JPH0219543B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing device equipped with an indexing function for recorded contents, and in particular, by changing the duty ratio of a control signal used to control the recording/reproducing operation of a main signal. The present invention relates to a magnetic recording/reproducing device for use in the present invention.

In a magnetic recording/reproducing device such as a video tape recorder, if an index signal corresponding to the recording section of the main signal such as an audio signal or a video signal recorded on the magnetic tape is recorded on the magnetic tape together with the main signal, the data can be reproduced. At times, the index signal can be used for various automatic operation controls such as finding the beginning of a recording section of a desired main signal and detecting the end of a tape.

In general, magnetic recording and reproducing devices equipped with index signal recording and reproducing functions forcibly write the index signal at the beginning of the main signal recording operation, but it is also possible to write the index signal by specifying an arbitrary recording section. If it is possible to delete unnecessary index signals, the index function can be used more effectively.
For example, when searching for a recording section of a target main signal using an index signal, if the unnecessary index signal is not written, not only can the search operation be performed quickly, but also there is a risk of malfunction. This will also decrease.

Furthermore, providing a recording track dedicated to the index signal on the magnetic tape in order to record the index signal not only increases the size of the device, but also limits the recording area due to the tape width. This is undesirable because the recording area becomes smaller.

SUMMARY OF THE INVENTION Therefore, the present invention provides a magnetic recording device having a control track on which a control signal is written corresponding to a recording track of a main recording signal, such as a video tape recorder using a rotating magnetic head device. The information of the index signal is written corresponding to the recording section of an arbitrary main signal according to the duty ratio of the control signal to be recorded, and it is possible to prevent unpleasant noise from being output as an audio signal during the writing operation. The present invention provides a magnetic recording/reproducing device with a new configuration.

Hereinafter, the present invention will be described in detail with reference to the drawings showing one embodiment.

FIG. 1 shows an example of the configuration of a tape running system in a video tape recorder to which the present invention is applied. The tape 2 is fed out from the supply tape reel 3 and wound onto the take-up tape reel 4.
It is guided by each guide pin 5. A full width erasing head 6 is provided upstream of the rotating magnetic head drum 1, and an audio head 7 and a control head 8 for recording and reproducing audio signals and control signals are provided downstream. The audio head 7 and control head 8 are integrally housed in a single head case 9, as shown in FIG.

The magnetic tape 2 running in the tape running system as described above is a video track formed at a predetermined inclination angle θ with respect to the tape running direction, as the tape format is shown in FIG.
Regarding TRv, a video signal is recorded and reproduced by the rotating magnetic head device 1, and an audio track is formed along one side edge of the magnetic tape 2.
Regarding TR _A , an audio signal is recorded and reproduced by the audio head 7, and the magnetic tape 2
Control signals are recorded and reproduced by the control head 8 on the control track _TRC formed along the other side edge.

In FIG. 4, which shows the circuit configuration of the essential parts of an embodiment in which the present invention is applied to a video tape recorder equipped with the above-described tape running system, the audio head 7 is It is designed to be selectively connected to the output side of the recording amplifier 21 or the input side of the reproducing amplifier 22. Further, the control head 7 is selectively connected to the output side of the recording amplifier 23 or the input side of the reproducing amplifier 24 via the second switch circuit 12. Each of the switch circuits 11 and 12 operates according to the recording mode and reproduction mode supplied via the first signal input terminal 31.
The switching operation is controlled by the REC/PB signal, and in the recording mode, each recording amplifier 21, 2
Audio head 7 and control head 8 are connected to the output side of 3, respectively, and in the playback mode, the audio head 7 and control head 8 are
is controlled so that it is connected to the input side of each regenerative amplifier 22, 23.

A recording amplifier 21 connected to the audio head 7 amplifies an audio signal (Audio) supplied via a second signal input terminal 32 and supplies the amplified audio signal to the audio head 7.
The audio signal is recorded on the audio track TR _A.

Furthermore, the reproducing amplifier 22 connected to the audio head 7 amplifies the reproduced audio signal (PBAudio) reproduced by the audio head 7 in the reproduction mode, and outputs the signal to the muting circuit 2.
It is designed to output via 5. This muting circuit 25 receives an index write command signal (INDX.WR) and an index erase command signal (INDX.ER) supplied to the third and fourth signal input terminals 33 and 34 via an OR gate circuit 49. It is supplied as a mutating control signal (MUT), and its operation is controlled according to the mutating control signal.

Furthermore, the recording amplifier 23 connected to the control head 8 receives a vertical synchronizing signal VD supplied from a fifth signal input terminal 35 via a third switch circuit 13, and receives a vertical synchronizing signal VD from a fourth monostable multivibrator 44, which will be described later. The supplied index write signal (WR.INDX) or the index erase signal (ER.INDX) supplied from the sixth monostable multivibrator 46 is amplified and supplied to the control head 8 to read the magnetic tape. A control signal (CTL) having index information is recorded on the second control track _TRC . Note that the third switch circuit 13
is the REC/ from the first signal input terminal 31.
Its operation is controlled by the PB signal, and it is closed during the recording mode to supply a vertical synchronizing signal (VD) to the recording amplifier 23. Furthermore, a reproduction amplifier 24 connected to the control head 8 amplifies and outputs a reproduction control signal (PB.CTL) reproduced by the control head 8 in the reproduction mode, and outputs the amplified reproduction control signal (PB.CTL) to a servo circuit (not shown) of the tape running system. supply Furthermore, the reproduction control signal (PB.CTL) outputted via the reproduction amplifier 24 is
The signal is supplied to the trigger input terminal of the first monostable multivibrator 41 via the fourth switch circuit 14. The first monostable multivibrator 41 supplies an output signal with a pulse width of T ₁ to each trigger input terminal of the second, third, and fifth monostable multivibrators 43 and 45. The second monostable multivibrator 42 supplies an output signal with a pulse width of _T2 to the second switch circuit 12 as a control signal, and during the period of the pulse width of _T2 , the output side of the recording amplifier 23 is forcibly connected to the control head 8 via the second switch circuit 12. Further, the third monostable multivibrator 43 supplies an output signal with a pulse width of T ₃ to the trigger input terminal of the fourth monostable multivibrator 44 . Furthermore, the fifth monostable multivibrator 4
5 supplies an output signal with a pulse width of _T5 to the trigger input terminal of the sixth monostable multivibrator 46. Here, the fourth switch circuit 14 receives an index write command signal (INDX.WR) or an index erase command signal (INDX.ER) from the third or fourth signal input terminals 33, 34 as a control signal. It is supplied via an OR gate circuit 47. Further, the fourth monostable multivibrator 44 is controlled by the index write command signal (INDX.WR) to enable reverse operation, and the sixth monostable multivibrator 4
6 is the index deletion command signal (INDX.
ER) to enable reversal operation.

In the embodiment configured as described above, the index information writing operation can be performed by the operation shown in the time chart of FIG.

First, in the normal recording mode in which video and audio signals are recorded as main signals on the video track TRv and audio track _TRA of the magnetic tape 2, control is performed based on the vertical synchronization signal (VD) as in a general video tape recorder. The signal (RecCTL) is the control track
As shown in FIG. _5A , the control track _TRC is 1/1/2 of the vertical synchronization signal.
Magnetization is performed such that the direction is reversed every two periods T ₀ . In other words, in the control track TR _C ,
A control signal CTL with a duty ratio of 50% is recorded.

Then, when the control signal CTL recorded in the control track _TRC is played back, the fifth
As shown in FIG. B, a reproduction control signal (PB.CTL) is obtained in which a rising differential pulse and a falling differential pulse are repeated every cycle _T0 . Normally, the rising differential pulse obtained as the reproduction control signal (PB.CTL) every 2·T ₀ , that is, every vertical cycle period V, is used for servo control of the tape running system.

Therefore, in this embodiment, the index information is provided by changing the duty ratio of the control signal CTL so as to shift the generation timing of the falling differential pulse without impairing the generation timing of the rising differential pulse. That is, in order to enter the playback mode for playing back the main signals (video signals and audio signals) recorded on the magnetic tape 2, and write the index information corresponding to the recording section of the desired main signal, the procedure shown in FIG. 5C is performed. When the index write command signal (INDX.WR) as shown is supplied to the third signal input terminal 33, the mutating circuit 25 and the fourth The switch circuit 14 is controlled to be in an on state. Therefore, the reproduced audio signal (PB.Audio) from the audio head 7 is muted. Further, the reproduction control signal (PB.CTL) from the control head 8 is supplied to the trigger input terminal of the first monostable multivibrator 41. The first monostable multivibrator 41 is triggered every rising differential pulse of the playback control signal (PB.CTL), and during the period Tw, T ₁ as shown in FIG. 5D.
Outputs an output signal with a pulse width of Then, as shown in FIG. ) and output signals with pulse widths T ₂ and T ₃ respectively. Furthermore, the fourth
The monostable multivibrator 44 is triggered at the timing of the trailing edge (falling edge in this example) of the output signal from the third monostable multivibrator 43, as shown in FIG. _5G .
Outputs an index write signal with a pulse width of Here, each pulse width T ₁ , T ₂ , T ₃ , T ₄ of each output signal from each monostable multivibrator 41 , 42 , 43 , 44 is set to 1/2 period T ₀ of the vertical synchronization signal. On the other hand, it is set so that T ₁ +T ₃ <T ₀ T ₀ <T ₁ +T ₃ +T ₄ <T ₁ +T ₂ <2·T ₀ . That is, each pulse width is set so that the index write signal (WR.INDX) is outputted from the fourth monostable multivibrator 44 during a period that includes the falling differential pulse of the reproduction control signal (PB.CTL). T ₁ , T ₂ , T ₃ , and T ₄ are set. By writing the index write signal (WR.INDX) to the control track _TRC of the magnetic tape 2 via the control head 8, the control track _WRC becomes magnetized as shown in FIG. 5H, A control signal CTL with a duty ratio of, for example, 33% is recorded. Therefore, while the duty ratio of the normal control signal CTL is 50%, the duty ratio of the control signal during the period Tw is 33%, thereby making it possible to indicate index information.
As shown in Figure 5, the playback control signal (PB.CTL) when the above duty ratio is changed is that the timing of the generation of the falling differential pulse is shifted, but the timing of the generation of the rising differential pulse is not. There is no adverse effect on the servo control state of the traveling system. Furthermore, the above index information can be written in correspondence with any recording section of the main signal using an index write command signal.

Additionally, the index information written as described above is sent to the index erase command signal (INDX.
By supplying ER) to the fourth signal input terminal 34, the data can be erased by the operation shown in the time chart of FIG.

That is, by changing the duty ratio, a control signal given index information is recorded, and an index erase command signal (INDX.ER) corresponding to the section of the magnetized control track _TRC as shown in FIG. 6A is generated. When supplied to the fourth signal input terminal 34, the sixth monostable multivibrator is activated after a period _T1 + _T5 elapses from the timing of the rising differential pulse of the reproduction control signal (PB.CTL) as shown in FIG. 6B. 46 is triggered and an index erase signal (ER.INDX) with a pulse width of _T6 is output. Figure 6D
shows the output signal from the first monostable multivibrator 42, and FIG. 6E shows the output signal from the second monostable multivibrator 42. The operations of the first and second monostable multivibrators 41 and 42 are similar to the time chart in FIG. 5 described above. Further, the fifth monostable multivibrator 45 is triggered at the timing of the trailing edge (falling edge in this example) of the output signal from the first monostable multivibrator 41, and as shown in FIG. Outputs an output signal with a pulse width of ₅ . Here, the predetermined time T _E specified by the index erase command signal (INDX.ER) is
are set longer than the predetermined period Tw by the index write command signal, and the pulse width T ₅ of each output signal from the fifth and sixth monostable multivibrators 45, 46.
T ₆ is set so that T ₅ <T ₃ T ₁ +T ₅ +T ₆ =T ₀ . That is, the index signal from the sixth monostable multivibrator 46 includes the generation timing of the falling differential pulse of the reproduction control signal (PB.CTL), and also includes the generation timing of the falling differential pulse of the regular control signal. It is set to fall. The above index erase signal (ER.
By writing INDDX) into the control track _TRC , the magnetization state of the control track _TRC is changed to the duty ratio as shown in FIG. 6H.
Return to the state where the normal control signal CTL of 50% was recorded. Therefore, it becomes possible to reproduce the reproduction control signal (PB.CTL) as shown in FIG. 6 with the index information erased.

Furthermore, in this embodiment, during the operation periods Tw and _TE for writing and erasing the index information,
Since the muting circuit 25 is activated to mute the reproduced audio signal (PB.Audio), the index write signal (WR.Audio) is muted.
INDX) and index erase signal (ER.
INDX) is supplied to control head 8,
Noise due to crosstalk between the control head 8 and the audio head 7 can be prevented from being outputted via the regenerative amplifier 22. The control head 8 normally records a rectangular wave signal in saturation, so when a signal is supplied to the control head 8 when reproducing the main signal, the signal is transmitted via the audio head 7 to the reproduced audio signal (PB.
There is a high possibility that the signal will be superimposed on the audio). If an unnecessary signal is superimposed on the reproduced audio signal (PB.Audio), it will be output as noise.

In addition, the above playback audio signal (PB.Audio)
To apply muting to the regenerative amplifier 22
The gain or frequency characteristics may be controlled.

As described above, in this embodiment, index information can be written corresponding to any recording section of the main signal, and unnecessary index information can be erased. Moreover, since the index information is given by changing the duty ratio of the control signal, it can be written without providing a recording track dedicated to the index. Furthermore, since the reproduced audio signal is muted during the writing and erasing operations of the index information, no unpleasant noise is output.

As described above, according to the present invention, the main signal and the control signal are independently recorded and reproduced, and the duty ratio of the control signal recorded on the control track of the magnetic recording medium is made different from the normal value. In a magnetic recording/reproducing device in which a recording signal is supplied to a control signal recording means during an arbitrary period during the main signal reproduction operation, a muting means is provided in the main signal reproduction output system, and a muting means is provided in the reproduction output system of the main signal, so that the control signal is outputted from the recording signal. By applying muting to the main signal during the period in which the duty ratio is changed, index information can be recorded corresponding to any recording section of the main signal without requiring a recording track dedicated to index information. It is possible to prevent unpleasant noise from being output as an audio signal during the writing operation.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing a configuration example of a tape running system in a video tape recorder to which the present invention is applied. FIG. 2 is an external perspective view showing the structure of an audio head and a control head disposed in the tape running system. FIG. 3 is a plan view schematically showing the recording format of the magnetic tape run in the tape running system. FIG. 4 is a block diagram showing the circuit configuration of a main part of an embodiment in which the present invention is applied to the video tape recorder. FIG. 5 is a time chart for explaining the index information writing operation in the above embodiment. FIG. 6 is a time chart showing the index information erasing operation in the above embodiment. DESCRIPTION OF SYMBOLS 1... Rotating magnetic head device, 2... Magnetic tape, 3, 4... Tape reel, 5... Guide pin, 6... Full width erasing head, 7... Audio head, 8... Control head, 11, 12 ，
13, 14... Switch circuit, 21, 23... Recording amplifier, 22, 24... Reproducing amplifier, 25...
Muting circuit, 31, 32, 33, 34,
35...Signal input terminal, 41, 42, 43, 4
4, 45, 46... Monostable multivibrator, 47, 49... OR gate, TR _V ...
Video track, TR _A ...Audio track,
TR _C ...Control track.

Claims (1)

[Claims] 1 Equipped with a function to independently record and reproduce the main signal and the control signal, the recording signal that makes the duty ratio of the control signal recorded on the control track of the magnetic recording medium different from the normal value is recorded during the reproduction operation of the main signal. In a magnetic recording/reproducing device configured to supply a control signal to a recording means during an arbitrary period, a muting means is provided in the main signal reproduction output system, and during a period when the duty ratio of the control signal is changed by the recording signal. A magnetic recording/reproducing device characterized by applying muting to a main signal.