JPH0445121Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an arm lifter for a record player.

[Prior Art] As is well known, when the arm lifter conventionally manually moves the cartridge to a desired record groove and lowers the cartridge, the cartridge slips from the finger and falls onto the record surface, damaging the record and needle. In order to prevent this, the tone arm is temporarily held at a height such that the stylus and record surface do not come into contact with each other, and then the arm lifter is gradually lowered to achieve contact between the stylus and the record groove. This is what I did.

Further, when performing an automatic performance operation (auto lead-in), the arm lifter operates as follows.

Before operation, the arm lifter holds the tone arm at a height where the stylus and record groove do not come into contact. When the automatic performance operation is started, the tone arm is rotated to a predetermined position by a driving force using a dedicated motor or a turntable rotation drive motor.

When the stylus is rotated to a predetermined position, the driving force is cut off and the arm lifter begins to descend, slowly bringing the stylus into contact with the record groove.

[Problems to be solved by the invention] In the above configuration, the arm lifter surface and the tone arm are designed to reduce the load on the dedicated motor or the motor for driving the rotation of the turntable;
In order to accurately rotate the tone arm to a predetermined position, it is designed to have extremely low friction between the two.

On the other hand, tone arm devices have been commercialized that are equipped with an inside force canceller to cancel out the inside force, which is the inward force that acts on the tone arm when playing a record. Figure 4 is an example, where 01 is the tone arm, 02 is the bearing part,
03 is a balance weight for applying stylus pressure, 04 is an arm lifter, and 05 is a weight for inside force cancelling, which is connected to a lever 06 provided on the bearing part 02 with a thread 07, and is connected to the tone arm 0.
The inside force is canceled out by applying a force in the direction opposite to the rotational direction to 1.

In such a configuration, when the above-mentioned automatic performance operation is performed, the tone arm 0 reaches the predetermined position.
1 is rotated and the arm lifter 04 starts to descend, the inside force is not yet acting and only the outward force due to the inside force canceling force is acting on the tone arm, In addition, as mentioned above, the rotational driving force is cut off, and the frictional force between the tone arm 01 and the upper surface of the arm lifter 04 is extremely small.
There was a problem in that the tone arm 01 moved outward due to the cancel force, and the needle could not be lowered to a predetermined position.

[Means for solving the problem] In this invention, the lifter surface that the tone arm comes into contact with has a downward slope in the direction of rotation of the tone arm,
The arm lifter is such that the downward slope is proportional to the horizontal tracking angle of the tone arm.

[Function] With the above configuration, the cancel force can be canceled by the acting force in the tone arm rotation direction (inward direction) generated by the weight of the tone arm system, and movement of the tone arm when the arm lifter is lowered can be prevented. We have now been able to do it.

[Example] Figures 1 to 3 show an arm lifter 4 according to an embodiment of this invention, and the surface 4 that should come into contact with the tone arm 1
A is formed as an inclined surface having a downward slope in the rotational direction (inward direction) of the tone arm 1.

The angle of the inclined surface is proportional to the horizontal tracking angle of the tone arm 1 that abuts on that portion.

In other words, assuming that the inside force acts toward the center of the record, the inside force F is F=μWtanφ, where μ: coefficient of friction between the record and the stylus W: weight of the tone arm system φ: horizontal tracking angle , as shown in Figure 3, the canceling force
Fc has the same magnitude and acts in the opposite direction (outward direction).

Therefore, the component force Ff of the cancel force Fc along the arm lifter surface 4a is Ff=μWtanφcosθ.

However, θ is the inclination angle of the arm lifter surface portion that the tone arm comes into contact with.On the other hand, an inward force of Fw=Wsinθ is applied to the tone arm along the arm lifter 4a surface due to its weight.

Therefore, the cancel force Fc can be canceled by setting Ff=Fw.

That is, μWtanφcosθ=Wsinθμtanφ=tanθ...1, and according to equation 1, an inclination is formed on the arm lifter surface 4a of the portion in contact with the tone arm in proportion to the change in the horizontal tracking angle.

FIG. 2 shows an example of this, in which the inclination angle of the arm lifter surface 4a changes between 8° and 9.5° in proportion to the change in the horizontal tracking angle (24.5° to 29°).

In the figure, r1 is the final groove position of the EP record, r2 is the position where the horizontal tracking angle is the smallest,
r3 indicates the first groove position of the LP record.

Further, when the inside force is assumed to act in the tangential direction of the rotation locus of the tone arm, the inclination angle θ may be set by applying the equation μsinφ=tanθ instead of the above equation 1.

[Effect of the invention] According to the above configuration, when the arm lifter descends, due to the gravity of the tone arm system, a force acting in the opposite direction to the inside force canceller force acts on the tone arm, canceling out the previous inside force canceller force. The tone arm maintains the set position without moving and descends.

After that, the arm lifter and tone arm separate, so the acting force in the previous reverse direction disappears, and on the other hand, an inside force is generated and the inside force canceller force acts to cancel this, resulting in a predetermined inside force canceller operation. .

Therefore, according to this invention, it is possible to bring the record stylus into accurate contact with the set record groove position during an automatic lead-in operation or the like.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the arm lifter according to the embodiment of this invention, Fig. 2 is an illustration of the inclination angle of the arm lifter according to the embodiment of the invention, Fig. 3 is a force line diagram explaining the operation of this invention, and Fig. 4 1 is a perspective view of a main part of a record player using a conventional arm lifter.

Claims (1)

[Claims for Utility Model Registration] The surface of the lifter that the tone arm abuts has an inclination angle with respect to the rotating direction of the tone arm, and the inclination angle θ of the lifter at the abutment position is tanθ=μtanφ, where μ: An arm lifter characterized in that a coefficient of friction between the record and the record stylus φ is a horizontal tracking angle of the tone arm at the contact position.