GB1585268A

GB1585268A - Multiple track recording

Info

Publication number: GB1585268A
Application number: GB2937676A
Authority: GB
Original assignee: British Broadcasting Corp
Current assignee: British Broadcasting Corp
Priority date: 1977-10-14
Filing date: 1977-10-14
Publication date: 1981-02-25

Description

(54) MULTIPLE TRACK RECORDING (71) We, BRITISH BROADCASTING COR PORATION, a British Body Corporate of Broadcasting House, London, W1A 1AA, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement--- This invention relates to apparatus for recording a plurality of parallel signal tracks on a record medium.

Magnetic tape recording has now been developed to the point at which recording densities of some tens of thousands of cycles per inch (or, in the case of digital recording, of bits per inch) can be achieved within a single track, but the number of tracks per inch obtained using conventional headstacks is at present limited to about fifty.

Our British Patent Specification No.

1,478,340 describes and claims apparatus for recording a plurality of parallel signal tracks on a record medium, comprising a staggered array of heads, and means for relatively moving a record medium past the staggered array of heads, the heads being so positioned across the path of the record medium that, in use, part of the width of the signal track covered by each respective one of the heads, other than the last head, is overwritten by the signal track recorded by the next head in the array.

Reference should be made to the said Specification for a more detailed description of one example of such apparatus.

As described in our earlier Specification, the recording heads are evenly staggered across the width of the tape so that the recorded tracks are of equal width. We have now appreciated however, that it is possible to arrange the recording heads so that some of the recorded tracks are wider than the others.

Accordingly, in this invention the heads are unevenly spaced across the path of the record medium. The wider tracks can then carry signals which are more important than those carried by the narrower tracks; for example, if the recorded signal is a train of binary numbers the more signficant bits can be carried on the wider tracks and the less significant bits on the narrower tracks.

In this way the more important bits are better protected from noise, dropouts and other perturbations than those bits for which a greater error rate can be tolerated.

Thus heads (R1 to R4) which are of standard width can be arranged to lay down tracks of different width by adjusting the head-tohead spacing.

Furthermore, it is possible for each of the individual heads (R1 to R4) of the recording head array (12) itself to be a multi-track head.

Each head can then partially overwrite some of the tracks recorded by the preceding multi-track head and/or make use of the spaces between the tracks.

To read the recorded tracks apparatus based on that described in our British Patent Specification No. 1,478,339 may be used. To avoid complexities in the processing, the width of each track and each head should be a multiple of a common basic unit.

WHAT WE CLAIM IS: 1. Apparatus for recording a plurality of parallel signal tracks on a record medium, comprising a staggered array of heads, and means for relatively moving a record medium past the staggered array of heads, wherein the heads are so positioned across the path of the record medium that, in use, part of the width of the signal track covered by each respective one of the heads, other than the last head, is overwritten by the signal track recorded by the next head in the array, characterised in that the heads are unevenly spaced across the path of the record medium.

2. Apparatus according to claim 1, wherein the heads are magnetic recording heads.

3. Apparatus according to claim 1 or 2, wherein each of the said heads is itself a multi-track head.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (54) MULTIPLE TRACK RECORDING (71) We, BRITISH BROADCASTING COR PORATION, a British Body Corporate of Broadcasting House, London, W1A 1AA, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement--- This invention relates to apparatus for recording a plurality of parallel signal tracks on a record medium. Magnetic tape recording has now been developed to the point at which recording densities of some tens of thousands of cycles per inch (or, in the case of digital recording, of bits per inch) can be achieved within a single track, but the number of tracks per inch obtained using conventional headstacks is at present limited to about fifty. Our British Patent Specification No. 1,478,340 describes and claims apparatus for recording a plurality of parallel signal tracks on a record medium, comprising a staggered array of heads, and means for relatively moving a record medium past the staggered array of heads, the heads being so positioned across the path of the record medium that, in use, part of the width of the signal track covered by each respective one of the heads, other than the last head, is overwritten by the signal track recorded by the next head in the array. Reference should be made to the said Specification for a more detailed description of one example of such apparatus. As described in our earlier Specification, the recording heads are evenly staggered across the width of the tape so that the recorded tracks are of equal width. We have now appreciated however, that it is possible to arrange the recording heads so that some of the recorded tracks are wider than the others. Accordingly, in this invention the heads are unevenly spaced across the path of the record medium. The wider tracks can then carry signals which are more important than those carried by the narrower tracks; for example, if the recorded signal is a train of binary numbers the more signficant bits can be carried on the wider tracks and the less significant bits on the narrower tracks. In this way the more important bits are better protected from noise, dropouts and other perturbations than those bits for which a greater error rate can be tolerated. Thus heads (R1 to R4) which are of standard width can be arranged to lay down tracks of different width by adjusting the head-tohead spacing. Furthermore, it is possible for each of the individual heads (R1 to R4) of the recording head array (12) itself to be a multi-track head. Each head can then partially overwrite some of the tracks recorded by the preceding multi-track head and/or make use of the spaces between the tracks. To read the recorded tracks apparatus based on that described in our British Patent Specification No. 1,478,339 may be used. To avoid complexities in the processing, the width of each track and each head should be a multiple of a common basic unit. WHAT WE CLAIM IS:

1. Apparatus for recording a plurality of parallel signal tracks on a record medium, comprising a staggered array of heads, and means for relatively moving a record medium past the staggered array of heads, wherein the heads are so positioned across the path of the record medium that, in use, part of the width of the signal track covered by each respective one of the heads, other than the last head, is overwritten by the signal track recorded by the next head in the array, characterised in that the heads are unevenly spaced across the path of the record medium.