JPS6334081Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a pick-up arm lifting device installed in a record player.

Conventionally, in order to prevent damage to the record, a record stylus attached to the tip of a pick-up arm was slowly lowered to the top of the record placed on the turntable. The following mechanism was used.

In other words, the pick-up arm is slowly lowered using a solenoid, a spring, etc. as a driving source and the viscosity of the oil is used. However, since the viscosity of the oil changes depending on the ambient temperature, the lowering speed of the pick-up arm is limited. will change depending on the ambient temperature, and depending on the ambient temperature, the rate of fall may become quite fast and may damage the record.

Furthermore, if a solenoid is used as a drive source, it will generate impact noise during operation, so it is necessary to take soundproofing measures.

The present invention uses a stepping motor to lower the pick-up arm quietly and slowly at a constant speed, and also automatically raises the pick-up arm when the power is turned off. The drawbacks have been solved, and embodiments will be explained in detail below with reference to the attached drawings.

FIG. 1 is a side view of the device of the present invention, partially shown in longitudinal section, and FIG. 2 is a cross-sectional view taken from FIG. A pick-up arm 1 is provided at a predetermined position so as to be swingable in a horizontal plane and a vertical plane, and furthermore, a pick-up arm 1 is provided at a predetermined position slightly closer to the turntable 4' than the mounting position of the pick-up arm 1 to the board 9, which is the most important feature of the present invention. A lifting device is provided.

The pick-up arm elevating device consists of an elevation shaft 2 that vertically penetrates a base plate 9 and is integrally provided with a spring 7 that always urges downward, a cam 6 provided below the elevation shaft 2, and a pulse It is comprised of a stepping motor 5 that rotates the cam 6 to a predetermined angle each time an input signal is applied, and a spring 8 that always biases the cam 6 in one direction. The upper end of the elevation shaft 2 is integrated with a receiving part 2' extending in the horizontal direction so that it can always be engaged with the pick-up arm 1 even when the pick-up arm 1 swings in the horizontal direction. It is set as follows. Further, when the cam 6 is rotated to a position where it engages with the stopper 8' due to the elasticity of the spring 8, the elevation shaft 2 is raised, and the stepping motor 5 is operated to move the cam 6 at a predetermined angle by the spring 8.
The upper surface is formed into a high surface 10 and a low surface 12 that are continuous via an inclined surface 11 so that the elevation shaft 2 can be lowered when rotated against the rotation.

Note that 3 is a record needle provided at the tip of the pick-up arm 1.

The operation of the pick-up arm elevating device for a record player constructed as described above is as follows.

FIG. 1 shows a stopped state in which the record needle 3 is separated from the record 4. When a play start switch (not shown) is turned on, the turntable 4' is driven to rotate at a predetermined number of revolutions, and the stepping motor A DC voltage is constantly applied to the terminal 5, and a pulse signal from a pulse generator (not shown) is also applied.

Therefore, the stepping motor 5 rotates by a predetermined angle every time one pulse signal is applied, and the cam 6
also rotates against the spring 8 to the predetermined angle. When the cam 6 rotates, the position where the lower end of the elevation shaft 2 contacts the upper surface of the cam 6 changes from the high surface 10 to the low surface 12 via the inclined surface 11, and the elevation shaft 2 is lowered. As a result, the record needle 3 attached to the tip of the pick-up arm 1 descends, and the record needle 3 finally fits into the record groove of the record 4, and the information recorded on the record 4 is reproduced thereafter.

When the reproduction of the record 4 is finished, it is sufficient to stop applying the DC voltage to the stepping motor 5. By doing so, the rotor (not shown) of the stepping motor 5 becomes free, so that the spring 8
The cam 6 rotates in the opposite direction to that described above due to the elasticity.

Therefore, the elevation shaft 2 is raised in the opposite direction to the above, and the record stylus 3 can be separated from the record 4.

Of course, at this time, the rotation of the turntable 4' is also stopped.

Further, even in the event of a power outage during the reproduction operation of the record 4, the cam 6 is rotated by the spring 8 in the same manner as described above, so that the record stylus 3 can be separated from the record 4.

In the above case, the distance between the record 4 and the record needle 3 when stationary is 10 mm, one step of the stepping motor 5 is 3.75 degrees, and the angle of the length of the inclined surface of the cam 6 with respect to the center of rotation (in Fig. 2) is 10 mm. θ)
If it is 45 degrees, the cam 6 can be rotated 45 degrees by operating the stepping motor 5 in 12 steps. Therefore, the stepping motor 5 is
The descending height of the pick-up arm during step operation is 10/12 mm, or approximately 0.83 mm.

Here, the impact force at the moment when the record needle 3 collides with the record 4 is proportional to the momentum mv, and the falling velocity v is proportional to the 1/2 power of the height, so the record needle 3 under the above conditions The impact force between the record 4 and the record 4 is approximately 1/3.5 of the impact force when this device is not installed.

That is, since the angle of one step of the stepping motor 5 and the angle θ can be set freely, the angle of one step can be made smaller, and the angle θ can be set as much as possible within a range that does not impair the function of the device of the present invention. If it is made larger, the impact force can be further reduced, and damage to the record stylus 3 and the record 4 can be reliably prevented.

Further, in the above embodiment, the case where the inclined surface 11 is flat is explained, but if the inclined surface 11 is made to be a concave curved surface, the descending distance is increased at the beginning of the descending of the record stylus 3, and the descending distance is increased at the end of the descending. In this case, the descending distance can be made smaller, so that better effects can be achieved.

As described above, the present invention allows the pick-up arm to be lowered at a sufficiently low speed without being affected by ambient temperature at all times, without impact, and moreover, when the power is turned off, the pick-up arm is reliably raised. By holding the record needle in place, the record needle and the record can be sufficiently protected.

[Brief explanation of drawings]

FIG. 1 is a side view of the device of the present invention, a part of which is shown in longitudinal section, and FIG. 2 is a cross-sectional view along the line shown in FIG. 1. 1...Pickup arm, 2...Elevation shaft, 5...Stepping motor, 6...Cam, 7, 8...Spring, 10...High surface, 11...
Inclined surface, 12...low surface.

Claims (1)

[Scope of utility model registration request] Fix the cam to the output shaft of the stepping motor,
An elevation shaft that engages with the cam and moves up and down following the rotation of the cam to raise and lower the pick-up arm is provided vertically through the board, and further, an A return spring that urges the cam in a direction to raise the pick-up arm is provided between the two, and a pulse signal is input to the stepping motor to cause the cam to resist the urging force of the return spring. A pick-up arm elevating device for a record player, characterized in that the pick-up arm is lowered by rotating the pick-up arm.