JPS5942628A - Tape guide drum device - Google Patents

Abstract

PURPOSE:To raise a rotation torque without using an exclusive back yoke, and also to make a titled device small in size and light in weight, by positioning a rotating side or fixing side transformer element so as to be opposed to a rotary magnet by having a suitable air-gap against a stator coil. CONSTITUTION:A stator coil 2 formed in a cylinder type, and a cylinder type fixing side transformer element 4A consisting of a magnetic material are fixed and supported coacially to a circuit substrate 6 of a motor, by which one stator unit is constituted. This stator unit is supported coaxially to a fixed drum 8, and constitutes one fixed unit. Subsequently, a rotary drum 16 for supporting a rotary magnetic head 14, a magnet case 20 made of a magnetic material, to which a cylinder type rotary magnet 18 is fitted, and a cylinder type rotating side transformer element 4B consisting of a magnetic material are supported so as to be rotatable as one body, to a rotary disk 12 formed as one body by fit- insertig a main shaft 10, by which one rotating unit is constituted. This rotating unit is supported so as to be freely rotatable by the fixed drum 8 by ball bearings 21, 22 held by the fixed drum 8.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a direct drive type tape guide drum device used in a video tape recorder.

Conventional configurations and their problems In recent years, coreless motors have been used to eliminate iron cores in small motors to prevent eddy current loss and hysteresis loss, and to obtain more precise rotation.

This coreless motor uses a magnetic material in the magnet case that holds the rotary magnets to increase the magnetic flux of the rotary magnets that intersect with the stator coils and align them as a means of increasing rotational torque. The stator coil was sandwiched between the two members, which were placed opposite the rotary magnet.

Hereinafter, the member made of the magnetic material described above will be referred to as a back yoke.

This back yoke is attached to rotate together with the rotary magnet, and the magnetic flux from the rotary magnet that has passed through the stator coil passes through this back yoke, passes through the stator coil again, and returns to the rotary magnet, creating a magnetic loop. to make. This improves the rotational torque of the motor. However, providing the back yoke requires space for the clearance between the back yoke and members such as the stator coil and the thickness of the back yoke, which increases the dimensions of a portion of the motor.

Furthermore, the weight of a part of the motor increases due to the back yoke.
The number of manufacturing processes will also increase.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a tape guide drum device that can improve rotational torque without using a dedicated back yoke, and can also be made smaller and lighter.

Structure of the Invention The present invention focuses on the fact that the transformer element of the rotary transformer unit is made of a high permeability magnetic material, and the rotating side transformer element ('= ! or fixed side transformer element), it fulfills the original function of transmitting magnetic recording or reproduction signals of the rotating magnetic head, and at the same time increases and aligns the magnetic flux of the rotary magnet that intersects with the stator coil. It is designed to also have the role of creating a magnetic loop.

Description of examples Hereinafter, the present invention will be explained based on illustrated embodiments.

The drawing is a side sectional view of an embodiment of the present invention having a circumferentially opposed type motor and a rotary transformer unit structure.

In this drawing, a cylindrical stator coil 2 and a cylindrical fixed transformer element 4A made of a magnetic material are coaxially fixedly supported on a circuit board 6 of the motor.
It constitutes one stator unit.

This stator unit is coaxially supported by the fixed drum 8 and constitutes one fixed unit.

Next, a rotating disk 12 into which the main shaft 10 is fitted is integrated, a rotating drum 16 supporting a rotating magnetic head 14, a magnetic case 20 made of a magnetic material to which a cylindrical rotary magnet 18 is attached, and a cylindrical case made of a magnetic material. The mold rotation side transformer element 4B is supported so as to be able to rotate together, and constitutes one rotation unit.

This rotating unit has a ball shaft 21 held on a fixed drum 8.
, 22, and is rotatably supported by the fixed drum 8.

When the rotating unit and fixed unit are assembled, the rotary magnets 18. Stator coil 22 rotating side transformer element 4B, stationary side transformer element 4A
are arranged so that they are respectively positioned with appropriate gaps.

With this configuration, the magnetic flux of the rotary magnet 18 passes through the stator coil 2, creates a magnetic loop by the rotating transformer element 4B, and returns to the rotary magnet 18.

Effects of the Invention As is clear from the above description, the present invention enables a highly efficient motor configuration without providing a new member as a back yoke, and reduces cost and weight.

The manufacturing process can be reduced, the motor can be made smaller, and the structure can be simplified.

Note that if the rotary magnet and the rotating transformer element that serves as the back yoke are rotated together as in the illustrated embodiment, eddy current loss and hysteresis loss are eliminated, resulting in lower power consumption. You can also do that.

Of course, the present invention is not limited to the illustrated structure;
Needless to say, the present invention can be similarly applied to a planarly opposed motor and a rotary transformer unit structure.

[Brief explanation of the drawing]

The drawing is a side sectional view of one embodiment of the present invention. 2... Stator coil, 4A... Fixed side transformer element, 4B... Rotating side transformer element, 6...
...Motor circuit board, 8...Fixed drum, 1o...Main shaft, 12...Rotating disk, 14...Rotating magnetic head, 16・・・・・・
...Rotating drum, 18...Rotary magnet, 20...Magnetic case, 21°22.
...ball bearing.

Claims (1)

[Claims] The rotary transformer unit includes a rotating drum having a rotating magnetic head, a coreless motor including a rotary magnet and a stator coil for rotating the rotating drum, and a rotary transformer unit including a stationary transformer element and a rotating transformer element. , sandwiching the stator coil,
A tape guide drum device characterized in that the rotary magnet and at least one of the rotating side and stationary side transformer elements of the rotary transformer unit are disposed to face each other.