced.

OBJECTS It is an object of the present invention to eliminate the drawbacks of the prior art and to provide a rotating recording medium tracking device that can properly track even if the rotating recording medium is eccentric.

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 body 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 a signal read by the playback head, and a head support means are controlled to move the playback head to a desired position among the tracks. The rotating recording body tracking apparatus 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, and the control means includes a , 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 rotating recording medium for one track. The control means detects the position of the reproducing head, calculates the average position of the plurality of detected positions, and controls the head supporting means to move the reproducing head to the average position.

Note that in this specification, "a plurality of tracks formed with a locus whose recording start and end coincide with each other" means, for example, in a magnetic disk, a large number of tracks formed concentrically around a rotation axis, and in a magnetic drum, a plurality of tracks formed concentrically around a rotation axis. Like many tracks formed in parallel in the circumferential direction, one track can be recorded without changing the relative position of the recording head with respect to the rotating magnetic recording medium.
means recorded to form one track.

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 approximately 50 layers, and a plurality of recording tracks, for example 50 recording tracks, are arranged concentrically on the recording surface 1B of the magnetic disk 10, and approximately 100 recording tracks are arranged concentrically on the recording surface 1B.
Recorded with a pitch of JL ya. 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 rask scanning.

The spindle motor 12 has a frequency generator 18 for generating an alternating current frequency signal, and is powered by a servo circuit 20 so that the disk 10 is rotated at a predetermined rotational speed, e.g.
, is servo-controlled to rotate at foot speed of 800 revolutions/minute. 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.

The phase detection section 28 and the servo circuit 20 respond to the reference clock generated by the reference generator 58. A reference signal of 80 Hz is supplied to the phase detection section 28, and a high-speed signal, for example 3.
A 58MHz clock is supplied.

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

Disposed above the recording surface 16 is a magnetic transducer or helad 32, which is carried by a head support mechanism 38, as shown conceptually by dotted lines 34. This support mechanism 36 is driven by a head motor 38 and moves 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 configured.

A peak position detection section 40 is connected to the head support mechanism 36, and a signal corresponding to the position of the head 32 on the recording surface 16 is supplied from the head support mechanism 3B to the human power 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 reproduction function of detecting a video signal from a track already recorded on the recording surface f6 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 3,600 revolutions/minute, so the video signal for one track, that is, the FM modulated video signal for one field, is transferred to the magnetic herad 32 every 1,780 seconds of one revolution. It will be played from. this is,
By being demodulated, it becomes compatible with standard color television systems such as the NTSG method.

The reproduction output 44 of the magnetic head 32 is transmitted through a preamplifier 46 to a video signal output terminal 48 and an envelope detection circuit 5.
Connected to 0. 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. The output 52 is input to a comparison circuit 54, and the latter output 5 days is connected to the peak position detection section 40.

The comparison circuit 54 is a circuit that compares the human power 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 determines the rotation angle of the magnetic disk 10 from the reference position, that is, the position where the signal PC is generated, by the signal PG obtained from the phase detector 24 at the input 60 and the reference signal obtained from the reference generator 58 at the input 82. In other words, it is a functional unit that detects the phase.

The peak position detection section 40 calculates the following information from the position information of the head 32 input from the head support mechanism 36, the envelope value input from the comparison circuit 54, and the rotational phase information of the magnetic disk 10 from the phase detection section 28. This is a functional unit that detects the position of the head 32 indicating the peak of the envelope, that is, the peak position.

The present device also has a track position calculation unit 64, which is a V&N function that calculates an optimal track position from the peak position detected by the peak position detection unit 40 by a predetermined calculation.

These functions 28, 40 and 64 are controlled by the control unit 22, which together with the control unit 22 are advantageously configured by a processing system, for example a microprocessor. In that case, an analog-to-digital conversion circuit,
Needless to say, appropriate interface circuits such as digital-to-analog conversion circuits or amplifier circuits are involved.

The control unit 22 is connected to an operation unit 6B that inputs instructions from an operator and displays the status of the system. Operation unit 6
The control unit 22 controls and supervises the entire device in response to instructions input from B.

The operation unit θB can, for example, start and stop the device, set a desired track position, provide track selection instructions to move the magnetic head 32 to that position, and move the head 32 in the forward direction of the track number (for example, from the outer track). A forward direction phase instruction to cause the head 32 to be transferred to the inner track), a reverse direction phase 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, and this includes:
It 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,
Electric power is supplied from the motor drive circuit 71, and its rotation is controlled by the control unit 22. As a result, the control unit 22
The head 32 can be moved in the direction of arrow R by a predetermined length.

The head support mechanism 36, as conceptually shown in FIG.
The recording surface 1 of the magnetic disk 10 is moved by the head motor 38.
It has a carriage 100 that can be moved in the radial direction R of 6. A support part 102 is fixed to the carriage 100, and an arm 104 is supported on the support part 102 so as to be rotatable about @106. A head mounting stand 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 the arm 104 is spring biased in the direction of arrow A by a spring 112 fixed to the carriage 100 at one end.

A piezoelectric element 11 is provided on the end 110 side of the arm 104 between it and the main surface 112 of the carriage 100, as shown.
6 are arranged. An output 122 of an amplifier 120 of the vibration circuit 70 is electrically connected to the piezoelectric element 116 . The piezoelectric element 11B 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 around the fulcrum 106 by a certain amount.

Amplifier 120 is a variable gain amplifier whose gain is controllable by control input 128, and signal input 124 includes:
A power supply 130 is connected via a switch 128.

The power supply 130 is advantageously used in this embodiment as a power supply which generates a sinusoidal signal with a frequency of 80 Hz, ie substantially equal to the field frequency of the video signal recorded on the disk 1o. The switch 128 is a normally open switch element, and its opening/closing is controlled by the control section 22 as conceptually indicated by a dotted line 132. The control input 12B also receives a signal from the control unit 22 for setting the gain of the amplifier 120 from a digital-to-analog converter (DAC).
134.

For example, a photointerrupter type head position detector 140 is coupled to the output shaft 144 of the head motor 38 . In this detector 140, a slit plate 142 having an optical slit 148 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, and a light detection element 150 such as a photodiode is disposed on the opposite side of the slit plate 142. ing. The output 42 of the photodetector element 150 is connected to the peak position detector 40. As a result, as the slit plate 142 rotates, each time the slit 14B passes through the position of the optical axis 152 from the light emitting element 148 to the photodetecting element 150, the light from the light emitting element 148 enters the photodetecting element 150. A signal is output from the photodetecting element 150 to the output 52. In the peak position detection section 40, this signal is detected by the head 32.
used for position detection.

In this embodiment, tracking is performed as follows. While moving the magnetic head 32 in one radial direction of the magnetic disk 10, 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 certain position θ1 at a certain rotation angle or phase θ of the magnetics 10. , its peak is detected.

Therefore, the head position r1 at this time is stored. Note that the phase angle 0 is based on a predetermined position, for example, the position where the signal PC is detected, and the phase angle θ1 at which envelope detection is performed first may be substantially the same as the position where the signal PG is generated.

Next, change the detection phase of the envelope peak to this phase angle θ1
The head 32 is further moved in the same direction or in the opposite direction while advancing or retarding the envelope by 90" at a phase angle θ2. In this way, as shown in FIG. As the head 32 is moved toward or inward, envelope peaks are detected at four phase angles.

For example, when envelope peaks are detected at four phase angles 01 to θ4, a simple average of those head positions "1 to r4" is calculated, and the magnetic head 32 is basically moved to the position indicated by the average value. Thereafter, signals are reproduced from the magnetic disk 1o by the magnetic head 32 centered on this position.When reproducing signals, the head 32 may be fixed at this head position and static tracking may be performed, or , so-called dynamic tracking may be performed in which the position of the head 32 is moved according to the degree of eccentricity.

As can be seen from FIG. 3, if the rotation center of the magnetic disk 1o is eccentric with respect to the center of the recording track circle, the positions r1 to T4 of the envelope peaks detected at the four phase angles 01 to θ4 are 18o°. Those with different phases form a pair with respect to the center position of the track. Therefore, by finding the median value for each of these pairs, ie, rl and r3, and r2 and r4, and calculating the track position from this, a track position ro at which the envelope can be sensed on average can be obtained. That is, ro=[(rl+r3)/2-(r2+r4)/2]/
2+(r2+r4)/2-(rl+r2+r3+r4)
/4 By positioning the magnetic head 32 at MrO of this extent, the head 32 can always read the recorded signal at a position relatively close to its envelope peak even if the track is eccentric.

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 same results can be obtained even if the envelope peaks are read at n positions with substantially equal phase intervals per one rotation of the magnetic disk 10 and the n head positions detected are simply averaged over the n positions. This number n
is preferably an even number.

An example of the operation of dynamic tracking in this apparatus will be described with reference to the flows shown in FIGS. 4A to 4C. This operation flow is mainly executed by each functional unit such as the control unit 221, the phase detection unit 28, the peak position detection unit 40, and the track position calculation unit 84.

When tracking is instructed by the operation unit 68, the control unit 22 initializes related registers, counters, etc. (200), controls the motor drive circuit 71, and moves the head 32 by one unit length, for example, in the forward direction R1. (202).

When the phase generator 24 detects the signal PC 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 (20B). It goes without saying that this predetermined phase angle may be at the same timing as the generation of Ol, that is, the signal PC.

When an envelope exceeding a predetermined reference value is detected in the comparator circuit 54 (208), the head 32 at that time
The information indicating the position T1 of the disk 1 at that time is taken into the peak position detection section 40 from the head support mechanism 38, and
Information indicating a rotational phase angle θ1 of 0 is taken in from the phase detection unit 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 θl (212).

When a peak is detected, the peak position detection unit 40 advances or delays the envelope reading phase by 90 degrees from the phase θ1 in this embodiment (214) and performs the same detection (2
20-230). At this time, even if the magnetic helad 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, the envelope exceeding the reference value is not detected. If it is not detected (252), the moving 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 01 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 rack position calculation unit 64 calculates the detected position r of the head 32.
A simple average of 1 to r4 is taken and this is set as position 10 of that track. Also, find the difference r2-r4 between the maximum value, that is, the outermost position, r4 in this example, and the minimum value, that is, the innermost position, r2 in this example, and use this as the amplitude of the vibration of the head 32 (232 ).

Next, the control unit 22 controls the motor drive circuit 71 to transport the head 32 so that the head 32 is positioned at the inner peak position r2 (234). This is because the arm 104 of the head support mechanism 36 is biased by the spring 12 so that the head 32 is always located inside the disk 10, and the head 32 is configured to vibrate outward from this. It is. The amplitude value calculated in step 232 is set in the head vibration circuit 70 (23B).

Therefore, the control unit 22 determines that when a time corresponding to phase angle 02 has elapsed since the generation 238 of the next signal PC (240).

The head vibration circuit 70 is activated (242). Therefore, the magnetic head 32 vibrates in the direction of arrow B shown in FIG. As a result, as the magnetic disk drive 0 rotates, the head 32 detects the envelope beak 170 of the track.
(FIG. 3), the position changes in synchronization with this, and dynamic tracking is appropriately performed.

The embodiments described here are for illustrating the present invention, and the present invention is not necessarily limited to these embodiments, and modifications that can be made by those skilled in the art without departing from the spirit of the present invention. and modifications are within the scope of the invention. For example, although dynamic tracking is performed in this embodiment, it is not necessarily necessary to perform dynamic tracking, and stationary tracking may be used. In the case of stationary tracking, no vibration mechanism is provided in the head support mechanism 34,
Transfer the head to the position corresponding to the above-mentioned average value rO,
Therefore, it may be configured to perform fixed tracking. Further, the number of reading positions of the envelope peaks to be averaged may be any number greater than or equal to 2.

Effects As described above, the rotating recording body tracking device according to the present invention does not perform hill-climbing tracking, but detects the envelope of one track at a plurality of predetermined phase angles, and detects the peak of the envelope at these detected phase angles. The head position is tracked to the average position. Therefore, even if the rotating recording medium is eccentric, recorded signals can be appropriately reproduced. In particular, when this method is applied to dynamic tracking, the amplitude of vibration of the head is minimized, and it is effective in terms of preventing damage to the head support system and reducing noise.

[Brief explanation of drawings]

1 is a schematic block diagram showing an embodiment of a rotating recording body tracking device according to the present invention; FIG. 2 is a schematic diagram conceptually showing a magnetic head support mechanism and related parts in the embodiment shown in FIG. 1; FIG. 3 is a graph for explaining the present invention in detail in the same embodiment, and FIGS. 4A, 4B, 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 section 2B, ... Phase detection section 32, ... Magnetic head 3B, ... Head support mechanism 38, ... Head motor 40, ... Peak position Detection unit 50, envelope detection circuit 54, comparison circuit Ei4. ,,) Rack position calculation unit 70, , Head vibration circuit 11B, , Piezoelectric element 120, , Variable gain amplifier 130, , Power supply Patent applicant Fuji Photo Film Co., Ltd. Agent Takao Katori Takao Maruyama 3rd Figure 4A Figure 1 Net ll Enclosure 2-134872 (10) Figure 4C

Claims (1)

[Claims] 1. A reproducing head that reads signals from a plurality of tracks formed on a rotating recording body that rotates steadily at a predetermined rotational speed with a trajectory in which the starting and ending ends of recording coincide; a head supporting means movably supporting the rotating recording body; an envelope detecting means detecting an envelope of a signal read by the reproducing head; and controlling the head supporting means to determine the position of a desired one of the tracks. A rotating recording body tracking device comprising: a control means for moving the reproducing head on the rotary recording body, the apparatus comprising: a position detecting means for detecting the position of the reproducing head on the rotary recording body; and a position detecting means for detecting the rotational phase of the rotary recording body. the control means controls the head support means to move the reproducing head; and the position detection means controls the rotation of the rotary recording body for one track at a predetermined level. detecting the position of the reproducing head when the envelope detecting means detects the peak of the envelope at a plurality of phase angles, the controlling means determining the average position of the plurality of detected positions, and controlling the head supporting means. A rotating recording medium tracking device characterized in that the reproducing head is moved to the average position under control. 2. 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. , of the detected positions, two extremes in the direction of movement of the playback head.
A rotary recording body tracking device characterized in that the reproducing head is vibrated in synchronization with the rotation of the rotary recording body with an amplitude substantially equal to the difference between the two positions. 3. A rotating recording body tracking device according to claim 1, wherein the rotating recording body includes a magnetic disk. 4. The apparatus according to claim 3, wherein the plurality of phase angles are spaced apart from each other by substantially 90° in the rotational direction of the magnetic disk. Device.