JPH06187708A - Rotating head drum - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a rotary head drum in which the contact of the tape with the head at the drum outlet portion is improved and the occurrence of spacing can be reduced. [Structure] The upper surface of the lead 3 of the fixed drum 2 at the drum outlet portion is formed on the rotary drum side 4 in a reverse taper portion 6 where the diameter of the fixed drum 2 increases, and the formation range of the reverse taper portion 6 is on the drum outlet side. The tape 1 is separated from the fixed drum 2 in the part by about 90 degrees toward the drum entrance side.
Formed in an angular range of °.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type rotary head drum applied to a magnetic recording / reproducing apparatus such as a VTR (video tape recorder).

[0002]

2. Description of the Related Art Conventionally, in the loading state in which a tape is wound around a rotary head drum, the contact of the tape with the head is slightly different between the inlet side and the outlet side of the drum. It has been clarified that the reproduction output of the tape decreases due to the phenomenon. Therefore, conventionally, there is a method of providing a notch at the upper end of the fixed drum on the outlet side in order to secure the contact between the head and the tape on the outlet side of the drum. The method using the notch has a problem that dust or the like may enter from this portion and the tape may be damaged by the edge of the notch.

A tape loading state for a normal rotary head drum will be described with reference to FIG. In FIG. 11, reference numeral 1 is a tape, 2 is a fixed head, 3 is a lead for guiding the lower edge of the tape 1,
Reference numeral 4 is a rotary head, and 5 is a magnetic head (hereinafter referred to as a head) fixed to the rotary head 4. The side a is the drum inlet side, and the side b is the drum outlet side.

As described above, since the tape 1 is helically scanned, the locus of the head 5 should be located below the tape 1 on the drum inlet side a and above the tape 1 on the drum outlet side b. become. This drum outlet side b
FIG. 12 shows a cross-sectional view of the contact state of the tape 1 in FIG.

[0005]

[Problems to be Solved by the Invention] As shown in FIG.
An air film phenomenon f occurs between the tape wound around the rotary head drum and the upper surface of the lead of the fixed drum 2 due to the air flow generated by the high speed rotation of the rotary drum 4. At the same time, at the drum outlet side b, the tape 1 is in a negative pressure state in the gap e between the fixed head 2 and the rotary head 4,
A phenomenon occurs in which the tape 1 tends to be sucked into the gap e side. Therefore, when the head 5 contacts the upper side of the tape 1 in this state, the tape 1 strongly hits the lower edge of the head 5, and as a result, the tape should originally contact the center of the head 5, but A so-called spacing occurs between the portion and the tape 1.

FIG. 13 shows the above-mentioned spacing amount as d. The contact angle θ between the head 5 and the tape 1 increases as the head 5 moves away from the tape 1, and the spacing amount accordingly. d also increases in proportion. For this reason, there is a problem that the tape 1 hits the head 5 poorer as it approaches the drum outlet side b, and the so-called reproduction output decreases.

The present invention has been made in order to solve the above-mentioned problems, and provides a rotary head drum in which the contact of the tape with the head at the drum outlet portion is improved and the occurrence of spacing can be reduced. The purpose is to get.

[0008]

In order to achieve the above object, a rotary head drum according to the present invention comprises a fixed drum having a lead and a rotary drum having a magnetic head, and a tape is a helical scan type rotary head drum. A notch for making the lower edge of the tape closer to the center of the drum is formed on the upper surface of the lid of the fixed drum within a predetermined angle range from the drum outlet portion to the drum inlet side.

[0009]

In the rotary head drum of the present invention constructed as described above, the fixed drum is provided with the notch for making the lower edge of the tape closer to the center of the drum on the upper side surface of the lid. Is wound around the fixed drum, and therefore, the tape is not sucked by the gap e between the fixed drum and the rotating drum, so-called spacing can be eliminated and the tape can be normally hit against the head. .

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the head 5 on the drum outlet side b.
A cross-sectional view of the contact state of the tape 1 with the tape head is shown, and the same parts as those of the rotary head drum described in FIG.

According to the present invention, the fixed drum 2 is provided as one means for improving the contact of the tape 1 with the head 5 at the drum outlet portion and reducing the occurrence of spacing.
There is a method of forming a notch on the upper side surface of the lead 3. As an example thereof, the upper side surface of the lead 3 is formed on the rotary drum 4 side from the lower end to the upper end thereof in an inverse taper portion 6 where the diameter of the fixed drum 2 increases. As shown in FIG. 2, the formation range of the reverse taper portion 6 described above is an angle range of about 90 ° from the point where the tape 1 separates from the fixed drum 2 at the drum outlet side b portion (hatched portion). ) Is formed.

With the above-mentioned structure, the tape 1
Since the tape is wound along the reverse taper portion 6 on the upper side surface of the lead 3, the tape 1 comes to the outside of the drum, and therefore the gap e between the fixed drum 2 and the rotary drum 4 is negative. The suction of the tape due to the pressure is also alleviated, and the upper end of the tape 1 comes into contact with the head 5 in a substantially upright state.

This situation will be described in more detail with reference to the enlarged view shown in FIG. 3. It can be understood from FIG. 3 that the tape 1 contacts the head 5 in a substantially upright state. The contact angle .theta. Becomes smaller, the relative distance between the center of the head 5 and the tape 1 becomes closer, and the spacing amount d also becomes smaller, so that the reproduction output of the tape is improved.

In the above-described embodiment, the upper side surface of the lid 3 is formed as the reverse taper portion 6, but the upper side surface of the lead 3 extends from the lower end to the upper end of the rotary drum 4.
Since it suffices that the diameter of the fixed drum 2 be increased to the side of FIG.
Even if the upper side surface of the lead 3 is an arcuate portion 7 as shown in FIG.

Further, as shown in FIG. 2, the forming range of the above-mentioned reverse taper portion 6 is from the point where the tape 1 is separated from the fixed drum 2 at the drum outlet side b portion from the drum inlet side a.
However, as shown in FIG. 5, the upper surface of the lead 3 is formed in the reverse taper portion 6 (hatched portion) at all the tape winding angles α of the fixed drum 2. However, such a configuration has the advantage that the contact of the tape 1 with the head 5 can be improved.

Further, as shown in FIG. 6, an angle range of about 90 ° from the point where the tape 1 is separated from the fixed drum 2 to the drum entrance side a on the entire surface where the tape 1 is wound around the fixed drum 2 or the drum exit side b. (Hatched part)
In, the reverse taper portion 6a having the same shape as the lead 3 may be formed.

On the other hand, as another means for improving the contact of the tape 1 with respect to the head 5 at the drum outlet portion and reducing the occurrence of spacing, as shown in FIG. As an example, there is a method of forming a thin portion 8 (hatched portion) as a notch over the width D of 25 ° ± 10 ° on the upper side surface.

With the above-described structure, the tape 1 wound around the fixed drum 2 has the lower edge portion of the tape 1 approaching the drum center direction in the thin portion 8 and the upper edge portion of the tape is tensioned. ,As a result,
As shown in FIG. 8, the tape 1 is in the upright state, and the relative distance between the tape 1 and the central portion of the head 5 becomes closer, so that the spacing amount d becomes smaller as in the above-described embodiment. .

Further, by forming a corner portion between the thin portion 8 and the fixed drum surface adjacent to the thin portion 8 on the curved surface 8a as shown in FIG. 9a or by forming a chamfer 8b as shown in FIG. 9b, the tape is formed. You can eliminate damage to 1.

Further, as shown in FIG. 10, the fixed drum 2
By forming the upper side surface of the lead at the drum outlet portion of the drum over the rough surface 9 over a predetermined width, the air film phenomenon between the fixed drum 2 and the tape 1 is improved and the spacing amount of the tape 1 with respect to the head 5 is reduced. The action that can be done is done.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention.

[0022]

As described above, in the rotary head drum of the present invention, the notch for making the lower edge of the tape closer to the drum center direction is formed on the upper side surface of the fixed drum within the predetermined angle range from the drum outlet. As a result, the spacing between the head and the tape at the drum outlet can be reduced, and the contact of the tape with the head can be ensured. As a result, the reproduction output of the tape is improved and the rotary head drum is highly reliable.

Further, the impact error of the tape at the outlet portion of the fixed drum can be eliminated, and the notch can be formed by simple processing of the fixed drum, so that the conventional fixed drum can be used.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a rotary head drum according to the present invention.

FIG. 2 is a front view of a state in which a tape is wound around a rotary head drum.

FIG. 3 is an enlarged cross-sectional view of a head and a tape.

FIG. 4 is a cross-sectional view of a modified example of a reverse taper portion as a cutout portion.

FIG. 5 is a diagram of a rotary head drum showing another example of the reverse taper portion.

FIG. 6 is a side view of a rotary head drum showing another example of the reverse taper portion.

FIG. 7 is a diagram of a rotary head drum showing another example of the cutout portion.

FIG. 8 is a cross-sectional view of the rotating head drum of FIG.

9 is a diagram of a modified example of the fixed drum of FIG.

FIG. 10 is a side view of another example of the fixed drum.

FIG. 11 is a front view of a conventional rotary head drum.

FIG. 12 is a sectional view of a conventional rotary head drum.

FIG. 13 is an enlarged cross-sectional view of a conventional head and tape.

[Explanation of symbols]

 1 Tape 2 Fixed Head 3 Lead 4 Rotating Head 5 Head 6, 6a Lead Top Side 8 Thin Wall 8a Curved Surface 8b Chamfer 9 Rough Surface

Claims (6)

[Claims] 1. A rotary drum having a fixed drum having leads and a rotary drum having a magnetic head, wherein the tape is a helical scan type rotary head drum, and the lower edge of the tape is brought closer to the center of the drum on the upper side surface of the lid of the fixed drum. The rotary head drum is characterized in that a notch for forming is formed within a predetermined angle range extending from the drum outlet portion to the drum inlet side. 2. The rotary head drum according to claim 1, wherein the cutout portion is formed on the rotary drum side in an inverse taper portion where the diameter of the fixed drum increases. 3. The rotary head drum according to claim 1, wherein the cutout portion is a thin portion in which a lid upper side surface of the fixed drum surface is cut off. 4. The rotary head drum according to claim 1, wherein the magnetic head is fixed to the rotary head and integrally rotates. 5. The rotary head drum according to claim 1, wherein the angular range of the cutout portion is 90 °. 6. A reverse taper portion is formed on the side of the rotary drum from the lower end to the upper end of the upper surface of the lead so that the diameter of the fixed drum increases.
Alternatively, the rotary head drum according to item 2.