HK8596A - Process and device for copying magnetic tapes - Google Patents

Abstract

In conventional copying processes, signals recorded in addition to the actual useful information, e.g. control signals for the synchronisation of recording-head switchover impulses, are not copied. Additional information can, however, be encoded in a variation of these signals, and this information is thus also not copied. In the invention, digital information recorded on the control track and detected by a reproduction device is transmitted by a transmission stage to a recording device where it is recorded again in digitally encoded form in an appropriate time gate on the control track. The process and device are of use in the copying of magnetic tapes containing address or index marks.

Description

The invention relates to a method for copying magnetic tapes, particularly audio, video or data tapes.

In the case of conventional copying, the information contained in a pre-recorded media is played back by a player, transmitted via a transmission line to a recording device and recorded on a media to be played. Ideally, the media to be played will contain the same information as the original after the playback process has been completed. The copying process does not affect any additional information that is recorded in certain recording standards, such as the VHS standard, for the internal control of the playback operation of the device in addition to the actual information.

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The variation in the relative position of the south/north transitions can thus be used, for example, for digital coding. In the VHS standard, this has been used to place magnetic markers on the magnetic tape - for example to find certain places in a recording - distinguishing between two types of markers, the so-called VISS markers (VHS index search system), which represent an immutable digital information, and the so-called VASS markers (VHS address search system), which contain an individual address in digitally coded form.

In particular, when recording relatively short entries as useful information in relation to the total length of the tape, it is advantageous to insert a trade mark at the same time as the start of a recording in order to locate exactly the beginning of such an entry in the playback operation.

A process known from Patent Abstracts of Japan, Vol. 12, No. 220 (P-720) is known from the general concept of claim 1, whereby on the side of the playing videorecorder an integration of voltages obtained by touch conditions is performed. If a predetermined threshold is exceeded during integration, a signal concerning the control track is given to the recording videorecorder.

The purpose of the invention is to transmit, when copying magnetic tapes, additional information contained in a control track.

This problem is solved by the features given in claim 1 and by the features given in claim 7.

Preferably, the recording shall be done in the nearest time window at the same time as the recording of the tax trail.

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It is envisaged that the digital information will be stored in a buffer on the side of the reproducing device until a multi-bit address is read out completely; this complete address can then be transmitted via serial interfaces and an infrared band between them to the recording device, where it is then recorded again in a digitally encoded form with the control track.

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It is understood that any other data bus connection can be used instead of the D2B bus.

Further features, advantages and details of the invention are explained below by means of the drawing, showing:Fig. 1 shows a schematic representation of a digital coding used for a VHS video recorder control track,Fig. 2 shows the structure of an address code,Fig. 3 shows a schematic representation of an infrared transmission format,Fig. 4 shows an example of a device of the invention for performing the copying process,Fig. 5 shows a detail of the device in Fig. 4 and a flowchart for the program flow in the detail shown in Fig. 5.

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Figure 4 shows a block diagram of an example of a device according to the invention for performing the copying process.

A first VCR1 video recorder is in playback operation, a second VCR2 video recorder is in recording operation. The two VCR1 and VCR2 recorders are connected by a line 20, which can be a SCART or a video line. This line 20 transmits image and sound from one (VCR1) to the other (VCR2) video recorder in the conventional way. The VCR1 and VCR2 video recorders are also both connected to a D2B bus 30 through which they can exchange data and commands with each other according to the standard set by the IEC.

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The transmission of the digitally encoded data in the control track may also take the form of complete data words, for example in the infrared transmission format described in Figure 3.

In the case of the transfer procedure, although it is inevitable that the copy will have a time lag between the visual/sound utility information on the one hand and the VISS or VASS mark recorded on the copy, as compared with the original, this delay in copying the mark is relatively small and, depending on the mode of transfer and the number of persons or spaces available, may generally be in the range of one or a few seconds.

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Any other data bus can be used instead of the D2B bus, for example the still free pins of the SCART line 20 can be used.

Figure 5 shows, as an example of the video recorder VCR1 intended for reproduction, from Figure 4, how the data contained in the control track of the volume 50 to be copied, such as the corresponding data for VISS or VASS marks, can be read and, if necessary, processed and transmitted.

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The keyboard processor μP2 controls, for example, a display unit which can display the marks - for example as decimal or alphanumeric characters. The storage of tape marks - for example in the recording operation of the VCR2 video recorder, which is not present here but is present - can also be controlled by the keyboard processor μP2.

Finally, the μP2 keyboard processor also controls the transfer of the codes for the tape marks to or from a D2B interface via a line 54 connected via lines 55 to the D2B bus 30 (Fig. 4).

The D2B bus 30 transmits the codes to the VCR2 video recorder (Fig. 4) for recording, where they are recorded, in the same way as the VCR1 video recorder, together with the control data generated by the local servo processor, by means of the CTL head of the VCR2 video recorder on the control track of the tape intended for copying.

D2B interface and D2B bus are also mentioned above as alternatives to other suitable bus systems, which may include the I2C bus system, RS232 interface connections or the like.

Figure 6 shows a flowchart of a program running on the keyboard processor μP2 using the example of the VCR1 video recorder, which is intended here as a playback device. It is understood that for the recording operation as shown for the VCR2 video recorder in Figure 4 a correspondingly adapted program is provided. It is also understood that the VCR1 and VCR2 video recorders are preferably set up for both playback and recording operation.

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Otherwise, the data for the transmission protocol is generated and finally output via the D2B interface of the VCR1 to the D2B bus lines, with a jump back to the starting point and the program starts again.

Claims (7)

1. Method for copying magnetic tapes, in particular, audio- or video- or data- magnetic tapes, wherein additional items of digital information contained in a control track of the tape which is being copied (50) that are detected when copying the magnetic tapes from a first, reproducing tape device (VCR1), are transmitted via a transmission path (20; 30) to a second, recording tape device (VCR2) and are recorded there in a digitally coded form onto the control track during a corresponding time window, characterised in that, initially, at the reproducing device end, the items of digital information are intermediately stored in a buffer store for a length of time sufficient for an address consisting of a plurality of bits to be completely written in, that thereafter this address is completely transmitted via serial interfaces (D²B-interfaces) to the recording device (VCR2) where it is then re-recorded in a digitally coded form by the control track.
2. Method in accordance with Claim 1, characterised in that, if necessary, the transmission of the address takes place via an infra-red path arranged between the serial interfaces (D²B-interfaces).
3. Method in accordance with Claim 1 or 2, characterised in that, this recording takes place in the next attainable time window conjointly with the recording of the control track.
4. Method in accordance with any of the preceding Claims, characterised in that, the transmission of an item of digital information "0" or "1" takes place via so-called Scart-connecting cables (20).
5. Method in accordance with Claim 4, characterised in that, the level of approximately 0 or approximately 5 volt corresponds to the items of digital information "0" or "1".
6. Method in accordance with any of the preceding Claims, Claims, characterised in that, an address is transmitted from the reproducing (VCR1) to the recording device (VCR2) via a D2B-bus (30).
7. Apparatus for copying magnetic tapes, in particular, audio- or video- or data- magnetic tapes, wherein additional items of digital information contained in a control track of the tape which is being copied (50) that are detected when copying the magnetic tapes from a first, reproducing tape device (VCR1), are transmitted via a transmission path (20; 30) to a second recording tape device (VCR2) and are recorded there in a digitally coded form onto the control track during a corresponding time window, characterised in that, at the reproducing device end, there is provided a buffer store in which the items of digital information are initially intermediately stored for a length of time sufficient for an address consisting of a plurality of bits to be completely written in, and that serial interfaces (D²B-interfaces) are provided via which this address is thereafter completely transmitted to the recording device (VCR2) where it is then re-recorded in a digitally coded form by the control track.