JPH04109451A - Rotary head assembly - Google Patents

Abstract

PURPOSE:To attain the prevention of the damage and the reduction of the traveling load of a magnetic tape by providing a fixed cylinder with an air hole to blow out air flow from an air feeding mechanism from a tape traveling surface to the magnetic tape, and opposing a spiral groove to the tape traveling surface of the outer circumference of the fixed cylinder. CONSTITUTION:A spiral groove part 108 to generate pumping action by the rotation of a rotary cylinder 5 is provided in the inside of a rotary head assembly, and the width of the spiral groove part 108 in the axial direction of the fixed cylinder 1 is changed so as to be opposed to the tape traveling surface 107 of the outer circumference of the fixed cylinder 1. Accordingly, generated air quantity is increased according to the increase of the width, and the air quantity corresponding to the area of the tape traveling surface 107 can be supplied, and the magnetic tape 2 can be floated up uniformly extending over the whole circumference of the tape traveling surface 107 on the fixed cylinder 1. Thus, the prevention of the damage and the reduction of the traveling load of the magnetic tape due to sliding friction can be attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a rotary head assembly for a magnetic recording and reproducing device such as a video tape recorder, a digital audio tape recorder, etc.

[Prior art] Figures 4 and 5 are, for example, disclosed in Japanese Patent Application Laid-Open No. 1100-1983.
FIG. 64 is a perspective view and a vertical sectional view showing a rotary rad asseprin in a conventional video tape recorder disclosed in Japanese Patent No. 64.

In the same figure, (1) is a fixed cylinder, and its outer peripheral surface (
102) has a lead groove (1,01) for spirally guiding the magnetic tape (2). (3) is a central shaft that is rotatably supported by the fixed cylinder (1) via a ball bearing (4), (5) is a rotating cylinder that is fixed to the central shaft (3), and is rotatably supported by the central shaft (3). ) and a main body (502) fixed to this flange (501).
).

(6) is a magnetic head, which is attached to the main body (502) of the rotary cylinder (5) so as to slightly protrude outward from the outer peripheral surface of the main body (502), and is attached to the lead groove (+0
1) records information on a magnetic tape (2) running along the magnetic tape (2), and reproduces information recorded on the magnetic tape (2).

(1,013) is an air hole penetrating the fixed cylinder (1), (17) is a spacer that supports the ball bearing (4), (
8) is a collar that applies preload to and fixes the ball bearing (4).

(103) is an air hole provided in the fixed cylinder (1), one end of which communicates with a plurality of air supply passages (18) formed in the fixed cylinder (1), and the other end as shown in FIG. As shown, it opens on the tape running surface (107) of the fixed cylinder (1). (19) is a circumferential air supply path provided at the bottom of the fixed cylinder (1), which communicates with an air pump (20) that generates compressed air via a supply vibrator (21).

Figure 7 shows a detailed sectional view of Figure 5, and as clearly shown in the figure, the tape running surface (1) of the fixed cylinder (1) is
07) at the lower end where it intersects with the lead groove (101),
A notch (20) is provided along the lead groove (101), and an exhaust path (25) communicating from the notch (24) to the inside of the rotary head assembly is provided. In (28), (
27), (28), and (29) are tape guide posts, respectively.

Next, the operation of the above configuration will be explained.

As shown in Figure 4, a plurality of tape guide posts (21
3) Supported by , (27), (28), and (29),
To rotation.

The magnetic tape (
2) runs at a constant speed, and the magnetic head (8) fixed to the one-rotation cylinder (5) rotates at high speed to rotate the magnetic tape (
2) Record and reproduce signals.

By the way, since the rotating cylinder (5) rotates at high speed,
An air film is formed between the magnetic tape (2) and the outer circumferential surface (503) of the rotating cylinder (5) due to the air entrainment action, and the magnetic tape (2) receives the floating blade at the portion of the rotating cylinder (5).

On the other hand, in the fixed cylinder (1) part, the magnetic tape (2)
Since the relative speed between the tape running surface (107) of the fixed cylinder (1) and the fixed cylinder (1) is extremely small, the above-mentioned air film is not formed, and the magnetic tape (2) is
The tape will slide in contact with the tape running surface (10?).

Here, the air supply path (18), (18) is connected to the air pump (20) that generates compressed air through the air supply vibrator (21).
When compressed air is supplied to these air supply paths (18), (1
8), the compressed air is discharged from the air hole (103) to the tape running surface (10?) as shown by the arrow (A) in Fig. 87, and the compressed air is discharged from the air hole (103) to the tape running surface (10?), and then the running magnetic tape (2) and the fixed cylinder (1) An air film is formed between the tape running surface (107) of the magnetic tape (2) and the magnetic tape (2) is levitated.

On the other hand, a part of the air discharged from the air hole (103) flows upward and is discharged through the slit portion (B) of the rotating cylinder (5) and the fixed cylinder (1), but at the same time, the air is discharged from the air hole (103). Air also flows downward, and the magnetic tape (2)
) is discharged so that the magnetic tape (2) floats uniformly over the entire tape running surface (to?), thereby reducing the frictional sliding resistance between the magnetic tape (2) and the fixed cylinder (to?).

[Problems to be Solved by the Invention] According to the conventional rotary head assembly configured as described above, the magnetic tape (2) for one rotation cylinder (1)
Although the sliding friction of the magnetic tape (2) can be reduced, since the magnetic tape (2) is helically wound around the rotating head assembly, the magnetic tape (2) is Tape (2) and fixed cylinder (
1) The contact area with the upper tape running surface (10?) will gradually increase.

Therefore, in order to levitate the magnetic tape (2) in a negative direction from the tape running surface (107) in the traveling direction of the magnetic tape (2), the air holes (107) must be
It is also necessary to increase the amount of air discharged to the tape running surface (107) through 03). However, in the conventional example with the above configuration, the amount of air discharged through the air hole (103) is constant with respect to the traveling direction of the magnetic tape (2), and depending on the amount of air discharged, the amount of air discharged through the air hole (103) is constant. At the exit of the cylinder where the magnetic tape (2) separates from the rotating head assembly, the amount of air is insufficient and the magnetic tape (2) falls on the tape running surface (10
7) causes sliding friction, or conversely, there is an excessive amount of air at the cylinder inlet, making the running state of the magnetic tape (2) unstable. Further, there is also the problem that an air pump must be separately installed outside the rotating cylinder as an air supply device.

This invention was made in order to solve the above-mentioned problems, and uses an air supply mechanism provided inside the rotating door assembly to uniformly distribute the magnetic tape over the entire circumference of the tape running surface on the fixed cylinder. An object of the present invention is to provide a rotating head assembly that can be levitated to a stationary cylinder, prevent damage to the magnetic tape caused by sliding friction of the magnetic tape against a fixed cylinder, and reduce the running load on the magnetic tape. .

[Means for Solving the Problems] A rotating head assembly according to the present invention provides a rotating cylinder and a fixed cylinder with overlapping cylindrical surfaces that fit into each other through a small gap, and a spiral on the opposing inner surfaces of the cylinders. A group part is provided, and the air discharged from the spiral group part as the rotary cylinder rotates is discharged to the outside from an air discharge opening provided on the tape running surface of the outer peripheral surface of the fixed cylinder. [Function] According to the present invention, a spiral group portion that generates a pumping action by rotation of the rotary cylinder is provided inside the rotary head assembly, and the axial width of the fixed cylinder of this spiral group portion is equal to the outer circumference of the fixed cylinder. Since the width of the magnetic tape is changed so that it faces the tape running surface, the amount of air generated increases as the width increases, making it possible to supply an amount of air corresponding to the area of the tape running surface. can be uniformly floated over the entire circumference of the tape running surface on the fixed cylinder.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a vertical sectional view of a rotary head assembly in a video tape recorder according to an embodiment of the present invention, and FIG. 2 is a spiral provided on the overlapping inner surface of a stationary cylinder used as an air supply mechanism in the embodiment of FIG. 1. It is a perspective view of a part of a group, and in the figure, the same or equivalent parts as in the conventional example shown in FIGS. 4 to 7 are given the same reference numerals, and detailed explanation thereof will be omitted.

In Figures 1 and 2, (1,04) is the cylindrical inner surface formed on the fixed cylinder (1), and (11) is the motor for rotating the rotating cylinder (5) around the central axis (3). , a stator (111) and a rotor (112).

(504) is the cylindrical outer surface formed at the lower part of the rotating cylinder (5), and the cylindrical inner surface (504) formed at the fixed cylinder (1).
104) is polymerized through a slight gap between
They form concentric cylindrical surfaces.

(to8) is a pump-out spiral group,
As clearly shown in Figure 2, the fixed cylinder (+
) is formed on the surface of the polymerized cylindrical inner surface (104).

In FIG. 2, the white part in the figure represents the spiral group (+08), and the blacked out part represents the land (109) between the spiral groups (108). The tape running surface (10) of the outer peripheral surface (102) of the cylinder (1)
7), the axial width of the fixed cylinder (1) is configured to vary spirally along the inner surface of the overlapping cylinder (104).

Next, the operation of the above configuration will be explained.

When the motor (11) is energized, the rotating cylinder (5) rotates counterclockwise around the central axis (3), and recording or reproduction on the magnetic tape (2) is performed in the same way as in the conventional one. . During this period, due to the rotation of the cylinder (5),
A spiral group (108) formed on the overlapping cylindrical inner surface (104) of the fixed cylinder (1)
) creates a downward air flow.

The air flow generated in the above-mentioned overlapping part is the inner surface of the overlapping cylinder (1
04) is discharged onto the tape running surface (107) of the fixed cylinder (1) through the air hole (103) provided in the portion 04), providing a floating edge to the magnetic tape (2).

Spiral group bearings have a shallow spiral group machined on one surface that rotates relative to each other, and obtain load characteristics by the pumping action of the group due to shaft rotation.The fluid filling the gap is forced along the group, and the so-called Pressure is generated by the wedge membrane effect.

The magnitude of the pressure generated by this is determined by the spiral group (
+08), so if the width is changed spirally along the inner surface of the overlapping cylinder (104) as shown in Fig. 2, As a result, the pressure generated there increases continuously.

Here, since the spiral group (108) is configured to face the tape running surface (107) of the fixed cylinder (1), the central axis (
3) As the width in the direction increases, the air pressure generated in the air hole (103) provided there increases, and the amount of air discharged from there also increases, causing the tape running surface (103) to increase.
7) The amount of air corresponding to the area is to be supplied,
The magnetic tape (2) can be uniformly levitated over the entire circumference of the tape running surface (107) on the fixed cylinder (1).

In the above embodiment, the discharge portion of the air hole (+03) to the tape running surface (107) was configured as shown in FIG. 6, as in the conventional example, but as shown in FIG. In the embodiment shown in FIG. 3, air holes (103) may be provided in the tape running surface (107) of the fixed cylinder (1).
A shallow groove (105) is further provided in the portion including the air hole (103). With this configuration, air discharged from the air hole (103) is directed to the tape running surface (10?) via the groove (+05).
) can be configured to lead more evenly.

[Effects of the Invention] As described above, according to the present invention, an air feeding mechanism using a spiral group that produces a pumping effect by rotation of a rotating cylinder is provided in the rotating head assembly, and the fixed cylinder is provided with the air feeding mechanism described above. An air hole is provided to blow the airflow generated from the tape running surface of the fixed cylinder toward the magnetic tape, and the axial width of the fixed cylinder is adjusted so that the spiral groove faces the tape running surface on the outer periphery of the fixed cylinder. Since the magnetic tape is configured to change in a spiral along the inner surface of the overlapping cylinder, it is possible to uniformly levitate the magnetic tape over the entire circumference of the tape running surface on the fixed cylinder, which reduces the sliding friction of the magnetic tape against the fixed cylinder. This makes it possible to prevent damage to the magnetic tape and reduce the running load on the magnetic tape, thereby making it possible to always perform stable recording and reproduction.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a rotary head assembly for a video tape recorder according to an embodiment of the present invention, and FIG. 2 shows a spiral group provided on the overlapping inner surface of a fixed cylinder used as an air supply mechanism in the embodiment of FIG. A perspective view of a portion;
FIG. 3 is a perspective view of a rotary head assembly showing another embodiment of the present invention, FIG. 4 is a perspective view of a conventional rotary head assembly, FIG. 5 is a longitudinal cross-sectional view of the same, and FIG. The perspective view and FIG. 7 are the same partial sectional views. (1)...Fixed cylinder, (102)...Outer peripheral surface,
(103)... Air hole, (104)... Polymerized cylinder inner surface, (107)... Tape running surface, (108)...
...Spiral group, (2) ...Magnetic tape, (
3)... Central axis, (5)... Rotating cylinder, (50
4) ... Outer surface of polymerized cylinder, (6) ... To magnetic field. Note that the same reference numerals in the figures indicate the same parts or parts with Japanese names.

Claims (1)

[Claims] (1) A fixed cylinder having a cylindrical portion, a rotating cylinder having a cylindrical portion having approximately the same diameter as the fixed cylinder and rotating relatively on the same axis in close proximity to the fixed cylinder, and a magnetic field supported by both cylinders. The rotary cylinder and the fixed cylinder have overlapping cylindrical surfaces that fit into each other through a small gap, and a spiral group portion is provided on the opposing inner surfaces of the cylinders, and the rotation of the rotary cylinder causes the above-mentioned A rotary head assembly characterized in that air discharged from a spiral group portion is discharged to the outside from an air discharge opening provided on a tape running surface on an outer peripheral surface of a fixed cylinder.