JPS63291208A - Rotary magnetic head device - Google Patents

Abstract

PURPOSE:To realize the small diameter of a cylinder and to function a device compatibly with a standard VTR, by providing different rotary driving devices for a rotary magnetic head in sections where the rotary magnetic head is brought and not brought into contact with the magnetic tape. CONSTITUTION:The rotary magnetic heads 13 and 14 are driven by the rotary driving means with different methods in a contact section and a non-contact section with the magnetic tape. Therefore, the rotary magnetic head 14 on the other side can be set so as not to be brought into contact with the magnetic tape when the rotary magnetic head 13 is brought into contact with it in spite of the winding quantity of the magnetic tape for the cylinders 1 and 2. Thereby, compatibility with the standard VTR can be realized by providing two rotary magnetic heads 13 and 14 to be used and by increasing the winding quantity of the magnetic tape for the cylinders 1 and 2. In such a way, it is possible to realize the small diameter of the cylinders 1 and 2 and also, to always bring only one rotary magnetic head into contact with the magnetic tape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a helical scan type magnetic recording/reproducing device, and more particularly to a rotating magnetic head device that allows a cylinder to be made smaller in diameter.

(Prior Art) A so-called standard helical scan magnetic recording/reproducing device (hereinafter referred to as a helical scan magnetic recording/reproducing device) is a VTR in which a magnetic tape is wound approximately 180 degrees around a cylinder equipped with two rotating magnetic heads. However, there is a known VTR that uses a cylinder with a smaller diameter than the cylinder used in the standard VTR, and that also provides a tape pattern that is compatible with the standard VTR. Reducing the diameter makes it possible to make the VTR smaller and lighter, and this is particularly actively used in camera-integrated VTRs.

As one way to reduce the diameter of the cylinder while maintaining compatibility with standard VTRs,
As disclosed in Japanese Patent No. 03, there is a method in which three or more rotating magnetic heads are mounted on a cylinder, and the amount of magnetic tape wound around the cylinder is increased according to the number of mounted rotating magnetic heads.

According to this method, when the number of rotating magnetic heads mounted on a cylinder is n, these rotating magnetic heads are arranged equiangularly on the cylinder, and the magnetic tape is placed on the cylinder at a distance of 360" n) Wound and travels.Each rotating magnetic head starts scanning the magnetic tape sequentially with a delay of 1/n rotation period, and scans the magnetic tape for each (1-1/n) rotation period.Therefore, one One field of a video signal is recorded or reproduced during the (1-1/n) rotation period in which the rotating magnetic head scans the magnetic tape, and the rotating magnetic head is preceded by the 1/n rotation period and the next (1-1/n) rotation period.
1-1/n) rotation period The rotating magnetic head that scans the magnetic tape records or reproduces the next field of the video signal, and each rotating magnetic head scans the magnetic tape every (1-1/n) rotation period. The video signal is recorded or played back one field at a time.

In this case, in order to maintain compatibility with standard VTRs,
Assuming that the running speed of the magnetic tape is the same, the distance that the rotating magnetic head moves during one field period of the video signal (i.e., the length of the winding of the magnetic tape around the cylinder) must be equal to that of a standard VTR. ,
If the diameter of the cylinder on which the above n rotary magnetic heads are mounted is d, and the diameter of the cylinder in a standard VTR is D, then (1--) πd=πD/2, and therefore. Since n is an integer of 3 or more, d<[), and the diameter of the cylinder is reduced.

[Problem that the invention seeks to solve]

However, according to the above-mentioned conventional technology, the following problems occur because the number of rotating magnetic heads used increases.

(1) The cost and assembly cost for the rotating magnetic head increases.

(2) It is necessary to increase the number of channels in the rotary transformer, which leads to deterioration of electromagnetic characteristics and an increase in the diameter of the rotary transformer.

(3) To get the bearing of the electromagnetic conversion characteristics of the rotating magnetic head.

(4) Since the rotating magnetic head, which is not performing recording and reproducing operations, also scans the magnetic tape, the life of the rotating magnetic head and the magnetic tape is shortened, and the running performance of the magnetic tape is degraded.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a rotary magnetic head device which eliminates such problems, uses two rotary magnetic heads, has a smaller diameter cylinder, and is compatible with standard VTRs.

[Problem that the invention seeks to solve]

In order to achieve the above object, the present invention uses different means for driving the rotation of the rotating magnetic head depending on the section where the rotating magnetic head contacts the magnetic tape and the section where the rotating magnetic head does not come into contact with the magnetic tape.

[Effect]

Each rotary magnetic head is driven by the rotary drive means in different ways for the contact section and the non-contact section of the magnetic tape. Therefore, regardless of the amount of winding of the magnetic tape around the cylinder, when one rotary magnetic head is in contact with the magnetic tape, it is possible to keep the other rotary magnetic head out of contact with the magnetic tape. For this reason, by using two rotating magnetic heads and increasing the amount of magnetic tape wrapped around the cylinder to ensure compatibility with standard VTRs, the diameter of the cylinder can be reduced. , the number of rotating magnetic heads in contact with the magnetic tape is always one.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a rotating magnetic head device according to the present invention, in which 1 is an upper fixed cylinder, 2 is a lower fixed cylinder, 3 is a shaft, 4 and 5 are arms, and 6 to 9 are bearings. , 10 is a stopper, 11° 12 is a helad base, 13.
14 is a rotating magnetic head, 15 and 16 are friction members, 17 is a piezoelectric conversion section, 18 is a voltage application section, and 19 to 21 are low retransformers.

In the figure, an upper fixed cylinder 1 and a lower fixed cylinder 2 are fixed concentrically to a shaft 3 with a slight gap between them.

A bearing 6.7 is mounted on the lower fixed cylinder 2 side of the shaft 7.
Therefore, the arm 4 is rotatably mounted, and
A bearing 8.9 is mounted on the upper fixed cylinder 1 side of this shaft 7.
The arm 5 is thus rotatably mounted, and the stops 10 provide a suitable preload to these bearings 6-9.

A head base 11 is provided at the top end of the arm 4, and the head base 11 has an upper fixed cylinder l,
A rotating magnetic head 13 is attached to protrude from the gap between the lower fixed cylinders 2, and a rotating magnetic head 14 is similarly attached to the top end of the arm 5 via a head base 12. There is. These rotating magnetic heads 13 and 14 are arranged on the same plane perpendicular to the shaft 3. In addition, the Herad base 1 on the top of the arm 4
An annular rotary transformer 20 is attached to the inner side of the helad base 12 on the upper surface of the arm 5, and an annular rotary transformer 21 is similarly attached to the inner side of the helad base 12 on the upper surface of the arm 5. They are arranged on a plane and concentrically with the shaft 3, and both face an annular low retransformer 19 attached to the inner surface of the upper fixed cylinder 1 with the shaft 3 as the central axis. The rotary transformer 20 is electrically connected to the rotating magnetic head 13, the rotary transformer 21 is electrically connected to the rotating magnetic head 14, and the rotary transformer 19 is electrically connected to a signal processing system (not shown).

Furthermore, inside the lower fixed cylinder 2, an annular voltage applying section 1 is provided.
8 and a piezoelectric transducer 17 are provided concentrically on the shaft 3. A friction member 15 is provided on the lower surface of the arm 4,
A friction member 16 is also provided on the lower surface of the arm 5, and the arm 4 and the arm 5 are pressed against the piezoelectric transducer 17 through the friction member 15 and the friction member 16 with predetermined pressing forces, respectively. . The piezoelectric converting section 17, the voltage applying section 18, the friction member 15.16, and the arm 4.5 are connected to the rotating magnetic head 1.
3.14 constitutes a surface wave motor serving as a rotational drive means, the piezoelectric converter 17 serving as its stator, and the arms 4 and 5 serving as its rotors. Regarding the drive principle of surface wave motors, see, for example, "Denpa Shimbun" April 17, 1986.
It is explained in detail on pages 21 to 23 of issue 354 of Japan as "Bitechnology Part 2 - Special Feature on Electronics." Although detailed explanation is omitted here, when a predetermined AC voltage is applied to the voltage application section 18, piezoelectric conversion occurs. A predetermined traveling wave is excited on the surface of the piezoelectric transducer 17, and the arm 4.5, which is pressed against the surface of the piezoelectric transducer 17 via the friction member 15.16, is rotated in a predetermined direction at a predetermined speed. be done.

FIG. 2 is a perspective view showing the rotational drive means of the rotary magnetic head 13 in more detail, and FIG. 3 is a perspective view showing the rotational drive means of the rotary magnetic head 14 in more detail.
Parts corresponding to the figures are given the same reference numerals.

Now, as shown in FIG. 4, the magnetic tape 22 is moved by the tape guides 23 and 24 into the upper fixed cylinder 2 and the lower fixed cylinder 3 (hereinafter, these will be simply referred to as cylinder 2,
In FIGS. 2 and 3, the piezoelectric transducer 17 is connected to the magnetic tape of the cylinder 2.3 in FIGS. 22 (hereinafter referred to as the tape-wrapped section), and a portion of the cylinder 2゜3 where the magnetic tape 22 is not wound (hereinafter referred to as the non-tape-wound section). The non-wrapped portion 17b facing the
Opposed to this, the voltage application section 1B is also divided into a wound section 18a and a non-wound section 18b. AC voltages of different magnitudes are applied to the wound portion 18a and the non-wound portion 18b of the voltage application portion 18, so that the arms 4.5 are located at the wound portion 17a of the piezoelectric conversion portion 17, respectively. The rotational speed differs depending on when it is in the non-wrapped portion 17b and when it is in the non-wrapped portion 17b.

Next, the operation of this embodiment will be explained with reference to FIGS. 4 and 5.

In Figure 4, the magnetic tape 22 moves at a speed V in the direction of the arrow X.
t, the arms 4 and 5 rotate in the direction of the arrow Y, and their circumferential speed (that is, the rotational speed of the rotating magnetic heads 13 and 14) is set to . One field of the video signal is 1/60 second, as shown in FIG. 5(a). The head 13 moves the magnetic tape 22 from position A to position B via position A' in FIG.
The section of the angle ψ wrapped around the tapes 2 and 3 (that is, the tape winding section) is defined as one field period of the video signal (
That is, it rotates at a speed of 1/60 second), and then the piezoelectric converter 1
7 from position B to position B in FIG.
'The magnetic tape 22 up to position A is connected to cylinders 2 and 3.
Similarly, the section away from the tape (that is, the section where the tape is not wound) is rotated in one field period of the video signal. Therefore, the rotating magnetic head 13 rotates once during one frame period of the video signal.

Therefore, if the diameter of the cylinder 2.3 is d, the rotational speed of the rotary magnetic head 13 in the tape winding section is the fifth
As shown in the figure, ψ is ψ, and the rotating magnetic head 13 in the tape-unwrapped section is
The rotational speed of is as shown in FIG.

The same applies to the rotating magnetic head 14, but in FIG. 4, when the rotating magnetic head 13 is rotating in the tape winding section, the rotating magnetic head 14 is in the tape non-winding section; When the head 13 is in the tape non-winding section, the rotating magnetic head 14 is rotating in the tape winding section, and when one rotating magnetic head reaches position i1B, the other rotating magnetic head is at position A. Make it as follows.

Therefore, as shown in FIG. 5, the rotational speed of the rotating magnetic head 14 changes at a timing shifted by one field period of the video signal with respect to the rotational speed of the rotating magnetic head 13 (FIG. 5). As a result, the rotating magnetic head 13
．． 14, the video signal can be alternately recorded or reproduced one field at a time, and as shown in FIG. 6, tracks of one video signal field at a time are alternately formed on the magnetic tape 22 by the rotating magnetic heads 13 and 14. It turns out.

By the way, in order for this embodiment to maintain compatibility with a standard VTR, the running speed of the magnetic tape 22 must be set at the same speed as the standard VTR.
The winding length of the magnetic tape 22 on the cylinder 2.3 must also be equal to that of a standard VTR. From this, if the diameter of the cylinder in a standard VTR is D, it must be ψ. Therefore, if ψ>180°, then d<D, and it becomes possible to reduce the diameter of the cylinder 2.3.

Next, another embodiment of the rotary magnetic head device according to the present invention will be described with reference to FIGS. 7 to 9. Note that parts corresponding to those in the previous drawings are given the same reference numerals. .

The configuration of this embodiment is the same as that of the previous embodiment, but in FIGS. 2 and 3, AC voltage is always applied to the wound part 18a of the voltage application part 18, whereas the unwound part An alternating current voltage is intermittently applied to 18b.

In FIG. 7, the diameter of the cylinders 2 and 3 is d', and the angle at which the magnetic tape 22 is wound around the cylinders 2 and 3 is ψ'.

Further, it is assumed that the one-dot chain line P represents the start position of the winding of the magnetic tape 22 around the cylinder 2.3, and the one-dot chain line 'aQ represents the end position of the winding. Therefore, the section of angle ψ' from the position on the dashed-dotted line P to the position on the dashed-dotted line Q becomes the tape-wrapped section, and the section of the other angle (360°-ψ') becomes the tape-unwound section.

Now, as shown in FIG. 7, suppose that the rotating magnetic head 13 is on the dashed-dotted line P and the rotating magnetic head 14 is on the dashed-dotted line Q (the time at this time is indicated as 1 in FIG. 8). ), as shown in FIG. 8, an alternating current voltage is constantly applied to the winding portion 18a (FIGS. 2 and 3) of the voltage application section 18, so that the piezoelectric transducer 17 is applied to the rotating magnetic head 13. A rotational driving force is applied by the winding portion 17a (FIG. 2, FIG. 1, and FIG. 3). At this time, as shown in FIG. 8, an AC voltage equal to the AC voltage applied to the wound portion 18a is also applied to the non-wrapped portion 18b (FIGS. 2 and 3) of the voltage application portion 18. As a result, the rotating magnetic head 1
4 is provided with rotational driving force from the non-wound portion 17b of the piezoelectric converter 17. This will rotate it.

As shown in FIG. 7(b), when the rotating magnetic head 14 reaches the middle of the tape non-loading section from the position on the dashed-dotted line Q to the position on the dashed-dotted line P (at time td, as shown in FIG. 8), Then, the application of the alternating current voltage to the unwound portion 18b of the voltage application section 1B is stopped, and the rotating magnetic head 14 is stopped by the action of the friction member 16.

However, the rotating magnetic head 13 is πd′ψ′ in the direction of the arrow Y.
It continues to rotate at a speed of /6.

Then, as shown in FIG. 7(c), the rotating magnetic head 1
When 3 reaches just before the position on the dashed line Q (time ti)
, as shown in FIG.
An alternating current voltage is applied to b, and the rotating magnetic head 14 moves in the direction of arrow Y.
It starts rotating at the same speed as the rotating magnetic head 13 in the direction.

As shown in FIG. 7(d), when the rotating magnetic head 13 comes on the dashed line Q, the rotating magnetic head 14
reaches above the dashed-dotted line P, and the operation starts again from the state shown in FIG. 7(a).

According to this operation, the period in which the rotating magnetic head 13° 14 rotates in the tape winding section from the position on the dashed-dotted line P to the position on the dashed-dotted line Q, and from the position on the dashed-dotted line Q to the position on the dashed-dotted line P. Each period in the tape-unwound section corresponds to one field period of the video signal, and therefore, the rotating magnetic heads 13 and 14 alternately record or reproduce the video signal one field at a time.

According to this embodiment, since the rotating magnetic head is stopped in the tape winding section, this tape non-winding section can be narrowed, and therefore the magnetic tape is wound around the cylinder at an angle of ψ. Since ' can be set sufficiently larger than 180', the diameter of the cylinder d' can be made sufficiently smaller than the diameter of the cylinder in a standard VTR, based on a relational expression similar to equation (3).

Note that the rotating magnetic heads 13 and 14 within the tape winding section
If the stop period of is T (Fig. 8), b
From tiU, it is expressed as.

By the way, in this embodiment, the speed of the rotating magnetic head in the tape-unwinding section by the non-winding section 17b of the piezoelectric converting section 17 is changed from the speed in the tape-winding section of the rotating magnetic head by the winding section 17a of the piezoelectric converting section 17. Although the speed of the former is set equal to the speed of the latter, the speed of the former may be slower than the speed of the latter.

FIG. 9 is a timing chart in this case, in which the AC voltage intermittently applied to the non-wound part 18b of the voltage application part 18 is lower than the AC voltage applied to the wound part 18a.

Now, when winding a magnetic tape onto a cylinder, let the angle be ψ" and the diameter of the cylinder be d#, and as shown in FIG.
′, and the stopping time of the rotating magnetic head in that section is T′, then the following relationship holds true. In addition, in order to be compatible with a standard VTR, if the diameter of the cylinder of this VTR is D, then ψ' holds true as in equation (3), so from the above two equations, the following relational expression is created: is obtained. Therefore, from this relational expression,
By decreasing the rotational speeds 1 and 2 and increasing the stop time T', the cylinder diameter d'' can be made smaller than that of a standard VTR.

The above equation (6) also holds true when the rotational speed of the rotating magnetic head in the tape-unwound section shown in FIG. 8 is equal to the rotational speed in the tape-wound section. Therefore, assuming that the stopping period of the rotating magnetic head in the tape non-winding section is equal, if the rotation speed of the rotating magnetic head in the tape non-winding section is made slower than the rotation speed in the tape winding section, then The diameter of the cylinder can be made smaller than when the rotational speed of the rotating magnetic head in the tape-unwound section and the tape-wound section are made equal, and the voltage applied to the non-wound section 18b of the voltage application section 18 can be lowered. (Since it can be done, power consumption can also be reduced.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to reduce the diameter of the cylinder by using two rotating magnetic heads, and it is possible to realize a smaller, lighter weight, and lower cost of the rotating magnetic head device.
In addition to maintaining compatibility with standard VTRs, since only one rotating magnetic head is always in contact with the magnetic tape, performance deterioration of the rotating magnetic head and magnetic tape can be suppressed. The excellent effect of being able to freely set the diameter of the

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of a rotating magnetic head device according to the present invention, FIGS. 2 and 3 are perspective views showing the rotating magnetic head driving means in FIG. 1, and FIG. FIG. 5 is an explanatory diagram showing the rotational operation of the rotating magnetic head in another embodiment of the rotation in FIG. 1, and FIG. FIG. 9 is a timing chart showing changes in the rotational speed of the rotary magnetic head in still another embodiment of the rotary magnetic head device according to the present invention. 1...Upper fixed cylinder, 2...Lower fixed cylinder, 4.5...Arm, 11.12...
... Head base, 13.14 ... Rotating magnetic head, 15.16 ... Friction member, 17 ...
... Piezoelectric conversion section, 17a... Winding section, 17
b...Non-wound part, 18...Voltage application part, 18a...Wound part, 18b...Non-wound part. Figure 1 Figure 2 53VA Figure 4 Figure 5 VA U3 speed transfer □ Figure 6 Figure 117 Figure 8 Figure 9

Claims (1)

[Scope of Claims] A magnetic tape in which a magnetic tape is spirally wound at a predetermined angle around a cylinder equipped with one or two rotating magnetic heads, and the magnetic tape is scanned by the rotating magnetic heads. In the recording and reproducing apparatus, the rotational driving means for the rotating magnetic head is a first means for rotationally driving the rotating magnetic head in a tape winding section where the magnetic tape contacts the cylinder;
a second means for rotationally driving the rotary magnetic head in a tape-unwound section where the magnetic tape is remote from the cylinder; A rotary magnetic head device characterized in that it is configured to have different rotational drive states. 2. In claim 1, the rotating magnetic head is arranged alternately in the tape winding section and the tape non-winding section for each field period of the video signal, and in the tape winding section, the rotary magnetic head is arranged at a constant rate in the tape winding section. 1. A rotary magnetic head device which rotates at a high speed and is characterized in that when one of the rotary magnetic heads is in the tape winding section, the other rotary magnetic head is in the tape non-winding section. 3. The rotating magnetic head device according to claim 2, wherein the rotating magnetic head rotates at a constant speed in the tape-unwrapped section that is lower than the speed in the tape-wound section. . 4. The rotating magnetic head device according to claim 2, wherein the rotating magnetic head stops in the tape non-winding section. 5. Claims 1, 2, 3, or 4
2. The rotary magnetic head device according to item 1, wherein the rotational driving means for the rotary magnetic head comprises a surface wave motor.