JPH0363272B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention forms an inclined recording track on a magnetic tape using two rotating magnetic heads having different gap inclination angles (hereinafter referred to as azimuth angles). Regarding a helical scan type magnetic recording/reproducing device for reproducing signals from such inclined recording tracks, in particular, inclined recording tracks are sequentially and alternately formed on a magnetic tape with their side edges overlapping, and tracks having different azimuth angles are used. 1st and 2nd
a rotating magnetic head having a similar azimuth angle as the first of these and located adjacent to a second rotating magnetic head;
The present invention relates to a magnetic recording and reproducing apparatus provided with a third magnetic head section used during variable speed reproduction.

BACKGROUND TECHNOLOGY AND PROBLEMS When recording signals using a two-head, helical scan type magnetic recording and reproducing device widely used in home video tape recorders, two rotating recording tracks are placed on the magnetic tape. Alternately formed by magnetic heads. In this case, in order to increase the recording density on the magnetic tape, gaps, so-called guard bands, are not placed between adjacent recording tracks, and the recording tracks that are arranged in sequence are adjacent to each other. Adjacent track crosstalk disturbances at times are generally reduced by having the two rotating magnetic heads having different azimuth angles. Also, when playing,
In addition to normal playback, which is performed by keeping the relative speed of the rotating magnetic head to the magnetic tape the same as during recording, variable-speed playback such as still playback and double-speed playback is performed; however, in the case of variable-speed playback, the rotating magnetic head This results in scanning at an angle different from the inclination angle of the track. Therefore, in order to efficiently obtain signal reproduction output from the recording track during such variable speed reproduction, the effective track width of the recording track formed on the magnetic tape is set to be less than or equal to the gap width of the rotating magnetic head. In that case, as the inclined recording tracks are formed one after another, the side edges of one recording track overlap with the side edges of the next recording track, so that one recording track is The width of the track is narrowed by the next recording track to determine the effective track width.

In the magnetic recording and reproducing apparatus that forms a tilted recording track on a magnetic tape as described above, a new tilted recording track is formed on a part of the magnetic tape on which a tilted recording track has already been formed, overlapping the recording track formed there. When insert recording is performed by overwriting to form a recording track,
At the end of the insert recording portion, a portion occurs where the effective track width of the recording track changes. Figure ₁ shows how the effective track width changes on the magnetic tape.
_.about.t3 represents a recording track formed before insert recording, and _{T.sub.o-4.about.T.sub.o represents} a new recording track formed by overwriting by insert recording. Further, arrow h indicates the scanning direction of the rotating magnetic head, and arrow r indicates the running direction of the magnetic tape. Furthermore, W _p represents the recording track width corresponding to the gap width of the rotating magnetic head, and W _e represents the effective track width that ultimately remains on the magnetic tape. In this way, the side edges of each recording track overlap, but the last recording track T _o of the new recording tracks T _o-4 to _{T o} formed by insert recording overlaps with the adjacent recording track T o. Since the width is not narrowed by the track, its effective track width W _e is as wide as the recording track width W _p , while the recording track formed before insert recording, which is the next recording track after the recording track T _o , is The recorded track _t1 has both side edges narrowed by the recorded track _t2 and the recorded track _To , and its effective track width _We becomes a narrow width We _' .

When a magnetic tape on which insert recording has been performed by overwriting in this manner is reproduced, the reproduction output level obtained from the rotating magnetic head varies in accordance with the effective track width. Fig. 2 shows the situation of fluctuations in the reproduction output level, and in Fig. 2, ST _o-4 to _{ST o} are
The recording tracks T _o-4 to _{T o} shown in FIG.
represents the reproduced signal obtained from St ₁ to _{St 3} ,
Each represents a reproduced signal obtained from recording tracks t ₁ to _{t 3} shown in FIG. 1, respectively. In this way, the level of the reproduced signal ST _o obtained from the recording track T _o with a wide effective track width is high, and the level of the reproduced signal St ₁ obtained from the recording track t ₁ with a narrow effective track width is small. I become confused. Here, there is no problem with the reproduced signal ST _o whose level is high, but there is no problem with the reproduced signal whose level is low.
As for St _1, the problem arises that the signal-to-noise ratio becomes extremely degraded, or that St 1 itself becomes a noise component in the entire reproduced signal.

In particular, two rotating magnetic heads having different azimuth angles from each other forming an inclined recording track on a magnetic tape, i.e., two rotating magnetic heads having the same azimuth angle as the first rotating magnetic head of the first and second rotating magnetic heads. and a third rotating magnetic head disposed in close proximity to the second rotating magnetic head;
When performing slow playback or frame-by-frame playback in variable speed playback during playback, the first and third rotating magnetic heads described above are used to form a recording track on the magnetic tape with the first rotating magnetic head. Only every other one that has been scanned is repeatedly scanned to obtain a reproduced output, but in such a case,
When the above-mentioned recording track t ₁ whose effective track width _We is narrow width We _′ is scanned by the first and third rotating magnetic heads, the reproduction signal St ₁ whose level is small is Since it is used repeatedly, there is an inconvenience that the quality of the reproduced image deteriorates significantly.

OBJECTS OF THE INVENTION The present invention provides a first, second and third rotating magnetic head portion corresponding to the first, second and third rotating magnetic heads as described above, and a magnetic tape. and the recording track formed by the first rotating magnetic head is repeatedly scanned by the first and third rotating magnetic head for the portion where insert recording by overwriting has been performed by the second rotating magnetic head. It is an object of the present invention to provide a magnetic recording and reproducing device which prevents significant deterioration in the quality of a reproduced image when variable speed reproduction is performed to obtain a reproduction output.

SUMMARY OF THE INVENTION A magnetic recording/reproducing apparatus according to the present invention includes first and second rotating magnetic heads having different azimuth angles, which sequentially and alternately form inclined recording tracks on a magnetic tape with their side edges overlapping. and a third rotating magnetic head section having the same azimuth angle as the first rotating magnetic head section and located close to the second rotating magnetic head section. , the first and third rotating magnetic head sections allow a state in which reproduction output is obtained only from the recording track formed by the first rotating magnetic head section. When the first and second rotating magnetic head sections perform insert recording by overwriting onto a magnetic tape on which a tilted recording track has already been formed, the first and second rotating magnetic head sections perform insert recording by overwriting. The supply of the recording signal is controlled according to the contact status of the first and second rotating magnetic heads with the magnetic tape,
A final inclined recording track by insert recording is formed by the first rotating magnetic head.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 3 and 4.

FIG. 3 shows a main part of an example of a magnetic recording/reproducing apparatus according to the present invention. In this example, terminal 1 is an input terminal to which a recording signal, for example a video signal, is supplied.
This terminal 1 is connected to the input terminal of the recording amplifier 2,
Its output end is connected via a recording signal supply switch 3 to recording side contacts R of two interlocking recording/reproduction changeover switches 4 and 5, respectively. record/
Reproduction side contacts P of each of reproduction selector switches 4 and 5
are connected to the input terminals of regenerative amplifiers 6 and 7, respectively. The output terminals of the regenerative amplifiers 6 and 7 are connected to the first
The movable contacts of the first head changeover switch 8 are connected to the playback output terminal 9. Further, the movable contact of the recording/reproduction changeover switch 4 is connected to the first rotating magnetic head section a, and the movable contact of the recording/reproduction changeover switch 5
The movable contact is selectively connected to the second rotating magnetic head section b or the third rotating magnetic head section a' via the second head changeover switch 10. Here, the first rotating magnetic head section a and the second rotating magnetic head section b have different azimuth angles, and during recording or reproducing operation, the magnetic tape as a recording medium is They are placed in alternating contact with each other with a slight overlap period. Further, the third rotating magnetic head section a' has the same azimuth angle as the first rotating magnetic head section a, and is located very close to the second rotating magnetic head section b.

The terminal 11 is a control input terminal to which a switching signal SP is supplied that changes in accordance with the state of contact of the first and second rotating magnetic heads a and b with the magnetic tape. It is connected to the control terminal of the head changeover switch 8, and also connected to the control terminal of the head changeover switch 8, and also connected to the control end of the D-flip-flop circuit (hereinafter referred to as D-FF) 12.
Connected to the clock terminal CL of the One of the control output terminals of the operation control section 13 is connected to the data terminal D of the D-FF 12, and its output terminal Q is connected to the control terminal of the recording signal supply switch 3. Furthermore, another one of the control output terminals of the operation control section 13 is connected to the control terminal of the recording signal supply switch 3.

In such a configuration, when normal recording is performed, a control signal N is issued from the operation control section 13 and supplied to the control end of the recording signal supply switch 3, and the recording signal supply switch 3 is turned on. will be maintained. In addition, record/playback switch 4
and 5 are connected to the recording side contact R, and furthermore, the second head changeover switch 10 connects the movable contact of the recording/reproduction changeover switch 5 to the second rotating magnetic head section b. The state is set to connect.

As a result, after the recording signal from the terminal 1 is amplified by the recording amplifier 2, the recording signal supply switch 3,
The first and second head switching switches 4 and 5 and the second head switching switch 10
is supplied to the rotating magnetic heads a and b. Then, each time the first and second rotating magnetic heads a and b come into contact with the magnetic tape, an inclined track is formed on the magnetic tape and recorded.

In addition, when normal playback is performed, the recording/
Only playback selector switches 4 and 5 are switched,
These movable contacts are connected to the playback contact P, respectively. At this time, the first head changeover switch 8 is controlled by the above-mentioned changeover signal SP from the terminal 11, and the first rotating magnetic head section a
The output end of the regenerative amplifier 6 is connected to the reproducing output terminal 9 during the period when the second rotating magnetic head part b is in contact with the magnetic tape, and the output end of the regenerative amplifier 7 is connected to the reproducing output terminal 9 during the period when the second rotating magnetic head part b is in contact with the magnetic tape. It is connected to terminal 9.

As a result, the playback output obtained when the first rotating magnetic head section a comes into contact with the magnetic tape is supplied to the playback amplifier 6 via the recording/playback switch 4, and The playback output obtained when the head comes into contact with the magnetic tape is transmitted to the second head changeover switch 10 and the recording/playback changeover switch 5.
The signal is supplied to the regenerative amplifier 7 via. The outputs of these regenerative amplifiers 6 and 7 are alternately taken out by a first head changeover switch 8, and a reproducing signal is obtained at a reproducing output terminal 9. In this case,
When the first rotating magnetic head section a comes into contact with the magnetic tape, the recording track formed by the first rotating magnetic head section a or an equivalent head section is thereby scanned, and the recording track formed by the first rotating magnetic head section a or an equivalent head section is scanned. When the head part b comes into contact with the magnetic tape, the recording track formed by the second rotating magnetic head part b or a corresponding head part is thereby scanned.

Furthermore, when variable-speed playback such as slow playback or frame-by-frame playback is performed, the state is the same as when the above-mentioned normal playback is performed, but the second head changeover switch 10 is switched and the third The rotating magnetic head section a' of the recording/reproducing switch 5 is connected to the movable contact of the recording/reproducing switch 5. Therefore, in this case, in terms of circuit operation, the third rotating magnetic head section a' is used in place of the second rotating magnetic head section b in the state where the above-mentioned normal reproduction is performed. However, the running state of the magnetic tape is changed, and the first and third rotating magnetic head sections a and a' are moved to the first rotating magnetic head section a on the magnetic tape, or the first rotating magnetic head section a on the magnetic tape. The same recording track formed by the corresponding head section is repeatedly scanned. Therefore, in this case, the second rotating magnetic head part b on the magnetic tape,
Alternatively, the recording track formed by the corresponding head section will not be used.

Next, the first and second rotating magnetic heads a
and b, or when insert recording by overwriting is performed on a magnetic tape on which an inclined recording track is formed by a head section corresponding to these, except for the recording signal supply switch 3,
The other conditions are the same as those in the case of normal recording described above. In this case, a control signal IN is generated from the operation control section 13 instead of the control signal N, and is supplied to the data terminal D of the D-FF 12. In addition, the above-mentioned switching signal SP from terminal 11
is supplied to the clock terminal CL of the D-FF12.

For example, as shown in FIG. 4A, the control signal IN takes a high level H during a period when insert recording is to be performed, and takes a low level L during other periods. In addition, the switching signal SP is, for example,
As shown in FIG. 4B, the level H is high during the period when the first rotating magnetic head a is in contact with the magnetic tape, and the level H is low during the period when the second rotating magnetic head b is in contact with the magnetic tape. shall be taken.
The D-FF 12 has an output that maintains a level corresponding to the level of the signal supplied to the data terminal D at each point in time when the signal supplied to the clock terminal CL changes from a high level to a low level. It is assumed that a signal is produced at its output terminal Q.

Therefore, in this case, the output terminal Q of D-FF12
As shown in FIG. 4C, after the time when the control signal IN falls from a high level to a low level, the control signal IN continues until the first time x when the switching signal SP falls from a high level to a low level. takes a high level H corresponding to the high level H of , and after time x, the control signal IN
An output signal IS is obtained which takes a low level L corresponding to the low level L of . Therefore, the time point x when the output signal IS falls from a high level to a low level is the time point when the switching signal SP falls from a high level to a low level, that is, when the first rotating magnetic head section a is It will coincide with the end of one period of contact with the tape. This output signal IS is then supplied to the control end of the recording signal supply switch 3, whereby the recording signal supply switch 3 is turned on when the output signal IS takes a high level H, and takes a low level L. When it is turned off.

By controlling the recording signal supply switch 3 as described above, the output signal IS from the D-FF 12 is
Only when the signal is at a high level, the recording signal from the terminal 1 is supplied to the first and second rotating magnetic heads a and b, and insert recording by overwriting is performed. Then, the output signal IS from D-FF12
The time point x of the fall from the high level to the low level is
Since this coincides with the end of one period in which the first rotating magnetic head a is in contact with the magnetic tape, the insert recording state always ends with recording by the first rotating magnetic head a. It turns out. That is, the final inclined recording track by insert recording is formed by the first rotating magnetic head section a.

As a result, the new recording track formed by insert recording becomes the next recording track after the last recording track, and its effective track width is narrowed. The recording track _t1 in FIG.
It is formed by Therefore, when performing variable speed playback such as slow playback or frame-by-frame playback in which the playback outputs from the first and third rotating magnetic heads a and a' are used, the first rotating magnetic head Since the signal is reproduced only from the recording track formed by part _a , the effective track width is narrowed. Therefore, the reproduced image will not be adversely affected.

Note that the second and third rotating magnetic head portions b and
In the above example, a' is provided with an independent rotating magnetic head, but these second and third rotating magnetic head parts b and a' have different azimuth angles. It may also consist of an integrated rotating magnetic head with two gaps.

Effects of the Invention As is clear from the above description, according to the magnetic recording/reproducing apparatus according to the present invention, the side edges of adjacent inclined recording tracks formed on a magnetic tape overlap. By doing so, it is possible to achieve high-density recording and to efficiently obtain signal reproduction output during variable speed reproduction.Moreover, insert recording is performed by overwriting on the magnetic tape, which narrows the effective track width. When variable speed playback, such as slow playback or frame-by-frame playback, is performed on a portion where a recorded track occurs, the negative effect of the recording track whose effective track width is narrowed can be avoided, and the slow playback image or frame-by-frame playback can be avoided. Deterioration of image quality can be prevented.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining insert recording by overwriting on a magnetic tape, and FIG. 2 is a diagram for explaining signal reproduction from a portion of the magnetic tape where insert recording by overwriting has been performed. FIG. 3 is a block connection diagram showing essential parts of an example of a magnetic recording/reproducing apparatus according to the present invention, and FIG. 4 is a diagram used to explain the operation of the example shown in FIG. 3. In the figure, 3 is a recording signal supply switch, 4 and 5 are recording/reproduction changeover switches, 8 is a first head changeover switch, 10 is a second head changeover switch, 1
2 is a D-flip-flop circuit, 13 is an operation control section, a is a first rotating magnetic head section, b is a second rotating magnetic head section, and a' is a third rotating magnetic head section.

Claims (1)

[Claims] 1. First and second rotating magnetic heads having mutually different gap inclination angles, which are sequentially and alternately formed with inclined recording tracks on a magnetic tape with their side edges overlapping; and the first rotating magnetic head. A third rotary magnetic head section having a similar gap inclination angle and located close to the second rotary magnetic head section is provided so that the first and third rotary magnetic heads can A state is established in which reproduction output is obtained from the head section, and the first
During insert recording by overwriting on a magnetic tape on which a tilted recording track has already been formed, which is performed by the second rotating magnetic head section, the final tilted recording track by insert recording is performed by the first rotating magnetic head section. A magnetic recording/reproducing device made to be formed.