JPH0682449B2 - Rotating drum device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] This invention is, for example, a video tape recorder (hereinafter referred to as VTR
Abbreviated), which was made especially to improve the playback image quality of the VTR.
The present invention relates to a rotating drum device in which a head can be moved in the width direction of a magnetic tape to faithfully trace a magnetic recording trace.

[Conventional technology]

FIG. 9 is a sectional view showing a conventional rotary drum device. In the figure, (1) is a rotary shaft, (2) is a fixed lower drum,
(3) is a rotating upper drum, (4) is a head that is detachably screwed to the upper drum (3), (5) is a head fixed to the tip of the head (4), and (6) is A bearing in which the rotary shaft (1) can freely rotate with respect to the lower drum (2), (7) an upper transformer that rotates together with the upper drum (3), (8) a stationary lower transformer, ( 9)
Is a pedestal supported by the rotating shaft (1) and carrying the upper drum (3), and (13) is a magnetic tape.

The head (5) is held at a fixed position with respect to the upper drum (3), and the tip of the head (5) slightly projects from the outer circumference of the upper drum (3). The upper drum (3) is rotated at a constant high speed. The magnetic tape (13) is wound around the outer peripheral surfaces of the upper drum (3) and the lower drum (2) slightly obliquely and runs at a predetermined speed. Thus, the head (5) contacts the magnetic tape (13) to magnetically record or reproduce a video (or audio) signal.

The upper transformer (7) is attached to the pedestal (9) and rotates together with the pedestal (9). The head (5) is the connection part (10),
It is connected to the upper transformer (7) via the wiring board (11) and the connecting portion (12). The lower transformer (8) faces the upper transformer (7) at a slight interval. The upper and lower transformers (7) and (8) are magnetically coupled to each other and transmit signals to each other. The lower transformer (8) is connected to an external signal processing device (not shown).

The head (5) diagonally crosses the magnetic tape (13) by the running of the magnetic tape (13) and the rotation of the head (5). These transverse lines are parallel to each other. FIG. 10 is a diagram for explaining this in detail. In the figure, (13
(a) is the track of the magnetic tape (13), (V ₁ ) is the magnetic tape (1)
3) Normal feed rate, (5a) is head (5) trajectory,
(V ₀ ) is the rotational speed of the head (5). Trajectory (13a)
And the locus (5a) intersect as shown. Thus, the relative locus (the transverse cutting line) drawn on the magnetic tape (13) by the head (5) becomes A as shown in FIG. 10 (a). By the way, the feeding speed of the magnetic tape (13) is from V ₁ to V ₂
It is increased as follows (for example, during high-speed research),
The relative locus of the head (5) with respect to the magnetic tape (13) is B as shown in FIG. 10 (b).

[Problems to be solved by the invention]

The magnetic tape (13) may be reproduced at a speed different from the normal feeding speed (V ₁ ) for recording. For example, stationary, slow, high speed research playback, etc. In such a case, the relative locus between the head (5) and the magnetic tape (13) deviates from the normal relative locus (A) shown in FIG. 10 (a). The relative locus (B) is as shown in FIG. In other words, the head (5) does not accurately follow the relative locus (A) at the normal feed speed, that is, the recording trace, and the head (5) deviates from it. When it comes off, the signal level picked up by the head (5) becomes low, which makes it difficult to obtain a clear reproduced image and causes noise.

The present invention has been made in order to solve the above problems, and reproduces a recording trace on a magnetic tape recorded under a normal feeding speed (V ₁ ), that is, a relative locus (A). An object of the present invention is to obtain a rotary drum device in which the head (5) accurately tracks (C) the recording trace even when the feeding speed of the magnetic tape is arbitrarily changed.

[Means for solving problems]

The rotary drum device according to the present invention is such that the head is controllably moved in the tape width direction (T), and is characterized in that the head is attached to the rotating drum via a leaf spring. Tape head in tape width direction (T)
It is said that it is movable, and a cylindrical coil is attached to this leaf spring,
A cylindrical permanent magnet that magnetically exerts a reaction force on the cylindrical coil is fixed to the rotating drum, and an electrode (slip ring) is provided on the rotating drum to pass a control current through the cylindrical coil. A contactor that makes sliding contact with the slip ring is placed outside, a cylindrical permanent magnet is surrounded by a yoke to prevent interfering magnetic flux from leaking to the head and magnetic tape, and a leaf spring is housed inside it to make it compact. Is.

[Operation] In the rotary drum device according to the present invention, a head is magnetically moved in the width direction (T) of the tape by externally applying a control current to the cylindrical coil through the rotating electrode to match the recording mark on the tape. Further, since the cylindrical coil for driving the leaf spring and the cylindrical permanent magnet are mounted on the rotating drum, these can be integrated as a driving unit to form a unit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view showing a main part of a rotary drum device according to the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a plan view showing the main part of the present invention in more detail, and FIG. FIG. 5 is a sectional view of FIG. In these figures, (1) to (3) and (5) to (13) show the same members as the conventional device. In FIGS. 1 and 2, (4a) is a drive unit for fixing the head (5) to the tip and for moving the head (5) in the width direction of the tape.

Reference numeral (50) is a recess provided in a part of the upper drum (3) for accommodating the drive section (4a), and is formed slightly larger to adjust the position of the drive section (4a). An upper drum is provided with a hole (48b) for attaching a drive unit and a plurality of head position adjusting holes (51) arranged around the hole (48b). One hole (51) on the center line between the rotary shaft of the upper drum and the head.
A pair of (a) and (b) of the hole (51) are arranged on both sides of the center line so that the center line between the holes (a) and (b) is the center line. And for adjusting the head circumferential position index so that they are orthogonal to each other, align the intersecting point and the center point of the annular gear that are orthogonal to each other, and make the radius (48b) for attaching the drive section to the intersecting point. It is arranged in a different direction. The mounting screw hole (48a) is provided at a distance of 1 from the center of the yoke (47).
Positioning in direction (d) is made by pushing the yoke (47) to (a) and (b) of the head position adjusting hole (51) with a rod, and direction (e) by the holes (51) and (c). Position the head (5) and fix it with the screw (48). In addition, (14) is a non-rotating contactor for supplying a control current to the drive part (4a), and (15) is a rotating part provided in a part of the pedestal (9) so as to make sliding contact with the contactor (14). The electrode to turn on, (1
Reference numeral 6) is a connection portion that is electrically connected from the electrode (15) to the drive portion (4a) via the connection portion (12) and the wiring board (11). Head (5) is connection part (10), wiring board (11), connection part (12)
Is electrically connected to the upper transformer (7).

3, 4 and 5 show the drive part (4a) in detail, (41) is a non-magnetic plate spring having a head (5) attached to the tip, and (43) is a plate spring (41). ) Is attached to the coil bobbin, (44) is a cylindrical coil for driving wound around the coil bobbin (43), and (42) is a coil bobbin (4) supported by the coil bobbin (43) and deformed together with the leaf spring (41).
3) a leaf spring for allowing linear movement, (45) a cylindrical permanent magnet, (46) a cylindrical permanent magnet (45) with the same magnetic poles facing each other, and (46a ) Is a ferromagnetic center pole provided between a pair of cylindrical permanent magnets (45) and (46), and (47) is a yoke. The yoke (47) houses and holds the leaf springs (41) and (42), the cylindrical coil (44), the coil bobbin (43), the pair of cylindrical permanent magnets (45) and (46), and the center pole (46a). In addition, it is divided into parts (47a), (47b), and (47c) for easy storage and assembly. (48
a) is a screw hole for attaching and fixing the yoke (47) to the upper drum. (49) is a window provided in a part of the yoke (47). The head (5) projects through the window (49) and is arranged on the upper drum so as to be in sliding contact with the tape (13). The cylindrical coil (44) and the coil bobbin (43) are movably arranged vertically in an environmental gear formed between the pair of cylindrical permanent magnets (45) and (46) and the center pole (46a) and the yoke. ing. The leaf spring (41) is sandwiched between the yoke (47) portions (47a) and (47b), and the leaf spring (42) is sandwiched between the portions (47b) and (47c). .

6 and 7 are detailed views of the leaf springs (41) and (42). The leaf spring (41) includes a coil bobbin mounting portion (41a), an arcuate intermediate portion (41b), and a yoke (47). Part (47a),
And a circular outer peripheral portion (41c) sandwiched between (47b) and held. A head mounting portion (41e) extends from the coil bobbin mounting portion (41a). An arcuate slot is provided in the arcuate intermediate portion (41b), and a connecting hand is provided in the radial direction (f). At least a pair of such arcuate intermediate portions (41b) are symmetrically arranged between the coil bobbin mounting portion (41a) and the circular outer peripheral portion (41c), and the coil bobbin mounting portion (41a) and the circular outer peripheral portion (41c) are connected by their connecting hands. ) Is connected with. The circular outer peripheral part (41c) has a notch (41d) for positioning in the rotational direction on a part of the outer periphery. When the leaf spring (41) is mounted on the yoke (47), the notch (41d) fits into a convex portion (not shown) of the inner wall of the yoke so that the head (5) protrudes accurately from the window (49). Is configured. Leaf spring (4
2) is the same as the leaf spring (41) and the coil bobbin mounting part (42
a), an arcuate middle part (42b), a circular outer peripheral part (42c), and a notch (42d), but this leaf spring (42) does not have a head mounting part (41e), and an arcuate middle part. (Four
The leaf spring (41) differs from the leaf spring (41) in that the connecting hand of 2b) is arranged in the radial direction (G) which is deviated by 90 ° from the radial direction (F). With this structure, the coil bobbin (43)
Is held movably only in the vertical direction, and the head (5) can move linearly only in the vertical direction without rotating in the direction (h).

Referring to FIG. 4, the magnet (45) is connected to the yoke (47) (47).
Magnetic flux (D) is radially generated from the center pole (46a) toward the yoke due to the closed magnetic circuit formed by a) and (47b). Similarly, the magnet (46) creates a magnetic flux (E) by forming a closed magnetic path in the opposite direction with the portions (47b) and (47c), and the magnetic fluxes (D) and (E) both cause the annular gear to move in the same direction. Cross over. Thus, the combined magnetic flux of the magnets (45) and (46) traverses the cylindrical coil (44). When a current is applied to the coil (44) from the contact (14) through the electrode (15) and the connecting portions (12) and (16), the coil (44), the coil bobbin (43) and the head (5) are integrated. Move up and down in parallel. Thus, the head (5) is displaced in the tape width direction.

Since the magnets (45) and (46) are completely covered by the yoke (47) portions (47a), (47b) and (47c), it is necessary to use a yoke material having a high permeability or to use the window (4a). By making the size of) smaller, the magnetic field acting on the coil can be increased while the leakage flux to the head (5) and the upper transformer (7) and other outside remains small.

Although the leaf springs (41) and (42) are arranged so as to sandwich the center pole (46a) in the above embodiment, (41) in FIG.
You may arrange collectively on one side of the yoke (47) like (42).

The magnets (45) and (46) are shown to have symmetrical shapes, but the main magnet (46) has a large size, and the auxiliary magnet (45) has a small size to prevent leakage flux and to have an appropriate magnetic flux density across the annular gear. It may be sized.

The portions (47a), (47b), (47c) of the yoke (47) are shown as a horizontal division type, but the number of divisions may be two or more, or may be another division shape, or a whole enclosing shape. All you have to do is connect.

Although the leaf spring has a substantially circular shape, it may have another shape.

Although the outer shape of the yoke is shown as a circular shape, it may be another shape such as a square shape.

〔The invention's effect〕

As described above, according to the present invention, the head mounted on the upper drum can be controlled and moved in the tape width direction. The drive unit is configured as one set, and it is magnetically shielded by itself and can be stored in the upper drum, so that the assembly and adjustment are easy, the device can be inexpensive, and the highly accurate product can be obtained. is there.

[Brief description of drawings]

FIG. 1 is a sectional view showing a rotary drum device of an embodiment according to the present invention, FIG. 2 is a plan view thereof, FIG. 3 is a plan view showing the main part in more detail, and FIG. 4 shows the inside thereof. FIG. 5 is a front view of FIG. 4, FIG. 6 is a plan view of a leaf spring to which a head is attached, FIG. 7 is a plan view of the other leaf spring, and FIG. 8 is another embodiment. FIG. 9 is a sectional view showing a driving part of the conventional rotary drum device, and FIGS. 10 (a) to 10 (c) are sectional views for explaining a relative track of a tape and a head in a VTR. It is a figure. In the figure, (2) and (3) are upper and lower drums, (4a) is a drive unit, (5) is a head, (7) and (8) are upper and lower transformers, (13) is a tape, and (14) is a contactor. , (15) is an electrode,
(41) and (42) are leaf springs, (44) is a cylindrical coil, and (4)
5) and (46) are cylindrical permanent magnets, (47) is a yoke, (4)
9) is a window. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (10)

[Claims] 1. A rotary drum device which is arranged so as to cross a magnetic flux in a magnetic path and which is capable of recording / reproducing on / from a magnetic tape by moving the head according to the movement of the coil connected to the head by energizing the coil. A rotary drum device, characterized in that a head drive unit, in which a portion other than a head extraction hole provided in a direction perpendicular to the moving direction of the head is covered with a yoke, is housed and arranged in the rotary drum device. 2. A permanent magnet, a center pole, a yoke accommodating and holding the permanent magnet and the center pole by forming a magnetic gap around the center pole, and a coil arranged in the magnetic gap. The rotary drum device according to claim 1, further comprising a head drive unit having a pair of leaf springs held in the yoke and movably carrying the coil, and the head. . 3. The rotary drum device according to claim 2, wherein the permanent magnets are arranged so that the center poles are sandwiched between the permanent magnets and the same magnetic poles face each other. . 4. The rotary drum device according to claim 3, wherein the pair of permanent magnets has an asymmetric shape with respect to the center pole. 5. The rotary drum device according to claim 4, wherein the pair of permanent magnets has a shape smaller than the other of the permanent magnets on the head side. 6. The rotary drum device according to claim 2, wherein the yoke is divided into three parts so as to be divided by the mounting surfaces of the pair of leaf springs. 7. The rotary drum device according to claim 6, wherein a fitting portion is provided between the leaf spring and the yoke. 8. The rotary drum device according to claim 2, wherein the head is attached to one of the pair of leaf springs. 9. The rotary drum device according to claim 2, wherein the pair of leaf springs are arranged so as to sandwich the center pole. 10. A mounting hole for the head drive section, a hole arranged on a center line between the rotary shaft of the upper drum and the head,
A pair is arranged on both sides of the center line, and the center line has a hole orthogonal to the center line, and the center of the intersecting point and the magnetic gap in the head drive section as viewed from the rotation axis direction of the upper drum. 2. The rotary drum device according to claim 1, wherein the mounting holes of the head drive portion are arranged so as to be offset from each other in the radial direction of the upper drum with respect to the intersection.