JPH0724125B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to a magnetic recording / reproducing apparatus suitable for use in so-called continuous shooting.

[Summary of the Invention] The present invention is provided with a clock generator which internally generates a clock signal, and counts the clock signal instead of the control signal when there is no control signal when rewinding the tape for continuous shooting. By calculating the amount of tape rewinding based on this, it is possible to avoid the tape rewinding too much due to the lack of a control signal, and to prevent the tape from sagging and falling off the drum and damaging the tape. is there.

[Conventional technology]

In a VTR that records diagonally discontinuous tracks on a magnetic tape to record a video signal and reproduce it,
There is a case where the tape running is stopped and the recording or reproducing is temporarily stopped, and then the tape is run again to record a new signal in the previous recording trace. In such so-called continuous shooting, if the gap between the control signal recording traces on the tape is not constant at the joint between the recording traces formed before and after the recording traces on the tape, continuous reproduction is performed. When this happens, synchronization is disturbed at this joint and the playback screen becomes unstable.

Conventionally, as a method for making the interval of the recording traces of the control signal constant at such a recording seam, for example, Japanese Patent Application No. 53-14
Methods such as those disclosed in 0670 (JP-A-55-67965) and Japanese Patent Application No. 53-162015 (JP-A-55-89907) are known.

In continuous shooting, for example, when recording is paused from the recording state, the tape is rewound by a predetermined amount, the tape is stopped, and after the recording suspension is released, the tape is moved to the playback state by the predetermined amount of rewinding tape. I try to enter the recording state again. When the tape is rewound by a predetermined amount, the control neighborhoods set at the above-described constant intervals are counted, and the tape is stopped when a predetermined number of control signals are counted.

[Problems to be solved by the invention]

By the way, when the tape is rewound by a predetermined amount during continuous shooting, the control signal is counted as described above to determine the rewinding amount of the tape. However, when this control signal is not recorded, a problem occurs. Come on. For example, when performing continuous shooting using a virgin tape, it is difficult to determine the rewind amount because the control signal to be counted is not recorded. For example, the rewind amount increases and the tape sags and falls from the drum. There was a flaw that caused damage to.

The present invention has been made in view of the above circumstances, and provides a magnetic recording / reproducing apparatus that can reliably perform continuous shooting even if a control signal is not recorded and does not damage the tape. Is.

[Means for solving problems]

A magnetic recording / reproducing apparatus according to the present invention comprises a judgment circuit (11) for judging the presence or absence of a control signal recorded on a tape, a clock generator (21) for generating a clock signal, and an output of the judgment circuit (11). It is provided with selection circuits (6) and (24) which are controlled and select the control signal and the clock signal, and when there is no control signal at the time of tape rewinding for continuous shooting, the clock signal is used to rewind the tape. Is configured to calculate.

[Action]

A judgment circuit (11) for judging the presence / absence of a control signal recorded on the tape and a clock generator (21) for constantly generating a clock signal are provided, and it is confirmed by the judgment circuit (11) that there is a control signal. Then, depending on the output, the selection circuit (6),
(24) is controlled, and the counter in the system controller is counted through a predetermined number of control signals to calculate the rewinding amount when rewinding the tape for continuous shooting. On the other hand, if the decision circuit (11) confirms that there is no control signal, the output controls the selection circuits (6) and (24) to pass a predetermined number of clock signals from the clock generator (21) to the system controller. The internal counter is used to calculate the rewinding amount when rewinding the tape for continuous shooting.
As a result, even if the control signal is not recorded, the clock signal can be counted instead and the amount of rewinding the tape can be calculated, so that the rewinding amount becomes incorrect and the tape falls off the drum and damages the tape. There is no such thing.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 shows a circuit configuration of this embodiment. In FIG. 1, (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 capstan forward / rebus instruction 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 end of an exclusive OR (hereinafter referred to as EXOR) circuit (5) via a resistor (4) and to one input end of a NOR circuit (6). Connected. Input terminal (2) is EXOR via resistor (7)
EXOR circuit (8) connected to one input end of circuit (8)
The other input end of is connected to the positive power supply terminal + B. The input terminal (3) is connected to one input end of the EXOR circuit (10) via the resistor (9), and the other input end of the EXOR circuit (10) is grounded.

The output terminal of the EXOR circuit (5) is connected to the input terminal of the monostable multivibrator (11) as a judgment circuit, and the output terminal of the EXOR circuit (8) is reset terminal of the monostable multivibrator (11) and (12). The output terminal of the EXOR circuit (10) is connected to the input terminal of the monostable multivibrator (12). The monostable multivibrator (11) has a time constant circuit consisting of a resistor (13) and a capacitor (14), and the monostable multivibrator (12) is a resistor (1
5) It has a time constant circuit consisting of a capacitor (16).

The output terminal of the EXOR circuit (10) is grounded via the resistor (17) and the capacitor (18), and the connection point of the resistor (17) and the capacitor (18) is connected via the resistor (19) to the NOR circuit ( 20)
Is connected to one of the input terminals. (21) is a clock generator for generating a pulse having a duration of, for example, 8 milliseconds as a clock signal, and the clock generator (21)
Is connected to the other input end of the NOR circuit (20) via the resistor (22). The output end of the NOR circuit (20) is EXOR
EXOR circuit (23) connected to one input of circuit (23)
The other input end of is connected to the positive power supply terminal + B. EXOR
The output end of the circuit (23) is connected to one input end of the NOR circuit (24).

The output terminal of the monostable multivibrator (12) is connected to the other input terminal of the EXOR circuit (5), and the output terminal of the monostable multivibrator (11) is connected to the other input terminal of the NOR circuit (24). Is also connected to the other input end of the NOR circuit (6). The output end of the NOR circuit (6) is the NOR circuit (25)
Is connected to one input terminal of the NOR circuit (24), and the output terminal of the NOR circuit (24) is connected to the other input terminal of the NOR circuit (25). And
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 circuit operation of FIG. 1 will be described with reference to the signal waveforms of FIG.

Now, the signal S ₁ as shown in FIG. 2A is supplied from the system controller to the input terminal (2), and this signal S ₁ is timed.
At t ₁ , when the recording pause command changes from “1” to “0”,
The output of the EXOR circuit (8) becomes "1", and this is supplied to the monostable multivibrators (11) and (12) as a reset signal, and these operate. To "0" from the signal S ₂ is a capstan speed information as shown at time t ₂ after a predetermined time falling of the signals S ₁ in FIG. 2 B supplied to the input terminal (3) is "1" The output of the EXOR circuit (10) changes to "1", which is the monostable multivibrator (12).
Is supplied to. Then monostable multivibrator (12)
A signal S ₃ as shown in FIG. 2C is generated at the output terminal of
This is supplied as a trigger signal to the monostable multivibrator (11) via the EXOR circuit (5). The output of the EXOR circuit (10) is supplied to the NOR circuit (20) as a signal S ₄ as shown in FIG. 2D due to the time constant of the resistor (17) and the capacitor (18). When the signal S ₂ falls, the capstan that had been in the normal rotation state until then becomes the reverse rotation state.

Further, the clock signal (S ₅ ) as shown in FIG. 2E is generated from the clock generator (21), which is the resistor (22).
Is supplied to the NOR circuit (20) via the output of the NOR circuit (20), and as a result, a signal S ₆ as shown in FIG. 2F is obtained at the output side of the NOR circuit (20). This signal S ₆ is supplied to the EXOR circuit (23), and the signal S ₇ as shown in FIG. 2G is obtained at the output side of the EXOR circuit (23). This signal S ₇ is used as a clock signal for determining the tape rewinding amount when there is no control signal as described later. Time t ₂ capstan becomes tape rewinding state and reverse from the control signal or clock signal as described below is counted by the counter of a predetermined number system controller, FIG. 2 H from the system controller at time t ₃ A pinch-off signal S ₈ is generated as shown in, and the signals S ₁ and S ₂ are also changed from “0” to “1” in synchronization with the rising of the signal S ₈ , and the tape being rewound is stopped at this point. . Then, at this point, the capstan enters the normal rotation state and enters the standby mode, and the pause mode is released to enter the reproduction mode. After rewinding, the recording mode is resumed.

Next, FIGS. 2I to 2O are provided for explaining the operation when there is a control signal. When the control signal S ₉ as shown in FIG. 2I is applied from the input terminal (1), the control signal S ₉ is supplied to the EXOR circuit (5) and also to the NOR circuit (6). Then, the signal S ₁₀ as shown in FIG. 2J is obtained at the output side of the EXOR circuit (5), and this signal S ₁₀ is supplied to the monostable multivibrator (11). The monostable multivibrator (11) sequentially maintains the output for the time constant determined by the resistor (13) and the capacitor (14) in synchronization with the rising edge of each pulse of the supplied signal S ₁₀ , and as a result, the monostable multivibrator. At the output side of (11), the signal S ₁₁ as shown in FIG. 2K is obtained. This signal S ₁₁ is supplied to the NOR circuit (24), and a signal S _{12 of} "0" as shown in FIG. 2L is obtained at the output side of the NOR circuit (24). That is, when the control signal is present, the gate of the NOR circuit (24) is closed by the signal S _{12 which} becomes “0”, and the clock signal from the clock generator (21) is output.
Delivery of S ₅ is stopped.

Further, an inverted signal of the control signal S ₉ and the signal S ₁₁ is supplied to the NOR circuit (6), and the signal S ₁₃ as shown in FIG. 2M is obtained at the output side of the NOR circuit (6). This signal S ₁₃ is a signal
It is supplied to the NOR circuit (25) together with S ₁₂ , and as a result, a signal S ₁₄ as shown in FIG. 2N, that is, a signal substantially the same as the control signal S ₉ is obtained at the output side of the NOR circuit. This signal
S ₁₄ is supplied to the system controller (not shown) via the output terminal (26) and the rising edge is counted by the built-in counter. The pinch-off signal as shown the signal S ₁₄ in FIG. 2 O from the system controller in a predetermined number for example four counts for the time t ₃ at Taunta S ₈
(Same as FIG. 2H) is generated, which causes the signal S ₁
And S ₂ changes from “0” to “1”, and the tape being rewound stops at this point. That is, in this case, the control signal is substantially 4
When the number of pieces is counted, it is determined that the rewinding of the tape has been performed by a predetermined amount, and the rewinding of the tape is stopped. After that, similarly to the above, the pause mode is released to enter the reproduction mode. After rewinding, the recording mode is resumed.

Next, P to T of FIG. 2 are provided for explaining the operation when there is no control signal, and a signal is output to the output side of the EXOR circuit (5) at time t _2.
A signal S ₁₅ as shown in FIG. 2P is obtained corresponding to S ₃ ,
This signal S ₁₅ is supplied to the monostable multivibrator (11) as a trigger signal, and in response thereto, the signal S ₁₆ as shown in FIG. 2Q is obtained at the output side of the monostable multivibrator (11). . Period of "1" of the signal S ₁₆ is observant whether the control signals are adapted to vary the control signal is determined that there is no "0". Such a signal S ₁₆ is supplied to the NOR circuit (24), and the NOR circuit (24) outputs “0” of the signal S _16.
The signal S ₇ is passed only for a period, and as a result, the signal S ₁₇ as shown in FIG. 2R is obtained at the output side of the NOR circuit (24).

This signal S ₁₇ is supplied to the NOR circuit (25), and as a result, the signal S ₁₇ as shown in FIG.
₁₈ is obtained. That is, when there is no control signal, the signal S ₁₈ corresponding to the clock signal S ₅ from the clock generator (21)
Is obtained in the Noah circuit (25). This signal S ₁₈ is supplied to the system controller via the output terminal (26) in the same manner as described above, and its rising is counted by the built-in counter. Then, when the counter counts the signal S ₁₈ by a predetermined number, for example 4, four, the system controller generates a pinch-off signal S ₈ (same as that in FIG. 2H) as shown in FIG. 2T, whereby signals S ₁ and S ₂ are generated. Changes from "0" to "1" and the tape being rewound stops at this point. In other words, in this case, when four clock signals that substantially substitute for the control signal are counted, it is determined that the tape rewinding has been performed by a predetermined amount, and the tape rewinding is stopped. After that, similarly to the above, the pause mode is released to enter the reproduction mode. After rewinding, the recording mode is resumed. The time of signal S ₁₈ t ₂
The length of ˜t ₃ is set equal to the length of the time S ₂ ˜t ₃ of the signal S ₁₄ and four clock signals are included in this case.

[Effects of the Invention] As described above, according to the present invention, when there is no control signal recorded on the tape at the time of tape returning for continuous shooting, a clock signal is used instead of the control signal to determine the amount of rewinding of the tape. Since it is calculated, continuous shooting can be performed reliably, and there is no control signal, so the amount of tape rewinding will not be too large and the tape will not sag and fall from the drum to damage the tape. .

[Brief description 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. (5), (8), (10) and (23) are exclusive or (EXOR) circuits, (6), (20), (24) and (25) are NOR circuits, (11) and (12) ) Is a monostable multivibrator,
(21) is a clock generator.

Claims (1)

[Claims] 1. A determination circuit for determining the presence or absence of a control signal recorded on a tape, a clock generator for generating a clock signal, and a control signal for controlling the control signal when the control signal is present by the output of the determination circuit. When there is no signal, a selection circuit for selecting each of the clock signals is provided, and when rewinding the tape for continuous shooting, the signal selected by the selection circuit is used to calculate the amount of rewinding of the tape. Characteristic magnetic recording / reproducing device.