JPS62232742A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To surely perform a consecutive recording even when no control signal is recorded, and to prevent a tape from being damaged, by providing a decision circuit which decides the presence/absence of the control signal, a selection circuit, and a clock generator. CONSTITUTION:A decision circuit 11 decides the presence/absence of the control signal recorded on the tape, and when deciding the presence of the control signal, it controls selection circuits 6 and 24 by its output, and passes a prescribed number of control signals. The signal is counted in a system control, and controls the rewinding quantity of a consecutive recording tape at the rewinding time the tape. Also, when the absence of the control signal is decided in the circuit 11, the circuits 6 and 24 are controlled by the output, and a prescribed number of clock signals from a clock generator 21 are permitted to pass. The signal is counted in the system controller, and controls the rewinding quantity of the consecutive recording tape at the rewinding time of the tape. In such a way, a consecutive recording can be performed accurately even when no control signal is recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus, and particularly to a magnetic recording and reproducing apparatus suitable for use in so-called splicing operations.

[Summary of the invention]

This invention provides a clock generator that internally generates a clock signal, and counts the clock signal instead of the control signal if there is no control signal when returning the tape during splicing operation.
By controlling the amount of tape rewinding based on this, the amount of tape rewinding is too large due to the lack of a control signal, and the tape becomes slack. This is to prevent the tape from falling off the drum and being damaged.

[Conventional technology]

In a VTR that records video signals by forming diagonal discontinuous tracks on a magnetic tape and plays them back, tape running is stopped, recording or playback is temporarily interrupted, and then the tape is run again. A new signal may be recorded on the previous recording trail.

In such so-called splicing, if the interval between the control signal recording traces on the tape is not constant at the joint between the recording trace formed before and the recording trace formed later on the tape, continuous playback will occur. When this occurs, synchronization disturbance occurs at this seam, making the playback screen unstable.

Conventionally, as a method for making the intervals between the recording traces of control signals constant at such recording joints, for example, Japanese Patent Application No. 1983-
Methods such as those disclosed in Japanese Patent Application No. 140670 (Japanese Unexamined Patent Publication No. 55-67965) and Japanese Patent Application No. 162015-1982 (Japanese Unexamined Patent Publication No. 55-89907) are known.

Now, in continuous shooting, for example, from the recording state, recording is paused, the tape is rewound by a predetermined amount, the tape is stopped, and after the recording pause is released, the tape is set to playback mode and the tape has run by the predetermined amount. I am trying to enter the recording state again.

When rewinding the tape by a predetermined amount, control signals are counted at regular intervals as described above, and when a predetermined number of control signals are counted, the tape is stopped.

[Problem that the invention seeks to solve]

By the way, when rewinding the tape by a predetermined amount during splicing, the amount of rewinding of the tape is determined by counting the control signal as described above, but a problem arises when this control signal is not recorded. It's coming. For example, when splicing virgin tape, it is difficult to determine the amount of rewinding because the control signals that should be counted are not recorded. It had the disadvantage of causing damage.

This invention has been made in view of the above, and provides a magnetic recording and reproducing device that can perform splicing operations reliably even when no control signals are recorded, and that does not damage the tape. It is.

[Means for solving problems]

The magnetic recording/reproducing apparatus according to the present invention includes a determination circuit (11) that determines the presence or absence of a control signal recorded on a tape, a clock generator (21) that generates a clock signal, and an output of the determination circuit (11). A selection circuit (6), (24) J that is controlled and selects the control signal and the clock signal.
If there is no control signal when rewinding the tape during a splicing operation, the clock signal is used to control the amount of rewinding of the tape.

[Effect]

A determination circuit (11) that determines the presence or absence of a control signal recorded on the tape and a clock generator (21) that constantly generates a clock signal are provided, and the determination circuit (11) confirms that there is a control signal. Then, the selection circuit (
6) and (24) are counted by a counter in the system controller through a predetermined number of control signals, and the amount of rewinding when rewinding the tape during splicing operation is controlled.

On the other hand, when the determination circuit (11) confirms that there is no control signal, its output selects the selection circuits (6), (2
4), a predetermined number of clock signals from the clock generator (21) are passed through and counted by a counter in the system controller, and the amount of rewinding when rewinding the tape during splicing operation is controlled. This allows the clock signal to be counted instead of the control signal and controls the amount of tape rewind, which could result in an inaccurate rewind amount and the tape falling off the drum and causing damage to the tape. There will be nothing to give.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIGS. 1 and 2.

FIG. 1 shows the circuit configuration of this embodiment. In the figure, (1) is an input terminal to which a control signal detected from a predetermined portion of the tape by a control signal detection head (not shown) is supplied; (2) is an input terminal to which a cab forwarding/rebus command is supplied from a system controller (not shown), and (3) is an input terminal to which capstan speed information is supplied from the system controller.

The input terminal (1) is connected to one input terminal of an exclusive OR (hereinafter referred to as EXOR) circuit (5) via a resistor (4), and is also connected to one input terminal of the NOR circuit V&+61. Ru. The input terminal (2) is connected to one input terminal of the EXOR circuit (8) via a resistor (7), and the EXOR circuit (8) is
The other input terminal of the OR circuit (8) is connected to the positive power supply terminal B.
Connected to one input terminal of the EXOR circuit (10), HX
The other input terminal of the OR circuit (lO) is grounded.

The output terminal of the EXOR circuit (5) is connected to the input terminal of a monostable multivibrator (11) as a discrimination circuit, and!
! The output end of the XOR circuit (8) is connected to the reset signal of the monostable multivibrators (11) and (12), and
The output terminal of the XOR circuit (10) is connected to the input terminal of the monostable multivibrator (12). The monostable multivibrator (11) has a resistor (13) and a capacitor (1
4), and the monostable multivibrator (12) has a resistor (15) and a capacitor (1
6) has a time constant circuit consisting of:

f! The output end of the XOR circuit (10) is grounded via a resistor (17) and a capacitor (18).
A connection point between the capacitor (18) and the capacitor (18) is connected to one input end of a NOR circuit (20) via a resistor (19). (
21) is a clock generator that generates a pulse having a duration of, for example, 8 milliseconds as a clock signal, and the output side of this clock generator (21) is connected to the °ζ NOR circuit (20) via a resistor (22). ) is connected to the other input end of the The output terminal of the NOR circuit (20) is l! XOR circuit (23)
The other input terminal of the 14XOR circuit (23) is connected to the positive power terminal B. [!
The output end of the XOR circuit (23) is connected to one input end of the NOR circuit (24).

The output terminal of the monostable multi-bi break (12) is EXO
The output terminal of the monostable multivibrator (11) is connected to the other input terminal of the R circuit (5), and the output terminal of the monostable multivibrator (11) is connected to the other input terminal of the NOR circuit (24). connected to. The output terminal of the NOR circuit (6) is connected to one input terminal of the NOR circuit (25), and the NOR circuit (2) is connected to one input terminal of the NOR circuit (25).
The output terminal of 4) is connected to the other input terminal of the NOR circuit (25). An output terminal (26) is taken out from the output end of the NOR circuit (25), and this output terminal (26) is connected to the system controller.

Next, the operation of the circuit shown in FIG. 1 will be explained with reference to the signal waveforms shown in FIG. 2.

Now, a signal S1 as shown in FIG. 2A is applied to the input terminal (2).
is supplied from the system controller, and when this signal SL changes from "1" to "0" at time t1 due to a recording pause command, II! The output of the XOR circuit (8) becomes "1", which is supplied as a reset signal to the monostable multivibrators (11) and (12), so that they become operational. At time t2, which is a predetermined time after the fall of the signal S1, the signal S2, which is capstan speed information as shown in FIG. 2B, supplied to the input terminal (3) changes from "1" to "0".
”, the output of the t!XOR circuit (10) becomes “1”, and this is supplied to the monostable multivibrator (12).

Then, a signal S3 as shown in Figure 2C is generated at the output terminal of the monostable multi-bi break (12), and this is supplied as a trigger signal to the monostable multi-bi break (11) via the EXOR circuit (5). . Il again! The output of the xOR circuit (lO) is connected to the resistor (17) and capacitor (1
8) etc., the signal S4 as shown in the second diagram is generated and supplied to the NOR circuit (20).

Note that at the time when the signal S2 falls, the capstan, which had been in the normal rotation state, becomes in the reverse rotation state.

In addition, the clock generator (21) generates a lock signal S5 as shown in FIG. 2E, which is connected to the resistor (
22) to the NOR circuit (20), and as a result, a signal S6 as shown in FIG. 2F is obtained at the output side of the NOR circuit (20). This signal S6 is [! X0Rffl path (23) is supplied, [! On the output side of the XOR circuit (23), a signal %S7 as shown in FIG. 2G is obtained. This signal S7 is used as a clock signal to determine the amount of tape rewind when there is no control signal, as will be described later. At time t2, the capstan is reversed and enters the tape rewind state, and as described later, when a predetermined number of control signals or clock signals are counted by the system controller counter, at time t3, the system controller sends the tape as shown in FIG. 2H. A pinch-off signal s8 is generated, and in synchronization with the rise of the signal SL1, the signal S
1 and S2 also change from '0' to '1', and the tape being rewound stops at this point.Then, at this point, the capstan turns forward and enters standby mode, and when the pause is released, it enters playback mode. It enters the recording mode, progresses by the amount of time it was rewound, and then enters the recording state again.

Next, Fig. 2 1-0 provides an explanation of the operation when a control signal is present. When a control signal Ss as shown in Fig. 2 (■) is applied from the input terminal (1), this control signal S9 II
! Supplied to the XOR circuit (5) and the NOR circuit (6)
supplied to Then, a signal Sso as shown in FIG. 2J is obtained on the output side of the BXOR circuit (5), and this signal SIO is supplied to the monostable multi-by-break (11). The monostable multi-bi break (11) connects the resistor (13) in synchronization with the rise of each pulse of the supplied signal Sho.
The output is maintained sequentially for a time constant determined by the capacitor (14) and the monostable multivibrator (11), and as a result, a signal S11 as shown in FIG. 2K is obtained at the output side of the monostable multivibrator (11). This signal S11 is supplied to the NOR circuit (24), and a signal S12 of 0" as shown in the second diagram is obtained at the output side of the NOR circuit (24). In other words, when the control signal is present, a signal S12 of "0" is obtained. '' signal S12 closes the gate of the NOR circuit (24) and stops sending out the clock signal S5 from the clock generator (21).

Further, the control signal S9 and an inverted signal of the signal 311 are supplied to the NOR circuit (6), and a signal S13 as shown in FIG. 2M is obtained at the output side of the NOR circuit (6). This signal 3
13 is supplied to the NOR circuit (25) together with the signal S12,
As a result, a signal S14 as shown in FIG. 2N, that is, a signal substantially the same as the control signal S9, is obtained on the output side of the NOR circuit (25). This signal S14 is output from the output terminal (26)
The signal is supplied to the system controller (not shown) via the controller, and its rising edge is counted by a built-in counter.

When the taunter counts a predetermined number of signals S14, for example 4, the system controller sends a pinch-off signal Ss (see H in Fig. 2) at time t3.
) is generated, which causes signals 81 and S2
changes from "O" to "1" and at this point the tape being rewound stops. That is, in this case, when four control signals are counted, it is determined that the tape has been rewound by a predetermined amount, and the tape rewinding is stopped. After that, as described above, the playback mode is entered by canceling the pause, and after progressing by the amount of rewinding, the recording state is entered again.

Next, Fig. 2 P-T serves to explain the operation when there is no control signal, and at time t2, the output side of the FiXOR circuit (5) corresponds to the signal S3, and the Signal Sz
s is obtained, this signal Sts is supplied to the monostable multivibrator (11) as a trigger signal, and in response, the output side of the monostable multivibrator (11) is supplied with a second signal Sts.
A signal Sxe as shown in FIG. Q is obtained. During the '1' period of the signal S1@, the presence or absence of a control signal is checked, and when it is determined that there is no control signal, it changes to '0'.Such a signal 31s is connected to a NOR circuit (24). The NOR circuit (24) passes eight signals by 0'' of the signal 31s, and as a result, a signal SIT as shown in FIG. 2R is obtained on the output side of the NOR circuit (24). .

This signal 31? is supplied to the NOR circuit (25), and as a result, a signal Srs as shown in FIG. 2S is obtained at the output side of the NOR circuit (25). That is, when there is no control signal, the NOR circuit (25) obtains the signal S1s corresponding to the clock signal S5 from the clock generator (21). This signal Sts is supplied to the system controller via the output terminal (26) as described above, and its rising edge is counted by the built-in counter. Then the counter outputs the signal Szs
When a predetermined number, for example 41, is counted, the system controller outputs a pinch-off signal Ss as shown in FIG.
(same as in Figure 2H) is generated, which causes the signal S
1 and S2 change from '0' to '1' and the tape being rewound stops at this point.In other words, in this case, when 4 clock signals are counted instead of the control signal, the tape rewinding stops. It is determined that the amount has been quantified, and the rewinding of the tape is stopped.After that, as described above, the pause is released to enter the playback mode, and after a pause corresponding to the amount of rewinding, the tape enters the recording state again.It should be noted that the signal S1@ The length of time t2-t3 is set to be equal to the length of time t2-t3 of signal S14 and includes four clock signals in this case.

〔Effect of the invention〕

As described above, according to the present invention, when there is no control signal recorded on the tape when rewinding the tape for splicing, a clock signal is used instead to control the amount of rewinding of the tape. , splicing up and down can be performed reliably, and there is no possibility that the tape will be returned too much due to the lack of a control signal, causing the tape to become slack and fall off the drum, causing damage to the tape.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram showing one embodiment of the present invention, and FIG. 2 is a signal waveform diagram for explaining the operation of FIG. 1. (51, (81, (10), (23) are exclusive OR (EXOR) circuits, (6), (20
), (24), (25) are NOR circuits, (1
1) and (12) are monostable multibibreaks, (
21) is a clock generator.

Claims (1)

[Scope of Claims] A determination circuit that determines the presence or absence of a control signal recorded on a tape; a clock generator that generates a clock signal; and a control circuit that selects the control signal and the clock signal under the control of the output of the determination circuit. 1. A magnetic recording and reproducing apparatus, comprising: a selection circuit, and the clock signal is used to control the amount of tape rewinding when there is no control signal when rewinding the tape for splicing.