JPS6370902A - Rotary magnetic head device - Google Patents

Abstract

PURPOSE:To reduce the number of short rings by activating a rotary erasing head within the nonacting period of a magnetic head connected to a specific coil, setting the mounting angular position theta on a rotary transformer of a rotary erasing head within a specific range, and specifying the erasing track width of the rotary erasing head. CONSTITUTION:The rotary erasing head Hfe connected to a signal transmission coil Lfe for erasing is activated only within the nonacting period of a magnetic head connected to a signal transmission coil disposed neighboring the rotary erasing head Hfe itself. Taking the mounting angular position of the magnetic head on the rotary transformer for the reference 0 deg., the mounting angular position of the rotary erasing head theta is denoted as 90 deg.-alpha-beta>=theta>=-90 deg.+alpha+beta, and the erasing track width Tw of the rotary erasing head is denoted as Tw>=8Tp/3 where Tp is the recording track pitch; accordingly, the erasing action is made to be executed twice while a drum rotates three times. As a result, the signal transmission coil Lfe for erasing and the signal transmission coil L1a can be disposed neigh-boring each other on the core of the rotary transformer without necessitating any short ring.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Industrial field of application B1 Summary of the invention C9 Prior art 6 Problems to be solved by the invention E1 Means for solving the problems 70 Effects G. Example G-1. Schematic structure of one example (Figure 1.2) G-2, Operation explanation (Figure 3.4) G-35 rotation erase head conditions (Figure 5.6) G-4,
Comparative example of effective core area (Fig. 7) G-Example of 5,340'' winding VTR (Fig. 8.9) H1 Effect of the invention A. Industrial field of application The present invention relates to a rotating magnetic head device, and particularly The present invention relates to a rotating magnetic head device in which four magnetic heads are arranged on a rotating drum, signals are transmitted via a rotary transformer, and these magnetic heads are sequentially switched and operated.

B3 Summary of the Invention The present invention has a rotating drum on which a magnetic recording medium is wound at an angle of 270'' or more, and the drum has two sets of two (11) magnetic heads with different azimuth angles, a total of four magnetic heads. The magnetic heads are arranged adjacent to each other at 90 degrees, and these magnetic heads are sequentially switched and operated,
In a rotating magnetic head device having a configuration in which a rotating erase head, a so-called flying erase head, is provided on a rotating drum, the above signal transmission is connected to two sets of four magnetic heads, each of which has the same azimuth angle. The coils are arranged next to each other on the core of the rotary transformer, and a short ring is arranged between each set of two signal transmission coils arranged next to each other, and four signal transmission coils are arranged on the core of the rotary transformer. A signal transmission coil for erasing the rotating erasing head is arranged adjacent to the innermost or outermost end coil of the transmission coil, and the rotating erasing head is operated during the non-operating period of the end coil. With respect to the mounting angular position of the magnetic head connected to the rotary transformer, the mounting angular position θ of the rotary erasing head on the rotary transformer is set as 90'-α-β≧θ≧-90@+α+β, and the erasing of the rotary erasing head The track width Tw is 8 T p / 3
By setting the above (Tp is the recording track pitch), the number of grooves on the core of the rotary transformer is reduced, the requirements for processing accuracy and assembly accuracy of the core are relaxed, and the mutual interaction between each signal transmission coil is reduced. This improves the magnetic coupling characteristics of the rotary transformer while preventing interference and enables good signal transmission.

C1 Conventional technology - In a rotating magnetic head device used in a VTR (video tape recorder), etc., electrical connection (signal transmission) between a rotating magnetic head and a circuit section fixed to the VTR main body is required. In order to perform this, a so-called rotary transformer or the like is used.

Here, FIG. 10 shows an example of a rotary magnetic head device having the above-mentioned rotary transformer.

In FIG. 10, a rotary shaft 14 is rotatably mounted at the center of a fixed drum 12 of a rotary magnetic head device which is fixedly attached to a mounting base 11 such as a chassis of a device body such as a VTR. Supported. This rotating shaft 14
A magnetic head 16 is attached to a rotating drum 15 fixedly attached to the rotating drum 15 so that its tip slightly protrudes from the outer peripheral surface. A fixed core 18 and a rotating core 19 of the rotary transformer 17 are provided on opposing surfaces of the fixed drum 12 and the rotating drum 15, respectively, and are arranged to face each other. On each opposing surface of these cores 18 and 19, signal transmission coils L are provided in several grooves formed concentrically, and each signal transmission coil of the rotating side core 19 is connected to each of the magnetic fields. Each signal transmission coil of the fixed side core 18 is connected to a circuit section fixedly arranged on a main body of a device such as a VTR. Here, rotary transformer 1
A so-called short ring SR for shielding or crosstalk prevention may be provided between each signal transmission coil L of 7, if necessary.

D9 Problems to be Solved by the Invention By the way, for example, in the so-called 81m VTR (video tape recorder) standard, the videotape is wound around a rotating head drum at an angle of 180 degrees or more using a rotating two-head system. The diameter of the drum is said to be 40fi, but for the purpose of further miniaturization, the applicant previously proposed in Japanese Patent Application No. 54-89612 etc. that four magnetic heads were installed on the rotating drum. By wrapping the magnetic tape at an angle of 270° or more, the drum diameter can be reduced to approximately 2
We are proposing a magnetic recording/reproducing device that can reduce the number to about 270/3. In this magnetic recording/reproducing device, there are at least three magnetic heads in contact with the magnetic tape at all times, so the short ring described above is provided for the signal transmission coil of the rotary transformer to prevent crosstalk between each head. That is required.

In other words, the rotary transformer has a total of 7 grooves, 4 grooves for signal transmission coils and 3 grooves for short rings.
grooves are required.

Furthermore, in the so-called g vm V TR, -1'
G is equipped with a so-called flying erase head, which is a rotating erase head suitable for continuous shooting, etc. In this case, it is necessary to install a signal transmission coil in the rotary transformer for supplying a flow of erase to the rad to the flying erase. The number of grooves for signal transmission and the groove for short rings are increased by one each, and it becomes necessary to form a total of nine grooves in the core of the rotary transformer.

However, as mentioned above, in the rotary transformer used in the magnetic recording/reproducing device with a small drum diameter of about 271M, the diameter of the core is small, and the usable core area is considerably small, so it is difficult to form the concentric grooves. This requires high accuracy in processing, and also limits the coupling characteristics as a transformer.

In particular, since the conductive portion of the core of a rotary transformer generally has poor coupling characteristics, it is necessary to make the area of the core opposing portion other than the groove as wide as possible. When the width of the above-mentioned nine grooves is d, the width per channel (one magnetic head or erasing head) of the portion facing the core is (W-9d)15. Therefore, the processing margin is If the groove width d is widened in order to increase the width of the core facing part per channel, the width of the core facing part per channel becomes narrower.
ilt! d becomes extremely narrow, requiring extremely high processing accuracy, and making it difficult to arrange the coil and short ring.

Specifically, the above-mentioned effective width W of the annular core is determined by taking into consideration the center axis and peripheral margin of the rotary transformer, for example.
The limit is to achieve a radius of approximately 10 mm in the range from 2 to 31 mm to 12 to 13 mm. It is necessary to drill and form as many as nine grooves as described above in this annular region with an effective width W = 10 mm, and if the groove width d is set to about 1 square which can be drilled and formed using normal technology, each channel According to the above formula, the width of the core facing portion is extremely small, 0.21 m, and is almost impossible to realize.

The present invention has been made in view of these circumstances, and it is possible to reduce the number of grooves in the core of the transformer while preventing mutual interference between the five signal transmission coils provided in a small-diameter rotary transformer, and to improve rotation speed. An object of the present invention is to provide a rotating magnetic head device that can improve signal transmission characteristics between a magnetic head and a stationary side circuit section, as well as improve productivity and reduce costs.

E9 Means for Solving Problems In order to solve the above-mentioned problems, the rotating magnetic head device according to the present invention has a rotating drum around which a magnetic tape is wound at an angle of 270° or more, and the azimuth angles of which are different from each other. A total of four magnetic heads using two sets of two magnetic heads are arranged adjacent to each other at 90 degrees, and a rotating erasing head is also arranged, and these magnetic heads, the rotating erasing head, and the fixed side circuit In the rotary magnetic head device, the magnetic heads are sequentially switched and operated by transmitting signals between the two sets of magnetic heads via a signal transmission coil of a rotary transformer, and The signal transmission coils connected to magnetic heads having the same azimuth angle are arranged in adjacent grooves on the core of the rotary transformer, and between each set of two adjacent signal transmission coils. A short ring is disposed in a groove formed in the eraser, and the short ring is connected to the rotary eraser head adjacent to a predetermined coil disposed at the innermost or outermost circumference of each of the signal transmission coils. A signal transmission coil is disposed, and the rotating erasing head is operated during a non-operation period of the magnetic head connected to the predetermined coil, and the mounting angle position θ of the rotating erasing head on the rotary transformer is set as described above. When the mounting angle position of the magnetic head connected to a given coil is the reference Oo, it is within the range of 90°-α-β≧θ≧-90゛1α+β,
The erasing track width Tw of the rotary erasing head is Tw≧87p/3, where Tp is the recording track pitch.

F0 effect The short ring between the signal transmission coils of the magnetic head having the same azimuth angle and the short ring between the signal transmission coil of the magnetic head and the erasing signal transmission coil are no longer required, and the number of grooves in the core of the rotary transformer can be reduced. As the diameter of the rotary drum becomes smaller, processing accuracy and assembly accuracy when forming the grooves of the rotary transformer can be reduced, and the effective core area per channel (one magnetic head) can be increased. The magnetic coupling characteristics of the transformer are also improved.

G, Example G-1, Schematic configuration of an example (FIGS. 1 and 2) FIG. 1 is a schematic cross-sectional view of a rotary transformer used in a rotating magnetic head device according to an example of the present invention. Further, FIG. 2 shows a schematic plan view of a rotating drum used in the rotating magnetic head device. Note that the overall configuration of the rotary magnetic head device may be configured in the same manner as shown in FIG. 10 described above, for example, so a description thereof will be omitted.

First, in FIG.
``Four magnetic heads H1a arranged next to each other.
, H2a, Hlb, and H2b, the subscript 1.2 indicates the difference in azimuth angle, and a and b indicate the difference between the sets, and a pair of magnetic heads H1a and H2a having different azimuth angles form one set. The remaining pair of magnetic heads H1b and H2b forms another set. The rotary erasing head Hfe is disposed at a position at a predetermined angle θ from one magnetic head H1a serving as a reference. The magnetic tape (videotape) MT is wound around the rotating drum 15 over an angle of 270° or more (270°+α+β) and is driven to run in the direction of arrow F. The rotating drum 15 is rotationally driven in the direction of arrow R along the tape running direction.

Four such magnetic heads H1a, H2a, Hl
b.

H2b and one rotary erasing head Hfe are electrically connected to a fixed circuit section on the video tape recorder main body side (
(signal transmission), in the embodiment of the present invention, the first
A rotary transformer 17 having a configuration as shown in the figure is used. In FIG. 1, a rotary transformer 17 having a central axis (line 11 in the figure) as its rotation axis is constructed by having two annular magnetic cores 19 arranged opposite to each other. Each opposing surface 18f of each of these magnetic cores 18.19,
19f has a width W in the radial direction, and six concentric grooves G1 to G6 centered on the rotation center axis (dotted chain line) are bored on each of these opposing surfaces 18f and 19f, respectively. It is formed. In five of these six grooves, for example, grooves G2 to G6, the two sets of magnetic heads H1a,
, H2a and Hlb, H2b, the signal transmission coil L is connected to the magnetic heads H1a, Hlb (or H2a, H2b) having the same azimuth angle, respectively.
la, Llb (or L2a, L2b) are arranged next to each other, and each pair of signal transmission coils Lla, Llb (or L2a, L2) are arranged adjacently, and two of these are arranged next to each other.
A short ring SR is arranged between the pair b. Furthermore, an erasing signal transmission coil Lfe for supplying erasing current to the rotary erasing head Hfe is arranged adjacent to the innermost signal transmission coil Lla (or the outermost signal transmission coil L2b). That is, in the example of FIG. 1, the erasing signal transmission coil Lfe, the signal transmission coils Lla, L are arranged in order from the groove G1 to the groove G6.
lb,'/Yodo ring SR1 and signal transmission coil L2
a, L2b are installed. Here, examples of combinations that satisfy the above conditions are shown in Table 1 below. In this Table 1, the arrangement form of each signal transmission coil L1a=L2b, Lfe and short ring SR is as follows:
In addition to the combination of Lfe and short ring SR, it may also be a combination for grooves G6 to G1 shown at the bottom.

Table 1 As is clear from this Table 1, signal transmission coil Ll
They can be exchanged arbitrarily between a and Llb, and between L2a and L2b, and the coils Lla, LIbO
The set and the set of coils L2a and L2b can also be interchanged arbitrarily. Furthermore, the erasing signal transmission coil L
fe may be arranged either on the innermost circumferential side or on the outermost circumferential side.

Here, as described later, the rotary erasing head Hfe connected to the erasing signal transmission coil Lfe is operated only during the non-operation period of the magnetic head connected to the adjacent signal transmission coil, and the magnetic With the mounting angle position of the head on the rotary transformer as a reference (0°), the mounting angle position θ of the rotary erasing head is 90” −α−β≧θ≧−90° +α+β, and the above rotation erasing head By setting the erase track width Tw as Tw≧87p/3, where Tp is the recording track pitch, the erase operation is performed twice for every three revolutions of the drum.

G-2. Explanation of operation (FIGS. 3 and 4) Next, the reason why the above arrangement is possible will be explained. FIG. 3 shows the four magnetic heads H1a shown in FIG.
, H2a, Hlb, H2b magnetic tape MT
It shows the timing of recording and reproducing operations for. - In this FIG. 3, each magnetic head H1a, H2a, H
The period during which lb and H2b actually perform recording and reproducing operations on the magnetic tape MT is indicated by the hatched area in the figure, and each magnetic head is activated every time the rotating drum 15 rotates 270°. Hla, H2a, Hlb, H2
As can be seen from Fig. 2, the white areas before and after the hatched area in Fig. Then, a magnetic tape M is placed on the rotating drum 15.
A so-called overlamp portion, which is a portion where T is excessively wrapped beyond the predetermined angle of 270°, is shown, and the overlap angle on the artificial side of the tape MT is α, and the overlap angle on the exit side of the tape MT is β. Further, the thick solid line portions in the figure indicate the portions where the magnetic heads H1a, )(2a, Rlb, H2b) are only in contact with the magnetic tape MT.

That is, four magnetic heads H1a, H2a, Hl
b, H2b are sequentially IV (1
A recording or reproducing operation is performed for each field (field), and one switching cycle for all four heads is formed between these 4V. This 1 cycle (4V, 3 rotations of drum)
For each magnetic head H1a, H2a, Hlb,
H2b comes into contact with the magnetic tape three times each, and an actual recording or reproducing operation is performed at each one of these three times.

If we pay attention to FIG. 3, we can see that magnetic heads H1a and Hlb (or magnetic helads H2a and H2b) have the same azimuth angle and are arranged 180° opposite each other in FIG.
) pairs never operate simultaneously, even considering the overlap part described above.

Therefore, when considering the arrangement of signal transmission coils on the rotary transformer, it is important to consider the signal transmission coils (fixed By controlling to short-circuit (short-circuit) the
Even if the signal transmission coils of the set of heads with the same azimuth angle are arranged adjacent to each other, adverse effects such as mutual interference can be prevented. That is, the signal transmission coils of the set of magnetic heads having the same azimuth angle are arranged adjacent to each other on the core of the rotary transformer, and each signal transmission coil (the fixed side coil) of the set of magnetic heads is placed in the operating state of the head. By performing short-circuit control accordingly, the signal transmission coil of an unused head can be used as a short ring, and the need for a dedicated short ring as in the past can be eliminated.

By the way, short circuiting of the signal transmission coils corresponding to the heads that are not in use can be realized by using a circuit as shown in FIG. 4, for example. That is, in FIG. 4, the rotating magnetic head H is connected to the signal transmission coil on the rotating core side of the rotary transformer 17, and the signal transmission coil on the fixed core side of the rotary transformer 17 has one end connected, for example. grounded, and the other end (
The non-grounded end) is connected to an amplifier 21 such as a reproducing amplifier. The non-grounded end of the signal transmission coil L on the fixed side is grounded via a switching element 22 such as a transistor,
A control signal for short-circuiting the fixed side signal transmission coil L is supplied to the control input terminal 23 of the switching element 22. As for the signal transmission coil on the fixed side for the magnetic head H which is not used, by controlling the switching element 22 to be in a short-circuited state, it is made to function as a short ring, and other adjacent signal transmission coils are This prevents negative effects such as signal leakage from the

Next, a rotating erase head (so-called flying erase head)
Erasing signal transmission coil L for supplying Hfe erasing current
fe will be explained.

This erasing signal transmission coil Lfe is arranged adjacent to the endmost coil of the signal transmission coils L1a=L2b, that is, inside the innermost coil or outside the outermost coil. However,
It is necessary that the erasing signal transmission coil Lfe operates only during the non-operation period of the adjacent signal transmission coil. For example, as in the example shown in FIG. 1, the erasing signal transmission coil Lfe is arranged adjacent to the inner side of the signal transmission coil Lla arranged on the innermost side of the signal transmission coils L1a=L2b of the rotary transformer. In this case, the rotary erasure head Hfe is operated only during the non-operation period of the adjacent signal transmission coil Lla (the magnetic head H18 connected thereto). That is, the magnetic head H1a operates only during a rotation angle of 270°+α+β during one cycle (3 rotations of the rotating drum, 1080° rotation) shown in FIG. If the rotary erasing head Hfe is short-circuited as described above and is operated only during the non-operation period of the magnetic head H1a, the erasing signal transmission coil Lfe will be connected to the core of the rotary transformer.
and the signal transmission coil Lla can be arranged adjacent to each other without a short ring.

As shown in FIG. 1, each signal transmission coil Ll corresponding to the magnetic heads H1a and Hlb having the same azimuth angle
A, L Ib set and each signal transmission coil L 2a, L 2b set corresponding to the magnetic helads H2a, H2b are provided with a dedicated short ring St? Therefore, the number of grooves for the signal transmission coil, signal transmission coil for erasure, and short ring to be drilled and formed in the core of the rotary transformer is six in total, compared to the nine grooves required conventionally. This means that the number can be reduced by 3.

G-30 Rotation Erase Head Conditions (Figures 5 and 6) By the way, the rotation erase head Hfe is operated only during the non-operation period of the adjacent coils as described above, and the entire surface of the magnetic tape MT is covered. In order to erase, the following conditions are required.

First, the timing at which the rotating erasing head Hfe comes into contact with the magnetic tape MT is determined according to the mounting position (angle θ) of the head Hfe on the rotating drum 15 shown in FIG. For example, the fifth time is based on the mounting angle position of one magnetic head H1a on the rotating drum 15! The contact timing with the magnetic tape at each angular position (vertical axis in FIG. 5) when # (0°) is shown. Similarly to FIG. 3, the thick solid lines in this FIG.
2b shows the operating period. Regarding α and β, which are the overlap angles on the entrance and exit sides of the magnetic tape, the vertical axis of FIG. It is preferable to perform erasing during the period of contact with the magnetic tape according to the mounting angle position shown. In other words, if erasing is performed regardless of the timing of contact with the magnetic tape as shown in FIG. It is important to perform the erasing operation at a timing that is synchronized with the head contact timing shown in Figure 5, because erasing may start or end at a position in the middle of a track. It is possible to prevent erasure from starting or ending. Here, if we consider the case where the erasing operation that satisfies the above conditions is performed during the non-operating period of the magnetic head H1a (see FIG. 3), the erasing operation during one cycle (three rotations of the drum) will be considered. The number of operations is two or one.

Next, in order to perform the erasing operation twice during three rotations (one cycle) of the drum, the following restrictions arise on the mounting position (angle θ) of the rotary erasing head Hfe. That is, when the magnetic head H1a rotates in the direction of the arrow R from the reference state (the state shown in FIG. 2), the above-mentioned effective tape contact occurs within the rotational angle range from 270° to 1080", unless the overlapping portion is taken into account. The head mounting angle position θ to obtain twice is in the range of 90' to -90'',
Considering the overlaps α and β on the inlet side and the exit side of the magnetic head H1a, and the overlaps α and β on the rotary erase head Hfe, as is clear from FIG. The angular position θ is 90°−α−β≧θ≧−90°+α+β. By arranging the rotary erasing head Hfe within the range of angle θ that satisfies this condition, it is possible to realize two erasing operations during three rotations (1 cycle) of the drum.

Next, the conditions for the erasing track width Tw of the rotary erasing head Hfe in order to erase the entire surface of the magnetic tape by performing the erasing operation twice during three rotations (one cycle) of the drum are as follows.
This will be explained with figures. In FIG. 6, the magnetic tape MT
When considering the head trajectory for the recording track pattern above, four magnetic heads H1 per three revolutions of the drum.
Recording of 4v (4 fields) by a-H2b and/
Or, during playback, the tape MT advances in the direction of arrow F by 4 track pitches (4Tp). Therefore, focusing on one magnetic head, for example, Hla, the tape MT advances by 3/4 rotation (270°) while the drum rotates 3 times. ), the recording/reproducing operation for IV is performed on the recording track Tla in FIG. 6, and the trajectory of the head H1a during the remaining period is as follows.
It appears like the dashed track in the figure. In this broken line track, the magnetic helad H1a only contacts the tape MT and does not operate. As is clear from FIG. 6, the magnetic head advances by 4/3 track pinch (4Tp/3) for each rotation of the drum, so if the erasing operation is performed twice for each three rotations of the drum, , when the magnetic tape MT advances 4Tp/3 during each erase operation and 8Tp/3
There is a time to move on. Therefore, in order to erase all tracks on the magnetic tape MT without leaving any traces, the rotating erase head Hfe
The erase track width Tw of at least 8 T p / 3
The above condition, that is, Tw≧87p/3 However, Tp needs to be the recording track pitch.

Note that each recording track T1a=T2b in FIG. 6 is recorded and/or recorded by each magnetic head H1a-H2t+, respectively.
Also, in the figure, Sv indicates a video signal recording portion, and sp indicates an audio PCM signal recording portion.

G-4. Comparative example of effective core area (Fig. 7) Next, the present invention is implemented.By arranging each signal transmission coil of a set of magnetic heads that do not operate simultaneously in this way, the rotary transformer can be The following advantages arise in terms of effective core area. That is, FIGS. 7A and 7B show the embodiment of the present invention and the conventional example of the core 18 of the rotary transformer 17. To simplify the explanation, there is a gap between the outer peripheral end of the core 18 and the short ring SR. A case in which two signal transmission coils, for example, the above-mentioned coils L2a and L2b, are provided will be compared. First, in the seventh recess (embodiment of the present invention), when one coil, for example Llb, is controlled to the short-circuited state, the other coil, for example L2
The effective core area for the coil L2a is within the width Wa shown in FIG. 7A, and conversely, when the coil L2a is controlled to be in the short-circuited state, the effective core area for the other coil L2b is as shown in FIG. 7A. Since the width is within the range of wb, these common portions Wc are used overlappingly, resulting in high core utilization efficiency.In contrast, the core of a conventional rotary transformer as shown in Figure 7B In this case, when trying to arrange the two signal transmission coils L2a and L2b between the short ring SR and the short ring SR+ as above, the short ring SR+
are required, and the effective core area of each coil L2a and L2b is the width W0 and Wbl of FIG. 7B, respectively.
Each range is .

In other words, not only the effective area of the groove width bone for the short ring SRt is small, but also the width of each signal transmission coil L2a and L
Each effective core portion for 2b is separated from each other, resulting in a structure without a common use portion Wc as shown in FIG. Therefore, the effective core area per channel (per magnetic head) is larger in the embodiment of the present invention shown in FIG. 7A than in the conventional example B.

In reality, in the region not shown in FIG. 7, the short ring between the erasing signal transmission coil Lfe and the adjacent signal transmission coil is not necessary in the embodiment of the present invention, but is necessary in the conventional example. . Therefore, when using cores 18 having the same external dimensions, the distance W from the outer peripheral end of the core 18 to the short ring SR in the embodiment of the present invention (FIG. 7A)
h and the same distance wh' of the conventional example (B in the same figure), the distance wh
becomes larger, and the difference in effective core area is further expanded. Therefore, between the embodiment of the present invention shown in FIG. 7A and the conventional example shown in FIG. It is clear that the structure of the embodiment of the present invention is advantageous also in terms of margin.

Example of G-5,340" winding VTR (Figures 8 and 9) By the way, in the case of a so-called 8fi video tape recorder, a track for recording audio PCM signals is placed on an extension of the video signal track on the magnetic tape. Many video tape recorders are also available, which adopt a format that can be used to record and/or play back PCM tracks.

In such a rotating magnetic head device for a video tape recorder, as shown in FIG. The magnetic tape MT is wound in an extra amount.

The timing of recording and reproducing operations for each of the seven magnetic fields H1a, H2a, HLb, and H2b in the rotary magnetic head device shown in FIG. 8 will be explained with reference to FIG. 9.

Similar to FIG. 3 above, in FIG. 9, the hatched area in the figure indicates the period during which each of the magnetic disks H1a to H2b actually performs recording and reproducing operations on the magnetic tape MT. ing. That is, first of all, focusing only on the video signal, each magnetic head enters the recording or reproducing operation state for one field (IV) in the order of Hla, H2a-Hlb, and H2b every 270' rotation of the rotary drum 15.

The above 2 by each of these heads H1a=H2b
Each field of the video signal corresponding to 70° rotation (IV
), prior to recording or reproducing the audio PCM signal for a certain angle (approximately 70 degrees), the recording or reproducing operation is performed. Note that V in the hatched area in FIG. 7 indicates the video signal portion, and P indicates the audio PCM signal portion. Moreover, the white parts before and after the hatched part indicate the so-called overramp part, and as is clear from FIG. The angle is β. Furthermore, the thick solid line portions in FIG. 9 indicate the magnetic heads H1a, H2a, Hlb,
This shows a portion where H2b is only in contact with the magnetic tape MT.

In the case of this rotary magnetic head device of a video tape recorder capable of recording and/or reproducing audio PCM signals,
9th rj! As is clear from J, the pair of magnetic heads H1a and Rlb (or the pair of magnetic heads H2a and H2b) with the same azimuth angle never operate at the same time, even when considering the PCM signal recording/reproducing part and the overlap part. . Therefore, as mentioned above, by short-circuiting the signal transmission coils corresponding to unused heads of the magnetic herad pairs that have the same azimuth angle and do not operate simultaneously, adverse effects such as mutual interference can be avoided. While preventing this, each signal transmission coil of the cough head pair can be placed adjacently on the core of the rotary transformer, and short rings can be reduced. Furthermore, by using a rotary erasing head that operates only during the non-operating period of the magnetic head connected to a predetermined signal coil disposed at the innermost or outermost of the signal transmission coils,
The erasing signal transmission coil of the rotary erasing head can be disposed adjacent to the predetermined signal transmission coil (without intervening a short ring). Here, when erasing is performed only once during three rotations (one cycle) of the drum, the mounting position of the rotating erasing head can be arbitrary, but the erasing track width TW of the head is 4 troughs (4Tp).
The above is necessary, and the erasing operation can be performed using this rotary erasing head in synchronization with the timing of contact with the magnetic tape.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be applied, for example, to rotary magnetic head devices that use multiple magnetic heads with small drum diameters, in addition to so-called 3-second VTRs. can.

H0 Effects of the Invention According to the rotating magnetic head device of the present invention, the signal transmission coils of the magnetic heads that have the same azimuth angle can be short-circuited by short-circuiting the signal transmission coil of the magnetic head that is not in an operating state. The erasing signal transmission coil of the rotary erasing head, which operates only during the non-operating period of the magnetic head, can be placed adjacent to the magnetic head's signal transmission coil without any intervening ring (short circuit). (without intervening rings), it is possible to reduce the number of short rings in the rotary transformer. Therefore, it is possible to improve the productivity by relaxing the machining dimensional accuracy and assembly accuracy of the core of the rotary transformer, and it is also possible to improve the magnetic coupling characteristics of the transformer and enhance the performance of the rotary transformer. Moreover, since erasing is performed twice for every three rotations of the drum, the erasing track width Tw of the rotating erasing head is 8 T p / 4 or more (
However, Tp may be the recording track pitch), which is the recording track pitch.

It is possible to erase the data without leaving any traces remaining, and by widening the erase track width, it is also possible to reduce the single erasing current.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a rotary transformer used in a rotating magnetic head device according to an embodiment of the present invention, FIG. 2 is a schematic plan view of a rotating drum used in the embodiment, and FIG.
The figure is a time chart showing the operation timing of each rotating magnetic head in Figure 2, Figure 4 is a circuit diagram showing the short circuit of the signal transmission coil of the rotary transformer, and Figure 5 is the arrangement angle of the rotating erasing head. A time chart showing the contact timing with the magnetic tape to explain the position, FIG. 6 is a schematic plan view showing the recording track pattern on the magnetic tape, and FIG. 7 is a schematic showing a comparative example of the effective core area of the rotary transformer. The cross-sectional view, Figure 8, shows a 340° winding type V.
A schematic plan view of a rotating drum of a rotating magnetic head device of TR,
FIG. 9 is a time chart showing the operation timing of each head in FIG. 8, and FIG. 10 is a sectional view showing the schematic structure of the rotary magnetic head device. 15...Rotating drum 17...Rotary transformer 1 day...Fixed side core 19...Rotating side core Hla-H2b...Magnetic head Hfe...Rotating erase head MT...Magnetic tape L1a= L2b... Signal transmission coil Lfe... Signal transmission coil for erasing SR... Seat ring 01 to G6... Groove

Claims (1)

[Scope of Claims] A total of four magnetic heads, each consisting of two sets of two magnetic heads with different azimuth angles, are attached to a rotating drum around which a magnetic tape is wound at an angle of 270° or more, each at an angle of 90° to each other. At the same time, a rotating erasing head is arranged on the rotating drum, and these magnetic heads and rotating erasing head are electrically connected to the stationary side circuit section via a signal transmission coil of a rotary transformer. In a rotary magnetic head device having a configuration in which magnetic heads are sequentially switched and operated, the signal transmission coils connected to the magnetic heads having the same azimuth angle among the two sets of magnetic heads are connected to the core of the rotary transformer. A short ring is arranged between each set of two signal transmission coils arranged next to each other, and a short ring is arranged at the innermost or outermost periphery of each of the signal transmission coils. An erase signal transmission coil connected to the rotary erase head is disposed adjacent to the predetermined coil, and the rotary erase head is operated during a non-operation period of the magnetic head connected to the predetermined coil. The mounting angle position θ of the head on the rotary transformer is 90°−α−β≧θ≧−90°+α+β, when the mounting angle position of the magnetic head connected to the predetermined coil is 0° as a reference. , and an erase track width Tw of the rotary erase head, Tw≧8Tp/3, where Tp is a recording track pitch.