JPH0695406B2 - Magnetic recording / reproducing device - Google Patents

Description

The present invention relates to an oblique scanning type magnetic recording / reproducing apparatus, that is, a VT for recording / reproducing a composite video signal or information signal including a synchronization signal.
More specifically, regarding the R (video tape recorder), a tape position marking signal (queue signal) suitable for performing a cue operation for obtaining a stop mode, a still image mode, etc. at a predetermined position on the tape is recorded and reproduced. The present invention relates to a magnetic recording / reproducing device having a function.

Conventional commercial VTR magnetic tapes are often provided with two audio tracks. Therefore, when two audio tracks are provided, a tape position marking signal (queuing signal) for cueing may be recorded on one audio track. in this case,
The audio signal in the portion where the marking signal was recorded is erased, but there was no audio track because there was another audio track.

However, since a small VTR tape generally has only one audio track, if the marking signal is recorded on the audio track, the audio signal is erased. Therefore, if the audio signal is not desired to be erased, the marking signal cannot be recorded. In order to solve this kind of problem, it is possible to provide a dedicated track for recording the marking signal, but inevitably
VTR becomes large, complicated and expensive.

On the other hand, recording a marking signal (cue signal) on a control track together with a control signal is disclosed in, for example, Japanese Patent Publication No. 54-23804. However, a magnetic recording / reproducing apparatus capable of accurately and easily writing a marking signal so that it can be clearly distinguished from a control signal has not yet been proposed.

Therefore, an object of the present invention is to provide a magnetic recording / reproducing apparatus in which a marking signal can be accurately written so as to be clearly distinguished from a control signal, and this writing can be easily achieved.

In order to achieve the above object, the present invention provides a control track extending in the longitudinal direction of the magnetic tape by obliquely scanning the magnetic tape with a rotary head to record and reproduce a composite video signal or information signal including a synchronization signal. Oblique scanning type magnetic recording / reproducing apparatus having a structure in which a fixed control head scans to record and reproduce a control signal corresponding to the synchronizing signal, and a marking signal indicating the position of the magnetic tape is recorded and reproduced on the control track. At a vertical sync signal separation circuit for separating the vertical sync signal from the composite video signal to be recorded, and one cycle (one field) of the vertical sync signal in response to the vertical sync signal separated by the vertical sync signal separation circuit. Has a pulse width that is long and shorter than two periods (one frame) of the vertical synchronization signal, and A pulse signal generating circuit for generating a rectangular wave whose edge is separated from the vertical synchronizing signal by a predetermined distance as a recording control signal and supplying the recording control signal to the control head in the recording mode, and the marking signal. A marking instruction signal input terminal for inputting a marking instruction signal for instructing recording on the control track, and a predetermined time width of 4 cycles (2 frames) or more of the vertical synchronization signal in response to the marking instruction signal. The marking signal recording section instruction pulse generating circuit for generating a marking signal recording section instruction pulse, the recording control signal pulse generating circuit, and the marking signal recording section instruction pulse generating circuit are connected to the marking signal recording section instruction pulse Within the occurrence period A recording signal which is generated twice or more and is supplied to the control head, wherein the marking signal is within the period from the trailing edge of the recording control signal pulse to the next vertical synchronizing signal. The present invention relates to a magnetic recording / reproducing apparatus, comprising: a marking signal generating circuit which is set so as to be generated at a predetermined time position where it does not interfere with the leading edge of the working pulse.
Incidentally, explaining the correspondence relationship between the present invention and the embodiment, the recording control signal pulse generation circuit is a mono multivibrator 13, the marking signal recording section instruction pulse generation circuit is a mono multivibrator 15, the marking signal generation circuit An input inverting AND gate 16 and a mono-multi-vibrator 17, 18.

The present invention has the following effects.

(B) Since the recording control signal pulse generation circuit is provided, the trailing edge of the recording control signal pulse is separated from the vertical synchronizing signal by a predetermined interval, and the marking signal is arranged with the trailing edge of this pulse as a reference, so that during playback, It is possible to accurately achieve the distinction between the marking signal and the leading edge of the control signal.

(B) Since a marking signal recording section instruction pulse having a predetermined time width is formed in four or more cycles (2 frames) of the vertical synchronization signal and the marking signal is recorded twice or more within this section, the marking signal is recorded plural times. Repeated recording can be achieved accurately and easily.

Next, a VTR according to an embodiment of the present invention will be described with reference to FIGS.

The VTR of this embodiment is a general-purpose small VTR of a diagonal scanning type for home use.
A mechanism for pulling out the tape (1) from a cassette (not shown), a drum for obliquely guiding the tape (1), a head drum for rotating a pair of video heads, a capstan, a pinch roller, and a reel drive mechanism. Etc. are provided. In addition to the diagonal video track (2), the tape (1) has one audio track (3) and one control track (4) extending in the longitudinal direction of the tape (1). A fixedly arranged audio head (5) faces the audio track (3), and a fixedly arranged control head (6) faces the control track (4). still,
Audio Head (5) and Control Head (6)
Are arranged in the horizontal running section of the tape (1), so that the tape is scanned horizontally along the tape running direction indicated by the arrow (7). On the other hand, since the video head (not shown), that is, the rotary head, comes into contact with the tape (1) running obliquely while being rotated by the head drum, it scans obliquely as shown by the arrow (8).

(9) is a head drum servo circuit for controlling a head motor (not shown) for rotating the video head, which is controlled by a control signal. (Ten)
Is a tape running control circuit that controls the tape running system such as reel motor, capstan, etc. to the state according to each mode such as forward constant speed running, forward fast forward, backward fast forward, still image, stop, etc. is there. Therefore, the tape running control circuit (10) sets each mode in response to a manual mode setting operation switch, and also responds to a tape position marking signal (queuing signal) related to the present invention. Set the still image mode, etc.

A control signal recording circuit and a marking signal recording circuit are connected to the control head (6) in order to obtain a reproduction control signal and a reproduction marking signal to be supplied to the head drum servo circuit (9) and the tape running control circuit (10). Further, the control signal and the marking signal detection circuit are connected.

The control signal recording circuit includes a vertical sync signal separation circuit (12) connected to an input terminal (11) to which an NTSC composite video signal is input, and a second circuit obtained from the separation circuit (12).
FIG. 2B in response to the leading edge of the vertical sync signal of FIG.
And a first mono-multivibrator (13) indicated by MMV that generates a rectangular wave with a pulse width of T _{2 in} the period T ₁ .

Marking signal recording circuit, the second for generating a negative pulse width T ₃ of t ₂ ~t ₉ shown in Figure 2 in response to a trigger signal supplied from the marking trigger signal input terminal (14) (C) NO that inputs the mono multivibrator (15) and the inverted outputs of the two mono multivibrator (13) (15) respectively
Inverting type AND gate with R gate function (16)
And a third mono-multivibrator (17) which is triggered by the leading edge of the output pulse of FIG. 2 (D) obtained from the gate (16) to generate a pulse of the time width T ₄ of FIG. 2 (E). )
And a fourth mono-multivibrator (18) which is triggered by the trailing edge of the pulse obtained from this mono-multivibrator (17) to generate a recording marking signal of the time width T ₅ shown in FIG. 2 (F). . In order to combine the recording control signal and the recording marking signal and supply them to the control head (6), an OR gate (19) to which both signals are input is provided, and this gate (19) is a capacitor (2).
0) to the control head (6). Further, in order to enable the marking signal to be recorded in both the recording mode and the reproduction mode, the first switching switch (21) is provided between the first mono-multivibrator (13) and the OR gate (19). ) Is provided, one input line of the OR gate (19) is connected to the first mono-multivibrator (13) via the contact REC in the recording mode, and is grounded via the contact PB in the reproducing mode. . A second switching switch (22) interlocking with the switch (21) is provided between the output terminal of the first mono-multivibrator (13) and one input terminal of the input inverting type AND gate (16). , In the recording mode, the output of the mono-multivibrator (13) is input inverting type AND gate (1
6), and in the playback mode, the signal indicating the marking signal section determined based on the playback output is input via the contact PB.

The control signal and marking signal detection circuit includes a forward direction amplifier (23) coupled to the control head (6), a reverse direction inverting amplifier (24), and an amplifier (23) with a contact FWD when traveling in the forward direction. Output and the switching switch (25) that selects the output of the inverting amplifier (24) at the contact REV when traveling in the reverse direction, and the negative differential pulse formation extraction circuit (26) connected to the output stage of this switch (25). ) And the positive differential pulse formation and extraction circuit (27) and the negative differential pulse formation and extraction circuit (26) in response to the pulse of FIG. 2 (I), the time width T ₆ shown in FIG. A fifth pulse-width-variable mono-multivibrator (28) for generating a pulse, an inverter (29) for inverting the output of the mono-multivibrator (28) to obtain the output of FIG. 2 (K), and a second Figure (J)
AN for control signal detection to which the output of the fifth mono-multivibrator (28) and the output of the positive differential pulse formation extraction circuit (27) shown in FIG.
The output of the D gate (30), the inverter (29) of FIG. 2 (K), and the positive differential pulse formation extraction circuit (27) of FIG. 2 (L).
AND gate (31) for detecting a marking signal that receives the output of the AND gate and a second output gate of the AND gate (31).
A marking detection counter (3 that sends a marking detection output when three reproduction marking signals in Fig. (N) are detected.
2) consists of The output line of the counter (32) is connected to the tape running control circuit (10), and the AND gate (30)
The output line of is connected to the servo circuit (9), and
It is also connected to the contact PB of the switching switch (22) by the output line (33) of the mono-multivibrator (28). Further, there is provided a time constant variable resistor (34) for changing the output pulse width T ₆ of the fifth mono multivibrator (28) according to the tape speed during reproduction.

Next, the recording / reproducing operation of the marking signal and the control signal will be described.

If the marking signal is not recorded, the trigger signal will not be applied to the trigger input terminal (14), so that FIG.
The signals shown in (D), (E), and (F) are not generated. Therefore, only the control signal having the pulse width T ₂ shown in FIG. 2B is supplied to the control head (6) in the cycle T ₁ . The repetition frequency of the control signal in FIG. 2 (B) is set to the repetition frequency of the vertical synchronization signal (frame synchronization signal).
In order to halve, the pulse width T ₂ is set to be slightly larger than the period (about 16.6 msec) of the vertical synchronizing signal and smaller than the period T ₁ . As described above, when only the control signal is recorded, only the control signal is detected even in the reproducing mode, and the control signal is generated corresponding to the leading edge of the pulse in FIG. 2B. Is sent to the servo circuit (9).

When recording the marking signal in the recording mode, the marking trigger signal is supplied to the input terminal (14) at time t _{2 in} FIG. 2 in correspondence with the desired tape position. As a result, a negative pulse having a time width T ₃ (about 100 msec), which is about three times the period T ₁ of the control signal of FIG. 2 (B), is applied to the second mono-multivibrator (15) in the section from t ₂ to t _9. Arises from. Inverted input type AND gate (1
6) includes the first and second mono-multivibrator (13)
The output of (15), that is, the signals of FIGS. 2 (B) and (C) are input,
A logical product output of these inverted signals is provided as shown in FIG. The pulse of FIG. 2 (D) designates a section for recording the marking signal. In this embodiment, the time from the trailing edge of the control signal of FIG. 2 (B) to the leading edge of the next control signal. A positive pulse having a width occurs three times. Third Mono Multivibrator (17)
Is in response to the leading edge of the pulse of FIG. 2 (D).
Of the time width T ₄ is generated, and the pulse of the time width T ₅ shown in FIG. 2 (F) is generated from the fourth mono-multivibrator (18) in response to the trailing edge of this pulse. That is, the second
The recording marking signal is generated with a time width T ₄ delayed from the trailing edge of the control signal in FIG. Fig. 2 (B)
The recording control signal of FIG. 2 and the recording marking signal of FIG. 2 (F) are added by the OR gate (19) to become the signal of FIG. 2 (G), which is the control head (6).
Is recorded in the control track (4). That is, the marking signal is recorded in the vicinity of the trailing edge of the control signal so as not to interfere with the control signal.

When the tape (1) on which the marking signal is recorded is detected in the normal direction or at high speed (fast forward) in the forward direction and the marking signal is detected, the contact FWD of the switching switch (25) is closed to close the tape (1). Run in the forward direction and scan the control track (4) with the control head (6).
As a result, the reproduction output is obtained from the control head (6) in the state of the differential waveform shown in FIG. 2 (H). The playback output, which contains both the control signal component and the marking signal component, is connected to capacitor C ₁ , resistor R ₁ and diode D _1.
If the negative differential pulse formation extraction circuit (26) consisting of
The negative differential pulse shown in FIG. 2 (I) is extracted. That is,
It is possible to extract a pulse indicating time t ₄ corresponding to the trailing edge of the recording control signal. On the other hand, the positive differential pulse shown in FIG. 2 (L) is obtained at the output stage of the positive differential pulse forming / extracting circuit (27) consisting of the capacitor C ₂ , the resistor R ₂ and the diode D ₂ . That is, it is possible to obtain the output of FIG. 2 (L) that includes the differential pulses indicating the leading edge of the recording control signal and the leading edge of the recording marking signal, respectively. Fig. 2 (L)
Since it is necessary to separately detect the reproduction control signal at time t ₁ and the reproduction marking signal at time t ₅ ,
The negative differential pulse of FIG. 2 (I) triggers the fifth multivibrator (28), and the negative pulse having the time width T ₆ larger than the time interval t _{4 to} t ₆ of the two negative differential pulses is the first pulse. It occurs as shown in FIG. Then, the negative pulse of FIG. 2 (J) is inverted by the inverter (29), and the negative pulse of FIG. 2 (K) becomes the input of the AND gate (31). When the AND gate (31) is opened for the time of t ₄ to t ₇ , only the positive differential pulse at the time of t _{5 in} FIG. 2 (L) passes through it, and the output line of this AND gate (31) receives the first pulse. The reproduction control signal shown in FIG. 2 (N) is obtained. The time width T ₆ monostable multivibrator (28) because it is set to a value that does not reach the time t _8, never positive pulse t ₈ time passes AND gate (31). In this embodiment, since the marking signal is recorded three times, three marking pulses are generated as shown in FIG. 2 (N), and these are input to the marking detection counter (32) and the three marking pulses are the coefficients. When this is done, a marking detection output is generated, the tape running control circuit (10) enters, for example, the stop mode, and the cue or search of the desired recording portion is completed. On the other hand, since the signals shown in FIGS. 2 (J) and (L) are input to the control signal detecting AND gate (30), the reproduction marking signal cannot pass through the gate (30) at the time point t _5. Only the reproduction control signal at the time point ₁ and t ₈ is shown in FIG.
0) and is supplied to the head drum servo circuit (9).

When the tape (1) is run in the reverse direction and the marking signal is detected, the switching switch (25) is inserted into the contact REV. As a result, the output of the control head (6), which has become the opposite pole for traveling in the opposite direction, is returned to the same polarity as when traveling in the forward direction, and the marking signal and the control signal can be detected as in the case of traveling in the forward direction. I can.

When changing the tape speed when detecting the marking signal, the time constant of the fifth mono-multivibrator (28) is changed by the resistor (34) in conjunction with the change of the tape speed. The output pulse width T ₆ is kept in a constant relationship with the cycle of the reproduction control signal. That is, the time width T ₆ is set so that the marking signal at the time point t ₅ is extracted regardless of the change in the tape running speed.

When recording the marking signal in the reproduction mode, the switches (21) and (22) are respectively put into the contacts PB. As a result, the signal shown in FIG. 2 (J) and the signal shown in FIG. 2 (C) are input to the input inversion type AND gate (16), and as a result, the signal is shown by the dotted line in FIG. 2 (D). An output having such a pulse width is obtained, and based on this, the pulses shown in FIGS. 2 (E) and (F) are sequentially obtained, and the marking signal of FIG. 2 (F) is reproduced at the control head (6) during reproduction. Recorded in Control Track (4).

As is clear from the above, the device of this embodiment has the following advantages.

(A) Since the marking signal is recorded in the control track (4) together with the control signal, the marking operation, that is, the cue operation can be performed even with a VTR of a system having no marking signal recording track.

(B) Since the marking signal is formed by using the trailing edge of the recording control signal and is recorded, it is easy to record the marking signal without disturbing the control signal.

(C) Fifth mono-multivibrator during playback (28)
Since the output of is used for forming the marking signal, the marking signal can be easily recorded during reproduction. Therefore, it becomes possible to easily record the marking signal while watching the reproduced image.

(D) Since the time constant of the fifth mono-multivibrator (28) is changed in accordance with the change in tape speed, and the time width T ₆ of the output pulse is set to the marking signal detectable width,
The marking signal can be detected at tape speeds from low speed to high speed. Therefore, it is possible to locate the recording area by the marking signal at various tape speeds.

(E) Since it is possible to detect the marking signal even when traveling in the reverse direction, it is possible to quickly perform cueing or the like by the marking signal.

(F) Since the marking signal is recorded a plurality of times (three times) and the marking detection output is based on the detection of a plurality of times during reproduction, a highly reliable marking operation is possible.

The embodiment of the present invention has been described above, but the present invention is not limited to this, and can be further modified. For example, it is also applicable to the case where the video signal and the non-video information signal are alternately recorded, for example, every one horizontal scanning period or one vertical scanning period. It is also applicable to the case where non-video information such as measurement data is arranged and recorded in a television signal format. Further, a trigger signal for generating a marking signal may be generated at a constant cycle and the marking signal may be recorded in the control track (4) at a constant cycle. Further, not only one marking signal is generated at t ₅ as shown in FIG. 2 (N), but also a marking signal may be further generated in the vicinity thereof. Further, the marking signal may be a digital signal and may include information such as stop and still images.

[Brief description of drawings]

FIG. 1 is a block diagram showing a part of a VTR according to an embodiment of the present invention, and FIG. 2 is a waveform diagram showing the states of points A to N in FIG. In the reference numerals used in the drawings, (1) is a tape, (2) is a video track, (3) is an audio track, (4) is a control track, (6) is a control head, and (9) is a servo. Circuit, (10) tape running control circuit, (13) first mono-multivibrator, (14) marking trigger signal input terminal, (15) second mono-multivibrator, (16) input inversion AND
Gate, (17) is the third mono-multivibrator, (1
8) is a fourth mono-multivibrator, (19) is an OR gate, (21) and (22) are switching switches, (26) is a negative differential pulse formation extraction circuit, (27) is a positive differential pulse formation extraction circuit,
(28) is a fifth mono-multivibrator, (30) is a control signal detection AND gate, and (31) is a marking signal detection AND gate.

Claims (1)

[Claims] 1. A control head in which a control track extending in the longitudinal direction of the magnetic tape is fixed by recording and reproducing a composite video signal or information signal including a synchronizing signal by obliquely scanning the magnetic tape with a rotary head. A composite video to be recorded in an oblique scanning magnetic recording / reproducing apparatus configured to scan and record and reproduce a control signal corresponding to the synchronization signal, and record and reproduce a marking signal indicating the position of the magnetic tape in the control track. A vertical synchronization signal separation circuit for separating the vertical synchronization signal from the signal, and a vertical synchronization signal separation circuit which is longer than one cycle (one field) of the vertical synchronization signal in response to the vertical synchronization signal separated by the vertical synchronization signal separation circuit. It has a pulse width shorter than 2 cycles (1 frame) and the trailing edge is a vertical sync signal. A recording control signal pulse generation circuit that generates rectangular wave pulses separated by a predetermined interval as a recording control signal and supplies the recording control signal to the control head in a recording mode, and records the marking signal on the control track. Marking instruction signal input terminal for inputting a marking instruction signal for instructing that, and a marking signal recording section instruction pulse having a predetermined time width of 4 cycles (2 frames) or more of the vertical synchronization signal in response to the marking instruction signal. A marking signal recording section instruction pulse generating circuit, which is connected to the recording control signal pulse generating circuit and the marking signal recording section instruction pulse generating circuit,
The marking signal is generated twice or more during the generation period of the marking signal recording section instruction pulse and supplied to the control head, and the marking signal is generated next from the trailing edge of the recording control signal pulse. A marking signal generating circuit that is set to generate at a predetermined time position that does not interfere with the leading edge of the recording control signal pulse within the period up to the vertical synchronizing signal; Recording / playback device.