JPS59177754A - Rotary magnetic drum - Google Patents

Abstract

PURPOSE:To stabilize the travelling of a magnetic tape by forming a notched part on the edge of a slot formed on the fitting plate of a magnetic head and applying the component of frictional force oriented to the guide groove direction to the travelling magnetic tape. CONSTITUTION:The notched part 6e is formed by working an original edge 6c of a slot 6b with inclination to expand the slot 6b. Hatching indicates the surface of the notched part 6e. The frictional force generated at the edges 6f, 6d of the notched part 6e is shown by (n) and (m) respectively. A composite vector of a vector (u) obtained by moving the frictional force (m) and the frictional force (n) becomes (v) and the frictional force (v) is the total frictional force of the slot 6b part and has theta angle from the advancing direction A of the slot 6b. The component of the frictional force in the advancing direction of the magnetic tape 15 and the component of the frictional force in the vertical direction are (x) and (y), respectively. The component (y) of the frictional force acts as the force pressing the lower end of the magnetic tape 15 to the guide groove, so that the lower end of the magnetic tape 15 is prevented from being separated from the guide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotating magnetic drum such as a video tape recorder, and more particularly to an improvement in the structure around the mounting portion of a magnetic head in such a rotating magnetic drum.

FIG. 1 is a sectional view of a conventional rotating magnetic drum, and FIG. 2 is a front view showing a state in which a magnetic tape is suspended on the rotating magnetic drum of FIG. As shown in these drawings, the rotating magnetic drum includes a rotating shaft 1, to which an upper bearing 2 and a lower bearing 3 are fixed. These upper bearing 2 and lower bearing 3 are arranged on the inner diameter side of the long cylinder 4. A flange 5 is also fixed to the rotating shaft 1, and an upper drum 6 is attached to this flange 5. As shown in FIG. 2, four shallow air grooves 6a are formed in the upper drum 6. The upper drum 6 is also provided with a slot 6b, as shown in FIG.
The magnetic hen door is fixed.

The tip of the magnetic head 7 is positioned approximately on the diameter of the upper tram 6. A disc-shaped rotation 1 to a lance upper part 8 are fixed to the lower surface of the flange 5. The long cylinder 4 mentioned above has
A lower drum 9 is formed integrally with this. Second
As clearly shown in the figure, the lower drum 9 has a guide groove 9.
8 is formed with a stepped surface facing upward. A motor stator 10 and a rotor 11 are arranged inside the lower drum 9.

A lower rotating transformer 12 is provided on the upper surface of the motor stator 10 and faces the upper rotating transformer 8 in parallel.

A stopper 13 is fixed to the lower part of the rotating shaft 1 in a state in which a preload is applied to the bearing 3.

A flywheel 14 is fixed to the lower end of the rotating shaft 1. In such a configuration, the magnetic tape 15 is wound across the upper drum 6 and the lower drum 9 in a range of about 180 degrees, as shown in FIG. This magnetic tape 15 is positioned while being guided by two guide rollers 16.

A conventional rotating magnetic drum is constructed as described above and is fixed to the chassis of, for example, a video tape recorder. During recording or playback, the motor stator 10 in the rotating magnetic drum is energized to rotate the drum 6, and a tape drive motor (not shown) provided elsewhere drives the magnetic tape 15 at a constant speed. run at speed. In this case, since the magnetic head 7 traverses the magnetic tape 15 at an angle, the tracks 15a of the video signal recorded on the magnetic tape 15 become as shown in FIG.

The entire lower end of the magnetic tape 15 is connected to the guide groove 9 of the lower drum 9.
When the tracks 15a are properly traveling along the direction a, the rotational speed of the upper drum 6 and the running speed of the magnetic tape 15 are stabilized by controlling them, and the tracks 15a are regularly aligned.

However, if for some reason the lower end of the magnetic tape 15 does not come off the guide groove 9a by a small amount, for example, several μm+tm, the formation state of the track 15a will be disturbed, the S/N ratio of the reproduced video signal will decrease, and the reproduced image will be affected. There is noise or
Alternatively, the image may become shaken, resulting in a decrease in image quality.

In a conventional video tape recorder, magnetic tape 1
5 is wound around the upper drum 6 and the lower drum 9, and both drums 6.
A guide roller 16 etc. is installed at a symmetrical position away from 9 (
Therefore, care was taken to prevent the lower end of the magnetic tape 15 from coming off the guide groove 9a. However, although there is a slight air layer between the magnetic tape 15 and the upper drum 6 due to the action of the air groove 6a, there is a friction coefficient between the magnetic tape 15 and the edge of the slot 6b and the magnetic head 7. Therefore, under the condition that the magnetic tape 15 is running diagonally, the existence of the throwers l to 6b and the magnetic head 7 is
The magnetic tape 15 is separated from the guide groove 9a). When this force is generated, the magnetic tape 15 does not separate from the guide groove 9a in the portion close to the guide roller 16, but as it moves away from the guide roller 16, especially in the intermediate position between the guides I'' and 16. Since there is nothing to restrain the upward displacement of the magnetic tape 15, the magnetic tape 15 tends to separate from the guide groove 9a.

Next, the force for removing the magnetic tape 15 from the guide groove 9a will be explained with reference to FIGS. 4 to 6.

4 and 5 are respectively enlarged front views of the slot 6b portion of the upper drum 6, and FIG. 4 shows the slot 6b of the upper drum 6.
This is an example in which the width is constant regardless of the depth of the slot 6b, and FIG. 5 shows an example in which the width decreases with the depth of the slot 6b. In the example of the slot 6b in FIG. 4, the frictional force generated at the edges 6c and 5d of the slot 6b with the magnetic tape 15 is shown.

m is the same as the direction of rotation A of the thrower] to 6b.

In the example of the slot 6b in FIG. 5, since the edges 6c and 6d are inclined, frictional forces p and q are generated in directions close to perpendicular to the edges (3c and 5d), and the resultant force of the magnitudes of p and q is The direction is the direction of arrow A, as in the example of Fig. 4. In this way, if the slots 6b are symmetrical with respect to the center line, the frictional force generated in the slots 6b will be the direction of the arrow A. The direction of travel is the same as that of 6b.

In Figure 6, straight 1i! A is the traveling direction of the slot 6b or the iJ magnetic head 7, R is the IIJllI force between the magnetic tape 15 and the slot 6b-magnetic head 7, S is the component of the *vibration force in the longitudinal direction of the magnetic tape 15, and T is the The vibration force of l'Ii friction force perpendicular to the direction of S is shown.

The direction of the frictional force component S is the same as the traveling direction of the magnetic tape 15 and does not disturb the running of the magnetic tape 15 in any way, but the direction under the frictional force component forces the magnetic tape 15 into the guide groove. From 9a! d5 in line with the direction to remove it,
Due to the generation of this force T, the running of the magnetic tape 15 is disturbed, the formation of the track 15a is disturbed, and the picture quality of the television is deteriorated.

The object of the present invention is to eliminate the instability of the running of the magnetic tape attached to the conventional rotating magnetic drum mentioned above, and to improve the image quality.

Simply put, this invention focuses on the frictional force applied to a running magnetic tape, and makes a component of this frictional force act in the direction of the guide groove, thereby preventing the magnetic tape from separating from the guide groove. It is something.

The invention will now be described in conjunction with examples.

FIGS. 7 and 8 show essential parts of this embodiment of the present invention, and show enlarged views of the slot 6b, where FIG. 7 is a front view and FIG. 8 is a cross-sectional view. It is a diagram. Note that the same reference numerals as used in the conventional explanation are used for parts corresponding to the conventional one. Therefore, 6 and 6b shown as IJ3 in these drawings are the upper drum and thrower I~, respectively, which are the same as in the prior art. The feature of the embodiment shown here is that the notch portion 6e (hatched portion) is formed by obliquely machining the original edge 6C of the slot b, thereby enlarging the slot 6b. In FIGS. 7 and 8, such a notch 6
Although hatching is applied to e, it should be understood that this does not represent a cross section, but represents the surface of the notch 6e.

When the notch 6e is provided in this way, a frictional force as shown in FIG. 9 is generated. At 85 in FIG. 9, the frictional force generated at the six edges at the upper left end of the notch portion 6e is <n, and the frictional force generated at the right edge 6d is indicated by 1. The resultant vector of U, which is the movement of the frictional force m, and the above-mentioned vibrational force n becomes V, and this frictional force V causes the thrower [~
The total frictional force is 6b6b', and has an angle of θ with respect to the advancing direction A of the slot 6b. Next, the function of the friction bar on the magnetic tape 15 will be explained using FIG. 10.

410 also shows that the frictional force ■ forms an angle of θ with the traveling direction A. In this state, if we calculate the component force of the frictional force in the direction of movement of the magnetic tape 15 and the component force in the direction perpendicular to this, as shown in FIG.
It becomes x and y. The component force X is not related to the running of the magnetic chip 115, but the component force y is
It acts as a force to press against the guide groove 9a. This solves the conventional problem that the lower end of the magnetic tape 15 sometimes comes off the guide groove 9a, and the magnetic tape 15 can run stably.

In the above embodiment, the notch 6e was provided at the edge 6C on one side edge of the slot 6b of the upper drum 6.
As shown in FIG. 11, even if a notch 6h having an inclined edge 6Q is provided at the upper edge of the slot 6b,
Similar effects can be expected.

Note that in both of the above two embodiments, the slot 6
We decided to process only the opening part of b, but slot 6
A similar effect can be obtained even if the notch is formed so as to reach the depth of b.

As described above, according to the present invention, a notch is provided at the edge of the slot to which the magnetic tape is attached, and this applies a component of the frictional force directed toward the guide groove to the running magnetic tape. As edges are formed,
Stabilizes the running of the magnetic tape, and stabilizes the S of the video playback signal.
/ N ratio and TV playback images can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional rotating magnetic drum. 2 is a front view showing a magnetic tape suspended on the rotating magnetic drum of FIG. 1. FIG. FIG. 3 is a simulated diagram that does not show the state of track formation on the magnetic tape. FIG. 4 is an enlarged front view of the slot portion. FIG. 5 is an enlarged front view of the slot portion of another example. FIG. 6 is a conventional friction force vector diagram on a magnetic tape. FIG. 7 is an enlarged front view of a slot portion which is a main part of an embodiment of the present invention. Fig. 8 is an enlarged cross-sectional view of the slot portion of Fig. ¥87. Figure 9 is Figure 7 and ff
FIG. 10 is a diagram showing the magnetic tape operator's commercial curve vector diagram in the embodiment shown in FIGS. 7 and 8. Fig. 11 is a front view of the slot section, which is the main part of another embodiment of this device. In the figure, 6 is the upper drum, 6b is the slot, (3c
, 6(l is an edge, 6e, 5t+ are notches, 6[ is an upper left edge, 6Q is an upper edge, 7 is a head, 9 is a lower drum, 9a is a guide groove, and 15 is a magnetic j-beam. Agent Shin Kuzuno - (1 other person)
Figure 1, Z2, District, Figure 3, Figure 6, Figure 4, Figure 85, Figure 7, L, Figure 8, 6e, 6/L.

Claims (4)

[Claims] (1) In a rotating magnetic drum in which a magnetic head is attached to a rotating drum and a magnetic tape is wound around the drum to record and reproduce video signals, a slot is cut at the edge of a slot formed at the attachment point of the magnetic head. Provide a notch,
A rotating magnetic drum characterized in that an edge is formed to apply a component of vibration force in the direction of a guide groove to a running magnetic tape. (2) The rotating magnetic drum according to claim 1, wherein a notch forming an inclined edge is provided on one side edge of the slot. (3) The rotating magnetic drum according to claim 1, characterized in that the upper edge of the slot is provided with a notch forming an inclined edge. (4) The rotating magnetic drum according to any one of claims 1 to ff13, wherein the notch for cutting the ftJ slot is formed so as to reach the depth of the slot.