JPH04364261A - Drum unit for helical scan type magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain stable and secure head contact even in such cases of a drum of high speed rotation and a vapor-deposited tape of high surface property, etc. CONSTITUTION:The drum unit for the helical scan type magnetic recording and reproducing device is provided consisting of an upper drum 1 a a lower drum 2 arranged via a slit 3 on a coaxial line and a middle drum 4 supported coaxially with these drums 1 and 2 in their inner space and supported axially with a head 5 fitted to an outer circum-ference to be freely rotatable to face the above slit 3. In this unit, the middle drum 4 is formed to be cut off except a head fitting part from an outer circumferential part into a central part, and both side surfaces of a head supporting part remaining in a radial pattern are inclined (a taped surface 4f) to one way side of the rotating direction of the middle drum, so that the stable head contact with the tape can be obtained by pushing out ambient air upward in rotating the middle drum 4 in the direction of arrows.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a drum unit for a helical scanning magnetic recording/reproducing device, and particularly for digital VTRs and high-definition VTs that require stable head contact.
This invention relates to a drum unit suitable for R, etc.

[Summary of the Invention] The present invention provides a
This relates to a drum unit of a helical scanning type magnetic recording and reproducing device that is incorporated in a car, etc. The shape of the middle drum is formed radially, and both sides of the head support part are inclined in one direction with respect to the rotation direction. By generating dynamic pressure during rotation, the suction or discharge of airflow from the slit to the vicinity of the head can be adjusted, creating an optimal head even when the drum rotates at high speed or when using tape with good surface properties. This is so that you can get in touch with them.

0003

[Prior Art] A conventional drum unit of a helical scanning magnetic recording/reproducing device having a middle drum shape utilizes the air flow generated by the rotation of the head to form an air film between the tape and the upper and lower drums. This made the tape run smoothly. Furthermore, in order to optimize the thickness of the air film that supports the tape surface, a cylindrical part is formed on the outer periphery of the middle drum to which the head is attached, and a groove is formed on the outer surface of this cylindrical part. In some cases, dynamic pressure is generated to adjust the air film thickness.

0004

[Problems to be Solved by the Invention] However, in the former method in which an air film is formed using the air flow generated as the middle drum to which the head is attached rotates, the dynamic pressure generated depends on the rotational speed of the head. The floating height of the tape also becomes a constant value. Therefore, it is difficult to achieve optimal tape running.

[0005] The latter method of adjusting the tape flying height by providing grooves on the cylindrical surface of the middle drum is effective in increasing the tape flying height, but when the drum is used at high speeds such as digital VTRs and high-definition VTRs, When used for rotating objects, a more stable head contact is required. However, in reality, the drum rotates at a high speed and the dynamic pressure increases, so the tape flying height increases, going against the requirement, making adjustment even more difficult.

SUMMARY OF THE INVENTION Therefore, the present invention aims to solve the above-mentioned drawbacks of the prior art and to provide stable and reliable head contact even when the drum rotates at high speed and even against vapor-deposited tapes with high surface properties. shall be.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes upper and lower drums coaxially disposed through a slit, and a drum that is supported coaxially with the drum in an internal space of the drum. In a drum unit of a helical scanning magnetic recording/reproducing device, the middle drum is rotatably supported with a head mounted on the outer periphery facing the slit. It is characterized in that it has a shape in which the head support part is cut out over the middle drum, and both sides of the support part of the head that remain radially are inclined in one direction with respect to the rotational direction of the middle drum.

[0008]

[Function] According to the above structure, the middle drum is cut out from the outer periphery to the center excluding the head attachment part, and both sides of the head support part that remains radially are oriented in one direction with respect to the rotation direction. Due to the inclination, dynamic pressure is generated between the upper and lower sides of the middle drum as the middle drum rotates, and it becomes possible to adjust the suction or discharge of airflow from the slit between the upper and lower drums to the vicinity of the head.

[0009]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings.

FIG. 1 is a partial cross-sectional view showing the structure of a first embodiment of the present invention. Upper drum 1 and lower drum 2 are
They are supported coaxially through the slits 3, and the middle drum 4 is supported inside them. A head 5 is fixed to the lower surface of the outer periphery of the middle drum 4, and its tip is located in the slit 3. Further, the lower part of the middle drum 4 is connected to a rotary transformer 6, and is directly connected to a drum motor 7 installed below the lower drum 2 to be rotationally driven. In order to helically scan the tape T, the lower drum 2 is formed with a stepped portion 2a that is inclined with respect to the rotation axis and guides the tape running.

FIGS. 2 and 3 are external views showing the shape of the middle drum 4, which is the essential part of the present invention.

The middle drum 4 has a boss portion 4a at its center, a notch portion C is removed from a disk portion continuously formed on the outer periphery, and the remaining radial portions are called arm portions 4b. The outer wall portion 4c is formed from a continuous cylinder below the tip. The heads 5 are each fixed to the lower surface of the outer wall portion 4c. Tapered surfaces 4e and 4f are formed on both side surfaces of the arm portion 4b, which are also cut surfaces of the notch portion C, respectively. These tapered surfaces 4e and 4f act to push out the surrounding air upward when the middle drum 4 rotates in the direction of the arrow. That is, the four radially arranged arms 4b have the same function as blades in an axial fan, and generate positive dynamic pressure in the space above the middle drum 4. As a result, when the drum unit is incorporated into the middle drum 4 and driven to rotate as shown in FIG. static pressure decreases. As a result, air is sucked into the interior through the slit 3. This embodiment is used when the tape is rotated at high speed and the flying height of the tape becomes large, and air is sucked in and discharged from the tape running surface.
The flying height is reduced to the optimum value, and stable head contact can be obtained.

FIGS. 4 and 5 are external views showing the shape of the middle drum 14 according to the second embodiment. This example is
The taper directions of the tapered surfaces 14g and 14h formed on both sides of the arm portion 14b cut out by the notch portion C are opposite to those of the first embodiment. The rest of the structure is the same as that of the first embodiment. In this embodiment, when the middle drum 14 rotates in the direction of the arrow, it pushes out the surrounding air downward, generating positive dynamic pressure in the space below the middle drum 14. As a result, when the drum unit is installed in the middle drum 14 and driven to rotate, air is blown downward and out from the slit 3 (not shown). This embodiment is suitable for cases where a vapor-deposited tape with good surface properties is used, and an appropriate amount of air can be blown onto the running surface of the tape T to prevent the tape from adhering, thereby stabilizing the running.

FIGS. 6 and 7 are external views showing the shape of the middle drum 24 according to the third embodiment. This example is
This is applied to the disk-shaped middle drum 24, and the center is located at the boss portion 24, similar to the first and second embodiments.
a, and the radial portion that remains after removing the notch C from the disk portion continuously formed on the outer periphery is the arm portion 24b, and the head 5 is fixed to the lower surface of the tip of the arm portion 24b. Ru. Tapered surfaces 24g and 24h are formed on both side surfaces of the arm portion 24b, which are also cut surfaces of the notch portion C, respectively. In this embodiment, since the directions of the tapered surfaces 24g and 24h are the same as in the second embodiment, air is similarly blown out from the slit 3 to the outside.

FIGS. 8 and 9 are enlarged views of the arm portion 14b in the second embodiment. FIG. 8 shows the tapered surface 14g,
14h are both formed from a single plane. FIG. 9 shows a case where the tapered surface 14j is formed as a convex curved surface and the tapered surface 14k is formed as a concave curved surface. In this way, the tapered surface formed on the arm portion of the middle drum can have any shape. Furthermore, by appropriately setting the taper direction and angle, and the area of the tapered surface, it is possible to adjust the generation value of dynamic pressure and obtain the optimum dynamic pressure for tape running.

Furthermore, in the embodiments, the head 5 has four
However, it can be similarly applied to other types of drum units such as two heads.

[0017]

As explained above, according to the drum unit of the helical scanning magnetic recording/reproducing apparatus of the present invention, the middle drum is cut out from the outer periphery to the center excluding the head mounting portion, and remains radially. Because both sides of the support part of the head are inclined in one direction with respect to the rotation direction, dynamic pressure is generated on the upper or lower side of the middle drum as the middle drum rotates, causing pressure to flow between the upper and lower drums. The suction or discharge of airflow from the slit to the vicinity of the head can be adjusted.

As a result, when the drum is rotated at a higher speed and the tape flying height is large, airflow can be sucked in from the vicinity of the head to maintain the optimal tape flying height.

Furthermore, even if tape with good surface properties such as vapor-deposited tape is used, and the tape is strongly attracted to the upper and lower drums, making tape running unstable, it is possible to maintain optimal head contact. Stable tape running can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of a first embodiment of the present invention.

FIG. 2 is an external view showing the shape of the middle drum in the first embodiment.

FIG. 3 is a bottom view showing the shape of the middle drum in the first embodiment.

FIG. 4 is an external view showing the shape of the middle drum in the second embodiment.

FIG. 5 is a bottom view showing the shape of the middle drum in the second embodiment.

FIG. 6 is an external view showing the shape of the middle drum in the third embodiment.

FIG. 7 is a bottom view showing the shape of the middle drum in the third embodiment.

FIG. 8 is an enlarged view of main parts of the middle drum in the second embodiment.

FIG. 9 is an enlarged view of main parts of the middle drum in the second embodiment.

[Explanation of symbols]

1 Upper drum 2 Lower drum 3 Slit 4 Middle drum 4a Boss part 4b Arm part 4c　Outer wall part 4e Tapered surface 4f Tapered surface 5 Head 6 Rotary transformer 7 Drum motor 14 Middle drum 14b Arm part 14g Tapered surface 14h Tapered surface 14j Tapered surface 14k taper surface 24 Middle drum 24a Boss part 24b Arm part 24g Tapered surface 24h Tapered surface C Notch part T tape

Claims (1)

[Claims] [Claim 1] Upper and lower drums are arranged coaxially through a slit, and a head supported coaxially with the drum in the internal space of the drum and attached to the outer periphery faces the slit so as to be freely rotatable. In a drum unit of a helical scanning magnetic recording and reproducing device having a central drum supported by a shaft, the central drum is cut out from the outer circumference to the center excluding the head mounting portion, and the head support portion remains radially. A drum unit for a helical scanning magnetic recording and reproducing device, characterized in that both side surfaces of the drum unit are inclined in one direction with respect to the rotational direction of the middle drum.