JPS6189782A - Tracking device of rotary magnetic recording body - Google Patents

Abstract

PURPOSE:To attain a quick tracking with high accuracy at the time of traveling a head over tracks by detecting a peak position with the aid of the drop of an envelope level caused by the fact that a head passes through the peak posi tion and executing the tracking control so that the head can be returned in the vicinity of the peak position. CONSTITUTION:An envelope detector circuit 38 detects the envelope of an FM modulation video signal recorded on the track of a recording face 16, and outputs a voltage corresponding to the detected envelope to an output 42, which is connected to an analog/digital converter (ADC)46 through an envelope ampli fier 44. In accordance with the request of a controller 100, the ADC46 outputs said output as data of eight bits to the controller 100. It is a controller for supervising the control of the overall device in correspondence to an operator's handling, and formed with a microprocessor system, for instance.

Description

Detailed Description of the Invention Yoshinaoko 1 The present invention relates to a rotating magnetic recording body tracking device, particularly a rotating magnetic recording body that performs tracking when reproducing information recorded on a rotating magnetic recording body such as a magnetic disk or a magnetic drum. The present invention relates to a tracking device. In particular, the present invention relates to a rotating magnetic recording body tracking device that reproduces information recorded on concentric tracks formed on a magnetic disk 1- while applying tracking servo.

1. Recently, still images of subjects have been photographed purely electronically by combining imaging devices such as solid-state image sensors and image pickup tubes with recording devices that use magnetic disks, which are inexpensive and have a relatively large storage capacity, as recording media. Electronic still camera systems have been developed that record on a rotating disk and reproduce images using a separate television system or printer.

However, recording media used for such magnetic recording, especially magnetic disks, are prone to tracking defects due to anisotropy, eccentricity, thermal expansion, etc. There is a problem with scanning the tracks and creating crosstalk.

In order to avoid this problem, there is a method in which tracking servo is applied when recording information to record a tracking signal, and this tracking signal is used to apply tracking servo during reproduction. 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 and tracking defects during playback, to prevent the playback head from scanning the adjacent tracks, or even if the playback head scans the adjacent tracks, There is a way to compensate by not picking up the signal.

In addition to this, a so-called climbing method is also used.

During recording, the recording head is moved at a predetermined track pitch by a stepping motor without applying a tracking servo, and during playback, the envelope of the output signal of each track is detected and the optimal track is identified from the peak position. This applies tracking servo.

By the way, it is generally advantageous to use a reproducing device for a rotating magnetic recording medium such as a magnetic disk in such a manner that the rotating magnetic recording medium is removably attached to the rotating magnetic recording medium so that the rotating magnetic recording medium with various recording contents can be selectively used. It is. Therefore, each time a rotating magnetic recording medium is mounted, there is no guarantee that the track center will be correctly aligned with the center of the rotational drive shaft of the reproducing device, and there is usually some eccentricity involved. Furthermore, it is not guaranteed that the signals recorded on the rotating magnetic recording medium will accurately align with the center of rotation and form concentric tracks without eccentricity.

In this way, if the degree of eccentricity of the center position varies each time a rotating magnetic recording medium is installed in a reproducing device, or if the recording track itself is eccentric, the signal to be reproduced from now on will depend on the rotation of the rotating magnetic recording medium. The level will fluctuate in sync with.

If the signal recorded on the rotating magnetic recording medium is a field video signal, depending on the chucking state of the rotating magnetic recording medium, the level in the first half of the field may be relatively high, or the level in the second half may be relatively high, regardless of the content of the video signal. level is relatively high or average overall.

In the 111 retracking method, tracking control is performed according to the envelope level of the recording signal, as described above. Therefore, if the envelope level varies depending on the chucking state of the rotating magnetic recording medium, accurate tracking control cannot be performed.

Further, the magnitude of the reproduction signal level also changes depending on the orientation of the magnetic material of the magnetic recording medium and the contact of the reproduction/reading material with the recording surface. Therefore, even if the tracking control is influenced by such temporary fluctuations in the envelope level, the optimum track position will not be detected.

In a rotating magnetic recording medium used in an electronic still camera system, for example, a small disk with a diameter of about 501 mm has a track pitch of about 100 m, that is, a track width of about 50 to 80 gm, and a girt band width of about 50 m. ~50 tracks can be recorded at approximately 40g■. In a playback device, this magnetic disk plays at a speed of, for example, 3
, 800 rotations, and the video signal is reproduced at field or frame rate. Therefore, in the mountain climbing tracking method, precise tracking control must be performed with position refinement on the order of 10 gm or less.

In order to stably and quickly converge the system when moving the magnetic head between tracks, it is desirable that the range in which such tracking operation is performed during head movement be as narrow as possible. That is, from the viewpoint of stable video playback, it is required that the head be moved from one track to the next track as quickly as possible, and that the head position should quickly converge near the peak of the envelope level of that track.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a rotating magnetic recording medium tracking device that is capable of high-precision and rapid tracking.

According to the present invention, a rotating magnetic recording body is provided with a magnetic lid that reads signals from a plurality of tracks formed on a rotating magnetic recording body with tracks such that the relative positions of the recording start and end coincide with each other. 1. A head-and-hand moving device that supports a magnetic head and moves the magnetic head over a plurality of tracks; and a detection device that detects the level of a signal read by the magnetic head in accordance with the rotation of the rotating magnetic recording body. A rotating magnetic recording body tracking device comprising a control means for controlling a head moving means to perform tracking when instructed to move the lid between tracks, and moving the head to a desired position among the tracks. In response to an instruction to move the head, the detecting means reads the level of the signal, stores the value, moves the head by a first predetermined distance by the head moving means, and detects the level of the signal by the detecting means. Read the level, compare the read level with the memorized value, and when the read level is equal to the memorized value, update the memorized value with this read level and increase the read The movement and reading are repeated until the level is smaller than the stored value a predetermined number of times in a row, and when the read level is smaller than the stored value a predetermined number of times, the head moving means is controlled. to move the head in the opposite direction, thereby positioning the head back a distance substantially equal to the product of the first predetermined distance and the predetermined number of times.

Note that in this specification, "a plurality of tracks formed with a locus such that the relative positions of the recording start and end coincide with each other" refers to, for example, in a magnetic disk, a large number of tracks formed concentrically around a rotation axis. In addition, in a magnetic drum, recording is performed so as to form one trough without changing the relative position of the recording head with respect to the rotating magnetic recording medium, such as a number of tracks formed in parallel in the circumferential direction. means.

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

In the apparatus of this embodiment shown in FIG. 1, for example, a rotating recording medium such as a magnetic disk! 0 is the rotating shaft 1 of the DC motor 12
4 is removably attached. The magnetic disk 10 is □″
It has a magnetic recording material sheet with a diameter of about 50 mm, and a plurality of, for example, 50 recording tracks are recorded on the recording surface 18 at predetermined intervals (for example, about 10100 pL) in a concentric circle I-.Signals recorded on the recording tracks is a video signal in this embodiment, which may be, for example, a color video signal in which a moderation signal and a chroma signal are FM-modulated.This video signal may be, for example, a field video signal that forms a field of an image by rask scanning. is recorded to one track.

The DC motor 12 has a frequency generator 18 that generates a frequency signal and is powered by a servo circuit 20 so that the disk 10 is rotated at a predetermined rotational speed, e.g.
It is servo controlled to rotate at a constant speed of 0 revolutions/minute. The servo circuit 20 is a control device 100 that controls the entire device.
, and controls the rotational driving and stopping of the disk 10 in response to the signal DISK.

A pulse generator 22 is disposed at a predetermined position near the recording surface 16 of the disk 10, and is connected to the servo circuit 20 and the control device 100 via an amplifier 24. As a result, a timing mark formed corresponding to a predetermined position on the disk core 15 is detected, and a timing pulse PG is formed.

A magnetic transducer or magnetic head 26 is disposed on the recording surface 1B, and is carried by a support mechanism 28. This support mechanism is driven by a step motor (PM) 30 as conceptually indicated by a dotted line 28, and moves the head 26 in both radial directions along the recording surface 1B as indicated by an arrow R. It is configured so that any track on 18 can be selected.

The magnetic head 26 may have a magnetic recording function, but in this embodiment, since it has already been recorded on the recording surface 1B, the magnetic head 26 has a playback function of ejecting the video signal from the track and converting it into a corresponding electric signal. Those with the following are examples. As mentioned above, in this example, the distal lO force <'3,800 rotations/
The video signal for one track, that is, the FM modulated video signal '200 (FIG. 2) of one field, is reproduced from the magnetic head 26 every 1/80 seconds of one rotation of the ice cube, which rotates at a constant speed in minutes. That will happen. This is shown at the bottom of Figure 2□
After being demodulated, it becomes a video signal 202 that is compatible with standard color television systems such as the TSC system.
(The reproduction output 32 of the magnetic head 2B is connected through a device amplifier 34 to a C''C video signal processing circuit 38 and an envelope detection circuit 3B.
□ Signal processing the video signal detected by the head 28 □
□This is a circuit that outputs a composite color video signal in the NTSC format to the device output 40, for example. This is demodulated and converted from the NTSC format composite color video signal to the vertical synchronization signal V! It has a function of extracting JYNC'<first time) and supplying it to the control device 1100. Further, in response to the signal EE from the control device 100, the magnetic head 2
6 is separated from the processing circuit 3B, the processing circuit 3B is placed in the EE state (electrical system connection state S), and other signals, such as broadcasting signals, can be outputted to the device output, or the video signal can be outputted by receiving the signal MUTE. The muting operation is performed by using the effective horizontal scanning period as a blank signal. Note that the function of converting to such a standard format is not essential to this device, and the processing circuit 3B has a function of extracting synchronization from the video signal sensed by the hept 28 and simply transmitting this to the terminal 40 under the control of the control device 100. It may also have an output function.

The envelope detection circuit 38 detects the envelope of the FM modulated video signal recorded on the track on the recording surface IB.
204 (Figure 2) and outputs a voltage corresponding to this 4
This is a detection circuit that outputs to 2. This is connected via an envelope amplifier 44 to an analog-to-digital converter (AIIC).
) connected to 4B. In this embodiment, the ADC 4B has a quantization level of 25B, and outputs this to the control device 100 as 8-bit data in response to a request from the control device 100.

The control device 100 is a control device that centralizes control of the entire device according to the operations of the operator, as will be described in detail later.
For example, it is advantageously constructed by a microprocessor system.

In this embodiment, there is a raw key PL 11 for instructing start and stop F of the apparatus, a forward key FW for moving the head 2B in the forward direction of the track number (for example, from an outer track to an inner track), and a head 26. The control device 1 is provided with a reverse direction key RV for moving the
Connected to 00.

The number of the truck indicated by the key cocoon, RV etc. is determined by the number of the truck connected to the control device +00,
It is visually displayed on a display device 48 such as an RT display. Of course, it may also have a function of audibly displaying a warning or the like.

In this embodiment, the step motor 30 is a four-phase drive pulse operation motor, and responds to one drive pulse to
It rotates 8'. Therefore, 20 pulses make one rotation. The head support mechanism 28 moves the head 26 in the direction of the arrow H by about 8.311.degree. with l pulses (steps) combined with the step motor 30. tn transport. Therefore, with 12 pulses, the head 26 is approximately
100gra will be transferred.

This drive pulse is supplied from a drive circuit 50 consisting of a current amplifier, and the latter generates an excitation coil drive pulse for the step motor 30 according to an excitation pattern instructed by the control device 100. Such excitation pattern generation control is performed by a head feed control section 102 shown in FIG. 4.

FIG. 3 shows an example of the internal configuration of the control device 100 shown in FIG. 1, and in particular, conceptual functional blocks in an example where the control device 100 is configured with a microprocessor system are indicated by reference numerals in the 100s. It is. The operation of this embodiment will be described in detail with reference to the functional block diagram of FIG. 3 and the flowchart of FIG. 4.

For example, assume that the control unit w100 turns on the signal DISK to rotate the disk 10 at a constant speed, and the head 26 is exactly on track at a certain point (between positions, FIG. 5A). Therefore, a case will be described in which tracking is performed by operating the forward key FW or reverse key RV to move the head 26 to a corresponding adjacent track. After the reproduction key PL is operated, for example, when the FW main key is operated, the main control unit 104 starts the "tracking" operation shown in FIG. 4 in response.

The main control unit 104 first clears the buffer ^, B, step counter SC, and back step counter BS.
00), the head feed control unit 102 is controlled to drive the step motor 30 for seven pulses (302). The drive pattern of the excitation coil of the step motor 30 is stored in the excitation pattern storage section 112, and the head feed control section 102 drives the step motor 30 based on this. As a result, the head 26 is moved seven steps and reaches position H2.

Since the content of step counter SC is not 5 (304)
, further transfer 12 do 28 to one step (30B
) Increment step counter SC (30B
). The operation up to now has resulted in the head 26 being unconditionally transferred from the positioner to the position H3. Here, the main control unit +04 reads the envelope value AD-converted by the ADC 48 through the envelope detection unit 106 (3
10), save this to envelope storage +08 buffer B
(312).

A general explanation about envelope reading is as follows.
A video signal detected by the magnetic head 26 as the head 26 is moved is input as an envelope waveform, for example 204, to the ADC 4B through an envelope detection circuit 38 and an amplifier 46. When there is a request from the control unit N100, this is inputted to the control device 1100 in the form of digital data corresponding to the request.

In the above example, since buffer A has been cleared at this time (314), the contents of buffer B remain unchanged in the storage unit 1.
Transferred to buffer A of 08 (31B). The main control unit 104 clears the backstep counter BS (
318), repeat the operation 1- below.

This operation continues until the contents of buffer B equal or exceed the contents of buffer A, step 314. This comparison is performed by the level comparison and determination section 110. This operation moves the head 26 in the forward direction while checking the envelope level.

As a result of the comparison 314, when the currently detected envelope becomes lower than the contents of buffer A, that is, the maximum value of the envelopes detected so far, the control attempts to escape from this loop 334 (314) and increments the backstep counter BS. (3'24). In this example, since the count value of the backstep counter BS does not reach 2 at this time (32B), the control loops again to 33.
It costs 4.

In this loop 334, if the condition 314 is satisfied again, that is, if the envelope detected this time as well as the previous time becomes lower than the content of buffer A, the control exits from the loop 334 (314) and goes to the back step and further outputs the 9BS. Increment (3241°) As a result, the content of the back step counter BS reaches 2 (32B), and the process moves to judgment of the content of the step color counter SC (32B). This means that the envelope has passed two steps past the peak position of .

The reason why it is determined in step 328 whether the content of the step counter SC exceeds 5 is as follows. In step 304, step counter SC is 5.
When the value is reached, the determining unit 110 determines whether the contents of buffer B exceed the specified value (320). In other words, if an envelope level higher than the specified value is not detected at a position where the head 26 has been moved 12 steps from the vicinity of the envelope peak position of the previous track, it is determined that no head track is recorded at that position, and no header track is recorded at that position. Recording track detection processing 322 is performed. This specified value is set to a value lower than the peak value of the envelope by a predetermined tolerance. If the specified value is exceeded, control returns to loop 334 again. Therefore, in step 328, on the condition that the head 1B has been moved by at least 12 steps from the previous truck, the process moves to the next step 330, 332, that is, the head position convergence operation.

Thus, when it becomes clear that the head 26 has passed the peak position of the envelope, the head 28 is transported in the opposite direction and returned to its peak position. First, the head 2B is moved in the opposite direction by the number of steps, which is 2 plus 7 steps indicated by the back step counter BS (330). As a result, the head 2B reaches position H5. only in the positive direction/)”2B
When the head 2B is moved (332), the head 2B reaches the position 6. This eliminates the influence of bulk lash included in the head transfer system 30.28. □ Figures 5A to 5D show tracks 1 to 1121 in which video signals with various envelopes are recorded in this embodiment, and the control when the head 2B is moved to the non-recorded area @22. The pattern is shown schematically. In these figures, the white circles indicate the upper stop position of the head 28, the black circles indicate the positions where the head 28 finally stops due to tracking control, and the numbers indicate the contents of the step counter 9C. Also, the length in the vertical axis direction is A of the envelope.
/El corresponds to the size of the converted value. As will be seen, in this example, if the inter-track pitch is in the range of 8 steps to 16 steps, the head 28 can be appropriately stopped near the peak position of the envelope. Even if the head 2B stops due to a slight deviation from the peak position, it will not adversely affect the reproduction of the video signal.
There is no way.

Note that 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. Also,
The numerical values in the description of the illustrated embodiments are merely examples for explanation, and do not limit the construction of embodiments with different numerical values.

In this way, when the head is moved between tracks, the peak position is detected by the drop in the envelope level as the head passes through the peak position, and tracking control is performed to move the head around that position. ing. Therefore, highly accurate and rapid tracking is possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a rotating magnetic recording body tracking device according to the invention; FIG. 2 is a waveform diagram showing an example of a video signal reproduced by the device according to the embodiment shown in FIG. 1; 3 is a functional block diagram showing the functions of the control device shown in FIG. 1; FIG. 4 is a flow diagram showing an example of the operation of the control device of the embodiment shown in FIGS. 1 and 3; 5D are schematic diagrams showing examples of tracking operations in the embodiment of FIG. 1. Yo's thunder. 10. Magnetic disk 26, Magnetic head 2B, Head transport mechanism 30, Step motor 3fi, Video signal processing circuit 38, Envelope detection circuit 100, Control device 102. Head feed control section +04. ,,main control section 108,,,envelope detection section 110,,,level comparison judgment section

Claims (1)

[Scope of Claims] 1. A magnetic head that reads signals from a plurality of tracks formed on a rotating magnetic recording body along trajectories such that the relative positions of the recording start and end coincide with each other, and supporting the magnetic head; head moving means for moving the magnetic head across the plurality of tracks; detecting means for detecting the level of a signal read by the magnetic head in accordance with rotation of the rotating magnetic recording body; Then, in a rotating magnetic recording body tracking device comprising: a control means for controlling the head moving means to perform tracking and moving the head to a desired position among the tracks, the control means moves the head; In response to an instruction, the detecting means reads the level of the signal and stores the value, the head moving means moves the head by a first predetermined distance, and the detecting means reads the signal level. and comparing the read level with the stored value and updating the stored value with the read level when the read level is equal to or greater than the stored value; The movement and reading are repeated until the read level is smaller than the stored value a predetermined number of times in a row, and when the read level is smaller than the stored value a predetermined number of times, controlling the head moving means to move the head in the opposite direction, thereby returning the head a distance substantially equal to the product of the first predetermined distance and the predetermined number of times; A rotating magnetic recording body tracking device characterized in that: 2. In the apparatus according to claim 1, when there is an instruction to move the head, the control means causes the head moving means to control the signal level by the head moving means before the detection means reads the level of the signal. A tracking device characterized in that the head is moved by a second predetermined distance. 3. The tracking device according to claim 2, wherein the second predetermined distance is set longer than the first predetermined distance.