JPS6151677A - Tracking control device of disk - Google Patents

Abstract

PURPOSE:To read in no cross talk condition by dividing digital data into plural blocks and controlling a tracking which is suitable only for a block to be read when data are read. CONSTITUTION:In a RF output from a reading head 11, a video signal is demodulated through an amplifier 12 by a video processing circuit 13 and inputted to a digital processor 14. On the other hand, the RF output from he amplifier 12 is inputted through a detecting circuit 18 and an A/D converter 19 to a micro computer (MP)15. Each time a disk from a pulse generator 16 rotates once, one pulse PG is inputted through an amplifier 17 to MP15 and a head of No.0 track of respective tracks divided into plural blocks is detected. When an instruction DM reading the data of the prescribed block is inputted to MP15, a signal, in which an envelope detecting output of an RF output of the block becomes maximum, is sent to a motor driving circuit 20 and a tracking servo is loaded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to cases in which, for example, a flexible disk cartridge (video still floppy disk) for an electronic still camera is also used as a medium for storing digital data in a computer or the like. Regarding preferred techniques.

[Conventional technology]

The format of the conventionally used 8-inch or 5-inch floppy disk is defined, and almost all devices operate under the defined format.

For this reason, it is not possible to incorporate cutting-edge technology for high-density recording and reproduction, and furthermore, the rotation speed of the rotating magnetic disk stored in the floppy disk is only 300 rpm.
Also, since it is slow at 600 rpm, it is impossible to record and reproduce analog video signals in real time. Furthermore, if the video signal is digitized, it can be recorded and reproduced, but only about one image can be recorded on one floppy disk, even though the jacket size is large, such as 8 inches or 5 inches. Moreover, it is impossible to record and reproduce the digital video signal in real time, and therefore a frame memory is required in addition to an A/D converter and a D/A converter, making the drive device very expensive. Moreover, it becomes large.

Therefore, it is not practical to record and reproduce video signals on conventional floppy disks.

Therefore, the Electronic Still Camera Conference has proposed a so-called 2-inch floppy disk as a recording medium for electronic still cameras.

That is, in FIG. 6, (1) shows the proposed floppy disk as a whole, and (2) shows the rotating magnetic disk. This disk (2) has a diameter of 47 mm and a thickness of 40 μm, and is provided with a center core (3) in the center of which a spindle of a drive mechanism (not shown) is fitted. for,
A magnetic piece (4) is provided to provide a reference angular position when the disk (2) rotates.

So, (5) is that storage jacket, and this one is 60.
It has a size of 54 x 3.6 mm, in which the disk (2) is rotatably housed, and the core (3
) and a magnetic piece (4) are exposed to the outside from the central opening (5^) of the jacket (5). Further, the jacket (5) is formed with an opening (5B) through which the magnetic head comes into contact with the disk (2) during writing and reading, and when the disk (1) is not in use, the opening (5B) is formed in the jacket (5). is covered with a sliding dustproof shutter (6). Further, (7) is a counter dial that displays the number of images taken, and (8) is a claw for preventing erroneous recording, and the claw (8) is removed when recording is prohibited.

Fifty magnetic tracks can be formed concentrically on one side of the disk (2), with the outermost track being the first track and the innermost track being the fiftieth track. The width of the track is 60 μm, and the width of one band is 40 μm.

When shooting, the disc (2) is set at 360 Orpm.
(field frequency), and one field of color video signals is still recorded as one magnetic track. In this case, the recorded signal is as shown in FIG. 7, that is, the luminance signal sy
The sync chip is 6MHz.

The white peak is converted into a 7.5 MHz FM signal Sf. On the other hand, the color signals include an FM signal (center frequency 1.2 MHz) FM modulated by a red color difference signal and an FM signal (center frequency 1.3 MHz) FM modulated by a blue color difference signal.
MIIz) and a line sequential signal Sc is formed.

Then, a sum signal Sa of the FM color signal Sc and the FM luminance signal sy is recorded.

Thus, the floppy disk (1) shown in FIG. 6 has an appropriate size, function, and characteristics as a recording medium for color video signals.

However, this floppy disk (1) is standardized to be able to record and reproduce analog color video signals as described above, and therefore cannot handle digital data. For example, even if digital data is converted into a pseudo video signal and then recorded, as in the combination of a conventional audio PCM processor and VTR, the storage capacity is small compared to the original digital data; There are problems such as compatibility with floppy disks, differences in broadcasting methods, and enlarged circuit scale.

When recording and reproducing color video signals on the floppy disk (1), it may be possible to use the above-mentioned format, and when recording and reproducing digital data, it may be possible to use the conventional floppy disk format. Although 1) is for fairly high-density recording when viewed from the perspective of a video signal, when viewed from the perspective of digital data, the density is low and there is a lot of waste.

Furthermore, when recording and reproducing a mixture of video signals and digital data on one disc (1), the occupied bandwidth and characteristics of the two signals are significantly different, so it is optimal for electromagnetic conversion characteristics and head contact. It becomes difficult to record and play under such conditions. Also, when recording and playing back a mixture of discs (
1) The drive unit that rotates the
(600 rpm) and 3,600 rpm, and when switching between them, the disk (1) cannot be accessed for several seconds until the servo circuit stabilizes, and other problems arise, such as increased costs.

Therefore, it has been considered to adopt a formant as described below for the floppy disk (1) so that digital data can also be recorded and reproduced appropriately.

That is, in FIG. 8A, (2T) indicates an arbitrary trunk on the magnetic disk (2), and this track (2T) has four 90° sections in the length direction with the magnetic piece (4) as a reference. It is divided into equal parts, and each divided section is called a block BLCK. Furthermore, the block BLCK in the section including the magnetic piece (4) is the 0th block, and the 1st... Second. This is the third block.

Then, as shown in FIG. 8C, the block BLCX is
The 4° section from the start end is a gap section GAP for obtaining a margin during read/write, and the following 1° section is the section of the burst signal BR5T. In this case, in the 0th block, the center of the gap section GAP corresponds to the position of the magnetic piece (4).
l? ST is i, a preamble signal ii, and a signal +I! indicating the recording density of the signal. This is a signal that also serves as a flag signal indicating that the recorded signal is digital data.

Further, following the section of the burst signal BR5T, the section is the section of the index signal INDX. In this case, the index signal INDX is, as shown in FIG. 8B,
An 8-bit block synchronization signal 5YNC, an 8-bit block address signal IADR, an 8-bit flag signal FLAG, a 32-bit undefined signal R3VD, and an 8-bit block address signal IADR.
It consists of a bit check signal ICRC. The address signal IADH is the track number [1 to 2T].
50] and the number [0 to 3] of the block BLCK, and the flag signal FLAG is a signal indicating the number [0 to 3] of the block BLCK.
This signal indicates the status or attribute of the track (2T) to which CK belongs, such as whether it is a defective track or whether it has been erased. Further, the check signal rcRc is the CRCC for the signals FLAG, IADR, and RSVD.

Further, the remaining section following this section INDχ is divided into 128 equal parts, each of which is a section in which a signal called a frame FRM is recorded and reproduced.

That is, as shown in Figure 8, one frame FRM includes an 8-bit frame synchronization signal 5YNC in order from the beginning.
, a 16-bit frame address signal FADR, an 8-bit check signal FCRC, 16 symbols (1 symbol = 8 bits) of data DATA, 4 symbols of redundant data PRTY, and another 16 symbols of digital data DATA. , another 4 symbols of redundant data PRTY
to do. In this case, the check signal FCRC is the CRCC for the frame address signal FADR. In addition, data DATA is the original digital data that is accessed by the host device, but this data DATA is
Interleaving is completed within the digital data of one block BLCK, and redundant data PR
TY is parity data C1 and
It is C2.

Therefore, one block BLCK, track (2T
) and disk (1): 1 block: 4096 bytes (=32 symbols x 128 frames) 1 track: 16 bytes (=4096 bytes x 4 blocks) 1 disk: 800 bytes (=16 Bytes x 50 pieces).

Also, the number of focuses for one frame FRM and block BLCK is as follows: 1 frame: 352 bits (8 ÷ 16 + 8 bits + (16 + 4 symbols) x 8 bits x 21 fixed) 1 block (index section and frame section only)
: 45120 bits (=352 points x 128 frames), but in reality, when recording and reproducing digital signals on the disc (1), it is required that the DSV is small, and T min / T max are small. Since it is necessary for Tw to be large, all the digital signals mentioned above are recorded on the disk (1) after being subjected to 8-10 conversion with T max = 4T, and when played back, the inverse conversion is performed before being converted to the original data. signal processing is performed.

Therefore, for the data density mentioned above, the actual number of bits on disk (1) is multiplied by 1078 and one frame:
440 channel bits 1 block (index section and frame section only)
, : 56400 channel bits. Also, as a result, the entire section of one block is 59,719 channel bits (=56,400 channel bits x 90''/85
(in fact, since the length of each interval is assigned as described above from this number of channel bits, the total length of the frame interval is slightly shorter than 85°).

Therefore, the bit rate when accessing the digital signal (signal after 8-10 conversion) to disk (1) is 14.32 Mbit/s (: 59719 bits x 4 blocks x field frequency), which is 1 bit per second. corresponds to 69.8 ns (= 1/14.32 Mbits).

Thus, according to the format shown in Figure 8, it is possible to read and write 800 bytes of digital data on a 2-inch floppy disk (1), compared to the conventional 5
This is more than twice the capacity of an inch floppy disk (320 bytes), so it has a large capacity despite its small size.

In addition, since the rotation speed of the disk (2) is the same as that for color video signals, when recording and reproducing a mixture of color video signals and digital data, the frequency spectrum of both signals recorded and reproduced on the disk (2) etc., so that recording and playback can be performed under optimal conditions for electromagnetic conversion characteristics, head contact, etc. Furthermore, even when recording and reproducing a mixture of two signals, the rotation speed of the disk (2) does not change, so there is no need to consider the time required to switch the servo circuit, and the two signals can be used immediately. can. Furthermore, since the number of revolutions is the same and the mechanism such as the electromagnetic conversion system has the same characteristics or functions, it is advantageous in terms of cost.

In this way, even though the floppy disk (1) of FIG. 6 is for analog signals, by applying the format of FIG. 8 to it, it has new effects as a next-generation floppy disk.

[Problem that the invention seeks to solve]

By the way, in general, tracking control during video signal playback is performed by applying a closed-loop mountain-climbing servo to each track in order to achieve the best image quality during playback, so that just tracking can be performed at the position where the RF ratio output, which is the head output, is at its maximum. There is.

On the other hand, in the case of digital data, for high-speed access, the track scanning position of the head is determined by open-loop control of the step motor for moving the head. That is, the tracking position is determined with an accuracy of Ia. In order to ensure compatibility, when writing data to a disk, side erase is performed to erase a predetermined width on both sides of the data track, and a guard band of a predetermined width is always formed on both sides of the track. There is.

That is, as shown in FIG. 9, for example, although the center positions of the write/read head H and the gap in the width direction are aligned, preliminary erasing is performed using the erase head H which has a wider gap width than the write/read head. The writing/reading head H scans the central part of the erasing width, so that a guard band CB of a constant width, indicated by diagonal lines on both sides of the recording track T, is always formed.

In the case of a floppy disk, generally the track is divided into a plurality of blocks in the same way as described above, so that writing and reading can be performed in units of blocks. For this reason,
One track on the digital data disk does not lie on the same circumference, and as shown in Figure 10, each block BL (J) is shifted by the influence of the head's feeding accuracy in the disk radial direction, temperature, and humidity. Therefore, during readout, when the head scans in a circumference at a position determined by the mechanical precision by open loop, that is, by mechanical feeding, off-track is observed for each block. However, in the case of digital data, unlike analog video signals, r
It is only necessary to determine the state of OJ rlJ, and as long as data from adjacent tracks is not mixed in, the data can be reproduced almost correctly.

Therefore, if you make sure that there is a guard band of a specified width or more on both sides of each trunk by side erasing as described above, data from adjacent tracks will not be mixed in as kuko talk, and there will be no problem with playback. It is.

However, in the case of a disk in which a video track and a digital data trunk coexist, such as the video still floppy disk, performing the side erase described above causes the following drawbacks.

In other words, when writing to a digital data track or rewriting a video track, if a video track is already recorded next to that track, performing side erase will erase part of that video trunk. As a result, the track width in that area becomes narrower. This narrowing of the track width has little effect on digital data, but
In the case of an analog video signal, the S/N ratio deteriorates significantly and the reproduced image quality deteriorates. For this reason, in the case of a disc in which digital data tracks and video signal tracks coexist, it is necessary to perform tracking by performing closed-loop tracking control during playback, without performing side erase during recording (writing).

In this case, when trying to apply closed-loop tracking control to a conventional video disc, control is performed so that a certain point in the track becomes the best, or tracking is performed on the average of one trunk as a whole. Therefore, when reading digital data, in the worst case, the navel and do will extend to the adjacent track, and information from the adjacent track will be mixed in as crosstalk, causing a significant deterioration of the data error rate. 0 The above is true even when only digital data is recorded on one disc with one track divided into multiple blocks and this is played back, but when the density is increased by increasing the number of tracks per disc. When reading data,
Tracking servo must be applied to prevent the head from straddling adjacent tracks, which also occurs.

[Means for solving problems]

This invention divides one trunk into a plurality of blocks so that digital data can be written and read in block units, and when reading digital data, a closed loop is applied only to the data track portion of the block to be read. Apply tracking control. In other words, the tracking servo is not applied on a track-by-track basis, but on a block-by-block basis.

[Effect]

Tracking servo is applied to the read head so that the tracking position is optimal for the part of the block data to be read, and digital data can be read block by block without crosstalk.

〔Example〕

FIG. 1 shows one embodiment of the present invention, which is an example of the above-mentioned video still floppy reproducing apparatus.

(11) is a reading head, and the video processing circuit (
13) and a digital data processor (14). Then, the head output is decoded once in the video signal processing circuit (13), and when a horizontal synchronization signal is detected from the demodulated signal, the reproduced output from the head (11) is determined to be a video signal, and the video signal is The demodulated signal is supplied to the monitor receiver, and the video ii!
ii image is reproduced.

On the other hand, when the output from the head (11) is digital data, the RF ratio output from the head (11) and the gap portion GAP of 4° for each block result in a signal missing section as shown in Figure 2C. occurs. Therefore, from the rise of this RF specific output, the burst gate pulse BGP (B in the same figure)
is obtained. And which burst gate pulse BGP
is supplied to the microcomputer (15), which determines that the reproduced signal from that track is digital data, stores the block data in the digital data processor (14), and performs error correction and other predetermined data processing. It will be done.

The processor (14) takes in the data after the closed-loop tracking servo is applied and reproduced digital data can be stably obtained according to the processing of the microcomputer (15) as described below. Ru.

For example, a command D reads out the first block of data on a certain digital data track on the disk.
When M is supplied to the microcomputer (15), the optimal tracking servo for only gf1 of the first block is determined as follows.

Since data tracks are formed, the position of the head of the 0th block of each track can be determined from this pulse PG. This pulse PC is supplied to a microcomputer (15) via an amplifier (17). The microcomputer (15) can detect which part of the 0th block to the 3rd block of one track the head (11) is scanning from this pulse PC and the burst gate pulse BGP.

In addition, in this microcomputer (15), the RF output from the amplifier (engine 2) is envelope-detected in the detection circuit (1st), and the detected output is sent to the A/D converter (1st).
9), it is converted into a digital signal and supplied to the microcomputer (15).

In this microcomputer (15), only the envelope detection output of the requested RF output of the first block among the RF outputs from the head (11>) is sampled; Tracking servo is applied to maximize output.

That is, the motor drive pulse from the microcomputer (15) is sent to the motor drive circuit (20).
TE is supplied to a step motor (21) for feeding the disk of the head (11) in the radial direction.

Here, the head is moved one track by n pulses supplied to the motor (21). Therefore, one pulse moves in the radial direction by a minute distance of 1/n of the pulse. Of course, the direction of feed is also determined by the drive signal from the microcomputer (15). Therefore, the head is moved by minute distances both toward the center and toward the edge of the disk by pulse feeding.

The microcomputer (15) gradually changes the radial position of the head, that is, the tracking position, and finds the tracking position where the envelope detection output of the RF output of the first block is maximum, and the head is always kept at that position. The servo is applied to track it.

The tracking servo in this case is a so-called hill-climbing servo, and depending on whether the desired read track position is from the current trunk position toward the center (inside) or the outer circumference (outside) in the radial direction of the disk, it is located at a convenient end in the width direction of the track. The tracking position of the head (11) is gradually changed from the front side as shown by ■→■−■−■−■ in FIG.

Then, the envelope detection output of the RF output of the first block becomes as shown in FIG. 4, and the detection output becomes maximum at the tracking position (3). Microcomputer (15
), this maximum position is detected, and the head (11) is moved so that it comes to the tracking position (2).

The flowchart of an example of the above tracking control is shown in the fifth section.
As shown in the figure.

That is, first, in step (101), it is determined whether the current head position is outside the desired read track. For example, if the head (11) is on the outside and is off by N tracks, the step motor (21) moves the head (11) by (N-W) tracks and brings it to the outer end position of the target track. (step (102)). Also, when the current head position is inside the target track, the head (11) is (NM).
It is fed by a track, and is brought to the inner end position of the target track (step [201]).

The reason for doing this is that when N trunks are fed, it becomes unclear in which direction the target truck is deviated from the just tracking position due to the difference in mechanical loading. This is to set the position shifted in the direction, and to make the amount of head feed as small as possible.

After steps (102) and (201), steps (103) to (109) and steps (202) to
In (208), the tracking position where the RF small power envelope detection output of the first block is maximum is searched.

That is, first, it is detected whether a pulse PC is obtained at the tracking position (step (103)).
, (202)) Once the pulse PG is obtained, the burst gate pulse BGP is counted from the position of the pulse PC and the position of the head of the first block is detected (
Steps (104), (203)).

When the position of the head of the first block is detected, the RF detection output of the first block is converted into A/D (step 105).
, (204) ), the digital detection signal is 1
The block data is sampled four times (steps (106) and (205)).

Then, calculate the average of the four sampling values and store it (step (LOT), (206
)').

The reason for sampling four points and finding the average value is as follows.

Due to the eccentricity of the center spindle hole of the disk, the small RF output envelope from the head (11) undulates, but the undulation is at most two periods per rotation, and usually one period. Therefore, one block of A of one track falls within a half period of the undulation. Therefore, by sampling four locations and taking the average, a predetermined tracking evaluation value can be obtained.

After storing the average value, move the head (11) to the tracking position moved by one pulse (step (108)
, (207)'). In this case, Ste Tub (10
In B), the head (11) is moved toward the center of the disk, and in step ('109), the head (11) is moved toward the outer circumference of the disk.

Next, it is determined whether the maximum value (Nogata<) has been extracted from the stored average value (step 109).

(208) ), i Dai (until the direct is found, this station knob (103) ~ (109) or station knob (2)
02) to (20B) are repeated.

By moving the head multiple times, the maximum value is determined from the average value of the RF envelope detection output of the RF envelope detection output when the head is placed vertically. (1
1) is sent (Ste Nobu (110)). and,
In step (111) and step (112),
When the start position of the second pro-clock is detected from the pulse PC and the pulse BGP, the PLL forming the data extraction clock is locked by the burst signal BR5T (step [113]), and the digital data is read out. The data is stored in the puffer memory (step (11)
4) ).

The above example is a case in which the moving distance of the head from the current head position to the target track position can be made as short as possible, so that the direction of movement of the head of the mountain climbing servo is in steps (108) and (207). However, when the current head position is located inside the target track, in step (201) (N+
IA)) If the head is transferred by the rack, the head will be brought to the outer edge of the target track, so step (20)
In 7), mountain climbing servo can be performed by moving the head in the same direction as step (108).

Conversely, even if the head is sent by (N+IA) tracks in step [102], the same result will occur in steps (108) and (2).
In 07), mountain climbing servo is performed by step-feeding the head in the same direction, but in that case, the direction of feed is opposite to the above-mentioned case.

In this way, when the first block's small RF output envelope detection output is at its maximum and tracking is applied, the small RF output of the head (11) becomes as shown in FIG. 2C.

〔Effect of the invention〕

As described above, in this invention, an L track can be divided into a plurality of blocks, and digital data can be read and written in each divided block. Even if the track portions of the block are not on the same circumference, crosstalk from other tracks will hardly be a problem because tracking servo is applied to each block.

Therefore, reliability of data is improved.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of an example of the device of this invention, Fig. 2 is a waveform diagram for explaining it, Figs. 3 and 4 are diagrams for explaining its main parts, and Fig. 5 is a diagram of the device of this invention. Flowchart for detailed explanation; FIG. 6 is a diagram showing an example of a video still floppy cartridge to which the present invention is applied;
8 and 8 are diagrams for explaining the data written to the floppy disk, FIG. 9 is a diagram for explaining the conventional technology, and FIG. 10 is a diagram showing an example of the recording track and turn on the disk. It is. (2) is a magnetic disk, (2T) is a recording track, B
LCK is block, (11) hahe nodo, (21
) is a step motor for feeding. Same Hidemori Matsukuma (j4-'j+. ・-vl,・

Claims (1)

[Claims] Digital data is recorded as concentric tracks on a rotating magnetic disk housed in a jacket, and the digital data is further divided into a plurality of blocks within one track, and the digital data is written in blocks. . A disk tracking control device, in which a device capable of reading digital data is configured to perform optimal tracking control only on a block to be read out of the plurality of blocks when reading the digital data.