JPH0612601A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the quality of reproduced images and the quality of reproduced sounds by setting a track width and a track pitch at a specific relation and recording sound signals in the deep layer part of a tape, then overwriting video signals thereon. CONSTITUTION:Steps Td1, Td2 are provided at the height of the respective mounting surfaces of video heads (Hs) 2 to 5 and sound Hs 6, 7. The azimuth angles between the gap-facing surfaces of the respective Hs and the faces perpendicular to the rotating direction of the Hs are specified to +theta at the Hs 2, 4, -theta at the Hs 3, 5 and +psi, -psi at the Hs 6, 7. The crosstalks to the sounds and video signals between the adjacent and the same tracks are decreased by the azimuth loss. The video signals are recorded and reproduced by selecting the Hs 2, 3 in a standard speed mode and Hs 4, 5 in a low speed mode and are commonly used for the Hs 6, 7 and these modes. The quality of the images and sounds is improved by providing the relation that Tp<=TsXTp holds. In the equation; Tp: the track pitch of the low-speed mode, Ts: the track widths of Hs 6,7.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus (hereinafter referred to as VTR) for recording a video signal and an audio signal by using a magnetic tape, and more particularly, reproducing. The present invention relates to a method suitable for improving sound quality. 2. Description of the Related Art In a conventional helical scan VTR, in order to record a video signal and an audio signal on a magnetic tape, each of the dedicated heads is processed after the input video signal and the audio signal are processed. It is recorded in different places (tracks) on the magnetic tape via. That is, the video signal is recorded by a video head on a video track provided obliquely to the longitudinal direction of the magnetic tape, and the audio signal is recorded on an audio track provided along the longitudinal direction of the magnetic tape. There is. By the way, in recent years, magnetic recording / reproducing characteristics of video signals have been improved with the improvement of magnetic heads and magnetic tapes. For this reason, the amount of tape required to obtain a desired S / N has been reduced, and the tape speed has been reduced to improve the recording density. However, in this case, since the audio head is fixed, the audio signal has a drawback that the band of the reproduced audio output is narrowed and the S / N is deteriorated as the tape speed becomes slower. On the other hand, the audio signal is frequency-modulated,
As shown in FIG. 15, it has been proposed and studied to multiplex the FM audio signal 12 in a band between the FM-modulated luminance signal 10 and the low-frequency converted chroma signal 11. In this case, the relative speed between the tape and the head is greatly increased,
The sound quality is significantly improved. However, FM in the same band as before
When the luminance signal 10 and the low frequency conversion chroma signal 11 are set,
Since the band between both signals is narrow, both signals are FM audio signals 1
Close-talk with 2 causes deterioration of reproduced image quality or reproduced sound quality. That is, there is a drawback that it is difficult to realize improvement of reproduced sound quality while maintaining compatibility with the conventional art. Further, in the conventional VTR, there are a standard speed mode in which a tape is run at a standard speed for recording / reproducing and a low speed mode in which a tape is run at a lower speed (eg, 1/3 of the standard speed) for recording / reproducing. Some of them can be selected, and it is necessary to obtain good reproduction sound quality in any of these modes. In consideration of the above points, the object of the present invention is to improve the reproduced image quality and reproduced sound quality in a manner compatible with the conventional one not only in the standard speed mode but also in the low speed mode. To provide. To achieve the above object, the present invention provides first and second video heads for recording or reproducing a video signal by running a tape at a standard speed. An audio signal is transferred onto a rotating body provided with third and fourth video heads for recording or reproducing a video signal by running the tape at a speed lower than the standard speed, respectively, which are provided substantially symmetrically to the rotation axis. First and second voice heads for recording or reproducing are provided substantially symmetrically with respect to the rotation axis, and the first and second voice heads are provided.
The first and second video heads and the third and fourth video heads scan the tape along a scanning locus of the second audio head on the tape, and the first and second video heads scan the tape. The track width Ts of the audio head is Tp ≦ Ts ≦ 2 × Tp, where Tp is the pitch of tracks formed on the tape when the tape is run at a speed lower than the standard speed. An audio signal is recorded on the tape by the first and second audio heads, and the video signal is overwritten by any of the first, second video head, and the third and fourth video heads. Be able to record. In the recording in the standard speed mode in which the tape is run at the standard speed, and in the low speed mode in which the tape is run at the low speed, the voices are recorded on the tape by the first and second voice heads. The video signal is overwritten and recorded on top of the recorded signal, and the audio signal can be recorded by sharing the first and second audio heads in any mode. Since the track widths Ts of the first and second audio heads satisfy the above condition, the width of the recording track of the audio signal can be increased and the S of the audio signal to be reproduced can be increased.
/ N is improved, and the crosstalk from adjacent tracks at the time of reproduction can be significantly reduced, and since these are recorded in different areas in the depth direction of the tape, crosstalk between them is prevented. it can. Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are views showing the head arrangement in a cylinder of one embodiment of a VTR according to the present invention, in which 1 is a rotary cylinder, 2 to 5 are video heads, and 6 and 7 are audio heads. In FIG. 1, a pair of two image heads 2 and 3 are arranged on a rotary cylinder 1 at an interval of about 180 ° and have different azimuth angles, and two image heads 2 and 3 are also provided.
A pair of video heads 4, 5 are provided, and the video heads 2,
3 is for a standard speed mode in which a tape (not shown) is run at standard speed V1 for recording / reproduction, and video heads 4, 5 are for recording / reproduction by running the tape at a speed V2 lower than standard speed V1. It is for the low speed mode to be performed. Further, on the rotary cylinder 1, similarly,
Two pairs of audio heads 6 and 7 arranged at intervals of about 180 ° and different in azimuth angle are provided from the video heads 2 and 3 by an angle α ₁ , and the video head 4 and 7.
5 are provided at positions separated from each other by an angle α ₂ .
The arrow 8 indicates the rotation direction of the rotary cylinder 1. Here, the azimuth angle between the gap facing surface of each head and the surface perpendicular to the head rotation advancing direction 1 is
For example, the video heads 2 and 4 are + θ, the video heads 3 and 5 are −θ, and the audio heads 6 and 7 are + ψ and −ψ, respectively.
Azimuth loss reduces crosstalk to audio / video signals that occur between adjacent tracks and the same track. The video heads 2-5 and the audio head 6,
Steps T as shown in FIG.
d ₁ and Td ₂ are provided. As shown in FIG. 4, the track widths of the video heads 2 to 5 are set so that the recording track width can be as wide as possible and the S / N can be improved according to the tape speed in the mode in which they are used. Therefore, the track widths of the video heads 2 and 3 for the standard speed mode are wider than those of the video heads 4 and 5 for the low speed mode. Among the heads arranged as described above on the rotary cylinder 1, the image heads 2 and 3 are selected in the standard speed mode, and the image heads 4 and 5 are selected in the low speed mode. A video signal is recorded or reproduced by the audio heads 6 and 7 and is commonly used for these modes. And
Angles α ₁ and α ₂ and steps Td ₁ and Td ₂ shown in FIGS.
According to the tape running speed, the following relationship is established, so that the audio modulation signal is recorded first, and then the video modulation signal is overwritten in good condition in both modes,
A voice modulation signal is recorded deep inside the magnetic layer of the magnetic tape, and then a high-frequency luminance modulation signal is recorded on the surface of the magnetic layer.
It is recorded without being erased by the voice modulation signal. The case of the VHS of the VHS system for NTSC will be described below as an example. VHS system VTR for NTSC
With the improvement in recording density, it is possible to set the tape running speed to 1/3 times speed mode, which is 3 times slower than the standard speed mode, and high density recording is realized. in this case,
The video recording track pit Tp has a standard speed mode of Tp _{1 to} 60 μm and a 1/3 speed mode of Tp _{2 to 20} μm. First, the case of the 1/3 speed mode will be described. In this case, if the track widths Ts and Tv ₂ of the audio heads 6 and 7 and the video heads 4 and 5 are set to the track pitch Tp ₂ = 20 μm or more, the audio and video modulation signals are recorded at the full track pitch, Highest density recording can be achieved. By the way, since the video heads 4 and 5 trace the recording track later than the audio heads 6 and 7,
When there is no step Td between them, as shown in FIG. 5, the left end position Q ₂ of the recording start of the video heads 4 and 5 of the audio heads 6 and 7 corresponds to the angle α ₂ shown in FIG. There is a problem in that the left end position Q _{1 at the} start of recording is deviated and the immediately preceding left-side video track recorded in the figure is erased by the audio head. However, the amount of deviation between the position Q ₂ and the position Q ₁ is represented as _{α 2/180 ° × Tp 2} . Therefore, by providing a step Td ₂ that is equal to the amount of deviation in the mounting height of the audio heads 6 and 7 and the video heads 4 and 5, such positional deviation can be eliminated, as shown in FIG. Can be recorded on the same track. That, if substantially satisfy _{Td 2 = α 2/180 °} × Tp 2 ...... (1), high density recording of the video signal and the audio signal can be realized in the low-speed mode. On the other hand, in the standard speed mode, the track widths Ts and Tv of the audio heads 6 and 7 and the video heads 2 and 3 are
_{If 1 is set} to the track pitch Tp ₁ = 60 μm or more, the audio modulation signal and the video modulation signal are recorded at the full track pitch. Also in this case, if there is no step Td between these heads, as shown in FIG. 5, the recording start of the audio heads 6 and 7 and the video heads 2 and 3 is started as in the case of the 1/3 speed mode. of the left end position Q _2, Q ₁ to α _11/18
A shift of about 0 ° × Tp ₁ occurs, and as a result, a part of the video track formed immediately before is erased. Therefore,
In this case, and _{Td 1 = α 1/180 °} × Tp 1 ...... (2) so as to substantially satisfy, thereby, as shown in FIG. 6, to eliminate the deviation of the above. As described above, by arranging the heads so that the above equations (1) and (2) are satisfied at the same time, the video signal and the audio signal are on the same track in both the standard speed and the 1/3 speed modes. It is possible to record at full pitch, and the recording density can be maximized. In the above example, the low speed mode is set to 1
Although the third speed was taken up, even if the tape running speed is different from this, only the values of the track pitches Tp ₁ and Tp ₂ are different, and it is clear that the same effect can be obtained at any tape speed. is there. Further, in the above-mentioned example, the case where the low-speed mode is one in the standard speed mode and the low-speed mode is a total of two modes has been described. Also, if Tdn = αn / 180 ° × Tpn (3) is satisfied, the same effect can be obtained. In addition, Tdn,
αn and Tpn are the step difference between the audio head and the video head, the head arrangement angle, and the track pitch in the n mode, respectively. By the way, as concrete examples of numerical values shown in FIGS. 3, 4, 5 and 6, approximately α ₁ = 60 °, α ₂ =
90 °, Td ₁ = 20 μm, and Td ₂ = 10 μm, which both satisfy the above formulas (1) and (2).
Video heads 2, 3, video heads 4, 5, audio heads 6,
The track widths Tv ₁ , Tv ₂ , Ts of 7 are Tv ₁ ≧ 6, respectively.
By setting 0 μm, Tv ₂ ≧ 20 μm, and Ts ≧ 60 μm, it is possible to record the video signal and the audio signal in the full track pitch without a gap in both the standard speed mode and the 1/3 speed mode. However, in consideration of crosstalk from adjacent tracks at the time of reproduction, it is better to make the track width of the head as close to the track pitch as possible. Then, paying attention to the reduction of crosstalk (there is no azimuth effect at this time) from the close proximity of the audio signal in the low speed mode, and if the deterioration of the S / N of the reproduced audio signal in the standard speed mode is allowed, Tv ₁ ≈ 60 μm, Tv ₂ ≈ 20 μm, 20 μ
The most suitable place is m ≦ Ts ≦ 40 μm. Here, the recording track pattern is as shown in FIG. 7 in the 1/3 double speed mode, and in FIG. 8 in the standard speed mode.
As shown in. However, the track width Ts of the audio heads 6 and 7 was set to 30 μm. That is, as described above, by setting the track width Ts of the audio heads 6 and 7 to about 20 μm ≦ Ts ≦ 40 μm, in the 1/3 speed mode, the audio tracks are filled up to the track pitch Tp _2. Although it is formed, it is possible to prevent the occurrence of crosstalk from an adjacent track during reproduction, and in the case of the standard speed mode, the audio track is not full of the track pitch Tp _1, but
The width becomes wider and the S / N ratio of the reproduced audio signal can be increased. In general, the track pitch in the low speed mode is T
If pn, the track width Ts of the audio head may be Tpn ≦ Ts ≦ 2Tpn. FIGS. 9 and 10 are views showing the head arrangement in a cylinder of another embodiment of the VTR according to the present invention. The parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals. In FIG. 3, there is no step between the image heads 2 and 3 and the image heads 4 and 5, and
It is assumed that there is a step only between ~ 5 and the voice heads 6, 7. Here, the step Td ₁ = Td ₂ = 10 μm, α
_The equations (1) and (2) are satisfied by setting ₁ = 30 ° and α ₂ = 90 °. The track width of each head is the same as that of the above embodiment, for example, Tv ₁ = 60 μm, T
Let v ₂ = 20 μm and Ts = 30 μm. This allows
The recording track pattern in the 1/3 speed mode is as shown in FIG. 7, and the recording track pattern in the standard speed mode is as shown in FIG. The image heads 2, 3 and the image head 4,
In the case where there is no level difference with _No. 5, that is, when Td ₁ = Td ₂ , α ₁ / α ₂ = Tp ₂ / Tp ₁ may be satisfied from the above equations (1) and (2). FIGS. 11 and 12 are views showing the head arrangement in the cylinder of another embodiment of the VTR according to the present invention.
Parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals. In this embodiment, as shown in FIGS. 11 and 12, similar to the embodiments shown in FIGS. 9 and 10, there is no step between the image heads 2 and 3 and the image heads 4 and 5. It is assumed that there is a step only between the video heads 2 to 5 and the audio heads 6 and 7, and the track pitch in each mode and the track width of each head are the same as those in the embodiments shown in FIGS. 9 and 10. However, the angle α ₁ between the audio heads 6 and 7 and the video heads 2 and 3 is 40 °, and the angle α ₂ between the audio heads 6 and 7 and the video heads 4 and 5 is 120 °. is there.
In this case, by setting the step between the video heads 2 to 5 and the audio heads 6 and 7 to be Td ₁ = Td ₂ = 40/3 μm, the above formulas (1) and (2) are satisfied, In the 1/3 speed mode, the recording track pattern shown in FIG. 7 is obtained,
The recording track pattern shown in FIG. 8 is obtained in the standard speed mode. By the way, in the above embodiment, since the video signal and the audio signal can be recorded within the track pitch as much as possible, the sound quality and the image quality can be greatly improved. Step T of
If there are variations in mass production of d and angle α, these will deteriorate. That is, the above-mentioned shift amount α ₁ n / 180 ° × T
If pn fluctuates due to the above reasons, the audio head may trace part of the left video track and erase the video modulation signal. For this, the step difference for the above deviation may be set to be slightly larger, and Tdn ≧ αn / 180 ° × Tpn. On the contrary, if the track pitch Tpn is substantially fixed if it is fixed to a certain step, it is obvious that the angle αn should be made smaller. in this case,
If the margin width is 9, the recording track pattern is as shown in FIG.
(In the 1/3 speed mode) and FIG. 14 (in the standard speed mode), respectively, and particularly in the standard speed mode, there is an effect that the disturbance from the audio signal to the video signal due to the tracking deviation does not largely change. . In the above description, the voice heads 6 and 7 are used.
Although the azimuth angles of are set to + φ and −φ, respectively, the azimuth effect can be obtained even if they are reversed, and it is clear that the effect of the present invention can be obtained similarly. In the above embodiment, the VHS for NTSC is used.
Although it was the VTR of the system, the same applies to the VTR of the other system such as the PAL system VTR or the beta system home VTR. As described above, according to the present invention,
Both the standard speed mode and the low speed mode can record and reproduce the audio signal using the same rotary audio head, and it is possible to reproduce the audio signal with the best sound quality except crosstalk from another track. To do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing a mounting state of each head in a rotary cylinder of an embodiment of a magnetic recording / reproducing apparatus according to the present invention. FIG. 2 is a side development view of a mounted state of each head in the rotary cylinder shown in FIG. FIG. 3 is a diagram showing a scanning state of an audio head on a tape and a scanning state of a low-speed video head when there is no mounting step between the heads shown in FIG. 4 is a diagram showing a scanning state of an audio head on a tape and a scanning state of a low-speed video head when there is a mounting step between the heads shown in FIG. 5 is a diagram showing a scanning state of the audio head and a scanning state of the standard speed video head on the tape when there is no mounting step between the heads shown in FIG. 6 is a diagram showing a scanning state of an audio head on a tape and a scanning state of a standard speed video head when there is a mounting step between the heads shown in FIG. 2; FIG. 7 is a diagram for explaining the track width of the audio head when the audio head and the low-speed video head scan as shown in FIG. FIG. 8 is a diagram for explaining the track width of the audio head when the audio head and the video head for standard speed scan as shown in FIG. FIG. 9 is a plan view showing a mounting state of each head in a rotary cylinder of another embodiment of the magnetic recording / reproducing apparatus according to the present invention. FIG. 10 is a side development view of a state in which each head is attached to the rotary cylinder shown in FIG. FIG. 11 is a plan view showing a mounting state of each head in a rotary cylinder of still another embodiment of the magnetic recording / reproducing apparatus according to the present invention. FIG. 12 is a side development view of a state in which each head is attached to the rotary cylinder shown in FIG. FIG. 13 is a diagram showing a scanning state of an audio head and a scanning state of a low-speed video head in still another embodiment of the magnetic recording / reproducing apparatus according to the present invention. FIG. 14 is a diagram showing a scanning state of an audio head and a scanning state of a standard speed video head in still another embodiment of the magnetic recording / reproducing apparatus according to the present invention. FIG. 15 is a spectrum diagram showing an example of a recording method of a video signal and an audio signal in a conventional magnetic recording / reproducing apparatus. [Explanation of symbols] 1 rotating cylinder 2, 3 standard speed video head 4, 5 low speed video head 6, 7 audio head

Claims (1)

[Claims] 1. First and second video heads for recording or reproducing a video signal by running the tape at a standard speed on the rotating body are substantially symmetrical to the rotation axis of the rotating body, and further, the tape is moved from the standard speed. In a helical scan type magnetic recording / reproducing apparatus in which third and fourth image heads for recording or reproducing an image signal by traveling at a low speed are provided substantially symmetrically with respect to the rotation axis. A first and a second audio head for recording or reproducing an audio signal are provided substantially symmetrically with respect to the rotation axis, and the first and second audio heads are arranged along a scanning locus of the first and second audio heads on the tape. The first and second video heads and the third and fourth video heads scan the tape, and the track widths Ts of the first and second audio heads are set so that the tape is higher than the standard speed. When running at low speed The pitch of the tracks formed on the tape is Tp, and Tp ≦ Ts ≦ 2 × Tp is set, and an audio signal is recorded in a deep portion of the tape by the first and second audio heads, and A magnetic recording / reproducing apparatus characterized in that a video signal can be overwritten and recorded by any of the first, second video heads, and the third, fourth video heads. 2. In Claim 1, a step Td ₁ is attached to the mounting of the first and second audio heads and the first and second video heads on the rotating body, and the first and second steps are attached. A step Td ₂ is provided for mounting the audio head and the third and fourth video heads on the rotating body, and the straight line connecting the first and second audio heads and the first and second The angle formed by the straight line connecting the
₁ [deg], and the angle between the straight line connecting the first and second audio heads and the straight line connecting the third and fourth video heads is α ₂ [deg], and the standard speed of the tape and said than this when the track pitch at the low rate was respectively _{Tp 1, Tp 2, Td 1} ≧ α 1 [deg] × Tp _1/180 [deg] Td ₂ ≧ alpha ₂ [deg] × Tp _2/180 A magnetic recording / reproducing apparatus in which the respective heads are arranged on the rotating body so as to have a relationship of [deg].