JPS5923035B2 - magnetic tape playback device - Google Patents

Description

Detailed Description of the Invention The present invention provides, in addition to a main track on which information signals such as audio signals and data signals are recorded, a position signal for automatically searching for, selectively reproducing, etc. the recorded information. The present invention relates to a magnetic tape reproducing device (including a device having a recording function) equipped with a track for recording position signals.

Information retrieval using position signals as described above is generally performed at high speed, so even if a reproduction command signal is output immediately after detecting a position signal corresponding to the desired information, the inertia of the reel stand, brake delay, etc. There have been problems such as overtravel, and the target information cannot be reproduced from the beginning, or the information is reproduced from the end of the information before the information desired to be reproduced.

The present invention has been made in view of the above drawbacks, and detects the speed information of the magnetic tape from the pulse interval of the reproduced position signal, and detects the coincidence of the address of the information desired to be reproduced with the position signal and the speed information of the magnetic tape. To provide a magnetic tape reproducing device which can reliably reproduce information desired to be reproduced from the beginning with extremely little overtravel by obtaining a signal for controlling the running state of the magnetic tape. It is.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 shows a signal recording pattern of an example of a magnetic tape used in the present invention. On a predetermined signal track of the magnetic tape 1, a plurality of information signals A, , A, .
...An is recorded sequentially from the 1st to the nth, and the number of each information signal + 2 pulses is positioned in front of each information signal on another signal track as a position signal s. recorded. FIG. 2 is a circuit diagram of a main part of an embodiment of the present invention in which the position signal s is reproduced from the magnetic tape 1 and the information signal at a designated address is automatically reproduced.

To explain this, 1 is a magnetic tape on which a plurality of information signals and position signals similar to those shown in FIG. 1 are recorded;
3 is a magnetic head for reproducing the position signal (S in FIG. 1) corresponding to each of the above information signals, 3 is an amplifying means for amplifying the reproduced output of the magnetic head 2, and 4 is a position signal which is the output of the amplifying means 3. Counting means for counting pulse trains; 5 is an address specifying means for specifying the address of information desired to be reproduced; 6 is supplied with the output A of the counting means 4 and the output B of the address specifying means 5, and outputs their magnitude relationship. It is a means of comparison. The output pulse train of the amplification means 3 is supplied to the counting means 4, and a monostable multivibrator (hereinafter referred to as a monomultivibrator) 7 which can be retriggered, and a NAND gate circuit 8.
, is also supplied to the pulse train end detection means 9. A mono multivibrator 7 is connected to the other input terminal of the NAND gate circuit 8.
The output terminal of the flip-flop circuit 10 is connected to the set terminal S of the flip-flop circuit 10. The A>B output terminal and the A<B output terminal of the comparison means 6 are connected to the AND gate circuit 1 via inverters 11 and 12, respectively.
3 and 14, and each output terminal of those AND gate circuits 13 and 14 is connected to one input terminal of NOR gate circuits 15 and 16, respectively. The other input terminals of the NOR gate circuits 15 and 16 are commonly connected to the output terminal of the pulse train end detection means 9. On the other hand, the A=B output terminal of the comparison means 6 is connected to one input terminal of each of the AND gate circuit 17 and the NAND gate circuit 18, and the other input terminal of the AND gate circuit 17 and the NAND gate circuit 18 is connected to the flip-flop circuit 10, respectively. Connected to the output Q terminal and the Q terminal. Further, the output terminal of the AND gate circuit 17 is commonly connected to the input terminal of each one of the NAND gate circuits 19 and 20.
The output terminals of 0 are connected to other input terminals of AND gate circuits 13 and 14, respectively. The output terminal of the NAND gate circuit 18 is connected to one input terminal of the NOR gate circuit 21, and the other input terminal of the NOR gate circuit 21 is connected to the output terminal of the pulse train end detection means 9. The other input terminals of the NAND gate circuits 19 and 20 are connected to terminals 22 and 23, respectively, which attain the "H" level during fast forwarding and the "H2" level during rewinding.
The output terminals of are connected to a rewind command output terminal 24, a fast forward command output terminal 25, and a reproduction command output terminal 26, respectively. The output of the pulse train end detection means 9 is also supplied to the reset terminal π of the flip-flop circuit 10 via the delay means 27.

The above mono multivibrator 7, NAND gate circuit 8,
Flip-flop circuit 10 and delay means 27 constitute tape speed information detection means 28, and inverters 11, 12 and various gate circuits 13-21 constitute control signal generation means 29.

Note that there are a plurality of output lines (for example, four) of the counting means 4 and the address specifying means 5, and these are represented by thick lines. Further, since well-known magnetic heads, amplifier circuits, etc. for reproducing information signals can be used, illustrations and explanations thereof will be omitted here. Next, the operation of this embodiment will be explained, but before that, the recording waveform and reproduction waveform of the position signal will be explained.

As illustrated in FIG. 3, the pulse waveform of the position signal S recorded on the magnetic tape 1 has a pulse intensity τ.

For example, the repetition period T is 0.7 msec. is 5mfy3C
is allowed. Both the pulse width and repetition period of the reproduced waveform of the position signal S are inversely proportional to the tape speed, and since the tape bead is fast during normal fast forwarding and rewinding, they are considerably short.

Now, in FIG. 2, when the address of the information desired to be reproduced is specified by the address specifying means 5 and the magnetic tape 1 is put into a fast-forward state, for example, the position signal S is reproduced and amplified by the magnetic head 2 and the amplifying means 3. It is supplied to counting means 4.

The output A of the counting means 4 and the output B of the address specifying means 5 are supplied to the comparing means 6, and if A>B, the comparing means 6 sets the A>B output terminal to 2H2, and inverts the inverter 11. AND gate circuit 1
3, one input terminal of the NOR gate circuit 24 is set to "L".
''. On the other hand, the end signal of the pulse train is detected by the pulse train end detection means 9, the other input terminal of the NOR gate circuit 21 is set to 1'', and together with the A>B output, the rewind command output terminal 24 is set to ''. H'' and issue a rewind command.

If A<B, the comparison means 6 sets the A<B output to "H", sets one input terminal of the NOR gate circuit 16 to 1" via the inverter 12 and the AND gate circuit 14, and similarly detects the end of the pulse train. Together with the output of the means 9, the fast forward command output terminal 25 is set to "H" and a fast forward command is issued.When the tape running is controlled in this way and the position signal S corresponding to the information desired to be reproduced is reproduced, the comparison Means 6 A-
The B output terminal becomes "H".

Suppose now that a pulse waveform as shown in state 1 of FIG. 4a corresponding to desired information is reproduced in the fast forward state. on the other hand,
The mono-multivibrator 7 is triggered by the falling edge of the pulse train, and its pulse width is, for example, 1/2 of the pulse repetition period of 5 msec during recording, as shown in state 1 in FIG. 4b.
A single pulse of 2.5 msec is generated. Under these conditions, if the tape speed is faster than twice that during normal playback (recording), the output terminal of the NAND gate circuit 8, that is, the flip-flop circuit 10
The set terminal becomes 5"L", the flip-flop circuit 10 is set, and the Q output becomes "H" and the O output becomes 7L, as shown in state 1 of FIG. 4d and e. The Q output and the A-B output of "H'5" cause the AND gate circuit 17 and one input terminal of each of the NAND gate circuits 19 and 20 to become "H". Now, since we are in the fast forward state, the output of the NAND gate circuit 19 is set to "L" together with the terminal 22 which becomes "H" during fast forwarding, and one human input terminal of the NOR gate circuit 15 is set to "L" via the AND gate circuit 13. ”. Furthermore, in conjunction with the output of the pulse train end detection means 9 shown in state 1 of FIG. 4f, the rewinding command output terminal 24 is set to ``H'', and a rewinding command is issued as shown in FIG. 4h. Furthermore, when a position signal corresponding to desired information is reproduced in the rewinding state, the fast forward command terminal 25 is set to "L" and a fast forward command is issued in the same manner.

In other words, it reproduces the position signal corresponding to the information desired to be reproduced, and if the tape speed is fast, it receives a reverse fast winding command, reverses the running state of the tape, rewinds the overtraveled portion, and then returns the same position signal again. to play. By repeating this several times, the excess travel will gradually decrease. Therefore,
The rewinding time is reduced and the tape speed is also reduced due to the inertia of the reel stand. When the tape speed becomes less than twice the speed during playback, there is no time for both to become "H" as shown in the states a and b of FIG. 4, and the flip-flop circuit 10 is never set. Therefore, due to the A-B output and the O output, the NAND gate circuit 18
The output becomes 7L7, and together with the output of the pulse train end detection means 9, the regeneration command output terminal 26 becomes "H", and a regeneration command is issued as shown in the state shown in FIG. 41. In this case, since the tape speed is slow, overtravel does not occur, and the information desired to be reproduced can be reliably reproduced from the beginning.
In this embodiment, the output pulse width of the mono-multivibrator 7 was set to 1/2 of the repetition period of the recording position signal pulse, but it may be changed arbitrarily in consideration of the inertia of the reel stand, the performance of the brake, the allowable overtravel amount, etc. can be determined. Further, the pulse train end detection means 9 can be constructed using a well-known technique such as a time constant circuit, and the tape speed information detection means 28
can also be realized by an integrating circuit, a Schmitt circuit, etc.

As described above, the present invention specifies the address of the information desired to be reproduced, obtains the output B and the output A obtained by running the tape and reproducing and counting the position signals recorded on it, and if A<B, then a fast forward command is issued. is obtained, and if A>B, a rewind command is obtained, and A-
If it is B and the tape speed is fast, a reverse fast winding command is obtained, the overtraveled portion is rewound, and the same position signal is reproduced repeatedly.
If it is B and the tape speed is slow enough considering the inertia of the reel stand, brake performance, etc., a playback command is obtained, so it is possible to reliably playback from the beginning of the desired information. And the effect is very large.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a signal recording pattern of an example of a magnetic tape used in the present invention, Fig. 2 is a diagram showing a main circuit configuration of an embodiment of the present invention, and Fig. 3 is an example of a recording waveform of a position signal. The diagrams shown in FIG. 4A, b, c, d, e, f, g, h, and i are signal waveform diagrams of each part in FIG. 2. 1... Magnetic tape, 2... Magnetic head, 3... Amplifying means, 4... Counting means,
5... Address designation means, 6... Comparison means, 9... Pulse train end detection means, 28...
... Tape speed information detection means, 29 ... Immediate signal generation means.

Claims (1)

[Claims] 1. By using a magnetic tape on which a plurality of pulses are recorded on a position signal track as an address signal for distinguishing the position of the magnetic tape, and detecting the pulses by running the magnetic tape. A device for reproducing desired information recorded on the magnetic tape, comprising an address specifying means for specifying an address of the information to be reproduced, a counting means for counting the reproduced position signals, and an output of the address specifying means. a comparison means for comparing the output of the counting means; a tape speed information detection means for obtaining running speed information of the magnetic tape from the pulse interval of the reproduced position signal; and an output state of the comparison means and a specific output of the comparison means and the 1. A magnetic tape reproducing apparatus comprising control signal generating means for generating a signal for controlling the running state of the magnetic tape in combination with the output of the tape speed information detecting means. 2. In claim 1, when the output of the address designating means and the output of the counting means match and the speed of the magnetic tape is high, the control signal generating means causes the magnetic tape to enter a fast reverse winding state. . A magnetic tape reproducing apparatus, characterized in that the running state of the magnetic tape is controlled so as to put the magnetic tape into a reproducing state when the speed of the magnetic tape is slow.