GB2070841A

GB2070841A - Recording techniques

Info

Publication number: GB2070841A
Application number: GB8104521A
Authority: GB
Original assignee: Oxby D V
Current assignee: Oxby D V
Priority date: 1980-02-28
Filing date: 1981-02-13
Publication date: 1981-09-09

Abstract

Multiple recordings are accommodated on superimposed, overlapped or intersecting tracks of a recording medium such as a magnetic recording tape without cross-talk. The recordings are made, and subsequently are played back, either using plural heads 1, 2 which are at different azimuthal inclinations, or using a single head of adjustable inclination. The recordings may be audio, video or digital computer signals. The inclined tracks of a video tape may overlap with each other, Figures 5-7 (not shown), and/or may be overlaid by similar tracks inclined in the opposite direction, Figure 10. <IMAGE>

Description

SPECIFICATION Recording techniques This invention relates to recording techniques.

An object of the present invention is to provide a recording technique with which multiple recordings can be accommodated together on a common track of a recording medium such as a magnetic recording tape whereby the storage capacity of such medium can be extended.

According to one aspect of the invention therefore there is provided a recording technique wherein multiple recordings are made on a recording medium such as a magnetic recording tape during advancement of the medium relative to at least one recording head, characterised in that different said recordings are made on a common track of the medium with the pertaining head or heads at different respective angular inclinations relative to the said track.

With this technique it has been found possible to multiplex recordings in a remarkably simple yet effective manner. That is, a number of recordings can be readily made on top of each other using the inclined head or heads, and playback of the different recordings can be effected conveniently and with good separation using a playback head or heads with respective corresponding inclinations thereto.

In this way the storage capacity of the recording medium can be much extended.

The technique of the invention can be utilised with any suitable recording medium and in any suitable context, including in particular magnetic recording tape in the context of computer data, audio and video information recording. Either single track or multitrack recorders may be used and provision may be made for recordings to be made and/or played back one at a time or simultaneously as desired.

The or each said inclined head may have a permanent predetermined inclination thereto or, alternatively, provision may be made for adjustment of the inclination on a continuous orstepwise basis.

In a preferred embodiment, multiple inclined heads, one for each recording, are used; although it is also possible to use a single head which is switchable between different inclinations for different recordings. Any suitable inclinations may be utilised for the head or heads, and it has been found that a difference of as little as 150 or even less between different inclinations can be sufficient to give satisfactory separation without undue cross-talk.

According to a second aspect of the invention there is provided a recording apparatus for use in performing the recording technique described above comprising at least two recording heads and means for effecting advance of a recording medium relative to said heads such that a common recording track of said medium is scanned by both said heads, said heads being disposed at different angular inclinations relative to said track.

According to a further aspect of the invention there is provided recording apparatus comprising a recording head and means for effecting advance of a recording medium relative to said head such that a recording track of said medium is scanned by said head, said head being movable between different angular inclinations thereof relative to said track.

According to a still further aspect of the invention there is provided playback apparatus comprising at least two playback heads and means for effecting advance of said recorded medium relative to said heads such that a common recorded track of said medium is scanned by both said heads, said heads being disposed at different angular inclinations relative to said track.

According to a still further aspect of the invention there is provided playback apparatus comprising a playback head and means for effecting advance of a recorded medium relative to said head such that a recorded track of said medium is scanned by said head, said head being movable between different angular inclinations thereof relative to said track.

The playback apparatus of the invention may be separate to or combined with the recording apparatus of the invention. Where such recording and playback apparatus are combined the same head or heads may be adapted for use both for recording and playback purposes.

The invention will now be described further by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatic perspective view showing two heads of one form of recording/ playback apparatus in accordance with the invention; Figure 2 is a diagrammatic representation of the heads of the arrangement of Figure 1 in conjunction with a recording tape; Figure 3 is a diagrammatic representation of the arrangement of Figure 1 in conjunction with associated components; Figure 4 is a view similar to Figure 2 of a further embodiment; Figure 5 is a diagrammatic perspective view of part of one form of video recording/playback apparatus according to the present invention; Figure 6 is an enlarged view of a detail of the arrangement of Figure 5;; Figure 7 is a diagrammatic representation of the heads of the arrangement of Figures 5 and 6 in conjunction with a recording tape; and Figures 8 to 10 are views similar to Figure 7 of further embodiments.

With reference to Figure 1, an audio tape recorder has two stationary playback/recording heads 1, 2 past which a conventional magnetic tape 3 (e.g. an iron oxide coated plastics tape) is advanced longitudinally between separate reels or within a cassette using conventional drive techniques (i.e. giving continuous drive at a constant speed in the range say 4.5 to 19 cm/sec).

Each head 1, 2 is of conventional form and has a split-shaped air-gap 4 between magnetic poles thereof. The heads 1,2 are however not mounted with the slits perpendicular to the direction of tape advancement but rather are arranged with the slits oppositely inclined at angles of 15 to such direction (so that the slit 4 of one head 1 is at an angle of 300 to the slit 4 of the other head 2).

With this arrangement two separate recordings can be made on top of each other on the tape 3 using the two heads 1,2 (such recordings being made simultaneously or at different times) and, due to the different angular inclinations of the heads, the two recordings can be played back using the same heads (again either simultaneously or separately as desired) with satisfactory signal separation and quality.

Figure 2 shows the positioning of the slits 4 in relation to the tape 3 and it will be noted that the tape has two parallel tracks 5, 6. As shown in the drawing one track 6 is scanned by the slit heads 4 but the other track 5 can be scanned when desired by turning over the tape in conventional manner.

As shown in Figure 3, the heads 1,2 comprise coils 7 which are connected to appropriate electronic circuitry 8 which in turn is connected to switches 9 and to inputioutput devices 10 such as one or more loudspeakers, input sockets for microphones, control devices for the tape drive system and the like.

One of the switches 9 is operational to connect the heads 1,2 selectively (one at a time or both together) to the circuitry in accordance with requirements.

During recording the or each operational head is supplied with appropriate signals in accordance with conventional audio practice (i.e. audio signals superimposed on a bias signal), the circuitry 8 incorporating appropriate amplification, modulation, oscillation, and like circuits if desired duplicated for the two heads. During playback signals from the or each head are appropriately processed so as to be capable of operating a loudspeaker or other output device 10, the circuitry 8 incorporating appropriate amplification and like circuits if desired duplicated for the two heads.

Figure 1 shows only a simple arrangement of the two heads 1 and 2 and two tape guides 1 a, 2a. is however to be understood that other conventional devices such as guide rollers, one or more erase heads and the like will in practice also be provided.

Figure 4 shows two sets of heads 11, 12, 13, 14 each set arranged in similar manner to the heads 1,2 of Figures 1 to 3. These heads are provided in spaced disposition so that recordings can be made on four tracks 15,16,17,18 of a magnetic tape 19 (two on each "side"). In this way, by arranging for the four heads 11 to 14 to simultaneously record and also play back audio signals, the tape can conveniently be used as a two-sided quadraphonic audio tape. By providing switching arrangements for the heads such that the heads can be used simultaneously two at a time (say selectively the two heads 11, 13 or the two heads 12, 14) the four recording tracks of the tape can be utilised to give four different stereo audio recordings.

Figures 5 to 7 show an arrangement for use in a video/sound recorder. In conventional manner, the video magnetic tape 20 has edge sync and sound tracks 21,22 which are scanned by recordiplayback heads (not shown), and central inclined parallel video tracks (only three of which 23,24,25 are indicated) which are scanned by two record/playback magnetic heads 26, 27 which are mounted on a rotating drum 28 (Figure 6) around which the tape is advanced along a helical path (as shown in Figure 5).

The peripheral speed of the drum is greater than the speed of longitudinal advancement of the tape whereby the heads 26, 27 move at an angle across the tape at high speed. The two heads 26,27 are set at different inclinations to each other and are arranged so that overlapping tracks of the tape are scanned thereby. With this arrangement, the available recording/playing time of the tape is twice that which can be achieved with the conventional arrangement in which two heads scan adjacent non-superimposed tracks. That is, the same scanning rate can be achieved with half the speed of tape advancement with the overlapping tracks.

Figure 8 shows a multi-track magnetic computer tape 29 used with four side-by-side magnetic heads 30 at different inclinations. The tape 29 may be a wide multi-track computer tape (as shown) or alternatively may be a tape of the kind used in audio cassettes. The four heads 30 are used to record and play back digital computer data (i.e. pulse sequences) and provision is made for moving the set of heads transversely relative to the tape from track-totrack. Alternatively, a respective set of four heads may be provided for each track and in this case, if desired, provision may be made for recording/ playing back from all tracks simultaneously. Also, if desired, more than four heads may be used.

When the head inclinations are close together (as shown in Figure 8), it may be found desirable to provide a clipper at the output so that signals above a predetermined magnitude are selectively amplified and low level cross-talk signals are eliminated.

Figure 9 shows a wide multi-track magnetic tape 31 used with a single playback/record magnetic head 32 of adjustable inclination and adjustable positioning from track-to-track across the tape. With this arrangement it is possible to obtain say 1000 recordings on a single tape. The arrangement is particularly advantageous for digital data recording.

Figure 10 shows a further arrangement for use in a video/sound recorder. As illustrated, a video magnetic tape 33 has at each edge a respective sync and sound track 34, 35 and oppositely inclined video tracks 36,37 are scanned separately by an appropriately inclined head or heads. Separate heads may be provided for scanning each set of tracks 36,37 or alternatively the same head or heads may be used the tape being turned over to change the set of tracks being scanned. Thus, the recording1playback capac- ity of the tape can be doubled. If the features of the embodiment of Figure 10 are combined with those of the embodiment of Figure 7, a still further increase in such capacity can be obtained, and by appropriate selection of overlapping and cross-tracking techniques, it is possible to achieve a ten-fold or greater increase in capacity.

With the embodiments described above, in particularly simple and convenient manner good quality multiplexing of magnetic tape recordings can be achieved whereby the storage capacity of the recording tape can be much extended. Such extension of the storage capacity is of particular advantage in the case of computer data recording and also video recording where a considerable amount of information is to be stored.

It is of course to be understood that the invention is not intended to be restricted to the details of the above embodiment which are described by way of example only. Thus, for example, although reference is made herein to the use of a magnetic tape as the recording medium it is to be understood that any other suitable form of medium, including magnetic discs, can be used.

Claims

1. A recording technique wherein multiple recordings are made on a recording medium such as a magnetic recording tape during advancement of the medium relative to at least one recording head, characterised in that different said recordings are made on a common track of the medium with the pertaining head or heads at different respective angular inclinations relative to the said track.

2. A technique according to claim 1, wherein a plurality of heads respectively fixed at said different inclinations are used.

3. A technique according to claim 1, wherein a single head movable between the said different inclinations is used.

4. A technique according to any one of claims 1 to 3, applied to the recording of audio signals.

5. A technique according to any one of claims 1 to 3, applied to the recording of video signals.

6. A technique according to any one of claims 1 to 3, applied to the recording of digital computer data.

7. A technique according to any one of claims 1 to 6, applied to the making of multiple recordings on each track of a multi-track recording medium.

8. A technique according to claim 7, when dependent on claim 4, wherein each of two tracks has two audio recordings made thereon and the recordings on one track are made simultaneously with the recordings on the other track.

9. A technique according to claim 7 when dependent on claim 5, wherein two recordings are made respectively on two parallel overlapping tracks whereby each such track forms a common track for the two recordings.

10. A technique according to claim 7 when dependent on claim 5, wherein two recordings are made respectively on two mutually inclined tracks which cross each other whereby each such track forms a common track for the two recordings.

11. A technique according to claim 1,substantial- ly as hereinbefore described with reference to the accompanying drawings.

12. A recording medium when provided with multiple recordings on at least one track thereof in accordance with the technique of any one of claims 1 toll.

13. A playback technique wherein a recording medium according to claim 12 is advanced relative to one or more playback heads characterised in that playback is effected with said playback head or heads at different respective angular inclinations relative to said track, said different inclinations of the playback head or heads corresponding to the different inclinations of the head or heads used to make the recordings on the track.

14. A technique according to claim 13, wherein the same head or heads are used for playback and also recording purposes.

15. A technique according to claim 13 substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

16. Recording apparatus for use in performing the technique of claim 1 comprising at least two recording heads and means for effecting advance of a recording medium relative to said heads such that a common recording track of said medium is scanned by both said heads, said heads being disposed at different angular inclinations relative to said track.

17. Recording apparatus according to claim 16, wherein the angular inclination of each head is adjustable.

18. Recording apparatus for use in performing the technique of claim 1 comprising a recording head and means for effecting advance of a recording medium relative to said head such that a recording track of said medium is scanned by said head, said head being movable between different angular inclinations thereof relative to said track.

19. Recording apparatus according to any one of claims 16 to 18, which is adapted for use with a tape-recording medium.

20. Recording apparatus according to claim 19, which is adapted for use with a tape-recording medium in cassette form.

21. Recording apparatus according to any one of claims 16 to 20, wherein the arrangement is such that multiple parallel tracks are arranged to be scanned by multiple respective said differently inclined or differently inclinable heads.

22. Recording apparatus according to any one of claims 16 to 21, wherein the or each said head is a magnetic recording head, the said medium being a magnetic recording medium.

23. Recording apparatus according to any one of claims 16 to 22, which is adapted for the recording of audio signals on said medium.

24. Recording apparatus according to any one of claims 16 to 22, which is adapted for the recording of digital computer data on said medium.

25. Recording apparatus according to any one of claims 16 to 22, which is adapted for the recording of video signals on said medium.

26. Recording apparatus according to claim 25, when dependent on claim 19 or any claim dependent on claim 19, wherein the or each said head is adapted to scan successive tracks extending transversely across the tape medium.

27. Recording apparatus according to claim 26, wherein the or each head is mounted on a rotatable drum and means is provided for advancing the tape spirally around the outer surface of the rotating drum.

28. Recording apparatus according to claim 16 or 18, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

29. Playback apparatus for use in performing the technique of claim 13 comprising at least two playback heads and means for effecting advance of said recorded medium relative to said heads such that a common recorded track of said medium is scanned by both said heads, said heads being disposed at different angular inclinations relative to said track.

30. Playback apparatus for use in performing the technique of claim 13, comprising a playback head and means for effecting advance of a recorded medium relative to said head such that a recorded track of said medium is scanned by said head, said head being movable between different angular inclinations thereof relative to said track.

31. Playback apparatus according to claim 29 or 30, substantially as hereinbefore described and with reference to the accompanying drawings.

32. Playback apparatus according to any one of claims 29 to 31, when combined with the recording apparatus according to any one of claims 16 to 27.

33. The combination of claim 32 wherein the same head or heads are adapted for use both for recording and playback purposes.