Magnetic tape apparatus for recording and reproducing of signals

It is known by a matrix head large quantities digital data with extremely high bit rate, ie in short time, recorded on a magnetic tape (See EP-A-0277564 (Application number: EP 89 401 125.3)). thanks to the Matrix head, the parallel recording of a variety allows tracks without grass, can the fixed head the same recording density as helical scanning be achieved.

As the relative speed between tape and head with the Longitudinal recording with a plurality of parallel tracks is low, the scan when playing with transformers must take place, the speed-independent signal voltage supply. These are as magnetoresistive heads, or heads the exploit the magneto-optical Kerr effect. A Scanning for a plurality of parallel tracks, in which a laser beam by the magnetization of adjacent modulated marks and on a CCD line is projected, and in such a way that each pixel of the CCD line represented by the magnetization changes from a single Track modulated light is located in EP 89401125.3.

The number of pixels of the CCD line can also be greater than the its number of simultaneously scanned tracks, so that the CCD line an oversampling of adjacent tracks takes place. Digital filters then the signals of each track are separated without an exact Tracking is required. The coarse adjustment to a certain track range is made possible by the fact that the CCD line is designed so that it has a larger track area detected, and select the desired track area with electronic means done.

The accuracy requirements for the selection of Track areas required head displacement mechanism can are thereby substantially reduced.

The clocked out of the CCD line signal voltage, the Binary values ​​of the adjacent in the parallel tracks Bit cells represent. By suitable synchronizing information with Means of digital signal processing which originally recorded signal will be restored.

The invention is based on the object of this recording and Playback options for a handy tape recorder exploit. This object is achieved by the in claim 1 specified features of the invention dissolved. advantageous Further developments of the invention are defined in the subclaims indicated.

The device according to the invention is very large for storage intended amounts of sound signals as to data reduction Digital signal are recorded. The device is intended as a portable Reproducing apparatus are used and in dimensions, which only slightly larger than a standard magnetic tape cartridge are, to access music, for example, the content of ca. 200 CD's match, allow without band change. The advantage of the device according to the invention consists in the possibility of large record amounts of data in a very short time, because the Matrix head recorded as 512 parallel tracks simultaneously , whereby for each track a very high bit rate can be transferred.

However, this quick recording can only with special external recording devices be carried out because the portable magnetic tape unit to the recording signal with the can generate the required bit rate is still capable of the to provide energy for the rapid tape transport.

It must therefore be ensured that the users of the Magnetic tape recorders of the present invention have the ability to special recording stations such as the contents of a selection from CD's to store for a fee in their device. at a data reduction, noticeable still no has loss of quality, the content of a CD on ca 1.5 m 1/4 "tape to be accommodated, so that for 200 CD's Tape length of 300 meters is required.

At a belt speed of 5 to 6 cm / s requires Playing of the need for the contents of a CD band length about 1.5 m is less than 30 s. The signal to be recorded CD's after data reduction, division into sections and signal temporal reordering of these sections in a mass memory stored. The temporal reordering of signal sections required, since the reproducing head in each case only a portion of all parallel tracks, for example, 1/8 of 512 ie 64 tracks scans. Thus, the burden on the playback head is reduced and providing for a reduction of the data rate during playback. Such simultaneously sampled track segment later called macro track in this text. The recording of allows the contents of a CD in a limited band range quick access each within a CD.

If the device according to the invention also with its own Matrix head is equipped for recording, can except Quick Recording on the recording station also own Records in real time, and records by copying Device are made to the device. It makes sense to own Recording head for the same number of tracks as the playback head set. For example, when both heads of 64 tracks, ie 1/8 of the are on the tape tracks located, furnished, then requires copying from one device to the 8-fold time of Quick recording on the external recording device. Copying a full CD requires then including between the macro traces required return times about 5 minutes.

Since the tape speed not arbitrarily during playback can be reduced, is a start / stop operation of the tape provided. The case sampled time-compressed Signal portions by means of a buffer memory in the necessary for the sound continuous signal flow converted.

The recording in real time must also in the start / stop operation done. Here, the buffer memory is used for time compression the continuous sound signal, which is then in time separated Portions is recorded.

The invention will in the following with reference to the drawings explained. Therein:<dl tsize="9" compact="compact"><dt>Fig. 1</dt><dd>the quick recording at the recording station,</dd><dt>FIG. 2</dt><dd>is a block diagram for recording in real time,</dd><dt>Fig. 3</dt><dd>a block diagram for the quick copy function</dd><dt>Fig. 4-11</dt><dd>Abtastmöglichkeiten at various Recording formats.</dd></dl>

Fig. 1 shows an illustration of the data transmission from a external recording device to the invention Magnetic tape apparatus MP. The magnetic tape apparatus MP has a read head RH, a magnetic tape T and an electronic evaluation system on AE. The A recording device includes a recording electronics RE, a mass memory M, a reading head RH ', a magnetic tape T 'and a write head SK.

Magnetic tapes are located on the supporting tape MT or MT '. The magnetic tape T or T 'is moved longitudinally for Stylus SK. To record the magnetic tape recorder is MP This is inserted into the recording apparatus A. When playing of the magnetic tape T 'enter the data on the reading head RH' to the Stylus SK, who moved the data to the lengthwise Band T records. A recording electronics RE controls to about gambling data and the amount of data. The user can previously an input unit EA Select the desired data. After this operation, the magnetic tape device MP can be removed will. It is now possible via a transmitter AE to read data of the magnetic tape T with the aid of the reading head.

FIG. 2 magnetic tape device according to the invention shows MP own Recording electronics and private recording head for Recording in real time. The input signal from the example Digital output of a CD player is, for example, in the encoder EN data reduced according to the MPEG method. By Error coding in block ECC and data interleaving in Memory ME is possible later error correction. thereupon the signal which serves for recording matrix head SK fed via the head driver D. When playing the scans Core head RH, the parallel tracks of the tape from. It is Laser light depending on the magnetization in the tracks modulated, and projected onto a CCD line. Selected from the CCD line being clocked signal to A / D conversion in the block AP by digital signal processing in the blocks DP and ME and Error correction and interleaving in the blocks and ECC ME reconverted to the data reduced signal recording. With Help the decoder DE is from the original Input data stream restored.

Fig. 3 shows the block diagram for the dub from a magnetic tape device MPI for second Tape recorder MPII with the same recording format.

For recording on the magnetic tape device MP there is different recording formats described below will.

When playing recorded on magnetic tape signals it may be necessary, a coherent se Record in short, temporally separated portions scan.

The case occurs, for example, if in sampling a Längspuraufzeichnung with one or more parallel heads the relative movement between the tape and heads a particular Velocity value may not be less. The oversampling conditional bit rate can then be considerably higher than required for the signal processing and signal evaluation required bit rate.

The signal is delivered as it were time-compressed and must for expanding processing by means of a buffer memory will.

Because of the limited memory size must longer for signals Duration decomposition into short, temporally separated portions take place, the interval between the signal sections by the Verarbteitungsgeschwindigkeit is determined.

For the scanning of the individual portions of a digital Recording are the following two requirements to fulfill:<sl><li>1. The successive sections to each other overlap as the evaluable signal portions from establish the signal assignment with full sync blocks begin and end must and run-in areas for the Settling of the signal processing circuit required are.</li><li>2. The Synchblöcke must be numbered consecutively in order a double evaluation of sync blocks as a result of Signal overlap is avoidable.</li><li>3. to the relative speed between head and tape in order to generate a constant Abtastbitrate during Sampling a portion to be constant.</li></sl>

Fig. Figure 4 illustrates the relative movements between belt and readhead represents, to be carried out in order to meet demands. Fig. 4a shows the distribution of the tape recording in successively scanned portions. The overlaps are with d called. The arrows in the lines b and c indicate the Direction of the relative movement. The solid lines Mark band areas at a constant speed be paid. Position the dotted lines Relative movements with variable speed due Represents acceleration or deceleration. At the reversal points of Movement direction u can at adapting scanning required for the signal processing data flow Waits are inserted.

The illustrated by Fig. 4 scanning has over a continuous band scan following disadvantages:<sl><li>1. Increased stress and thus wear Strip material and for producing the relative movement between band and scanning serving Machanik.</li><li>2. Increased energy consumption</li><li>3. Increased noise</li></sl>

As shown in FIG. 5, is by the alternating scanning successive sections in the opposite direction the number of required floats between band and head halved. This also the effect of the above Disadvantages halved.

The signals from the sampled in the reverse direction Sections can use a memory in which writing and reading in the opposite direction takes place, in the correct Order to be brought. This reordering is done expediently in the reproducing circuit. The re-sorting could also be effected prior to recording. This would, however, mean that the type of scanning, and the location and size the sections is set.

A normal continuous recording, however, can in divided Any way when playing in sections will.

In the following, a further development is shown in which the sectionally division when playing through the Recording format is set:

Apparatus for magnetic recording and playback as digital Data information on a planar, shown preferably band-shaped recording medium in which the magnetic recording track shaped in the longitudinal direction of the carrier on several separate N (macro) tracks is applied, which each in turn from M together worked swaths exist, the V of the belt speed, the smallest usable wavelength λ, and the number K of the same read or written traces to be determined Available Data rate is significantly higher than that for the application (for example digital stereo sound) required data rate.

Example:

<tables><table><tgroup cols="2"><tbody><row><entry align="left">Carrier width a</entry><entry align="left">8 mm</entry></row><row><entry align="left">Tape speed v</entry><entry align="left">60 mm / s</entry></row><row><entry align="left">bit length a</entry><entry align="left">0.0003 mm</entry></row><row><entry align="left">Track width b</entry><entry align="left">0.01mm</entry></row><row><entry align="left">Tracks quantity K</entry><entry align="left">64</entry></row><row><entry align="left">Number macro traces N</entry><entry align="left">8th</entry></row></tbody></tgroup></table></tables>

This one is obtained over a longer period of time usable Gross data rate of R₀ = K * v / a = 64 * 60 / 0.0003 = 12.8 Mbit / s. The digital for recording stereo sound required data rate is on the other hand (so-called. CD format) only R₁= 2 * 44100 * 16 = 1.41 Mbit / s, or even at a data-reducing Coding (eg ISO / IEC 11172-3, Layer II) only R₂= 256 kbit / s.

As a result of this discrepancy, the recording and playback not in the form known to the continuous 'Serpentine method' done. Here, the recording or playing along a macro track from BOT to End-performed after the recording and Reproducing means in a suitable manner on a more macro-track positioned and then in the reverse direction from the end to Prime edited. Just as it is possible for the tape rewind the meantime and the processing in the further macro-track also carry out from beginning to end. The additional winding operation costs but unnecessary energy, for example in a portable device is a great disadvantage.

On the other hand it is clear both from the difference between Gross data rate and payload data and from the simultaneous presence of N macro traces the opportunity recording or reproduction at high time compression perform. By continuously processing a macro track alone, a time compression of up to R₀/ R₂, among Aid of N macro trace to N * R₀/ R₂ be achieved. With the above values ​​can be for example the duration of a Recording or playback of music from one in 'real time' 74 min continuous CD to values ​​below 30 sec bring (being one additional information for error protection and transition zones must be taken into account).

Slower speed

First, there is the possibility of the tape speed to reduce to the desired useful data rate. This is not recommended because of a hand with small Belt speeds problems with friction and shocks ; on the other but also at the end of the tape to Inverting a certain time is needed during the data non- continuously available. This could be by Buffering and briefly offset higher belt speed.

Intermittent recording / playback

The discrepancy between gross data rate and payload data leads directly related to an intermittent operation Intermediate storage, for example in an exchange buffer or continuous ring buffer. From the above calculated gross data rate and an appropriate size of such a buffer of eg 2 ... 4 Mbit yields, for example, an appropriate Length of a single block on the magnetic tape to 6mm, corresponding to a time duration of 0.1 sec and a data set 1.28 Mbit. This block can be the data for stereo correspond with a real-time of about 4 seconds. Of the So intermittent operation is in each case the alternation between 0.1 sec active processing of a data block on the ribbon and about 3.9 sec time for positioning to the logical following block which does not have to be spatially the following. Various proposals for this logical arrangement can offered this.

Each block should carry a unique addressing, wherein both the type of addressing and the reproducing function should be arranged so that also during fast tape (Previous rewinding), the blocks can be identified. When reading and writing provided in both tape directions , then it may be appropriate, the addressing data once each at the beginning and once at the end of each block provide.

The following are based on the different figures Possible solutions listed.

<u>Version 1, serpentine mode</u>

Fig. 6 shows the schematically illustrates a piece of tape with N = 4 macro-tracks, which are each divided into short blocks and, between those transition zones are provided. The length of this Transition zones is greatly exaggerated. For one Block is also shown that he is single in M, parallel tracks composed longitudinally. Further, nor the machine direction according to the serpentine principle indicated. It can be seen immediately that a to realize intermittent operation only at great expense is. For example, if after 0.1 sec continuous reading of the block no. 1 the tape drive for 3.9 sec has to be stopped, then must either be provided appropriately long transition zones, stop within which the tape and start again can (in shown Fig. 6 at the macro-lane 2), or it must after each Read the tape be rewound a short time, so that the initial can be read the next block safe (in Fig. 6 in the macro-track 3 shown). Likewise, except, naturally, for a Recording.

Version 2, zigzag fashion

Another possible embodiment is that the Tape is rewound each after each block such an extent that it is again positioned in front of the block, and then (vertical) to to position the following macro-track. This is shown in Fig. 7 shown.

Version 3, 'small' serpentine mode

The number of positions can be reduced, when one so to speak, a 'small' serpentine fashion used (s. Fig. 8th). It can be seen immediately that there are several versions on the number of macro-tracks and the treatment of may be the upper and lower reversal points. shown a version having an even number N, in which the on the first (blocks 1..4) following 'small' Serpentine (blocks 5..8) connecting low.

Version 4 continuous serpentine mode intermittent operation

A Wider solution is a uniform to combine tape movement with intermittent recording or playback. This is initially shown in Fig. 9. The tape-head movement is again indicated by arrows, and each active blocks are marked by dots. Here are a number of different versions possible. Important is total, that either the entire Available tape length can be processed accordingly, or that short pieces of tape each taken individually as a unit can be.

In Fig. 9, a tape piece is in each case considered, which at the above mentioned Parameters corresponding to a length of 3 * 4 * 60mm = 720mm. The length such a segment on the tape may, for example according to a Default for maximum positioning time can be selected.

Description of the process for different operating modes:

Fast recording and / or playback:

Either over the entire width of the belt or within only a macro-track, a quick recording or reproduction be achieved if all required data in a Memory available, and if the scrambling of Blocks is performed within this memory. In this mode, the transition zones can be very small being held.

Real-time recording on a new or erased tape:

It is characterized by a basically continuous tape, a Reversal of direction in each case by a specific number of Blocks, and the positioning of each of the next to writing block reference already existing, already written blocks.

The recording begins at block 1. In continuous Tape is after the predetermined time (in this example 3.9 sec) reaches the position of the block 2 and written to. After writing block 3 (or a number of other) is the Tape direction is reversed and the next macro-track positioned. If the tape drive at the right time again is started, then block 4 about under Block 3 to be written. This is repeated until the last Block has been reached in the last macro-track (here block 12). Dabnach only the tape direction is reversed and the following Block (here 13) in the strip running direction behind the next readable (Here 12) is written. This can be continued in accordance , until the entire bond is filled with blocks. Since each block following a block already written is written, due to the tolerances in the absolute Belt speed and the distance between the reading means (For positioning) and writing means a longer Transition zone required.

Real-time playback

Playback is in accordance with continuous Tape speed and by detecting the respective logical this block. Here, too, affects the growing Spacing of the logical blocks at the reversal points following disadvantageous. Ultimately as must the tape speed to the Reversal points can be increased, so that the next time logical block can be read.

Moreover, it may be expedient, each first two Blocks of a sound recording (not only 1 + 2, but as also 44 + 45) closely to follow each other, so that the Data buffer is filled safely at the beginning of playback and does not run empty. This can also be due to greater Belt speed are compensated by the buffer filling level is controlled.

version 5

This is a development of version 4, the time the Problems and the reversal points avoids.

It is characteristic that not at a first fixation only the payload blocks, but also equal to the intervening Blocks with dummy data, but with the correct address details to be written. At each end are not all, but written at least two further empty blocks which in then can be used following passage for positioning. Thus, for each additional pass a positioning for Letter to each logical unit possible without increased Lengths of the transition regions to compensate possible tolerances are necessary.

The sequence would be for example as follows (see Fig. 10): In the first run in the first macro-trace blocks 1,2,3 write the blocks in between 24 .. 49 and 23 .. 50 Write with dummy data and addresses at the end of the two blocks 22 and 27 write with dummy data and addresses.

After reversing and track positioning on macro-track 2 are the two blocks 28 and 21 and then empty block 4 with User data is written. With timely start of belt travel are these blocks as below 27, 22, and 3. FIG. This continues until the block 12 at the end of the macro trace. 4 This is followed by only a change of direction.

In all subsequent write operations can now each already shouting bene blocks are used for positioning.

Block 12 is used for positioning of block 13, block 11 for Block 14, block 10 for block 15. Thereafter now another Empty block (39) behind the already existing empty block 34 written so that once again two at the end are present. The pre-written blank block 33 is for positioning for Block 16 is used.

In this way is in each track and for each direction always at least one block (empty or with user data, but with correct address) is available for positioning of the can be used the next to be written block. The for ReverseTwist and track switching available Time allowed in addition a maximum of this proposal for Editing 4 blocks required. This allows the track ends no time problems.

version 6

This version is a further development of the Version 5, in which a further energy saving by reducing the track-positioning takes place. It is characteristic that initially a macro-track is completely filled before another Track is used. This is illustrated in Fig. 11.

Characteristic is again that at the end of a track at least two Empty blocks are gechrieben that for after reversal Positioning are used for the next write operation.

It is easy to see that an odd number of blocks (As illustrated) causes the read / write means on the End of the track is when it is completely filled. After that you can then the next track will be constructed in the reverse direction (as shown). An even number of blocks results that the read / write means after a complete Editing a track is at its beginning. Then can the next track will be constructed in the same direction, whereupon always returned to the top of the ribbon piece becomes.

With an odd number of blocks, it is additionally important whether the number of macro-tracks even or odd is.

In an odd track number, the read / write device is in completely filled band finally back at the end of the tape or Tape piece, which on for another read or write operations following pieces of tape can be advantageous, but longer Duration of positioning means back to the beginning.

With an even number of tracks the read / write device is in completely filled band finally back at the beginning of the tape, what a small duration of positioning to the beginning, but a longer Pause for further processing of a following piece of tape means.

The question of where the read / write means after the complete Editing a track is, but without much effect, allow sufficient time for a positioning and a pre-rewinding is available. For continuous Reproducing operation of data recorded on a tape portion Music, it may be advantageous if a mechanically continuous process yields. For the case of a real time recording own could be the very last passage omit to give a slight loss of memory given the opportunity, directly on the next continue magnetic tape piece.

The described version 6 has the additional advantage that a 'Moderate' Quick recording, for example, only using a 64-track head, macro-trace amounts can be carried out, and only the for that track data required in the recording apparatus in a memory must be available for scrambling.

From the above remarks it follows that for SDCR Audio Album the described version 6, are advantageously used should. Block number and track number are here just. A total of Several formats are defined:

Format for quick recording of data reduction

Here are 11 blocks as shown in Fig. In the individual Tracks provided. The distances between the blocks can be so are kept low, as for complete direct Recording and a sequential read operation required is.

In accordance with the above parameters could be found on a 6x24 cm long piece of tape 6x40 blocks with a length of 6 mm accommodate. This would per track minutes of playing time and 16 give a total of N x 16 min.

Format for own recording with data reduction

In self recording should be taken as to Version 6 has been described. As for positioning, and Delete Recording each safety distances and even run-in Sequences for the PLL are required, total fewer blocks are placed per track. At the same otherwise Tape would for example on the same length of 6x24 cm only 6x30 Blocks accommodate. The self-recording would then be a Shortening of recording time per tape piece lead, but at basically the same tape.

Format for own consumption without data reduction

Without data reduction, ie in 16 bit CD format are by a Factor 6 apply greater amounts of data. This can in turn with basically the same tape by denser result of logically achieve successive blocks on the tape. If above every 4 sec write or read a new block must be, so here it is then every 4/6 sec. That is, the logically related blocks are no longer 24 cm apart, but only 4 cm. With Safety distances to the neighboring blocks are not then more 30, but, for example 5 to accommodate.

In an otherwise identical tape is shortened so the Recording time according to the factor of data reduction.

Other formats

The proposed form of continuous tape movement, together with the intermittent reading and writing operation, can be readily adapted to other data formats and rates will.