JPS63173217A - Rotary drum device - Google Patents

Abstract

PURPOSE:To exactly allow a head to execute tracking, even in case a feeding speed at the time of reproduction is varied, against a recording mark which has been recorded at a regular feeding speed, by providing a plate spring for carrying a cylindrical coil so as to be movable in parallel. CONSTITUTION:A head 5 is moved so as to be controllable in the tape width direction. The head 5 is installed to a rotary drum through plate springs 41, 42 so that the head 5 is movable in the tape width direction, columnar permanent magnets 45, 46 for exerting magnetically a reaction force on a cylindrical coil 44 attached to the plate springs 41, 42 are fixed to the rotary drum, a contact for sliding and coming into contact with a slip ring (electrode) provided on the rotary drum in order to allow a control current to pass through the cylindrical coil 44 is placed at the outside, so that a disturbance magnetic flux does not leak, and also, the plate springs 41, 42 are contained and placed in theinside. Accordingly, the rotary drum device applies the control current to the cylindrical coil 44 from the outside through the rotating electrode and moves magnetically the head 5 in the width direction of the tape. In such a way, the head can be aligned with a recording mark of the tape.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention is applicable to, for example, a video tape recorder (hereinafter referred to as VT).
(abbreviated as "R") was developed specifically to improve the playback quality of VTRs.The video head mounted on a rotating drum was made movable in the width direction of the magnetic tape to faithfully trace the magnetic recording traces. The present invention relates to a rotating drum device configured to rotate.

[Conventional technology]

FIG. 9 is a sectional view showing a conventional rotating drum device. In the figure, (1) is a rotating shaft, (2) is a fixed lower drum,
(3) is a rotating upper drum, (4) is a head stand that is detachably fixed to the upper drum (3), (5) is a head that is fixed to the tip of the head stand (4), (6 ) is a bearing that allows the rotating shaft (1) to rotate freely relative to the lower drum (2), (the upper transformer rotates with the upper drum (3), the lower transformer (8) is stationary, (9) is a pedestal that is supported by the rotating shaft (1) and carries the upper drum (3), and (13) is a magnetic tape.

The head (5) is held at a fixed position relative to the upper drum (3), and its tip protrudes a little beyond the outer periphery of the upper drum (3). The upper drum (3) is rotated at a constant high speed. The upper drum (3) and lower drum (2)
) A magnetic tape (13) is wound slightly diagonally around the outer peripheral surface of the magnetic tape (13) and runs at a predetermined speed. Thus the head (5)
contacts the magnetic tape (13) to magnetically record or reproduce video (or audio) signals.

The upper transformer (power is attached to the pedestal (9)
). The head (5) is connected to the upper transformer (power) via the connection part (10), the wiring board (11), and the connection part (12).The lower transformer (8) is connected to the upper transformer (power) at a small interval. is facing.

The upper and lower transformers (7), T8) are magnetically coupled and mutually transmit signals. The lower transformer (8) is connected to an external signal processing device (not shown).

By running the magnetic tape (13) and rotating the head (5), the head (5) diagonally crosses the magnetic tape (13). These transverse lines are parallel to each other. FIG. 10 is a diagram for explaining this in detail. In the figure,
(13a) is the trajectory of the magnetic tape (13), (V,) is the normal feeding speed of the magnetic tape (13), (5a) is the trajectory of the head (5), (V,) is the rotation of the head (5) It's speed.

The trajectory (13a) and the trajectory (5a) intersect as shown. Thus, the magnetic tape (13) is moved by the head (5).
The relative locus (the above-mentioned crossing line) drawn in is shown in Fig. 10 (a
) as shown in A. By the way, magnetic tape (13)
When the feed speed is increased from Vt to V (for example, during high-speed research), the relative trajectory of the head (5) with respect to the magnetic tape (13) becomes B as shown in FIG. 10(b).

[Problem that the invention seeks to solve]

The magnetic tape (13) has a normal feed speed (Vl) during recording.
may be played at a different speed. For example, stationary
These include slow, high-speed research playback, etc. In such a case, the relative trajectory between the head (5) and the magnetic tape (13) deviates from the normal relative trajectory (A) shown in FIG. The relative trajectory (B) is as shown in the figure (bl).In other words, the head (5
) does not accurately track the relative trajectory (Al, that is, the recorded trace) at the normal feed speed, and begins to deviate from it. When it deviates from it, the signal level picked up by the head (5) becomes lower,
There was a problem in that it was difficult to obtain a clear reproduced image and noise was generated.

This invention was made in order to solve the above-mentioned problems, and the recording trace, that is, the relative trajectory (relative to Al,
To provide a rotating drum device in which a head (5) can accurately track (C) the recording trace even when the feeding speed of a magnetic tape during reproduction is arbitrarily changed.

[Means for solving problems]

The rotating drum device according to the present invention is configured to controllably move the head in the tape width direction +T), and is characterized by the head being attached to the rotating drum via a temporary spring. The head is movable in the tape width direction (T), a cylindrical coil is attached to this leaf spring, and a cylindrical permanent magnet that magnetically exerts a reaction force on the cylindrical coil is fixed to a rotating drum. A rotating electrode (slip ring) is provided on the rotating drum in order to pass a control current through the shaped coil, and a contactor that makes sliding contact with this slip ring is placed externally, and a yoke surrounds the cylindrical permanent magnet to connect the head and magnetic tape. This prevents the leakage of interfering magnetic flux, and furthermore, the board is housed inside, making it compact.

[Effect]

The rotating drum device of this invention magnetically moves the head in the width direction (T) of the tape by applying a control current to the cylindrical coil from the outside via rotating electrodes to match the recording trace on the tape.

Further, since the cylindrical coil and the cylindrical permanent magnet that drive the leaf spring are both attached to the rotating drum, they can be integrated as a driving part to form a unit.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 8. FIG. 1 is a sectional view showing the main part of a rotating 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 invention in more detail, and FIG. FIG. 5 is a front view. In these figures, (1) to (3) and (5) to (13) indicate the same members as in the conventional device. In FIGS. 1 and 2, (4a) is a drive unit that has a head (5) fixed at its tip and moves the head (5) in the width direction of the tape.

(50) is an upper drum (3) for housing the drive unit (4a).
) is a recess provided in a part of the drive part (4a), and is formed with a large circumference in order to adjust the position of the drive part (4a).

The upper drum is provided with a hole (48b) for attaching the drive unit and a plurality of head position adjustment holes (51) arranged around the hole (48b). The holes (51) (c) are arranged on the center line between the rotating shaft of the upper drum and the head to adjust the head protrusion, and the holes (51) are arranged in pairs (a) and (c) on both sides of the center line. (b), and the center line between these holes (a) and (b) is orthogonal to the center line (for head circumference position index adjustment), and the center line of the annular gap is aligned with the orthogonal intersection point. The drive unit mounting hole (48b) is arranged so as to coincide with the intersection point and to slide in the radial direction with respect to the intersection point.The mounting screw hole (48a) is located at a distance l from the center of the yoke (47). By pushing the yoke (47) using a rod or the like, the position of the head position adjustment hole (51) can be adjusted by pushing the yoke (47) to (a) and (b) of the head position adjustment hole (51).
Position the head (5) in the direction (e) according to step (c) of 51), place the head (5), and fix it with the screw (48). Note (1
4) is a non-rotating contact for supplying control current to the drive unit (4a), and (15) is a rotating electrode provided on a part of the base (9) so as to be in sliding contact with the contact (14). , (1
6) from the electrode (15) to the connection part (12) and the wiring board (11)
) is a connection part that electrically connects to the drive part ('4 a ). The head (5) is electrically connected to the upper transformer (power) via a connection part (10), a wiring board (11), and a connection part (12).

3, 4 and 5 show the drive unit (4a) in detail, (41) is a non-magnetic plate bar 4 with a head (5) attached to the tip, and (43) is a plate spring (4a). The coil bobbin (41) is attached to the coil bobbin, (44) is a driving circular I-shaped coil wound around the coil bobbin (43), and (42) supports the coil bobbin (43) and deforms together with the plate bar 4 (41). (45) is a cylindrical permanent magnet, and (46) is a cylindrical permanent magnet arranged with the same magnetic poles as the cylindrical permanent magnet (45) facing each other. The magnets (46a) are a pair of cylindrical permanent magnets (45
), (46) is a ferromagnetic center pole, and (47) is a yoke. This yoke (47) is a leaf spring (41).

(42), cylindrical coil (44), coil bobbin (43)
), a pair of cylindrical permanent magnets (45), (46), and a center pole (46a) are housed and held, and is divided into parts (47a) for easy storage and assembly.

It consists of (47b) and (470). (48a) 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). Head (5) through this window (49)
protrudes and is placed on the upper drum in sliding contact with the tape (13). Note that the cylindrical coil (44) and the coil bobbin (43) are a pair of cylindrical permanent magnets (45).

(46) and the center bow /l/ (46a) are arranged in an annular gap formed between the yoke and the yoke so as to be movable up and down. Also, board par + (41) is yoke (47
) is held between parts (47a) and (47b), and the leaf spring (42) is held between parts (47b) and (47c).

FIG. 6 and FIG. 7 are views showing the leaf springs (41) and (42) in detail, and the leaf spring (41) is attached to the coil bobbin mounting portion (4).
1a), an arcuate intermediate portion (41b), and a circular outer peripheral portion (41c) held between portions (47g) and (47b) of the yoke (47). Coil bobbin mounting part (4
A head attachment portion (41e) extends from 1a). The arc-shaped intermediate portion (41b) is provided with an arc-shaped slot and provided with a connecting arm in the radial direction. This arcuate intermediate portion (41b) is the coil bobbin attachment portion (41g).
and the circular outer peripheral part (41c), and the coil bobbin mounting part (41c) is arranged symmetrically between the coil bobbin mounting part (41c) and
1a) and the circular outer peripheral portion (41C). The circular outer periphery (41c) has a notch (41d) on a part of the outer periphery for positioning in the rotational direction. When the leaf spring (41) is attached to the yoke (47), this notch (41d) fits into a convex part (not shown) on the inner wall of the yoke, so that the head (5
) is configured to protrude from the window (49). Board bar 4
(42), like the leaf spring (41), includes a coil bobbin attachment part (42g), an arcuate intermediate part (42b), and a circular outer peripheral part (
42c) and a notch (42d), but this plate bar 4 (42) does not have a head attachment part (41e);
It differs from the leaf spring (41) in two points: and the connecting end of the arcuate intermediate portion (42b) is arranged so as to be in the radial direction (T), which is shifted by 90 degrees from the radial direction (T). With this configuration, the coil bobbin (43) is held movable only in the vertical direction, and the head (5) is capable of linear movement only in the vertical direction without rotating in any direction.

Referring to FIG. 4, the magnet (45) generates a magnetic flux (D
) are generated radially from the center pole (46g) toward the yoke. Similarly, the magnet (46) is connected to the part (47b
), (4'7c) create a closed magnetic path in the opposite direction and the magnetic flux (E)
, and the magnetic fluxes CD) and (E) both cross the annular gap in the same direction. Thus, the cylindrical coil (
44) is crossed by the total magnetic flux of magnets (45) and (46). The coil (44) is connected from the contact (14) to the electrode (15
), and the connecting parts (12) and (16), when a current is passed through the coil (44), coil bobbin (43), and head (5), they move vertically in a parallel straight line as one. The head (5) is thus displaced in the tape width direction.

Portions (47a) and (47b) of the yoke (47).

(47c) completely covers the magnets (45) and (46), so by using a yoke material with high magnetic permeability or by making the window (4a) smaller, the head (
5) and the magnetic field acting on the coil can be increased while the leakage magnetic flux to the upper transformer (7) and other external parts remains small.

In the above embodiment, the leaf springs (41) and (42) were arranged so as to sandwich the center pole (46a), but in the example shown in FIG.
41), (42), one side ◆ of the yaw (47) may be arranged together.

The magnets (45) and (46) are shown as having symmetrical shapes, but the main magnet (46) is made large, and the sub magnet (45) is made small to prevent magnetic flux leakage and to maintain an appropriate magnetic flux density across the annular gap. It can also be a dimension.

Portions (47a) and (47b) of the yoke (47).

(47c) shows a horizontally divided type, but the number of divisions may be two or more, and another divided shape may be used as long as it surrounds the whole.

Although the leaf spring is shown as having a substantially circular shape, other shapes may be used.

Although the outer shape of the yoke is shown to be circular, it may be of other shapes such as a rectangular shape.

〔Effect of the invention〕

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 section is constructed as a single unit, magnetically shielded, and can be stored in the upper drum, making assembly and adjustment easy, making the device inexpensive, and providing high precision. There is.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a rotating drum device according to an embodiment of 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. Figure 5 is a front view of Figure 4, Figure 6 is a plan view of the plate to which the head is attached, Figure 7 is a plan view of the other plate, and Figure 8 is a front view of Figure 4. A cross-sectional view showing the drive unit of the embodiment,
FIG. 9 is a sectional view showing a conventional rotating drum device, and FIGS. 10(a) to 10(c) are diagrams for explaining the relative trajectory of the tape and head in a VTR. In the figure, (21, (3) are the upper and lower drums, (4a) is the drive unit, (5) is the head, (force), (8) is the upper and lower transformer, (13) is the tape, (14) is the contact, ( 15) is an electrode, (41) and (42) are leaf springs, (44) is a cylindrical coil, (45) and (46) are cylindrical permanent magnets, (47)
is a yoke, and (49) is a window. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent Patent Attorney Masuo Oiwa @Figure 1 Figure 3 Figure 4 Figure 6 Figure 9 Figure 4: He-, 1" level 1θ diagram

Claims (5)

[Claims] (1) A rotating drum device in which the head is moved in the width direction of the tape so that the head trajectory during recording and the head trajectory during playback match even under any tape feed speed, and includes a pair of cylindrical permanent A magnet, a ferromagnetic center pole disposed between them, a ferromagnetic yoke forming an annular gap around these to house and hold them, and a cylindrical shape disposed within the annular gap. a coil, and two non-magnetic leaf springs held within the yoke to support the cylindrical coil so as to be movable in parallel, and extending an extension from one of the leaf springs to the outside of the yoke. a window is formed in the yoke for protrusion and to allow parallel movement of the extension, and a drive part having a head attached to the extension, which connects the two leaf springs and the center. The pole surfaces are arranged in parallel, and the pair of cylindrical permanent magnets are arranged so that the same magnetic poles face each other with the center pole in between, creating two closed magnetic paths in opposite directions between each cylindrical permanent magnet and the yoke. and a magnetic flux that crosses the annular gap in the same direction, further comprising a contactor, an electrode, an upper transformer, and a lower transformer, and the drive unit is housed in a rotating drum device together with these upper and lower transformers. Rotating drum device. (2) A hole for attaching the drive unit and a plurality of holes for adjusting the head position arranged around the hole are provided in the upper drum, and one hole is arranged on the center line between the rotation axis of the upper drum and the head. A pair of holes are arranged on both sides of the center line, and the center line between these holes is orthogonal to the center line to adjust the circumferential position of the head. The intersection point of the annular gap is aligned with the center point of the annular gap, and the drive unit mounting hole is arranged to be shifted in the radial direction with respect to the intersection point.
Rotating drum device as described in section. (3) The rotating drum device according to claim 1, wherein a fitting portion is provided between the leaf spring and the inner wall of the yoke for positioning the leaf spring. (4) The yoke is divided into 3 parts near the mounting surface of each leaf spring.
A rotary drum device according to claim 1, which is divided. (5) The rotating drum device according to claim 1, wherein a pair of leaf springs are arranged to sandwich the center pole.