JPS5847830Y2 - Tone arm drive device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tone arm drive device, and more particularly to an offset arm drive device in an auto player.

When playing a record player, for example, by turning on the start switch, the tone arm automatically starts the lead-in, descends to the playing starting point depending on the size of the record, and automatically rises after the playing is finished. There is also an auto player that performs a return operation and returns to the armrest.

In conventional offset arm type auto players, the tone arm during lead-in or return is driven by a phono motor or a small motor dedicated to driving the tone arm, which mechanically engages the motor and the rotation shaft of the tone arm to drive the gear and pulley. It was driven by a drive device including a driving force transmission member such as.

In such a drive device, since the tone arm and the drive section are mechanically engaged, if an external force is applied to the tone arm during automatic operation, an excessive load is applied to the drive mechanism section, causing deformation of the mechanical parts. This may cause problems such as overcurrent or excessive current flowing through the drive unit.

An object of the present invention is to provide a tone arm drive device that eliminates the above-mentioned problems.

The tone arm driving device according to the present invention includes a movable element consisting of an armature that is fixed to the rotation axis of the tone arm and is rotatable about the rotation axis, a conductive member interlocked with the tone arm, and a predetermined electromagnetic force attached to the movable element. It is characterized by including a stator made of a magnet provided to apply rotational force and to supply a magnetic flux substantially perpendicular to a predetermined surface of the conductive member to the conductive member.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a schematic side view of an embodiment of the tone arm drive device according to the present invention, and FIG. 2 is a plan view of the device in FIG. 1 with the tone arm removed, and equivalent parts in the figures are the same. Indicated by the symbol.

In the figure, a tone arm 1 has a cartridge 2 at its leading end and a counterweight 3 at its rear end, and is rotatably supported by a rotating shaft 4 in a vertical plane.

The rotating shaft 4 is rotatably held by a bearing member 6 attached to the player board 5.

A connecting member 7 is fixed to the lower end of the rotating shaft 4, and an armature 8 as a mover is attached to one free end of the connecting member 7. It can be rotated freely around the center.

The armature 8 is composed of a yoke 9 and a coil 10 wound around the yoke 9.

Note that the yoke 9 may be made of a magnetic material, or may be a bobbin or the like made of a non-magnetic material such as resin.

Furthermore, field poles made of magnets 11 as a stator are provided so as to form a predetermined magnetic gap with the armature 8, and supply magnetic flux to the armature 8.

This magnet 11 has, for example, a cylindrical shape with its circumferential wall magnetized into two poles. It is arranged so as to be located on the extension line of the line, and constitutes a drive mechanism together with the armature 8.

On the other hand, a conductive member 12 is attached to the other free end of the connecting member 7 so as to form a predetermined gap with the S pole surface of the magnet 11, and this conductive member 12, together with the magnet 11, brakes the rotation of the tone arm 1. It constitutes a braking mechanism.

In the tone arm drive device configured in this way,
The magnetic flux from the north pole face of the magnet 11 is introduced into the yoke 9 through the air gap.

Therefore, in the case of the coil winding direction shown in FIG. 2, by passing a predetermined current to the coil 10 from the terminal 10a, the current flowing to the coil 10 between the magnet 11 and the yoke 9 will change to the above-mentioned magnetic flux. In order to flow from the rear to the front at right angles to the plane of the paper and at right angles to the plane of the paper in Figure 2,
An upward force (in the direction of arrow A) in FIG. 2 acts on the coil 10 through which current flows.

Therefore, the armature 8 rotates counterclockwise in FIG. 2 about the rotating shaft 4, thereby causing the tone arm 1 to rotate.

It is obvious that if the direction of the current flowing through the coil 10 is reversed, the direction of rotation of the tone arm 1 will be reversed.

Therefore, the rotational direction and speed of the tone arm 1 can be controlled only by controlling the direction and magnitude of the current.

Furthermore, even greater driving force can be obtained by making the end face of the yoke 9 facing the magnet 11 into an arc shape centered on the rotating shaft 4.

On the other hand, when the conductive member 12 rotates counterclockwise in FIG. Since this magnetic flux passes through, an electromotive force is induced in the conductive member 12 by electromagnetic induction, and an eddy current flows.

This eddy current causes the conductive member 12 to flow in the clockwise direction (
In other words, an electromagnetic force is generated in the direction opposite to the rotation direction of the conductive member 12 (in the direction of arrow B), and this electromagnetic force becomes a braking force that brakes the rotation of the conductive member 12.

Further, when the conductive member 12 rotates clockwise in the figure in response to the rotation of the tone arm 1, a counterclockwise braking force is generated by electromagnetic induction to brake the rotation of the conductive member 12, as described above. It is easy to understand that.

Since the eddy current generated in the conductive member 12 is proportional to the rotating speed of the conductive member 12, a large braking force acts on the conductive member 12 rotating at high speed.

Therefore, since it is possible to prevent the tone arm 1 from rotating due to inertia when the driving of the tone arm 1 is stopped, the tone arm 1 can be reliably stopped at a desired position during automatic operation.

Note that when the stylus tip of the cartridge 2 traces the sound groove of the record, the rotational speed of the tone arm 1 is extremely slow, so the braking force acting on the conductive member 12 is extremely small. Therefore, there is almost no problem in the rotational movement of the tone arm 1.

As detailed above, according to the tone arm drive device of the present invention, even if an output is applied to the tone arm during auto operation, an excessive load is not applied to the drive section, and the auto operation is smooth and reliable. is obtained.

In addition, the reliability of automatic operation is improved because the number of mechanical parts in the drive part can be reduced, and since one magnet is used for both the drive part and the brake part, the mechanical part is simplified and costs are reduced. It is possible to reduce the

Furthermore, since the damping mechanism can damp floor vibrations transmitted to the tone arm 1 via the rotating shaft 4, vibrations due to sound pressure from the speakers, etc., resonance of the tone arm 1 caused by the above vibrations can be prevented. is also possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an embodiment of a tone arm driving device according to the present invention, and FIG. 2 is a plan view of the device shown in FIG. 1 without the tone arm. Explanation of symbols for main parts 1... Tone arm, 4... Rotating shaft,
6...Bearing member, 9...Yoke, 10
... Coil, 11 ... Magnet 12 ...
...Conductive member.

Claims (1)

[Scope of utility model registration request] A tone arm driving device for rotationally driving a tone arm within a predetermined plane, the tone arm driving device comprising: a movable element fixed to a rotation shaft of the tone arm and rotatable about the rotation shaft; A stator comprising an interlocking conductive member and a magnet provided to apply a predetermined electromagnetic rotational force to the movable element and to supply magnetic flux substantially perpendicular to a predetermined surface of the conductive member to the conductive member. A tone arm drive device comprising: