JPH04103006A - Digital tape recorder - Google Patents

Abstract

PURPOSE:To prevent the misalignment of a block of information by setting a delay time so that a recording position of a recording signal by a recording head coincides with a recording position of a tape of a signal reproduced from a reproducing head. CONSTITUTION:Since a distance L between a reproducing head 2 and a recording head 4 is known and constant, it can be set exactly. In such a state, when an actual running speed V of a magnetic tape 1 is calculated from a reference clock and a speed clock, a difference of the time when a specific position of the magnetic tape 1 passes through the reproducing head 2 and reaches the recording head 4 can be calculated. A delay time setting means 15 sets this delay time to a delaying means 12. Accordingly, a rewriting signal is recorded exactly in a position of a block recorded already. In such a way, it is possible to have an action by which a position of the block is not shifted.

Description

[Detailed Description of the Invention] [Purpose of the Invention (Field of Industrial Application) The present invention relates to a digital tape recorder that records digital signals on a magnetic tape. The present invention relates to a digital tape recorder that is useful when implemented in a digital tape recorder having a configuration similar to the above.

(Prior Art) Digital tape recorders are used to record digital signals on magnetic tape and to reproduce recorded digital signals.

This digital tape recorder has a construction that is quite different from that of an analog tape recorder in order to accurately and reliably perform recording and reproduction on tape.

One major feature is the recording pattern of signals on the tape. Digital tape recorders configure information in units of several blocks, and record on the tape and reproduce from the tape in units of blocks.

On the tape, a delimiter signal is recorded between one block and another block so that unit blocks can be identified.

On the other hand, with a digital tape recorder, it may be necessary to replace a portion of the already recorded tape with other information.

This information replacement is also performed in units of previous information blocks.

A common problem that arises with this swapping operation is whether the position of the block of information already recorded on the tape and the position of the block of information to be newly recorded match based on the delimiter signal. It is.

If the position of a block of information recorded later or the block of information already recorded is the same, the block will be destroyed by eroding the block recorded later or the block already recorded. be.

As a digital tape recorder that solves this problem, for example, the configuration shown in Japanese Patent Application Laid-Open No. 58-9202 is known.

In the digital tape recorder shown here, a playback head and a recording head are provided separately, and the playback head is placed upstream with respect to the running of the tape, and the playback head is placed downstream of either the recording head or the playback head.

When recording signals continuously with this digital tape recorder, the
Information is recorded one after another in units of information blocks, separated by delimiter signals.

At this time, it is assumed that the tape is running at a preset speed.

When reproducing signals continuously, the tape running speed is controlled so that the information reproduced by the reproducing head is reproduced in accordance with the timing clock used during recording. Therefore, the running speed of the tape during playback is exactly the same as during recording.

On the other hand, if you want to rewrite a specific block of information during playback, first make sure that the information played back by the playback head is played back in accordance with the timing clock used during recording, just as in normal playback. Playback while controlling the running speed of the tape.

Then, the position of the information block to be rewritten is specified by the delimiter signal of the information block reproduced by the reproduction head.

Since the information block to be rewritten first passes through the reproducing head and then the recording head, the recording operation is performed just as the information block to be rewritten passes through the recording head.

The timing of this recording can be controlled if the running speed of the tape and the physical distance between the reproducing head and the recording head are known.

Specifically, the time for recording information by the recording head is delayed by using a delay means that delays the transmission of the signal by a preset time.

(Problems to be Solved by the Invention) In conventional digital tape recorders, depending on the machine, the position of a rewritten information block may deviate from the position of an already recorded information block.

The reason for this is that the running speed of the tape is different from that of other machines when recording is performed continuously for the first time.

That is, in order to prevent the position of the information block from shifting during a rewriting operation, it is necessary that the tape running speed and the physical distance between the reproducing head and the recording head be fixed and constant.

On the other hand, when information is first continuously recorded on an unrecorded tape, there is no signal to be reproduced by the reproducing head yet, so the running speed of the tape depends on the accuracy of the tape drive mechanism.

In this case, the actual tape running speed during playback also depends on the tape running speed at the time of initial recording, and does not necessarily match the specifications.

The present invention provides a digital tape recorder that prevents the position of an information block from shifting during an information block rewriting operation even if the tape running speed is different when first recording information on an unrecorded tape. The purpose is to

[Structure of the Invention (Means for Solving the Problems) In order to solve the above problems, the present invention improves a conventional digital tape recorder, and includes a playback head for playing back signals recorded on a tape, and a playback head for playing back signals recorded on a tape, and A recording head arranged downstream of the playback head and recording a signal on the tape, a reference clock generation means for generating a reference clock, a tape drive means for driving the tape, and a playback signal played back from the playback head. clock demodulation means for demodulating the timing clock from the recording signal; speed control means for comparing the reference clock and the timing clock and controlling the tape driving means so that the timing clock is synchronized with the reference clock; recording means for recording on the tape by a head; delay means for delaying the transmission time of the recording signal with respect to the timing clock; speed clock detection means for detecting a speed clock corresponding to the running speed of the tape; a delay time for comparing the reference clock and the speed clock and setting the delay time of the delay means so that the recording position of the recording signal by the recording head matches the recording position of the signal reproduced from the reproduction head on the tape; The present invention is a digital tape recorder characterized by including a setting means.

(Function) With the above configuration, the reference clock generation means generates a clock that serves as a reference for the digital tape recorder system.

The clock demodulation means demodulates the timing clock included in the reproduction signal from the reproduction signal reproduced by the reproduction head. The speed clock detection means detects a speed clock corresponding to the running speed of the tape.

The running speed of the tape is controlled by the speed control means so that the reference clock and timing clock are synchronized.

On the other hand, the actual tape running speed can be measured by comparing the reference clock and the speed clock. The delay means delays the transmission time of the recording signal recorded by the recording head.

The delay time setting means compares the reference clock and the speed clock to set the delay time of the delay means.

The delay time is determined by adjusting the physical distance between the playback head and recording head and the actual tape running speed so that the position of the block of information reproduced by the playback head and the block of information recorded by the recording head do not deviate. It can be determined based on the standard.

Due to the above-described operation, even if a part of the information block on the recorded tape is newly rewritten, only the position of the information block is shifted.

(Example) FIG. 1 shows the configuration of an embodiment of the present invention.

1 is a magnetic tape. The magnetic tape 1 runs in the direction shown by the arrow 3.

2 is a playback head. A reproducing head 2 reproduces signals from the magnetic tape 1.

4 is a recording head. The recording head 4 records recording signals on the magnetic tape 1. The recording head 4 is arranged downstream of the reproducing head in the running direction 3 of the magnetic tape 1.

5 is a reference clock generating means. The reference clock generating means 5 generates a clock that serves as a reference for the entire digital tape recorder system shown in FIG. Specifically, the reference clock generating means 5 includes a crystal oscillation circuit.

6 is a clock demodulating means. The clock demodulation means 6 demodulates the timing clock included in the reproduction signal from the reproduction signal reproduced by the reproduction head 2.

7 is a tape drive means. Tape drive means 7 drives magnetic tape 1 in the direction shown by arrow 3.

The tape drive means 7 is provided coaxially with a capstan shaft 8 that drives the magnetic tape, and includes a rotation pulse generating mechanism 9 that generates a pulse signal according to the rotational speed of the capstan shaft 8.

10 is a speed control means. The speed control means 10 compares the timing clock output from the clock demodulation means 6 with the reference clock output from the reference clock generation means 5, and controls the tape drive means 7. Speed control means 10
controls the speed control means 10 so that the timing clock is synchronized with the reference clock.

11 is a recording means. The recording means 11 records recording signals on the magnetic tape 1 by the recording head 4.

12 is a delay means. 13 is an input terminal.

A recording signal is input to the input terminal 13. Delay means 12
transmits the recording signal input to the input terminal 13 to the recording means 11 with a time delay.

14 is speed clock detection means. The speed clock detection means 14 detects a pulse signal from the rotation pulse generation mechanism 9 of the tape drive means 7. The speed clock output from the speed detection means 14 corresponds to the running speed of the magnetic tape 1.

15 is a delay time setting means. Delay time setting means 15
compares the reference clock outputted from the reference clock generation means 5 and the speed clock outputted from the speed clock detection means 14, and sets the delay time of the delay means 12 based on the comparison result.

The operation of the configuration as described above will be explained next.

FIG. 2 schematically shows the recording pattern of information blocks on the magnetic tape 1 shown in FIG. In FIG. 2, 18 and 19 are independent information blocks. Separator signals 20 are used before and after independent information blocks 18 and 19.
．． It is separated by 21.22. For example, if the information in either or both of the information blocks 18 and 19 originally recorded on the magnetic tape 1 is to be rewritten later, the information block to be written later overlaps the information blocks 18 and 19, and It must be ensured that there is no deviation from the signal 20°21.22.

FIG. 3 is a graph explaining the operation of the digital tape recorder shown in FIG.

A in FIG. 3 represents the reference clock generating means 5 shown in FIG.
It shows the reference clock generated from the clock. The reference clock is, for example, a clock generated from a crystal oscillation circuit and whose cycle is fixed to X.

B in FIG. 3 shows the timing clock output from the clock demodulating means 6. The timing clock included in the reproduction signal reproduced from the reproduction head 2 is a clock with a period Y.

However, the period Y of the timing clock is
depends on the running speed. The speed control means 10 controls the running speed of the magnetic tape 1 so that the period X of the reference clock and the period Y of the timing clock match.

C in FIG. 3 is the speed clock output from the speed clock detection means 14. The speed clock during recording is synchronized with the reference clock.

Therefore, the actual tape running speed during recording is controlled by the mechanical precision of the tape drive system.

The tape speed during reproduction is controlled so that the timing clock recorded on the magnetic tape 1 and the reference clock are synchronized.

Therefore, the actual tape running speed during playback is not affected by the mechanical accuracy of the tape drive system, and the tape running speed during recording is faithfully reproduced.

The speed clock during reproduction has a period T if the magnetic tape 1 is running at a predetermined speed when information is first recorded on the magnetic tape 1.

However, if the vehicle is running at a speed that deviates from the predetermined speed when recording, it will also run at the same deviated speed during playback as during recording. This speed clock deviation can be detected by comparing the period of the reference clock and the period of the speed clock.

Since the distance between the reproducing head and the recording head 4 shown in FIG. 1 is known and constant, it can be set accurately. Then, by calculating the actual running speed V of the magnetic tape 1 from the reference clock and the speed clock, it is possible to calculate the difference in time between a specific position on the magnetic tape 1 passing through the reproducing head and reaching the recording head. The delay time setting means 15 sets this delay time in the delay means 12. Therefore, the rewrite signal will be recorded accurately at the position of the block that has already been recorded.

By performing such an operation, when a part of the information block on the magnetic tape 1 is rewritten, the digital tape recorder implementing the present invention can distinguish between the position of the already recorded information block and the rewritten information block. It can have the effect of not shifting the position.

In addition to the embodiments described above, other embodiments of the present invention can be considered. For example, the delay means 12 shown in FIG. 1 may be a combination of a first delay means whose delay time is fixed and a second delay means whose delay time can be arbitrarily set. This is because the delay time by the delay means 12 only needs to be adjusted very slightly in practice, and it is only necessary to make it possible to set the delay time by the amount of adjustment. This will make the configuration easier.

Furthermore, the speed clock may be obtained by using a tacho roller that is integrated with the running of the magnetic tape 1 instead of the tape drive means.

[Effects of the Invention] As described above, by configuring the present invention, it is possible to realize a digital tape recorder that can rewrite any part without depending on the mechanical precision of the running system of the digital tape recorder.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a schematic diagram of a recording pattern of a magnetic tape, and FIG. 3 is a timing chart for explaining the operation. DESCRIPTION OF SYMBOLS 1... Magnetic tape, 2... Reproduction head, 4... Recording head, 5... Reference clock generation means, 6... Clock demodulation means, 7... Tape drive means, 10...
Speed control means, 11... Recording means, 12... Delay means, 14... Speed clock detection means, 15... Delay time setting means. Mouth --- Figure 3

Claims (3)

[Claims] (1) A playback head that plays back signals recorded on a tape, a recording head that is arranged downstream of the playback head and records signals on the tape, a reference clock generating means that generates a reference clock, and the tape a tape drive means for driving a timing clock; a clock demodulation means for demodulating a timing clock from a reproduction signal reproduced from the reproduction head; a speed control means for controlling the tape drive means; a recording means for recording a recording signal on the tape by the recording head; a delay means for delaying the transmission time of the recording signal with respect to the timing clock; a speed clock detection means for detecting a speed clock corresponding to the running speed of the tape; and a speed clock detection means that compares the reference clock and the speed clock, and detects a recording signal by the recording head at a recording position on the tape of a signal reproduced from the reproduction head. and delay time setting means for setting the delay time of the delay means so that the recording positions of the two coincide with each other. (2) The digital tape recorder according to claim 1, wherein the delay means includes a first delay means having a fixed delay time and a second delay means having a settable delay time. (3) The tape drive means includes a capstan motor, the capstan motor includes a rotation pulse generation mechanism corresponding to the rotation speed, and the speed clock detection means rotates the capstan motor. 2. The digital tape recorder according to claim 1, wherein a speed clock corresponding to the running speed of the tape is generated by detecting a rotation pulse corresponding to the speed.