JPH0414403B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a rotating head drum tape running guide, and in particular, to a rotating magnetic head for simultaneously recording and reproducing audio and video signals using a single rotating transformer. The present invention relates to a running guide for a rotating head drum tape that can be rotated.

[Background of the invention]

A conventional rotary head drum tape running guide will be explained below.

FIG. 1 is a sectional view showing an example of a conventional rotary head drum tape running guide, and FIG. 2 is a sectional view showing another conventional example.

In these figures, 1 constitutes an image rotating transformer, 1a is a stationary rotating transformer, and 1b is a rotating rotating transformer. Further, 2 constitutes an audio rotary transformer, 2a a fixed side rotary transformer, 2
b indicates a rotating transformer on the rotating side. 3a and 3b are recording/reproducing heads for audio, 5 is a disk, 6 is a rotating head drum tape running guide (hereinafter simply referred to as a rotating drum), 7 is a ball bearing, and 8 is a fixed rotating head drum tape running guide. 8a is a bearing housing portion of the fixed drum 8, 9 is a rotating shaft, 10 is a screw, and 11 is an upper rotating transformer support body.

As is clear from FIGS. 1 and 2, in the conventional rotating magnetic head drum tape running guide that records or reproduces audio and video signals in a superimposed manner on a video track using a rotating magnetic head,
The rotary transformer was composed of two rotary transformers, a video rotary transformer 1 and an audio rotary transformer 2.
This is to eliminate crosstalk between the audio side and the video side in terms of distance.

Therefore, in the conventional rotary head drum tape running guide, supports etc. are required to support the two rotary transformers 1 and 2, respectively.
As a result, not only the structure becomes complicated, but also the cost becomes very high.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art as described above, to enable simultaneous recording and reproduction of audio and video signals on a rotating magnetic head by using only one rotating transformer, and as a result, to provide support for the rotating transformer. To provide a rotating magnetic head drum tape traveling guide body which has a simplified body structure and is inexpensive in terms of cost.

[Summary of the invention]

The present invention is characterized in that the transmission winding of the rotating magnetic head for video signals and the transmission winding of the rotating magnetic head for audio signals are arranged in one rotary transformer, and By disposing a short ring between the transmission wire windings, the rotary transformer can be disposed inside the fixed rotary magnetic head tape running guide.

[Embodiments of the invention]

Hereinafter, the present invention will be explained using the drawings.

FIG. 3 is a sectional view showing an embodiment of the rotary head drum tape running guide of the present invention, and FIG. 4 is a plan view of FIG. 3 clearly showing the state in which the magnetic head is attached.

In these figures, the same reference numerals as in FIGS. 1 and 2 indicate the same or equivalent parts. 4a and 4b are video recording/playback heads; 4c is a video playback-only head; 2
0 is a rotating transformer for both video and audio,
20a is a fixed side rotary transformer, and 20b is a rotary side rotary transformer. Also, 21 is a grounding brush, 2
2 is a terminal leader line.

Moreover, FIG. 5 is an enlarged sectional view specifically showing the structure of the rotary transformer 20 shown in FIG. 3, and FIG. FIG. 3 is a circuit diagram showing the connection relationship with the head.

In these figures, the same reference numerals as in FIGS. 3 and 4 indicate the same or equivalent parts. t ₁ , t ₃ and t ₅ to _{t 7} are
Transmission wire windings arranged on the rotating side rotating transformer 20b, t ₂ and t ₄ are shot rings T ₁ , T ₃ and T ₅ to _{T 7} arranged on the rotating transformer 20b.
is arranged in the fixed side rotating transformer 20a.
Transmission wire windings, T ₂ and T ₄ are the rotary transformer 20a
This is the shot ring installed in the.

In this embodiment, as is clear from FIGS. 3 and 4, the audio recording and reproducing heads 3a and 3b are mounted on the rotary drum 6 so as to face each other by 180 degrees.
Further, the video recording and reproducing heads 4a and 4b are also located approximately midway between the audio recording and reproducing heads 3a and 3b,
Both are attached to the rotating drum 6 so as to face each other at 180°.

Furthermore, in this embodiment, the video playback head 4c used for special playback such as still playback is located at a position approximately 180 degrees opposite the previous recording/reproducing head 4b and adjacent to the previous recording/reproducing head 4a. The head 4
It is installed on a head mounting plate that is integrated with the head mounting plate of a. That is, the heads 4a and 4c are
It is a composite head mounted on a single head mounting plate.

As is clear from FIG. 6, the input/output terminals of the heads 3a, 3b, 4a to 4c are connected to the transmission wire windings _t1 , t3 _{and t3} of the rotary transformer 20b by known means. Connected to _t7 to _t5 .

On the other hand, a fixed rotary transformer 20a is attached to the fixed drum 8 by adhesive, and the rotary transformer 20a is connected to the rotary transformer 20b.
At a position opposite to the transmission wire windings t ₁ , t ₃ and t ₅ to _{t 7} ,
As shown in Figure 5, the transmission wire windings T ₁ , T ₃ and T ₅
~ _T7 is located.

In addition, specifically, the rotary transformers 20a, 20
Seven winding grooves are arranged on each opposing surface of b,
Since the seven winding grooves are set to face each other, the transmission wire windings of the rotating and stationary rotary transformers 20b and 20a are opposed to each other. In this respect, shot rings t ₂ , T ₂ and
The same applies to t ₄ and T ₄ .

That is, as a result, the fixed side and the rotating side can be electromagnetically coupled during recording and reproduction, and recording and reproduction signals can be mutually transmitted.

By the way, in this embodiment, the one rotary transformer 20 is arranged almost inside the fixed drum 8, as is clear from FIG. Although it is in a fixed state because it is attached, the rotating side rotating transformer 20b is attached by adhesive to the disk 5 supported by the rotating shaft 9.
It rotates together with the rotating shaft 9. Also rotating drum 6
is fixed to the disk 5 with a screw 10, so that it rotates together with the rotating shaft 9.

Note that, as is clear from FIGS. 3 and 5, the rotary transformers 20 face each other with a predetermined gap G.

In this embodiment having such a configuration, the most problematic problem is crosstalk between the audio signal and the video signal during recording and reproduction. That is,
For example, during recording, an audio recording current i ₂ is applied to the transmission wire windings T ₁ and T ₃ of the fixed rotary transformer 20a.
, and video recording current is applied to the transmission wire windings T ₆ and T ₇ .
i ₁ , but in such a case,
For example, crosstalk between the transmission line windings T ₃ and t ₆ is the most problematic.

By the way, as is well known, the crosstalk between the video signal and the audio signal needs to be -50 dB or less. In terms of distance, in a case like this embodiment, a radius of about 10 mm or more is required on the rotating transformer 20. That is, in FIGS. 5 and 6, shot rings t ₄ , T ₄
If not provided, the distance between the transmission wire windings t ₃ and t ₆ , and hence the interval between T ₃ and T _{6 ,} must be set to approximately 10 mm or more.

In the case of a VHS type VTR, the internal diameter of the fixed drum 8 is specified to be 57 mm according to the standard. On the other hand, if the width of the groove of the winding is set to 1 mm and the inner diameter of the core of the rotary transformer 20 is set to 20 mm, in addition to the above-mentioned distance conditions, then the reproduction-only head 4
Even if the transmission wire windings t ₅ and T ₅ for transmitting and receiving the signals of c are not provided, when considering the inductance matching of each transmission wire winding, the outer diameter of the rotating transformer 20 at least is calculated as follows. It becomes about 80mm. That is, it becomes impossible to accommodate the fixed drum 8 within the inner diameter of 57 mm.

Therefore, in this embodiment, the distance between the audio transmission wire winding and the video transmission wire winding is set so that the crosstalk can be kept below -50 dB without requiring the distance of 10 mm or more. shoot ring
It is decided that t ₄ and T ₄ will be installed.

As a result, in this embodiment, the rotary transformer 20 having the audio and video transmission wire windings has an inner diameter of 57 mm.
It has become possible to make the size so that it can be stored in the fixed drum 8 of mm.

However, in this way shot ring t ₄ ,
Even when T ₄ is arranged, if the scheduled interval is not maintained between the short ring T ₄ and the adjacent transmission wire winding T ₆ , especially during recording, the video recording current will flow through the winding T ₆ . i ₁ is consumed in the shot ring T ₄ . For this purpose, video recording/playback heads 4a, 4
A difference occurs between the currents flowing through the terminals b, resulting in a difference between the outputs during playback, resulting in an unfavorable state for the playback image.

Therefore, in order to prevent this, in this embodiment, a radial distance difference of 4 mm is provided between the short ring T ₄ and the transmission wire winding T ₆ .

As a result, in this embodiment, this interval is used to send and receive signals to and from the video playback head 4c, without providing any special space for the transmission wire windings _t5 , _T5 that are not involved in recording. It became possible to place

Furthermore, crosstalk between audio signals and video signals will be explained with reference to the drawings.

The biggest problem with crosstalk between audio and video signals is that, as mentioned above, especially during recording, the audio recording current i ₂
This is the leakage of the crosstalk component from the winding T ₃ to _the video transmission wire winding t ₆ when the current flows to the video transmission wire winding t 3 . As mentioned above, if this crosstalk component is -50 dB or less in the transmission wire winding _t6 , there is no problem.

FIG. 7 shows the transmission line winding from the winding T ₃ to the short ring t ₄ when an audio recording current i ₂ with a center carrier frequency of 1.3 MHz is input to the transmission line winding T ₃ .
FIG. 3 is a transformer gap G-crosstalk characteristic diagram showing each crosstalk to t ₅ and t ₆ on the vertical axis and the gap G of the rotary transformer 20 on the horizontal axis.

In this transformer gap G-crosstalk characteristic diagram, curve a is a curve (crosstalk curve) indicating the degree of crosstalk component with respect to short ring _t4 , and curves b and c are curves for transmission line winding _t5 ,
This is a crosstalk curve for _t6 .

Normally, the transformer gap G is set in the range of 40 to 120 μm, but in such a range,
In order to keep the crosstalk below -50 dB, as is clear from curve b, the position of the transmission wire winding _t5 connected to the read-only head 4c is insufficient. Therefore, in this embodiment, as described above, the transmission wire winding t ₆ is arranged at a position approximately 4 mm away from the short ring t ₄ in terms of radius, and as is clear from the curve c, crosstalk is completely eliminated. It was set to below -50dB.

Therefore, to repeat what has been said above, in order to secure this -50dB or less, the rotating transformer 2 can be
Reproduction-only head 4c without enlarging the diameter of 0.
This made it possible to install the transmission line windings t ₅ and T ₅ that exchanged signals.

Next, in the method of recording an audio signal by superimposing it on a video track, since the audio signal is a continuous signal, the transmission wire windings t ₁ and T ₃ during recording and playback are
Crosstalk between t ₃ and T ₁ becomes a problem. Specifically, this crosstalk component is −
A desirable state is 20 dB or less.

The removal of crosstalk between audio signals in this embodiment will be described below with reference to the drawings.

FIG. 8 is a diagram showing how the magnetic tape is wound around the rotating drum. In this figure, the same reference numerals as in FIG. 4 indicate the same or equivalent parts. 13 is a magnetic tape.

As is clear from FIG. 8, the magnetic tape 13
is wound around the rotating drum 6 by 180°+2α° and travels in the direction of arrow A. Note that this α° is set to approximately 5° in the VHS system. Furthermore, the audio recording and reproducing heads 3a and 3b are switched by a switching signal every time the rotary drum 6 rotates 180 degrees, so that only one magnetic head is used to record and reproduce audio signals at all times. . That is, in FIG. 8, at the illustrated position, the recording/reproducing head 3b is switched to 3a, and recording or reproduction is performed for a period of 180° using only the head 3a.

Here, mutual crosstalk between audio signals will be explained using an example during playback.

Now, from the state in which the audio signal is being reproduced only on head 3b, as described above,
Considering the case where the magnetic tape 13 is switched to the head 3a and the audio signal is reproduced by the head 3a, the magnetic tape 13 is
α° before the 0° position, and further α° from the 180° position
Since they are wound around each other, the recording and reproducing heads 3a and 3b each reproduce the superimposed recorded signal on the audio track in this 2α overlap part. As a result, a current flows through the transmission wire winding t ₁ or t ₃ , and a corresponding crosstalk component leaks into the transmission wire windings T ₃ and T ₁ .

FIG. 9 is an output waveform diagram (time chart) of the audio signal recording and reproducing heads 3a and 3b for explaining the influence of crosstalk during a period corresponding to this overlap portion. In the figure, 14 is a period corresponding to the overlap portion.

As is clear from FIG. 9, the recording/playing head 3b reproduces the audio signal until time t ₀ (180° position in FIG. 8), and at that time t ₀ , it is switched to the recording/playing head 3a and Even if the head 3a starts playing, during the period 14 corresponding to the overlap part, the recording/playing heads 3a, 3b will play back the signal as described above, so the FM played back by the recording/playing heads 3b, 3a will be For example, the effect of crosstalk as shown in the figure appears on the original signal 15, which is a wave, and the S/N of the audio signal during this period 14 deteriorates.

Therefore _, in this embodiment, in order to eliminate the influence of such crosstalk, as _is clear _{from FIGS} . Shot rings t ₂ and T ₂ are provided.

The effects of providing the shot rings t ₂ and T ₂ will be explained below with reference to the drawings.

FIG. 10 is a transformer gap G-crosstalk characteristic diagram similar to FIG. 7. In the same figure,
Curve d is a curve (crosstalk curve) showing the degree of crosstalk between transmission line windings t ₁ and T ₃ in the absence of short rings t ₂ and T ₂ , and curve e is a curve (crosstalk curve) showing the degree of crosstalk between transmission line windings t 1 and T 3 without short rings t ₂ and T 2 . Transmission wire winding with ₂
This is a crosstalk curve between t ₁ and T ₃ .

As is clear from FIG. 10, when short rings t ₂ and T ₂ are not provided, the transmission wire windings t ₁ and T ₃
It can be seen that it is not possible to ensure the crosstalk between -20 dB or less in the range of 40 to 120 μm of the transformer gap G described above.

On the other hand, when short rings t ₂ and T ₂ are provided, the condition of -20 dB or less is sufficiently satisfied, which is obviously preferable.
However, the necessity of these short rings t ₂ , T ₂ is not as absolute as that of the above-mentioned short rings t ₄ , T ₄ . In other words, even if the above-mentioned -20 dB or less cannot be secured and there is crosstalk greater than that, if the crosstalk can be reduced to nearly -20 dB by reducing the transformer gap G as much as possible, then the above-mentioned short ring There is no practical problem even if t ₂ and T ₂ are omitted.

In this embodiment, as is clear from FIGS. 5 and 6, the head 4c is located adjacent to the transmission wire windings _t5 and _T5 for transmitting and receiving signals from the read-only head 4c.
The signal from the recording/playing head 4b located at a position approximately 180 degrees opposite to the recording/playing head 4c is transmitted without providing the transmission wire windings _t7 , _T7 for transmitting and receiving signals from the recording/playing head 4a located at approximately the same position as the head 4c. Transmission wire windings t ₆ , T ₆ that transmit and receive
has been set up.

The reason why the transmission wire windings are arranged in this way is as follows. That is, for example, when playing back with the read-only head 4c, as is clear from the above, the recording/playback head 4c is in almost the same phase.
Since a is also traced on the magnetic tape 13,
A crosstalk component occurs in the transmission wire winding _t7 . Therefore, if the transmission wire windings t ₇ and T ₇ are arranged adjacent to the transmission wire windings t ₅ and T ₅ , there is a risk that the crosstalk component will leak into the transmission wire winding T ₅ . is large. Of course, this is not preferable in terms of reproduced images.

However, if the transmission wire windings, ie, t ₆ and T ₆ , are arranged 180° opposite each other at the head position as in this embodiment, the recording/reproducing head 4b becomes almost magnetic during the reproduction period of the reproduction-only head 4c. Since it is not in contact with the tape 13, the leakage of crosstalk components as described above does not occur.

In other words, the video signal transmission wire winding is
By arranging them as shown in Figure 6, crosstalk between video signals can be reduced the most.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a rotary transformer having a diameter equal to or smaller than the inner diameter of a fixed drum can be installed by simply having a short ring between the audio signal side and the video signal side. It has become possible to wire transmission wire windings for audio signals and video signals.

In other words, according to the present invention, audio signals and video signals can be simultaneously recorded and reproduced on a rotating magnetic head by using only one rotating transformer, so compared to the conventional rotating head drum tape running guide. , the support structure and the like can be simplified, and the cost can also be reduced.

Furthermore, in the present invention, by providing the short ring, it is necessary to provide a certain interval between the recording/reproducing head for audio signals and the adjacent recording/reproducing head for video signals. Another advantage is that a read-only head that does not participate in recording can be installed without requiring special space.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing one conventional example, Fig. 2 is a sectional view showing another conventional example, Fig. 3 is a sectional view showing an embodiment of the present invention, and Fig. 4 is a state in which the magnetic head is installed. FIG. 3 is a plan view clearly showing the structure of the rotating transformer shown in FIG. 3, FIG. 5 is an enlarged sectional view showing the structure of the rotating transformer shown in FIG. 3, and FIG. Circuit diagrams showing the coupling relationship between the wire and the magnetic head, FIGS. 7 and 10, are transformer gear pumps.
Crosstalk characteristic diagram. Figure 8 is a diagram showing the winding state of the magnetic tape around the rotating drum. Figure 9 is a diagram showing the recording/playback head for audio signals to explain the influence of crosstalk in the period corresponding to the overlap part. FIG. 3a, 3b...Audio recording/playback head, 4a, 4
b... Video recording/playback head, 4c... Video playback head, 6... Rotating drum, 8... Fixed drum, t ₁ , t ₃ , t ₅ to t ₇ and T ₁ , T ₃ , T ₅ to _{T 7} ... Transmission wire winding, t ₂ , T ₂ and t ₄ , T ₄ ... Short ring.

Claims (1)

[Scope of Claims] 1. A rotating magnetic head tape running guide having two or more rotating magnetic heads for recording and reproducing video signals and two rotating magnetic heads for recording and reproducing audio signals, wherein the video signal A power transmission wire winding of the rotating magnetic head for the audio signal and a power transmission wire winding of the rotary magnetic head for the audio signal are arranged in one rotary transformer, and the power transmission wire winding for the video signal and audio signal is provided. A rotating device characterized in that a shot ring is disposed between the two, and a transmission wire winding of a reproduction-only head is disposed between the shot ring and the transmission wire winding of the rotary magnetic head for recording and reproducing video signals. Head drum tape running guide. 2. The transmission wire winding of the rotary magnetic head for recording and reproducing video signals, which is adjacent to the transmission wire winding of the reproduction-only head, is provided at a position facing approximately 180 degrees to the reproduction-only head at the head position. 2. A rotating head drum tape running guide according to claim 1, which is a power transmission wire winding of a rotating magnetic head for recording and reproducing video signals.