JPH05910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention allows a magnetic tape to be wound spirally at a predetermined angle and run along the rotation locus of at least one magnetic head provided on a rotating cylinder. , a helical scan rotary head type magnetic recording and reproducing apparatus (hereinafter referred to as VTR) in which the magnetic head sequentially records and reproduces video signals as a group of recording trajectories inclined with respect to the longitudinal direction of the magnetic tape.
It is particularly characterized by the recording of audio signals related to video signals.

Conventional Structure and Problems Conventionally, audio signals in helical scan VTRs have been sequentially recorded and reproduced as a recording trajectory extending in the longitudinal direction of a magnetic tape using a fixed head.

However, in recent years, due to high-density recording, the tape running speed has become slower, and the relative speed between the fixed head and the magnetic tape for recording and reproducing audio has become smaller, resulting in unsatisfactory frequency characteristics of the reproduced audio signal. It's coming.

Purpose of the Invention The present invention provides a means for solving the above problems, and includes providing a magnetic head for recording and reproducing audio signals on a rotating cylinder provided with a magnetic head for recording and reproducing video signals. This magnetic head sequentially records and reproduces the recording locus that is inclined with respect to the longitudinal direction of the magnetic tape in the same way as video signals, so even if the running speed of the magnetic tape decreases, the magnetic head can still function as an audio signal recording/reproducing magnetic head. The structure is such that a sufficient relative speed with respect to the magnetic tape can be obtained.

Structure of the Invention A magnetic tape is spirally wound at a predetermined angle and run along the rotation locus of a first magnetic head group consisting of at least one magnetic head provided on a rotating cylinder, and the first magnetic head In a magnetic recording and reproducing apparatus in which a group of heads sequentially records and reproduces video signals as a first group of recording trajectories inclined with respect to the longitudinal direction of the magnetic tape, each magnetic head of the first group of magnetic heads is mounted on the rotating cylinder. A second magnetic head comprising at least one magnetic head having a head gap at a different angle than the head gap.
A magnetic head group is provided, and the second magnetic head group sequentially records and reproduces audio signals as a second recording locus inclined with respect to the longitudinal direction of the magnetic tape, and the running speed of the magnetic tape is adjusted so that long-term recording is possible. mode speed and a normal recording mode speed that is an integral multiple of the long-time recording mode speed, and in the long-term recording mode, the second recording trajectory by the second magnetic head group can be switched selectively. The center approximately coincides with the center of the first recording trajectory by the first magnetic head group, and in the normal recording mode, the center of the first recording trajectory by the first magnetic head group and the center of the first recording trajectory to be recorded next. rotating the first magnetic head group and the second magnetic head group so that the center of a second recording trajectory by the second magnetic head group is positioned between the center of the first recording trajectory; This is a magnetic recording and reproducing device located on a cylinder.

DESCRIPTION OF EMBODIMENTS FIG. 1 is a plan view showing an outline of the main parts of a VTR according to a first embodiment of the present invention. Reference numeral 1 indicates a rotating cylinder, and the inclination (azimuth angle) of the head gap is
It has video heads 2a, 2b and audio heads 5a, 5b, which have different sizes. The video heads 2a, 2b are attached to the rotary cylinder 1 with a 180 degree positional relationship, while the audio heads 5a, 5b are attached to the rotary cylinder 1 with a 180 degree positional relationship, and It is attached at a positional relationship of 60 degrees with the heads 2a and 2b. A magnetic tape 3 is wound around the rotary cylinder 1 by tape guides 16 and 17 at an angle slightly larger than 180 degrees, similar to a conventional helical scan video tape recorder.
Moreover, it is wound in a spiral shape at a predetermined angle with respect to the rotation axis of the rotary cylinder 1.

In such a configuration, if the rotary cylinder 1 is now rotated in the direction of arrow B in the figure, the video heads 2a and 2b attached to the rotary cylinder 1 are moving in the direction of arrow A in the figure. A video signal is recorded on the magnetic tape 3 and reproduced.

FIG. 2 shows recording trajectories 4a and 4b on the magnetic tape 3 by the video heads 2a and 2b, and the recording trajectories 4a and 4b are partially overlappingly recorded. At this time, since the azimuths of the head gaps of the video heads 2a and 2b are set to ±6 degrees, the magnetization directions of the recorded recording trajectories 4a and 4b are tilted by ±6 degrees with respect to the running direction of the video heads 2a and 2b. Furthermore, the audio heads 5a and 5b attached to the rotary cylinder 1 are in the position shown in FIG. 1, and as shown by the broken line in FIG.
The installation height and head width (for example, video heads 2a, 2b
The width of the audio heads 5a and 5b is set to 30 μm, and the width of the audio heads 5a and 5b is set to 26 μm. The mounting height of the audio heads 5a and 5b is approximately 47μ higher than the mounting height of the video heads 2a and 2b on the cylinder.
m is set high.

That is, the video head 2b records the video signal as a recording trajectory 4b, superimposing it on the recording trajectory 6b where the frequency-modulated audio signal is recorded by the audio head 5b, and the video signal is superimposed on the recording trajectory 6a recorded by the audio head 5a. The head 2a records the video signal as a recording trajectory 4a.

Next, we will discuss the recording and reproduction of audio signals.The audio signal applied to the input terminal 7 shown in FIG.
Frequency modulate the carrier wave tuned to Hz. The output of the modulator 9 is applied to the rotary transformer 11 via an attenuator 18 and a switch circuit 10, transmitted to the rotary cylinder 1 side, and applied to the audio heads 5a and 5b. As shown in FIG. 4, the head gaps of the audio heads 5a and 5b are tilted in the opposite direction by several tens of degrees (for example, 30 degrees), so the magnetic tape 3 has tracks 6a and 6b shown in FIG. As shown, the magnetization directions are recorded even if they are tilted several tens of degrees in opposite directions.

At this time, the audio head 5a is arranged so that the angular difference in magnetization direction between the video track 4a and the audio track 6a, and between the video track 4b and the audio track 6b, which overlap each other, becomes large.
The head gaps of the video head 2a, the audio head 5b, and the video head 2b are set to have inclination angles in opposite directions.

Furthermore, the audio signal carriers recorded by the audio heads 5a and 5b are then duplicated by the video signals recorded by the video heads 2a and 2b.
Since the signal is attenuated by several dB, the carrier currents flowing through the audio heads 5a and 5b are set in consideration of this amount of attenuation so that the reproduction C/N of the audio carrier is about 20 dB. On the other hand, during reproduction, the carrier reproduced by the audio heads 5a, 5b passes through the rotary transformer 11, and is selected by the switch circuit 10 to obtain the output of the audio head 5a, 5b on the side where the carrier is being reproduced. Added to 12. If the carrier amplified by the amplifier 12 is demodulated by the demodulator 13 and amplified by the amplifier 14, the audio signal applied to the input terminal 7 can be obtained at the output terminal 15. During playback, the audio heads 5a, 5b are also in contact with the recorded portion of the video, but the audio heads 5a, 5b and the video heads 2a, 2b are
Since the azimuth of the head gap of the two is greatly different, the reproduced video signal is subject to attenuation called angular shift loss. Also, the audio carrier A is selected to be around 1.3MHz, as shown in Figure 6. It is recorded on video heads 2a and 2b. For example, the reduction of the video signal selected around 629MHz, away from the band of the color signal C (±500KHz),
Since the frequency band is selected to be sufficiently distant from the carrier (3MHz to 5MHz) of the frequency modulated luminance signal (Y(FM)) of the video signal, the frequency band near this audio carrier A is ))
This position corresponds to the high frequency component part of the luminance signal in the lower sideband, and since the level of the sideband in this part is also low, the audio signal receives little damage protection.

Similarly, the audio carriers reproduced by the video heads 2a and 2b also suffer from angular shift loss, and the recording level of the audio carriers actually recorded on the magnetic tape is attenuated due to the overlapping video signals. The effect on the video signal is small because the current is low.

Next, a case will be described in which recording is performed with the tape speed tripled in the above configuration (hereinafter, the case where the tape speed is slow will be referred to as long-time recording mode, and the case where the tape speed is tripled will be referred to as normal recording mode). In the normal recording mode, the running speed of the magnetic tape is faster than in the long-term recording mode, and the video heads 2a, 2b and audio heads 5a, 5b run on the tracks 4a, 4b and 6a, 6b shown in FIG. 7, respectively. Then, the video signal and the audio carrier are recorded on the magnetic tape 3. In this case, video tracks 4a, 4b and audio track 6
A and 6b only partially overlap, and the audio carrier in the non-overlapping portion is not attenuated by the video signal. Therefore, if the same carrier current as in the long-time recording mode is applied to the audio heads 5a and 5b, the recording level will be 10.
dB becomes higher, and video heads 2a and 2b become dB higher during playback.
When it runs slightly off track 4a, 4b (so-called tracking shift), it runs on audio tracks 6a, 6b with a high recording level.
Audio carrier interference appears in the video. To eliminate this problem, the output of the modulator 9 is attenuated by an attenuator 18 during recording by about 10 dB compared to long-time recording. Other recording and reproducing operations are the same as in the long-time recording mode. Since the recording current of the audio carrier is attenuated in the normal recording mode in this way, the reproduction level of the audio carrier reproduced from the magnetic tape 3 does not differ greatly between the long-time recording mode and the normal recording mode, and the reproduction level of the audio carrier reproduced from the magnetic tape 3 does not differ greatly between the long-time recording mode and the normal recording mode.
The level of the audio carrier reproduced by the 2b is sufficiently low in both the long-term recording mode and the normal recording mode, so that no audio interference appears on the video. On the other hand, since the audio carrier uses frequency modulation, it is possible to obtain good characteristics even if the recording level is low.
S/N is 55dB or more, frequency response is 20Hz to 20KHz,
Wow and flutter can be easily achieved at 0.005%, which is a big improvement over the previous model.

FIG. 8 shows an embodiment of the present invention in which a pair of video heads for the long-term recording mode and a pair of video heads for the normal recording mode are provided separately.

21a and 21b are video heads for long-time recording mode, and their head width is 30 μm, which is the same width as the video heads 2a and 2b.
2b is a video head for normal recording mode, and its head width is 55 μm for 22a and 40 μm for 22b.

Also, the audio heads 5a and 5b have the same head width of 26 μm as in the previous embodiment.

Also, video heads 21a and 22b, 22a and 21b each have the same head gap inclination, and video heads 21a and 22a have inclinations in opposite directions. The video heads 21a and 22a and 21a and 22b are mounted very close to each other and are mounted at an index angle of 180 degrees on the rotary cylinder 1 so that the lower ends of the heads are at the same height. There is.

The audio heads 5a and 5b are also rotated by the rotating cylinder 1.
with an index angle of 180 degrees and video head 2
It is attached with a 90 degree positional relationship with 1a and 21b.

With this configuration, in the long-time recording mode, the video signal is sent to the video head 21 as in the previous embodiment.
a, 21b, recording trajectories 4a, 4b in FIG.
The audio signals are recorded by the audio heads 5a, 5b as recording trajectories 6a, 6a, 6b in FIG.
It is attached to the rotary cylinder 1 by adjusting its mounting height as shown in FIG. 6b.

Therefore, similar to the embodiment shown in FIG. 1, video signals and audio signals are recorded and reproduced, and
Tape compatibility in long-term recording mode with the embodiment of FIG. 1 can also be achieved.

In the normal recording mode, the video signals are recorded using the video heads 22a and 22b, so the recording trajectory on the tape is slightly different from that of the previous embodiment.
That is, video heads 22a, 22b and audio heads 5a, 5b respectively draw video tracks 23a, 23b and audio tracks 6a, 6b in FIG.

In this case, the audio track 6b is recorded partially overlapping the video track 23a, so if the same recording current as in the long-time recording mode is applied to the audio heads 5a and 5b, the data is actually recorded on the audio track 6b. The recording level is about 10 dB higher than in long-time recording mode, and
Since a part of the previously recorded video track 23a is erased, the level of the audio signal reproduced by the video head 22a or 22b becomes high during reproduction, and the reproduced audio signal may interfere with the video signal. In order to eliminate this damage, it is preferable to attenuate the output of the modulator 9 during recording by about 10 dB using the attenuator 18 compared to when in the long-time recording mode. Also, even in long-time recording mode, the seventh
As is clear from a comparison of the recording patterns in the figure, tape compatibility is achieved with the previous embodiment.

Next, a second embodiment of the present invention is shown in FIG.

In this embodiment, as in the second embodiment, a pair of video heads for the long-time recording mode and a pair of video heads for the normal recording mode are provided separately.

In FIG. 10, 21a and 21b are video heads for long-time recording mode, and their head width is 32 μm, which is the same as the video heads 2a and 2b, and 22a and 22b are video heads for normal recording mode. , the width is both 22a and 22b
This is 70 μm, which is larger than video track pitch 3P (58 μm) in normal recording mode. Also,
The audio heads 5a, 5b have the same head width of 30 .mu.m as in the previous embodiment.

The video heads 21a and 22b, 22a and 2
1b have the same head gap inclination (azimuth angle), and video heads 21a and 22a
has a slope in the opposite direction.

These heads 21a, 22b, 5a, 21
There are index angles of 60 degrees between each head 22b, 22a, and 5b, and the mounting height of each head to the rotary cylinder 1 is the same as that of the video head 22a when the video head 22a is used as a reference. The height of the video heads 21a and 21b is approximately 38μ.
m high, and audio heads 5a and 5b are approximately 53 μm high.
It is set high.

With this configuration, in long-time recording mode,
As in the first and second embodiments, the video signals are recorded by the video heads 21a and 21b as recording trajectories 4a and 4b in FIG. 3, and the audio signals are recorded by the audio heads 5a and 5b as recording trajectories 6a and 6b in FIG. draw

Therefore, in the long-time recording mode, the first and second
And the third embodiment has tape compatibility. In normal recording mode, the video head 22
a, 22b and audio heads 5a, 5b respectively depict video tracks 23a, 23b and audio tracks 6a, 6b in FIG.

The recording pattern shown in FIG. 11 has achieved tape compatibility as is clear when compared with the recording patterns of FIGS. 7 and 9 in the normal recording mode of the first and second embodiments.

Note that in this third embodiment, the audio track 6
In the case of a and 6b, the video track is always recorded overlappingly over the entire track width in both the long-time recording mode and the normal recording mode, so a uniform playback output can always be obtained in both recording modes. be.

Note that in the third embodiment shown in FIG.
A similar recording pattern can be obtained by setting the video heads 21a, 21b, 22a, and 22b to the same height when mounting each head on the rotary cylinder 1, and setting the audio heads 5a and 5b to be approximately 53 μm higher than the video head. .

As shown in the first, second, and third embodiments, the arrangement of the video head of VHS VTRs currently on the market is such that the same magnetic head is used for long-time recording mode and normal recording mode. The type used (Figure 1), the type in which the wide head for normal recording mode is placed close to the head for long-term recording mode (Figure 8), the wide head for normal recording mode is used for long-term recording mode. There are three types, one located away from the head (Fig. 10), each of which has tape compatibility. Naturally, the audio heads of these commercially available VTRs are all fixed heads, and do not have the audio heads 5a and 5b shown in FIGS. 1, 8, and 10.

In order to add an audio head without changing the arrangement of these three types of video heads and to obtain tape compatibility with each other during long-time mode and normal recording mode, Examples 1, 2, and 3 are used.
As shown in , the end of the video track in the tape running direction (arrow A) in normal recording mode (this end is always protected from being repeatedly recorded by the video or audio track recorded later). ) to the end of the next video track in the tape running direction (video track pitch 3P)
The center of the audio track must be located on the opposite side of the tape running direction (arrow A) from the center of the tape.

Effects of the Invention As explained above, even if the carrier wave of an audio signal is recorded by an audio head attached to a rotating cylinder, and is recorded overlapping with a conventionally recorded video signal, it will not interfere with the video signal. This reduces wow and flutter during audio signal recording and playback.
10 or less, the S/N is good, the frequency characteristics can be improved, and the reproduced sound quality can be improved. If the audio signal is also recorded on the conventional audio track, it will be compatible with conventional video tape recorders and will be very effective.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the arrangement of magnetic heads on a rotating cylinder in one embodiment of the present invention, FIG. Figure 3 is a diagram showing the video track and audio track on the magnetic tape in the long-time recording mode in the same embodiment;
FIG. 4 is a front view of the audio head, FIG. 5 is a block diagram of the audio signal recording and reproducing system according to the present invention, FIG. 6 is a spectrum diagram of the video signal and audio signal recording signal according to the present invention, and FIG.
8 is a diagram showing a video track and an audio track on a magnetic tape in the normal recording mode in the same embodiment; FIG. 8 is a plan view showing the arrangement of magnetic heads on a head cylinder according to another embodiment of the present invention; FIG. 9 is a diagram showing the video track and audio track on the magnetic tape in the normal recording mode in the same embodiment, and FIG. 10 is a plan view showing the arrangement of the magnetic head on the head cylinder in still another embodiment of the present invention. , and FIG. 11 are diagrams showing a video track and an audio track on a magnetic tape in the normal recording mode in the same embodiment. 1...Rotating cylinder, 2a, 2b, 21a, 2
1b...Video head, 3...Magnetic tape, 5
a, 5b...Audio head.

Claims (1)

[Claims] 1. A magnetic tape is spirally wound at a predetermined angle and run along the rotation locus of a first magnetic head group consisting of at least one magnetic head provided on a rotating cylinder, and the first magnetic head is In a magnetic recording and reproducing apparatus for sequentially recording and reproducing video signals as a first group of recording trajectories inclined with respect to the longitudinal direction of the magnetic tape, the rotary cylinder includes a head gap of each magnetic head of the first magnetic head group. A second magnetic head group consisting of at least one magnetic head having a head gap at a different angle from the magnetic tape is provided, and the second magnetic head group converts the audio signal into a second magnetic tape inclined with respect to the longitudinal direction of the magnetic tape. In addition to recording and reproducing sequentially as a recording trajectory, the running speed of the magnetic tape can be selectively switched between a long-time recording mode speed and a normal recording mode speed that is an integral multiple of the long-time recording mode speed. In the time recording mode, the center of the second recording trajectory by the second magnetic head group and the center of the first recording trajectory by the first magnetic head group approximately coincide, and in the normal recording mode, the center of the second recording trajectory by the second magnetic head group approximately coincides with the center of the first recording trajectory by the first magnetic head group. The center of the second recording trajectory by the second magnetic head group is positioned between the center of the first recording trajectory by the head group and the center of the first recording trajectory to be recorded next. In the first
A magnetic recording/reproducing device in which a first magnetic head group and a second magnetic head group are positioned on a rotating cylinder.