JP2990894B2 - Rotating head drum device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head drum device which can be used for a video tape recorder.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view of a conventional rotary head drum device. To explain this, 1 is a fixed drum having a bearing surface 1a which guides a magnetic tape and faces a herringbone type groove 2a which will be described later, and 2 is processed by, for example, etching at two locations on the upper and lower outer peripheral surfaces in the axial direction. A rotating shaft having a herringbone type groove 2a and a lower end surface 2b and rotatably mounted on the fixed drum 1; 3, a sleeve for holding the rotating shaft 2 by a rotating shaft holding portion 3a; A thrust plate 5 having a spiral groove (not shown) on the upper end surface 4a opposite to the lower end surface 2b and screwed to the fixed drum 1 is fitted to the sleeve 3 coaxially with the rotary drum 5 and screwed.
Denotes a pair of magnetic heads screwed to the rotating drum 5, 7
Is a lubricant interposed in a minute gap between the herringbone type groove 2a and the bearing surface 1a and a minute gap between the lower end surface 2b of the rotary shaft 2 and the upper end surface 4a of the thrust plate 4.

The operation of the conventional rotary head drum device configured as described above will be described below.

When the rotating portion including the sleeve 3 of the rotary head drum device rotates, the herringbone type groove 2 is rotated.
a, a bearing surface 1a, and a lubricant 7 keep the centrifugal force of the rotating portion by the pumping action of the radial bearing, and further, a spiral groove (not shown), a lower end surface 2b of the rotating shaft 2 and the lubricant 7 As a result, a stable floating position of the rotating part can be obtained by the pumping action of the thrust bearing configured as above, and normal rotation can be maintained.

[0005]

However, in the above configuration, as shown in the relationship between the force acting on the rotating shaft holding portion 3a and the relative height of the pair of magnetic heads 6 in FIG. In the assembling process, for example, when the rotating drum 5 is screwed to the sleeve 3, a force P2 exceeding the maximum value P1 at which the rotating shaft holding portion 3a of the sleeve 3 stays within the elastic deformation region acts on the rotating shaft holding portion 3a, There has been a problem that the holding portion 3a undergoes plastic deformation, the perpendicularity of the rotating shaft 2 is impaired, the relative height of the pair of magnetic heads 6 is adversely affected, and normal recording and reproduction cannot be performed.

[0006]

According to the present invention, there is provided a stationary drum for guiding a magnetic tape, a rotating shaft rotating coaxially with the stationary drum, a sleeve for holding the rotating shaft,
A thrust plate opposed to the lower end surface of the rotating shaft and fixed to the lower end surface of the fixed drum, and mounted on a sleeve,
A rotating drum having a pair of magnetic heads, a lubricant interposed in a minute gap between the outer peripheral surface of the rotating shaft and the inner peripheral surface of the fixed drum, and a minute gap between the lower end surface of the rotating shaft and the upper end surface of the thrust plate. Lubricant, a groove for generating dynamic pressure provided on at least one of the outer peripheral surface of the rotating shaft and the inner peripheral surface of the fixed drum, and a lubricant provided on at least one of the lower end surface of the rotating shaft and the upper end surface of the thrust plate. Ri from pressure generating groove formed, the rotary drum sleeve
When the screw is fixed to the rotating drum, the
The gap formed by the lower end face and the upper end face of the fixed drum is displaced.
Thereby, but the force acting on the rotation shaft retaining part of the sleeve is A, when the rotation shaft holding portion of the sleeve to the maximum value of the force that Tomah the elastic deformation region B, and the force of screws
A configuration in which the lower end surface of the rotating drum is received by the upper end surface of the fixed drum so as not to exceed B, and a gap between the outer peripheral portion formed by the upper end surface of the fixed drum and the lower end surface of the rotating drum is set so as to satisfy A ≦ B. It is provided with.

[0007]

According to the present invention, the relative height of the normal magnetic head can be maintained without impairing the verticality of the rotary shaft even when a force is applied to the rotary shaft holding portion of the sleeve in the process of assembling the device. It is intended to provide a rotary head drum device capable of maintaining the above.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A rotary head drum device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a rotary head drum device according to one embodiment of the present invention. To explain this, 2 is a rotary shaft having a herringbone type groove 2a and a lower end surface 2b, 3 is a sleeve holding the rotary shaft 2, 4 is a thrust plate having a spiral groove (not shown) on an upper end surface 4a,
Reference numeral 6 denotes a pair of magnetic heads, and reference numeral 7 denotes a lubricant, which has the same configuration as the conventional example. Reference numeral 8 denotes a fixed drum which guides the magnetic tape and has a bearing surface 8a facing the herringbone type groove 2a, and 9 denotes a rotary drum fitted coaxially with the sleeve 3 and screwed.

The operation of the rotary head drum device configured as described above will be described below.

When the rotating part including the sleeve 3 rotates, the herringbone type groove 2a, the bearing surface 8a and the lubricant 7
By the pumping action of the radial bearing constituted by the above, the centripetality of the rotating part is maintained, and the pumping action of the thrust bearing constituted by the spiral groove (not shown), the lower end surface 2b of the rotating shaft 2 and the lubricant 7 As a result, a stable floating position of the rotating part can be obtained, and normal rotation can be maintained as in the conventional example. Here, FIG. 2 applies a vertical load to the position where the rotary drum 5 of the conventional rotary head drum device is screwed to the sleeve 3,
This figure shows the relationship between the force acting on the rotating shaft holding portion 3a and the amount of displacement in the height direction near the outer periphery of the lower end surface of the rotating drum 5 at that time. From this, the outer peripheral vicinity t displaced by child Togawakaru of the lower end surface of the maximum value P1 in the rotary drum 5 which rotates the shaft holding portion 3a of the sleeve 3 remains in the elastic deformation area. In this embodiment, the assembly process
To fix the rotating drum 9 to the sleeve 3 with screws
Then, the force to stop the screw rotates with the upper end face 8b of the fixed drum 8.
Displace the gap formed by the lower end surface 9a of the drum 9
Are the upper end surface 8b of the fixed drum 8 and the lower end surface of the rotating drum 9.
The gap at the outer peripheral portion composed of 9a is not more than t including the dimensional tolerance.
When the rotary drum 9 is screwed to the sleeve 3, the force acting on the rotary shaft holding portion 3a is P1.
Is exceeded, the lower end surface 9a of the rotating drum 9 is received by the upper end surface 8b of the fixed drum 8, so that the force acting on the rotating shaft holding portion 3a of the sleeve 3 becomes P1 or less. Therefore, the deformation of the rotating shaft holding portion 3a remains within the elastic deformation region, and the normal relative height of the magnetic head 6 can be maintained as shown in FIG. 4 without impairing the perpendicularity of the rotating shaft 2.

As described above, according to the present embodiment, the gap between the outer peripheral portion formed by the upper end surface 8b of the fixed drum 8 and the lower end surface 9a of the rotary drum 9 is set such that the deformation of the rotary shaft holding portion 3a is within the elastic deformation. By setting such that the magnetic head 6 stays at the normal height, the relative height of the normal magnetic head 6 can be maintained.

[0012]

As described above, according to the present invention, the relative height of a normal magnetic head can be maintained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rotary head drum device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a force acting on a rotating shaft holding portion of a conventional rotating head drum device and a displacement amount in a height direction near an outer periphery of a lower end surface of the rotating drum.

FIG. 3 is a sectional view of a conventional rotary head drum device.

FIG. 4 is a diagram showing a relationship between a force acting on a rotating shaft holding portion and a relative height of a pair of magnetic heads.

[Explanation of symbols]

 Reference Signs List 2 rotating shaft 2a herringbone groove 2b lower end surface 3 sleeve 3a rotating shaft holding portion 4 thrust plate 4a upper end surface 6 magnetic head 7 lubricant 8 fixed drum 8a bearing surface 8b upper end surface 9 rotating drum 9a lower end surface

Claims (1)

(57) [Claims] 1. A fixed drum for guiding a magnetic tape, a rotating shaft that rotates coaxially with the fixed drum, a sleeve that holds the rotating shaft, and a lower surface of the fixed drum that faces a lower end surface of the rotating shaft. A thrust plate fixed to a lower end surface, a rotating drum mounted on the sleeve, having a pair of magnetic heads, and a lubricant interposed in a minute gap between an outer peripheral surface of the rotating shaft and an inner peripheral surface of the fixed drum; A lubricant interposed in a minute gap between the lower end surface of the rotating shaft and the upper end surface of the thrust plate,
Grooves for generating dynamic pressure provided on at least one of an outer peripheral surface of the rotating shaft and an inner peripheral surface of the fixed drum, and dynamic pressure provided on at least one of a lower end surface of the rotating shaft and an upper end surface of the thrust plate. Ri consists generation groove, screws fixing the rotary drum to the sleeve
When the screw is tightened, the lower end surface of the rotating drum is
Displace the gap formed by the upper end surface of the fixed drum
Reduce the force acting on the rotating shaft holding portion of the sleeve.
A, the rotating shaft holding part of the sleeve is elastically deformed
When the maximum value of the force remaining in the area is B, screw it in.
Fix the lower end surface of the rotating drum to the fixed position so that the force does not exceed B.
Received on the upper end face of the fixed drum, and
It consists of the upper end of the fixed drum and the lower end of the rotating drum.
A rotary head drum device, wherein a gap at an outer peripheral portion is set .