JPH0253218A - Rotary drum device - Google Patents

Abstract

PURPOSE:To obtain a head driving part having the small gap area between yokes by composing the title device so as to press the neighborhood of a bridge part to be the supporting point of the displacement of a gimbal spring and eliminating the gap of the outer peripheral part of the yokes which do not contact with the gimbal spring. CONSTITUTION:A bridge part D of a first gimbal spring 14 is fitted in the groove 17 of a first yoke 18 and fixed through a protrusion G, and a bridge part D of a second gimbal spring 15 is fitted in the groove 17 of a second yoke 16 and fixed through a protrusion G. Further, the yokes in the parts which do not contact with the gimbal springs are under an adhered state. Consequently, the gap between the yokes 18 can be eliminated. Thus, since the spring characteristic of the gimbal spring 15 can be stabilized, and a head 1 can accurately move in a tape width direction, a more clear reproduced picture can be obtained, and since leakage flux becomes smaller, influence to the circumference can be minimized, and the quality of the product can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to, for example, a video tape recorder (hereinafter abbreviated as VTR), in which a video head provided on a rotating drum is movable in the width direction of a magnetic tape. This invention relates to an improvement of a rotating drum device that allows magnetic recording traces to be faithfully traced.

[Prior Art] FIG. 5 is a partial cross-sectional view showing a head drive section in a conventional rotary drum device disclosed in, for example, Japanese Patent Application Laid-Open No. 63-25821. )
(3) is a non-magnetic first gimbal spring with a head (1) attached to its tip, and (3) is a cylindrical coil (4) attached to the first gimbal spring in parallel with the first gimbal spring (2). ), a non-magnetic second gimbal spring (5) is attached to the other side of the cylindrical coil (3
) is a cylindrical magnet part that produces a magnetic reaction in order to move up and down, and is a ferromagnetic body joined to the first permanent magnet (5a), the second permanent magnet (5b), and the second permanent magnet (5b). ball (5c), and a first permanent magnet (5c).
A slight gap is formed between a) and the ferromagnetic ball (5c). (6) is a first yoke of ferromagnetic material that carries the first permanent magnet (5a) and is attached to the upper drum (7), and (8) constitutes a magnetic closed circuit together with the cylindrical magnet part (5). The second yoke (9) is the second permanent magnet (5b
) and a third ferromagnetic yoke on the other side carrying a ferromagnetic ball (5c). The first gimbal spring (2) and the second gimbal spring (4) are the first gimbal spring (2) and the second gimbal spring (4), respectively.
The outer peripheral portion is held between the third yokes (6), (9) and the second yoke (8). (10) is the head (
(1) is a first flexible substrate connected to the coil (10), (12) is a second flexible substrate connected to the cylindrical coil (3), (13)
is magnetic tape. 6(a) is a plan view of the first gimbal spring (2), and FIG. 6(b) is a plan view of the second gimbal spring (4). In these figures, (D) is a plan view of the yoke (6), ( 8), the outer peripheral part (E
) and the central spring part (F).

Next, the operation will be explained. The signal on the magnetic tape (13) is extracted from the coil (10) to the outside via the first flexible substrate (11). On the other hand, a cylindrical magnet part (5) and first, second and third yokes (6), (8) made of ferromagnetic material,
(9) constitutes a magnetic field, so when the direction of the current flowing from the external circuit (not shown) to the cylindrical coil (3) via the second flexible substrate (12) is changed, the cylindrical coil (3) is driven up and down. Along with this, the first and second gimbal springs (2) and (4) are displaced using the bridge portion (D) as a fulcrum, and thus the head (1) is moved against the magnetic tape (1).
3) is displaced in the width direction. Therefore, as shown in FIG. 7(a), with respect to the recording trace (A) recorded at the normal feed speed (V+) of the magnetic tape (13), the tape feed speed is
For example, when the speed is set to double (V, = 2V) as shown in Figure (b), a control current is applied to the cylindrical coil (3) as described above, and the head (1) is connected to the magnetic tape (13). By controlling the movement in the width direction (B) of the head (1), the relative locus (C) of the head (1) and the magnetic tape (13) is made to coincide with the recording trace (A), thereby accurately reproducing the signal.

Problem 1 to be Solved by the Invention The head drive unit in a conventional rotating drum device has a yoke (6) that covers the entire outer circumference (E) of the gimbal springs (2) and (4).
, (8), and (9), there may be variations in the thickness of the gimbal springs (2) and (4), and the yoke (6).

If the flatness of the parts that contact the gimbal springs (2) and (4) in (8) and (9) is poor, the bridge part (D), which serves as a fulcrum for vertical displacement, cannot be securely fixed, and the spring characteristics will deteriorate. As a result, the head (1) may not accurately match the recording traces on the tape, making it impossible to obtain a clear reproduced image.Also, since the gimbal spring is non-magnetic, a large gap will occur between the yokes, resulting in large leakage magnetic flux. There were problems such as affecting the audio head located near the rotating drum.

This invention was made to solve the above-mentioned problems, and aims to provide a head drive unit in which the bridge portion (D) is reliably held down and the gap area between the yokes is small.

[Means to solve the problem]

In the head drive unit of the rotating drum device according to the present invention, only the vicinity of the bridging portion between the outer circumferential portion and the spring portion of the non-magnetic gimbal spring protrudes in the outer circumferential direction, and this protruding portion is provided on the magnetic yoke. The gimbal spring is fitted into a groove and is fixed by being sandwiched between the yokes, and furthermore, a protrusion is provided on the portion that extends toward the outer circumference of the gimbal spring and is sandwiched and fixed in the yoke, or on at least one side of the yoke that comes into contact with the gimbal spring. , the gimbal spring is sandwiched between the yokes so as to crush the protrusion, and the yoke portion that is on the same circumference as the sandwiched portion of the gimbal spring and does not come into contact with the gimbal spring is brought into close contact with the gimbal spring.

[Function 1] In the head drive unit of the present invention, the vicinity of the bridging portion with the central spring protruding from the outer circumference of the gimbal spring is sandwiched and fixed by the yoke via a protrusion, and the portion of the yoke that does not contact the gimbal spring is tightly attached. This eliminates the gap between the yokes.

[Embodiment 1] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Figures 1 to 3, (9) is the same as the conventional device.
Showing the yoke. (14) and (15) are a first gimbal spring and a second gimbal spring in which only the bridge portion (D) protrudes in the outer circumferential direction and a protrusion (G) is formed in the part that contacts the yoke, and (16) is a gimbal spring. A second yoke (18) has a groove (17) in its contacting part, a first yoke (18) has a groove (17) in its contacting part with the gimbal spring like the second yoke, and the first gimbal spring (14) A notch (19) is provided so that the externally protruding portion of the yoke can be moved up and down. In addition, the second yoke (1
The contact surface of the third yoke (9) that fits into the third yoke (9) with the gimbal spring is flat, and the contact surface of the second yoke (16) that fits with the first yoke (18) with the gimbal spring is also flat.

FIG. 3 shows a state in which the above yoke and gimbal spring are combined, and the bridge portion (D
) fits into the groove (17) of the first yoke (18) and is fixed via the protrusion (G), and the second gimbal spring (
The bridging portion (D) of the second yoke (15) is connected to the groove (17) of the second yoke (16).
) and is fixed via the protrusion CG).

Also, the portion of the yoke that is not in contact with the gimbal spring is in close contact.

As described above, the bridging portion (D) with the center spring of the gimbal spring can be reliably adjusted to the first, second, third yaw (18),
(16) and (9), so the head (1) is moved to the magnetic tape (1) according to the tape feeding speed (■2).
3) There is no play when moving in the width direction of the head (1), and the linearity and reproducibility of the amount of movement of the head (1) in response to the control current supplied to the cylindrical coil (3) is improved. Since there is no gap between the yokes on the circumference, leakage magnetic flux is reduced.

In addition, in the above embodiment, the groove (17) was provided on one side of each of the first yoke (18) and the second yoke (16).
The opposite surface of the second yoke (16) and the third yoke (9)
) side surface or the surface of each yoke may be provided with a groove (17), or as shown in Fig. 4, even if the outer periphery between the bridge portions of the gimbal springs that are close to each other is left, the outer periphery may be formed. The rigidity of the yoke is increased, making it easier to handle, and the vicinity of the bridge portion (D) can be held down, and the gap between the yokes can be made smaller than before, so similar effects can be obtained. Further, the same effect can be obtained even if the protrusion is provided on the surface of the gimbal opposite to the embodiment or on the surface on the yoke side. Furthermore, even if a groove (17) with a depth not exceeding the thickness of the gimbal spring is provided in the part of the yoke that sandwiches the gimbal spring that contacts the gimbal spring without forming a protrusion on the gimbal spring or the yoke, the gimbal spring can be bridged. Since the area near part (D) is suppressed and the gap between the yokes is reduced compared to the conventional case, the spring characteristics are stabilized and leakage magnetic flux is reduced.

[Effects of the Invention] As described above, according to the present invention, the vicinity of the bridge portion, which is the fulcrum of the displacement of the gimbal spring, is held down, and the gap at the outer peripheral part of the yoke that does not contact the gimbal spring is eliminated, so that the spring of the gimbal spring is suppressed. Since the characteristics are stable and the head moves accurately in the tape width direction, clearer reproduced images can be obtained, and leakage magnetic flux is reduced, which reduces the influence on the surroundings and improves the quality of the product.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a gimbal spring of a head drive section in a rotating drum device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of the head drive section of the present invention showing its gimbal spring and yoke, and FIG. 4 is a plan view showing a gimbal spring according to another embodiment of the invention; FIG. 5 is a sectional view showing a conventional head driving section; FIG. FIG. 6 is a plan view showing a conventional gimbal spring, and FIG. 7 is a diagram for explaining the relative trajectory between a tape and a head in a VTR. In the figure, (1) is the head, (3) is the cylindrical coil,
(5) is a cylindrical magnet part, (9), (16), (18) are yoke, (10) is a coil, (14), (15) are gimbal springs, (17) is a groove, (G) is a protrusion It is. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa, patent attorney Diagram gear rough. Diagram

Claims (1)

[Claims] (1) A cylindrical permanent magnet, a magnetic yoke that forms an annular gap around its outer periphery, a cylindrical coil located within the gap, and a yoke that attempts to position this coil in a neutral position and a head and at least one non-magnetic gimbal spring integrally coupled to the yoke to move the head in the width direction of the tape and perform playback even under the head trajectory during recording and at any tape feed speed. A rotary drum device including a head drive unit configured to match head trajectories at the same time, wherein only a portion of the non-magnetic gimbal spring protrudes toward the outer circumferential direction in the vicinity of a bridging portion between an outer circumferential portion and a spring portion; This protruding part is sandwiched and fixed between magnetic yokes, and a groove is provided in the part of the yoke sandwiching the gimbal spring that contacts the gimbal spring, and the protruding part protrudes toward the outer circumference of the gimbal spring and is sandwiched between the yokes. A protrusion is provided on at least one side of the part to be fixed or the surface on the yoke side that contacts the gimbal spring, and the gimbal spring is sandwiched between the yokes so as to crush the protrusion. The rotating drum device has a yoke part that does not come into contact with the gimbal spring.