JPS6371904A - Rotary magnetic head device - Google Patents

Abstract

PURPOSE:To remarkably reduce the short rings of a rotary transformer and to almost halve the number of grooves of a core by short-circuiting the signal transmission coils of a magnetic head which is not is operating state for the signal transmission coils of the magnetic head that become the same azimuthal angle. CONSTITUTION:A set of magnetic heads H1a and H1b (or magnetic heads H2a and H2b) having the same azimuthal angle and arranged to oppose at 180 deg. do not operate simultaneously even overlapped part is considered. Accordingly, when considering arrangement of signal transmission coils on a rotary transformer, control is made to short-circuit signal transmission coils (fixed) corresponding to unused heads in the set of magnetic heads of the same azimuthal angle and do not operate simultaneously. Thereby, the adverse influences such as mutual interference etc., can be prevented even when the signal transmission coils of a set of heads of the same azimuthal angle are arranged adjacent to each other.

Description

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

A. Industrial field of application B. Summary of the invention C0. Prior art 0. Problems to be solved by the invention E6. Means for solving the problems. F8. Effects. G9. Example G-1. Schematic structure of one example (Fig. 1.2) G-2, Operation explanation (Fig. 3.4) Conditions of G-31 rotating erase head (Fig. 5.6) G-4,
Comparative example of effective core area (Fig. 7) Example of G-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.

B0 Summary of the Invention The present invention comprises a rotating drum on which a magnetic recording medium is wound at an angle of 270° or more, and the drum has a total of four magnetic heads, two sets of two 1&IL magnetic heads with different azimuth angles. The heads are placed next to each other at 90°,
In a rotating magnetic head device having a configuration in which these magnetic heads are sequentially switched and operated and a rotating erase head, a so-called flying erase head, is provided on a rotating drum, each of two sets of four magnetic heads has the same azimuth. The signal transmission coils connected to the corner magnetic heads are arranged next to each other on the core of the rotary transformer, and the erasing signal transmission coil is arranged between each set of two adjacent signal transmission coils. The rotary erasing head is configured to operate within a period in which two magnetic heads respectively connected to two adjacent signal transmission coils on both sides of the erasing signal transmission coil are in a non-operating state. This reduces the number of grooves on the core of the rotary transformer, eases the requirements for processing accuracy and assembly accuracy of the core, and improves the magnetic coupling of the rotary transformer while preventing mutual interference between the signal transmission coils. This improves the characteristics and enables good signal transmission.

C0 Prior Art-S 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 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. Signal transmission coils L are provided in several grooves formed concentrically on each opposing surface of these cores 18 and 19, and each signal transmission coil of the rotating side core 19 is connected to each of the magnetic heads. 16, and each signal transmission coil L 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 7, if necessary.

D0 Problems to be Solved by the Invention By the way, for example, in the so-called 8mm VTR (video tape recorder) standard, the videotape is wound around a rotating head drum at an angle of 180° or more using a rotating two-head system. The diameter of the drum is said to be 40 mm, 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 winding the magnetic tape at an angle of 270° or more, the drum diameter can be reduced to approximately 27°.
We have proposed a magnetic recording/reproducing device that can reduce the number of problems to about 3:27. 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. That is, the rotary transformer requires a total of seven grooves: four grooves for signal transmission coils and three grooves for short rings.

Furthermore, so-called 8xx VTRs generally employ a rotating erase head suitable for continuous shooting, a so-called flying erase head, and in this case, a signal transmission coil for supplying erase current to the flying erase head is used. This increases the number of signal transmission grooves and short ring grooves by one each, resulting in a total of 9i grooves having to be formed in the core of the rotary transformer.

However, as mentioned above, the rotary transformer used in a magnetic recording/reproducing device with a small drum diameter of about 27 u has a small core diameter, and the usable core area is extremely small. High precision is required for processing, and there are restrictions on the coupling characteristics as a transformer.

In particular, each port in the core of a rotary transformer generally has poor coupling characteristics, so it is necessary to make the area facing the core as wide as possible other than the groove. W and the width of each port of the nine grooves is d, the width per channel (one magnetic head or erasing head) of the portion facing the core is (W-9d)15. If the groove width d is widened to take a margin, the width of the core facing part per channel becomes narrower, and the width of the core facing part per channel is increased to improve the coupling characteristics of the transformer. ,
The groove width d becomes extremely narrow, requiring extremely high machining accuracy.
It also becomes difficult to install coils and short rings.

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 realize approximately 10 m1 of radius ranging from 2 to 3 fl to 12 to 13 mm. It is necessary to drill and form as many as nine grooves as described above in this annular region of effective width W=10n, and if the groove width d is set to about 11 that can be drilled and formed using normal technology, the number of grooves per channel is According to the above formula, the width of the core facing portion is extremely small, 0.2 m, which is almost impossible to realize.

The present invention was made in view of the above circumstances, and it is possible to prevent mutual interference between the five signal transmission coils (including the cancellation signal transmission coil) provided in a small-diameter rotary transformer, while also improving the core of the transformer. An object of the present invention is to provide a rotating magnetic head device that can reduce the number of grooves, improve signal transmission characteristics between a rotating magnetic head and a stationary side circuit, and improve productivity and reduce costs.

E8 Means for Solving Problems In order to solve the above-mentioned problems, the rotating magnetic head device according to the present invention has different azimuth angles for a rotating drum around which a magnetic tape is wound at an angle of 270° or more. 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 and rotating erasing head are connected to 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. To,
An erasing signal transmission coil connected to the rotary erasing head is provided, and two magnetic heads each connected to two adjacent signal transmission coils on both sides of the erasing signal transmission coil are both inoperable. It is characterized in that the rotary erasing head is operated during the period in which the state is reached.

21 Effect The short rings between the signal transmission coils of the magnetic heads having the same azimuth angle and the short rings between the signal transmission coil of the magnetic head and the erasing signal transmission coil are all unnecessary, and the number of grooves in the core of the rotary transformer is reduced. As the diameter of the rotating drum becomes smaller, processing accuracy and assembly accuracy when forming the grooves of the rotary transformer can be reduced significantly.
The effective core area per area is increased, and the magnetic coupling characteristics of the transformer are also improved.

G, Example G-1, Schematic configuration of an example (Fig. 1, Part 2) Fig. 1 is a schematic 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 helads Hla arranged next to each other by °,
In H2a, Hlb, and H2b, the subscripts 1 and 2 indicate the difference in azimuth angle, and the subscripts a and b indicate the difference in the set, and a pair of magnetic heads H1a and H2a having different azimuth angles form one set. None, the remaining pair of magnetic heads H1b and H2b form another set.

The rotation eraser head Hfe is arranged at a position at a predetermined angle θ from one magnetic head H1a serving as a reference. A 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. It is rotationally driven in the direction of arrow R along the tape running direction.

Four such magnetic hands H1a, H2a, Hl
In order to electrically connect (signal transmission) b, H2b and one rotary erasing head Hfe to a fixed circuit section on the video tape recorder main body side, in the embodiment of the present invention,
A rotary transformer 17 having a configuration as shown in FIG. 1 is used. In this figure 1, the central axis (dotted chain line in the figure)
The rotary transformer 17, which has a rotation axis of 18 and 19, is constructed by arranging two annular cores 18 and 19 facing each other. Each opposing surface 18f of each of these magnetic cores 18.19
, 19f have a radial width of W, and on each of these opposing surfaces 18f and 19f, there is a rotation center axis (dotted chain line).
Five concentric grooves G1 to G6 are formed, respectively, with the center at the center. These grooves are provided with magnetic heads H1a, H2a, H2a and Hlb, H2b having the same azimuth angle, respectively.
Signal transmission coil Lla, Llb (or L2a, L) connected to lb (or H2a, H2b)
2b) are placed next to each other, and furthermore, these two
Each signal transmission coil L la, L arranged adjacent to each other
An erasing signal transmission coil Lfe for supplying an erasing current to the rotary erasing head Hfe is arranged between the set lb and the sets L2a and L2b. That is, in the example of FIG. 1, signal transmission coils Llb, Lla, erasing signal transmission coil Lfe, and signal transmission coils L2a, L2b are arranged in order from tpGl toward 05. Here, combinations that satisfy the above conditions are listed in Table 1. In this Table 1, the arrangement form of each signal transmission coil Lla-L2b and erasing signal transmission coil Lfe includes not only the combination of each coil L1a=L2b and Lfe for valley grooves G1 to G5 shown in the top row, but also It may also be a combination for the grooves 05 to GI shown at the bottom. As is clear from Table 1, the signal transmission coils Lea and Llb and between L2a and L2b can be exchanged arbitrarily, and the coils Lla,
The set of Llb and the set of coils L2a and L2b can also be interchanged arbitrarily. However, regarding the rotational erasing head Hfe, as will be described later, the magnetic head H1 is connected to the signal transmission coils arranged on both sides of the erasing signal transmission coil Lfe, for example, Lla and L2a, respectively.
It is necessary to perform the erase operation within a period when neither a nor H2a is operating.

G-2. Explanation of operation (FIGS. 3 and 4) Next, the reason why the above arrangement is possible will be explained. Figure 3 shows the four magnetic fields in Figure 2 above.
Magnetic tape M by a, H2a, Hlb, H2b
The timing of the recording/reproducing operation with respect to T is shown. In 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 shown by the hatched area in the figure, and each magnetic head is Hla, H2a, Hlb, H2
The signals are switched in the order of b, and video signals of one field (1) are sequentially recorded or reproduced. As is clear from FIG. 2, the white parts before and after the hatched part (hunting part) in the figure indicate the position of the magnetic tape M with respect to the rotating drum 15.
The portion where T is excessively wrapped beyond the predetermined angle of 270°, the so-called overlap portion, is shown, and the overlap angle on the entrance side of the tape MT is α, and the overlap angle on the exit side of the tape MT is β. Furthermore, the thick solid line portions in the figure indicate the portions where the magnetic heads H1a, H2a, Hlb, and H2b are only in contact with the magnetic tape MT.

That is, four magnetic heads H1a, H2a, Hl
b, H2b are applied to the magnetic tape MT at 1 V (1
A recording or reproducing operation is performed for each field (field), and one switching cycle for all four heads is formed during these four times. This 1 cycle (4V, 3 rotations of drum)
For each magnetic helad t(la, 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 HLa and Hlb (or magnetic heads H2a and H2b) have the same azimuth angle and are arranged 180° opposite each other in FIG.
The sets never operate simultaneously, even considering the above-mentioned overramp portion.

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 helad 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 is connected to one end, for example. is 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. The signal transmission coil on the fixed side for the unused magnetic head H is made to function as a short ring by controlling the switching element 22 to be in a short-circuited state, Prevents negative effects such as signal leakage from the transmission coil.

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

This erasing signal transmission coil Lfe is arranged between each pair of signal transmission coils L1a=L2b that are arranged adjacent to each other, that is, the pair Lla, LLb and L2.
The erasing signal transmission coil Lfe operates only when both of the magnetic heads connected to the adjacent signal transmission coils on both sides are in a non-operating state. For example, as in the first example, when the signal transmission coils Lla and L2a are arranged adjacent to each other on both sides of the signal transmission coil Lfe for erasing The third
As shown in the figure, these signal transmission coils Lla and L2
The rotary erasing head Hfe is operated only during a period when both magnetic heads H1a and H2a connected to a are in an inactive state, that is, during a period when neither head H1a nor head H2a is operating. It is necessary to do so. That is, the magnetic head H1a is
1 cycle (3 rotations of the rotating drum, 1 cycle shown in Figure 3 above)
080° rotation), it operates only during the rotation angle of 270° + σ + β, and outside of this operating period, the signal transmission coil Ll
a is shorted as described above, and
Similarly, since the signal transmission coil L2a of the magnetic head H2a is also short-circuited outside of the rotation angle period of 270°+α+β during the three rotations of the rotating drum, both the magnetic heads H1a and H2a are inactive. If the rotary erasing head Hfe is operated only within the period, on the core of the rotary transformer, both the erasing signal transmission coil Lfe and the signal transmission coil Lla and between the coils Lfe and L2a are connected. Can be placed adjacent to each other without a short ring. Therefore, the number of grooves for the signal transmission coil and erasing signal transmission coil that must be drilled into the core of the rotary transformer is 5 in total, which can be reduced by 4 compared to the 9 grooves required conventionally. Therefore, the number of grooves is approximately halved.

G-39 rotation erase head conditions (FIGS. 5 and 6) By the way, the rotation erase head Hfe is operated only during the non-operation period of the adjacent coil 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, FIG. 5 shows the timing of contact with the magnetic tape at each angular position (vertical axis in FIG. 5) when the mounting angular position of one magnetic helad H1a on the rotating drum 15 is taken as the reference (0°). It shows. Similarly to FIG. 3, the thick solid lines in this FIG.
b shows the operating period. Regarding the overlap angles α and β on the entrance and exit sides of the magnetic tape, only a portion of which is shown in the diagram, the erasing operation of the 0-rotation erasing head Hfe is shown on the vertical axis of FIG. Preferably, this is done during the period of contact with the magnetic tape according to the indicated mounting angular position. That is, if erasing is performed regardless of the timing of contact with the magnetic tape in FIG. It is important to perform the erasing operation at a timing synchronized with the head contact timing of the recording trunk, thereby preventing the erasing from starting or ending at a position in the middle of trunking of the recording trunk.

Next, in order to perform an erasing operation that satisfies the above conditions during three rotations (one cycle) of the drum, the following settings must be made at the mounting position of the rotating erasing head Hfe (angle θ in Figure 2). Restrictions arise. That is, when the rotation angle when the magnetic head H1a rotates in the direction of arrow R from the reference state (the state shown in FIG. 2) is shown on the horizontal axis in FIG. Herad H1a
The period in which both H2a and H2a are inactive is the period in which the rotating drum rotates from 540° to 1080' in FIG. θ is 180°~-
The range is 90゛. However, in reality, there are overlaps α and β on the entrance and exit sides of the magnetic heads H1a and H2a, and overlaps a and β for the rotary erase head Hfe, so the mounting angle of the rotary erase head Hfe is As is clear from FIG. 5, the position θ is 180'-α-β≧θ≧-901+α+β.

Rotating erasing head H within the range of angle θ that satisfies this condition.
By arranging fe, the drum can rotate 3 times (1
One effective erase operation can be achieved during a cycle.

Next, the conditions for the erasing track width Tw of the rotary erasing pad Hfe in order to erase the entire surface of the magnetic tape by performing one erasing operation during three rotations (one cycle) of the drum are as follows.
This will be explained with figures. FIG. 6 shows the head locus with respect to the recording track pattern on the magnetic tape MT. In other words, if we focus on one magnetic head, for example Hla, the drum rotates 3/4 of the way (270 degrees) during the three rotations.
), the recording/reproducing operation for 1 inch is performed on the recording track Tla in FIG. 6, and during this time the tape MT advances in the direction of arrow F by one trunk pinch (T p ). The trajectory of the head H1a during the remaining period appears as a trunk indicated by a broken line in the figure, and in this trunk indicated by a broken line, the magnetic head H1a only contacts the tape MT and does not operate. As is clear from Fig. 6, the magnetic head rotates 4/3 track pitch (4T) per rotation of the drum.
p/3), so every three revolutions of the drum
When performing an erase operation of Tl, the magnetic tape MT advances by 4Tp between each erase operation. Therefore, in order to erase all the tracks on the magnetic tape MT without leaving any traces, Tw≧4Tp for the erase track t=”rw of the rotary erase head Hfe. However, Tp must satisfy the recording trunk pinch condition. be.

Note that each recording track T1a"T2b in FIG. 6 indicates a track recorded and/or reproduced by each magnetic head H1a"H2b, and Sv in the figure indicates a video signal recording portion, and Sp indicates a video signal recording portion. The audio PCM signal recording portions are shown respectively.

G-4. Comparative example of effective core area (Fig. 7) Next, as in the embodiment of the present invention, by arranging the signal transmission coils of a set of magnetic heads that do not operate simultaneously, the rotary transformer 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, and in order to simplify the explanation, the erasing signal transmission coil Lfe( Alternatively, a case where two signal transmission coils, for example, the above-mentioned coils L2a and L2b are disposed between the short ring SR) is compared. First, in FIG. 7A (embodiment of the present invention), when one coil, for example L2b, is controlled to the short-circuited state, the effective core area of the other coil, for example L2a, is equal to the width Wa in FIG. 7A. And conversely, when the coil L2a is controlled to the above-mentioned short-circuited state, the effective core area of the other coil L2b is in the range of the width wb shown in Fig. 7, so their common portion Wc overlaps. Therefore, the core usage efficiency is high. On the other hand, in the case of the core of a conventional rotary transformer as shown in FIG. A short ring SR is also required between the coils L2a and L2b, and the effective core area of each coil L2a and L2b falls within the widths W□ and Wb in FIG. 7B, respectively. That is, not only is the effective area small by the width of the groove for the short ring SR, but also the effective core portions of each signal transmission coil L2a and L2b are separated from each other, as shown in FIG.
It has a structure that does not have a commonly used part Wc like this.

Therefore, regarding the effective core area per channel (per magnetic head), the embodiment of the present invention shown in FIG. 7A has a larger area than the conventional example B.

In reality, in the conventional example (FIG. 7B), it is necessary to arrange the erasing signal transmission coil Lfe in a region not shown in FIG.
A short ring is required between the signal transmission coil and the adjacent signal transmission coil. Therefore, when using cores 18 having the same external dimensions, the distance wh from the outer peripheral end of the core 18 to the erasing signal transmission coil IJe in the embodiment of the present invention (FIG. 7A) is
Compared to the distance wh'' from the outer peripheral end of the core 18 to the short ring SR in the conventional example (FIG. B), the distance wh is naturally 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 the margin of machining accuracy.

G-5, 340' winding VTR (7) example (Figures 8 and 9) By the way, in the case of the so-called 8 Dragon video tape recorder,
Many video tape recorders employ a formant that can form tracks for recording audio PCM signals on an extension of video signal tracks on magnetic tape, and can record and/or play back on these PCM tracks. Supplied.

In such a rotating magnetic head device for a video tape recorder, as shown in FIG. 8, the angle at which the magnetic tape MT is wound around the rotating drum 15 is approximately 340°, and the angle is approximately 340°, and the angle is further reduced by the overlap angles α and β. An extra magnetic tape MT is wound around it.

The timing of recording and reproducing operations for each of the magnetic heads 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, the hatched areas in FIG. 9 indicate the periods during which each of the magnetic heads H1a to H2b actually performs recording and reproducing operations on the magnetic tape MT. . That is, first of all, focusing only on the video signal, each magnetic head enters the recording or reproducing operation state for one field (1) in the order of Hla, H2a, Hlb, and H2b every 270° rotation of the rotary drum 15. Each one field (I
Prior to recording or reproducing the audio PCM signals of a certain angle (approximately 70"), recording or reproducing operations are performed for each of the audio PCM signals at a certain angle (approximately 70"). Note that the shaded area (
V in the hatched portion) indicates the video signal portion, and P indicates the audio PCM signal portion. Also, the white parts before and after the hatched part indicate the so-called overlap part, and the 8th
As is clear from the figure, the overlap angle on the drum entrance side of the tape MT traveling in the direction of arrow F is α, and the overlap angle on the exit side is β. Furthermore, the thick solid line portions in FIG. 9 indicate the magnetic heads H1a, H2a, Hlb.
, H2b shows a portion where only contact is made 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,
As is clear from FIG. 9, the magnetic head pair H1a, Hlb (or the magnetic head pair H2a) with the same azimuth angle
, H2b) never operate simultaneously, even if the PCM signal recording/reproducing part and the overlap part are considered. Therefore, as mentioned above, by short-circuiting the signal transmission coils corresponding to the unused heads of the magnetic head pairs that have the same azimuth angle and do not operate simultaneously, adverse effects such as mutual interference can be avoided. The signal transmission coils of the pair of heads can be arranged adjacent to each other on the core of the rotary transformer while preventing short rings. Further, an erasing signal transmission coil connected to the rotary erasing head is arranged between each set of two adjacently arranged signal transmission coils, and the erasing signal transmission coils are arranged adjacent to each other on both sides of these erasing signal transmission coils. By operating the rotary erasing head within a period in which the two magnetic heads respectively connected to the two signal transmission coils are in a non-operating state, the erasing signal transmission coil of the rotary erasing head is activated. It can be arranged directly between each signal transmission coil (without intervening a short ring). Here, in order to erase all tracks without leaving any traces by performing erasing once during three revolutions (one cycle) of the drum, as mentioned above, the erasing track width Tw of the head must be set to 4 trunk pitches (4Tp). In addition to the above, it is also necessary to perform the erasing operation in synchronization with the timing of contact between the rotary erasing head and the magnetic tape.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be applied to, for example, a rotary magnetic head device other than a so-called 3 am VTR that uses many magnetic heads with a small drum diameter.

H8 Effects of the Invention According to the rotating magnetic head device of the present invention, for each signal transmission coil of the magnetic heads that have the same azimuth angle, the short ring is 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 can be arranged next to each other without intervening, and which operates only during the non-operation period of both magnetic heads, is arranged between each signal transmission coil of each magnetic head. The short ring of the rotary transformer can be significantly reduced, and the number of grooves in the core can be reduced by approximately half. Therefore, productivity can be improved by reducing the machining dimensional accuracy and assembly accuracy of the core of the rotary transformer.
Furthermore, the performance of the rotary transformer can be enhanced by improving the magnetic coupling characteristics of the transformer.

[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 a cough-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 of the rotation eraser. A time chart showing the timing of contact with the magnetic tape to explain the angular position. Figure 6 is a schematic plan view showing the recording track pattern on the magnetic tape. Figure 7 shows a comparative example of the effective core area of a rotary transformer. Schematic 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 18...Fixed side core 19...Rotating side core H1a=H2b...Magnetic head Hfe...Rotating erase head MT...Magnetic tape Lla to L2b ... Signal transmission coil Lfa ... Signal transmission coil for erasing SR ... Short ring 61 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. An erasing signal transmission coil connected to the rotary erasing head is disposed between each set of two adjacently arranged signal transmission coils, and the erasing signal transmission coil is connected to the erasing signal transmission coil. A rotary magnetic head device characterized in that the rotary erasing head is operated during a period in which two magnetic heads respectively connected to two adjacent signal transmission coils on both sides are in a non-operating state. .