JPH026482Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a novel magnetic recording and reproducing device. Specifically, in an area near one edge of the magnetic tape, the audio signal is transferred to the extension of the video track.
A video tape recorder that can selectively employ two rotating heads to perform PCM modulation and record, and a fixed head to record on a track specific to the audio signal at one edge of the magnetic tape. (hereinafter referred to as "VTR"), etc., uses a magnetic tape on which audio signals have already been recorded using one of the above methods to record a new audio signal using the other method. Even if the audio signal is recorded and played back, it is possible to prevent the played audio signal from being interfered with by the previously recorded audio signal.
The present invention relates to a magnetic recording and reproducing device that has magnetic tape compatibility between the two.

Background technology and its problems In magnetic recording and reproducing devices, such as VTRs,
A video signal for images and an audio signal for audio are magnetically recorded on a magnetic tape. Conventionally, these signals are stored in a central area of the magnetic tape by a rotating head for video signals, and by a fixed head for audio signals. Generally, recording was performed by forming separate tracks on one edge area of a magnetic tape. Video tracks for recording video signals are often helical scan tracks that are scanned diagonally with respect to the feeding direction of the magnetic tape, and in addition, guards are placed between adjacent video tracks to increase recording density. An azimuth recording method is adopted in which the directions of the magnetic lines of force of the magnetic signals recorded on each adjacent video track are made different in order to remove the band and prevent crosstalk from occurring due to the removal of the guard band. It is becoming common to do so.

In addition, regarding the recording and reproduction of audio signals in VTRs, recently, each audio signal input to the VTR is first converted into a pulse code signal, and the code is magnetically recorded on a magnetic tape. is read out, converted into individual audio signals, and output.
Consideration has been given to adopting the PCM recording method. This PCM recording has several advantages, such as being resistant to noise and not picking up tape hiss.

By the way, there are at least two possible ways to record audio signals. One method uses a fixed head to record a linear audio signal on one edge of the magnetic tape, and the other uses a rotating head to record PCM modulation on an area extending from the video track. This is a method to record the recorded audio signals. Therefore, the audio signal recording method may differ depending on the VTR format, which causes problems in magnetic tape compatibility. This problem will be explained in detail with reference to the drawings.

FIGS. 1 and 2 show an example of a recording pattern of a magnetic tape in which audio signals are recorded using a VTR capable of PCM recording using a rotating head.

In the figure, a indicates a magnetic tape. b is an audio track unique to a fixed head prepared for recording audio signals along one edge of magnetic tape a with a fixed head; When used, a linear audio signal is recorded on audio track b by a fixed head. c is a control track. d, d, . . . and e, e, . . . are video tracks formed in the central area in the width direction of the magnetic tape and partitioned into strips at a certain inclination angle with respect to the tape feeding direction f. There are two rotary heads installed in a rotary head cylinder (not shown) to control the tracks d and d for the first channel.
d, ... and tracks e, e, for the second channel.
. . . are sequentially and alternately forming tracks, each recording a video signal for one video field. The gap of the rotary head for recording video signals on each video track d, d, . . . and e, e, . . . is perpendicular to the scanning direction of the video tracks d, d, . The rotating head for recording on the video tracks d, d, . . . and the rotating head for recording on the video tracks e, e, . It is said to be at a different angle. That is, g indicates the direction of the gap of the rotating head for the first channel, and h indicates the direction of the gap of the rotating head for the second channel. As an example, the direction g of the head gap for the first channel is the track d, d, . . . and e, e, .
has an angle j of 10 degrees clockwise with respect to a straight line i extending in a direction perpendicular to the scanning direction of
The direction h of the channel head gap has an angle k of 10 degrees counterclockwise with respect to the straight line i. These angles j and k are the azimuth angles, and the video tracks d, d,
This angle is provided to prevent mutual crosstalk between the video signals recorded on the video tracks e, e, . . . for the second channel. l, l, ... and m,
m, . . . are formed in the extension area of each video track d, d, . . . and e, e, . 1 shows a PCM audio track on which audio signals are recorded.

In this way, according to the recording pattern of a magnetic tape recorded using a VTR in which a PCM audio signal is recorded in an area extending from the video track by a rotating head, the video track is recorded in the central area of the magnetic tape a. It is formed from the vacant recording area prepared for PCM audio tracks l, l, . . . and m, m, .

However, the magnetic tape a on which each signal has been recorded in this way is transferred to another VTR, that is, a rotating head.
PCM audio tracks l, l, ... and m,
If you use a VTR that does not form m,... and play back each signal that has already been recorded, the corresponding
Reproduction of video signals in a VTR involves PCM audio tracks l, l, ... and m, m, ... of the recording pattern on magnetic tape a and video signals d, d, ... and e, e, ... Since this is done over both tracks, the signal read from magnetic tape a for one screen includes the PCM audio signal, and therefore the signal read in this way is used to reproduce the signal. The video ends up with part of the screen completely missing.

This situation can occur if the above magnetic tape compatibility is reversed, that is, in the recording pattern shown in FIG. The video signal is transferred to the PCM audio track l,l, by means of a rotating head.
...and m, m, ... and video tracks d, d,
. . . and e, e, . . . on a magnetic tape recorded using a VTR that forms a video track for one field of video.
When playing back using the above-mentioned VTR, ie, a VTR that records PCM audio using a rotary head, the video will similarly have a portion of the playback screen missing.

Therefore, in order to avoid such an inconvenient situation, no matter which type of VTR is used, the video track has an area on the extension of the video track where the audio signal is optionally recorded, that is, the area where the audio signal is arbitrarily recorded. If the selective audio track area n shown as n in Figure 1 is left open, then
Any format with different audio recording methods
Even if a magnetic tape has a video signal recorded thereon by a VTR, a predetermined image can be obtained by reproducing the video signal.

However, when the above is done, if recording is made using a VTR in a format that does not allow PCM audio recording with a rotary head in the area n for the optionally recorded audio track, the optional The audio track area n becomes a waste area where no magnetic recording is performed. Therefore, in preparation for such a case, in a VTR that does not allow recording of PCM audio signals on an extension of the video track using a rotating head,
With fixed head specific audio track b,
It is conceivable to record a linear or PCM audio signal with a fixed head also in area n for the selective audio track. This not only makes it possible to effectively utilize the vacant selection audio track area n, but also improves the stability of the magnetic force of the audio signal recorded there by significantly increasing the track width of the formed audio track. This is also reasonable as it can improve the performance.

However, doing so creates another problem. For example, if some audio signal (such as a linear audio signal) is previously recorded in the selection audio track area n by a fixed head using the other VTR mentioned above, then the magnetic tape Using,
PCM audio recording is performed on the selection audio track area n using a rotary head, and the
When playing a PCM audio signal, other
The problem is that the audio signals recorded by the VTR are interfered with, resulting in a large error rate. In other words, when recording video signals and PCM audio signals using a rotating head on a VTR that will be recorded later, if the previously recorded audio signals are recorded without erasing them (dub-recording), residual magnetism may be present. This is because they are doing so.

Moreover, this error rate differs significantly between different PCM audio tracks l, l, . . . and m, m, . . . recorded and reproduced by different rotary heads. This is because, as mentioned above, the directions of the gap of each rotary head have different azimuth angles j and k, so the direction of the gap of one rotary head g and the direction h of the gap of the other rotary head are different from each other. This is because the direction of the gap of the fixed head used for recording, that is, the degree of approximation to the direction indicated by o in FIG. 1 is different.
An example of this error rate difference is shown in FIG.
In the figure, p indicates the error rate curve of the PCM audio signal reproduced by the rotating head for the first channel, and q indicates the error rate curve of the PCM audio signal reproduced by the rotating head for the second channel. As is clear from the curves p and q, the level of error rate is extremely different depending on the rotating head.

In this way, the error rate in one PCM audio track l, l, ... and the error rate in the other PCM audio track l, l, ...
If the error rates of PCM audio tracks m, m, .

Purpose of the invention The present invention was devised in view of the above-mentioned problems, and is capable of recording audio by selectively employing either recording using a rotating head or recording using a fixed head on an extension of the video track on a magnetic tape. Using a magnetic tape with a recording pattern on which an audio signal has been previously recorded by either a fixed head or a rotary head, the recorded audio signal is transferred to a selective audio track area prepared for recording. Reproduction that occurs when an audio signal is overwritten by one of the other heads above, and when the overwritten audio signal is reproduced, it is interfered with by the residual magnetism of the previously recorded audio signal. If the error rate of the signal can be sufficiently suppressed and the new recording/reproduction is performed by a rotating head, the level of the error rate should be made approximately equal in both rotating heads; Therefore, it is an object of the present invention to provide a magnetic recording/reproducing device that enables magnetic tape compatibility between VTRs with different audio signal recording methods.

Summary of the invention In order to achieve the above-mentioned purpose, the present invention has developed a method in which the audio signal is PCM-modulated and recorded by two rotating heads on an extension of the video track in an area near one edge of the magnetic tape. In a magnetic recording and reproducing apparatus that can selectively employ a method of recording audio signals on a track specific to an audio signal at one edge of the tape using a fixed head, the two rotating heads have different azimuth angles. Further, it is characterized in that it has a substantially equal azimuth angle with respect to the fixed head.

By doing this, it is possible to increase the recording density on the magnetic tape, improve the accuracy and stability of magnetic recording of audio signals, and make it possible to make magnetic tapes compatible with VTRs with different audio signal recording methods. Accordingly, it is possible to provide a magnetic recording and reproducing device with improved performance.

FIRST EMBODIMENT FIGS. 4 and 6 show the magnetic recording and reproducing apparatus of the present invention.
This shows an example of implementation applied to a VTR.

FIG. 4 shows an outline of the tape feeding mechanism, and numeral 1 indicates a magnetic tape. Reference numerals 2 and 3 denote tape reels, which are provided, for example, inside a tape cassette case, and are mounted on a reel stand of a VTR. A pinch roller 4 is supported by a base so that it can move toward and away from the capstan 5. Capstan 5 is regenerated (FWD)
The tape 1 is rotated at a constant speed during the mode and the recording (REC) mode, and the tape 1 is pressed between the pinch roller 4 and the tape 1 is held between the pinch roller 4 and the capstan 5 and rotated at a constant speed. Sent out. 6 is a rotating head cylinder, and from a slit 6a formed on the circumferential surface of the cylindrical cylinder outer circumferential surface at approximately the center in the vertical direction, a rotary head cylinder 6 supported at both ends of a head bar 6b with the center of the cylinder 6 as the center of rotation is inserted. Two rotary heads 7 and 8 are exposed to the outside. The head bar 6b within the rotary head cylinder 6 is rotated in the direction shown by an arrow 9 by a drive mechanism (not shown).

The tape 1 is wound around the outer peripheral surface of the rotary head cylinder 6 by approximately 220 degrees, and is wound obliquely at a certain angle with respect to the direction of rotation of the rotary heads 7 and 8. Reference numeral 10 denotes a full-width erasing head case, which is provided with a head for erasing magnetic signals such as video signals recorded on the tape 1. 11 is an audio cancellation head case;
A head is provided for erasing audio signals recorded on the tape 1. 12 is an audio/control head case, and a fixed audio head 13 records and reproduces audio signals on tape 1.
A control head 14 is provided for recording and reading a control signal that serves as a reference for aligning the rotational operation positions of the rotary heads 7 and 8 during recording and reproduction. Note that if the PCM recording method is used for audio signals, the fixed audio head 13 may be omitted.

Reference numerals 15, 15, . . . indicate guide posts, and arrows 16, 16, .

Then, the tape 1 is pulled out from the tape cassette by a tape pull-out mechanism (not shown) and set so as to pass through a predetermined tape path shown in FIG. 5 and runs at a constant speed, and is pulled out from the S reel 2 and wound onto the T reel 3. In addition, in the FF mode, the winding force generated by the rotation of the T reel 3 causes winding from the S reel 2 to the T reel 3, and further,
During rewinding, the winding force generated by the rotation of the S reel 2 causes the reel to be rewound from the T reel 3 to the S reel 2.

FIG. 5 conceptually shows the relationship between the above-mentioned rotary heads 7 and 8 and fixed audio head 13, and the recording pattern of the magnetic signal recorded on head 1 by each of the heads.

In the figure, 17 and 18 indicate the respective head tips of the two rotating heads 7 and 8 provided in the above-mentioned rotating head cylinder 6, 19 indicates the head gap of one of the rotating heads 7, and 2
0 indicates the head gap of the other rotating head 8. Reference numeral 21 denotes a fixed audio head 13 provided in the audio/control head case 12 described above.
22 indicates the fixed head 13.
The head gap is shown. Each of the heads records magnetic signals on the tape 1 in the following recording pattern. That is, 23
is a selective audio track area 23 formed in a region near one edge in the width direction of the tape, and this selective audio track area 23 is where audio signals are received by the fixed audio head 13 or the rotary heads 7 and 8. A track prepared to be recorded. It is assumed that a conventional linear audio signal is recorded in this selective audio track area 23.

24, 24, ... and 25, 25, ... are video tracks;
... by the rotary head 7 of one first channel, and the video tracks 25, 25, . . . by the rotary head 8 of the other second channel,
A video signal for one field of video is recorded in each case. Incidentally, each of these video tracks 24, 24,
. . . and 25, 25, . . . are in the longitudinal direction of the tape 1 because the tape 1 is run while being wound diagonally at a certain inclination angle, for example, at an angle of 5 degrees, with respect to the outer peripheral surface of the rotary head cylinder 6. , is formed on the tape 1 as a helical scan type track having a certain inclination angle (5 degrees in the above example) with respect to the running direction of the tape 1 as indicated by the round arrow 26. A control track 27 is formed in an area near the other edge of the tape 1 in the width direction, and a position signal is recorded by the control head 14 described above.

Therefore, the start end of each video track 24, 24, . . . and 25, 25, . . . is close to the control track 27,
The end is near the selective audio track area 23. Note that the audio signal recorded in the selective audio track area 23 is
When recorded by rotating heads 7 and 8,
The audio tracks are connected to each video track 24, 24, . . .
The selective audio track areas 23 are formed as extensions of 5 and 5, respectively, in the same running direction as the video track. Thus, when an audio signal is recorded by a rotating head on an extension of a video track, a PCM modulated audio signal is recorded.

Also, the two rotating heads 7 and 8 have different azimuth angles. That is, 30 and 31 are the head gaps 1 of the respective rotating heads 7 and 8.
9 and 20, and the respective orientations 30 and 31 indicate the rotation directions of the rotary heads 7 and 8, i.e. the video tracks 24, 24, . . . and 25, 2.
5, Straight line 3 indicating a direction perpendicular to the scanning direction of...
2, the orientation 30 of the head gap 19 of one rotary head 7 has an angle 33 of, for example, 5° in the clockwise direction, and the orientation 31 of the head gap 20 of the other rotary head 8 has an angle 33 in the counterclockwise direction. For example, it has an angle 34 of 15°. Each of these angles 33
and 34 is the azimuth angle. Therefore, the video tracks 24, 24, . . . and 25,
The direction of each video signal recorded in 25,... is,
In the figure, each video track 24, 24, . . . and 25, 25, .
. . . and 36, 36, . . ., each video track is given a constant azimuth angle with respect to the direction perpendicular to the running direction. It is known that the significance of each azimuth angle is to prevent crosstalk due to tracking deviation of the rotary heads 7 and 8.

Furthermore, the fixed head 13 also has an azimuth angle.
That is, 37 is the head gap 2 of the fixed head 13.
2, which orientations are at equal angles to the head gap orientations 30 and 31 of the two rotating heads, respectively. Therefore, the azimuth angle of the fixed head 13 in this embodiment is an angle 39 of 5° counterclockwise with respect to a straight line 38 indicating a direction perpendicular to the running direction of the tape 1 that is run while contacting the fixed head 13. By making such an angle, the direction 37 of the head gap 22 of the fixed head 13 is
will have equal azimuth angles for the head gap orientations 30 and 31 of the two rotating heads 7 and 8, respectively. Therefore, the direction of the audio signal recorded in the selective audio track area 23 by the fixed head 13 having such an azimuth angle is indicated by the broken lines 39, 39, . . . in the selective audio track area 23 in the figure.
As shown by . . . , a fixed azimuth angle is given to the direction perpendicular to the direction of travel of the audio track by the fixed head 14.

In this way, even if the magnetic tape 1 on which each video signal and audio signal is recorded is used for recording and playing back audio signals using another VTR with a different audio signal recording method, the previously recorded audio The tape 1 can be used interchangeably with little interference from the signal, ie the audio signal recorded by the fixed head 13 in the selective audio track area 23. That is, using the tape 1 recorded as described above, PCM is recorded on the extension of each video track 24, 24, . . . and 25, 25, . When an audio signal is dubbing recorded, in the selective audio track area 23, the PCM audio signal is overwritten, so to speak, on the linear audio signal previously recorded by the fixed head 13; The directions 39, 39, ... of the audio signals recorded are the directions 35, 35, ... and 3 of the newly recorded audio signals.
6, 36, . . . and newly recorded by the two rotary heads 7 and 8.
PCM audio track 28, which is an extension of...
28,... and second channel video track 2
5, 25, . . . (this direction is the direction of the video signal recorded on the respective video track 35, 35, .
6, 36, ...) are all the same, but the error rate level of the reproduced signal caused by dubbing is reduced to PCM. This is because the audio tracks 28, 28, . . . and 29, 29, .

FIG. 6 shows that, as described above, using the tape 1 on which an audio signal has been previously recorded in the selective audio track area 23 by the fixed head 13, each video track 24, 24, .
While forming PCM audio tracks 28, 28, . . . and 29, 29, . . . on the extension of 5, 25, . An example 40 of an erato curve is shown. As shown in this error curve 40, PCM audio tracks 28, 28, . . . and 29, 29, .
Even if the PCM audio signal recorded on the The level is 10 ^-4 level, which is within the range of acceptable levels for normal audio playback. Therefore, errors that unavoidably occur at a minute rate can be made negligible in terms of audio reproduction, and the reproduced audio is of good quality. It is possible to make tapes compatible even between VTRs with different values.

In the above embodiment of the VTR, the audio signal recorded by the fixed head 13 is a linear audio signal, but it is also possible to record a PCM modulated audio signal.

In addition, recording means for recording audio signals in the selective audio track area in one VTR can be performed by either a fixed head or a rotating head, and can be performed by either head as desired. It is also possible to selectively switch whether or not to record audio.

Second Embodiment In the above embodiment, the azimuth angle attached to the gap of the fixed head was set to an angle having an equal inclination with respect to the respective directions of the gap of the two rotating heads. The azimuth angle of the fixed head gap does not necessarily have an equal slope with respect to the respective orientations of the gap of the two rotating heads; Even if the azimuth angle is set to , interference caused by previously recorded audio signals can be sufficiently suppressed.

FIG. 7 conceptually shows the relationship between the orientations of the head gaps of two rotary heads and a fixed audio head. 42 indicates the direction of the gap on one rotating head, and 43 indicates the direction of the gap on the other rotating head. Reference numeral 44 indicates an imaginary straight line extending in a direction perpendicular to the running direction of the video track 7 formed on the magnetic tape by the rotating head, and the direction of the gap 42 of one rotating head is clockwise with respect to the imaginary straight line 44. The gap direction 43 of the other rotary head has an azimuth angle 45 inclined at an angle of, for example, 5° in the direction, and the direction 43 of the gap of the other rotary head is an azimuth angle inclined at an angle of, for example, 15° counterclockwise with respect to the virtual straight line 44. It has 46. 47 indicates the direction of the gap of the fixed audio head;
The direction 47 of this gap has an azimuth angle 48 that is inclined at, for example, 65 degrees clockwise with respect to the virtual straight line 44.

Therefore, the direction 47 of the fixed head gap is 2.
Although the azimuth angles are not equal for the gap directions 42 and 43 of the two rotating heads, respectively, the gap direction 47 of the fixed head and
Gap orientation of each of the two rotating heads 4
Since the relative angles 49 and 50 with respect to 2 and 43 both have a sufficiently large angular difference, the azimuth loss between the two rotating heads and the fixed head becomes large. Even if a new audio signal is dubbing recorded by the rotating head on a track on which an audio signal was previously recorded by the head, the newly recorded audio signal will interfere with the previously recorded audio signal. I have never experienced a large error rate caused by Therefore,
In that newly recorded audio signal,
Although the level of error rate may vary slightly between the two rotating heads that serve as playback heads,
Since the level of the error rate itself is extremely low, the effect it has on the reproduced audio can usually be ignored.

Effects of the Invention As is clear from the above description, the magnetic recording and reproducing apparatus of the present invention converts audio signals into PCM in an area near one edge of a magnetic tape onto an extension of a video track using two rotating heads.
In a magnetic recording/reproducing apparatus that can selectively employ a method of modulating recording and a method of recording with a fixed head on a track specific to an audio signal at one edge of a magnetic tape, the above two rotations are performed. Since the heads have different azimuth angles and have substantially the same azimuth angle with respect to the fixed head, the recording density on the magnetic tape can be increased, and the audio VTR with improved accuracy and stability of magnetic recording of signals and a different recording method for audio signals
It is possible to provide a magnetic recording/reproducing device that enables mutual interchangeability of magnetic tapes.

[Brief explanation of the drawing]

Figures 1 and 2 show the recording patterns of a magnetic tape on which each signal was recorded by a VTR equipped with a fixed head without an azimuth angle.
The figure is an overall plan view, Figure 2 is an enlarged plan view of main parts, and Figure 3 is an error in the reproduced signal when an audio signal is reproduced using a magnetic tape on which the recording pattern shown in Figure 1 is recorded. Graphs showing the rate, FIGS. 4 to 6 show a first embodiment in which the magnetic recording and reproducing apparatus of the present invention is applied to a VTR, FIG. 4 is a perspective view showing an outline of the tape running mechanism, and FIG. 5 6 is a diagram conceptually showing the relationship between the rotating head, the fixed head, and the recording pattern of the magnetic signal recorded on the magnetic tape by each head. FIG. 6 is a diagram showing the magnetic signal recorded with the recording pattern shown in FIG. FIG. 7 is a graph showing the error rate of the reproduced signal when an audio signal is reproduced using a tape. FIG. It is a diagram conceptually shown. Explanation of symbols: 1... Magnetic tape, 7, 8... Rotating head, 13... Fixed head, 24, 25...
Video track, 33, 34... Azimuth angle of rotating head, 39... Azimuth angle of fixed head.

Claims (1)

[Scope of utility model registration request] A method in which the audio signal is PCM-modulated and recorded on an extension of the video track in an area near one edge of the magnetic tape using two rotating heads, and a fixed head is recorded on a track specific to the audio signal at one edge of the magnetic tape. In a magnetic recording and reproducing apparatus that can selectively adopt a recording method using 1. A magnetic recording and reproducing device comprising: