GB2133200A - Sound reproducer with external drive shaft - Google Patents

Abstract

A sound reproducer having a central pin 2 supporting a turn-table 3 driven by a motor 4, which pin extends outside the casing to be used as an external shaft for driving other external attachments, the pin rotating at turn- table speed, and therefore providing a suitably reduced rotational speed and increased torque, compared with an extension of the motor output shaft. Also shown are speaker diaphragms 7 carried by sound transmitting member 6, and stylus pressure spring 11, adjustable by screw 17. Turn arm (18) and cam (21) (Fig.1) facilitate stylus pressure release at end of play, allowing pick-up 9 to return to start. <IMAGE>

Description

SPECIFICATION Motor driven sound reproducer with external drive shaft This invention relates to simple motor-driven sound reproducers having an external output shaft, for driving external attachments, formed by a central pin supporting a turn table and extended outside a casing so that the power of the reproducer motor may be utilised for driving any external attachments.

In conventional simple sound reproducers of the type used in dolls or other toys, if the motor power source is to he used to drive other means or apparatus into or with which the sound reproducer is incorporated it has been a common practice to extend the motor output shaft outside the casing, and attach thereon any necessary reduction gears.

However, this construction requires complex reduction means (gears) to reduce the rotational speed adequately for the specific purposes normally required, which inevitably makes the entire size of the device inconveniently massive and unsuitable to be incorporated into narrow internal spaces, and furthermore the noise produced by the speed reducing means interferes excessively with the reproduction of recorded sounds, during play-back and may render the playback virtually inaudible.

One object of the present invention is to provide a construction which can utilize the power source of the sound reproducer for some external means in a compact manner without undesirable noise such as may be caused by speed reduction means of the type required in conventional devices having a motor output shaft projecting from a housing.

In accordance with one exemplary embodiment of the invention there is provided a sound reproducer comprising: a turn-table supported in a casing on a central pin; a motor for driving said turn-table; a record disc disposed on or integral with said turn-table; a speaker unit composed of a sound transmitting member positioned to extend over said record disc, facing away therefrom, and having a speaker diaphragm carried by said sound transmitting member; a tone arm, having at its foremost end a pickup which extends between said record disc and said sound transmitting member, and swingably mounted at its rear end so that said pickup can be reciprocally swung between the starting point and end point of sound reproduction; and a stylus pressure spring for imparting necessary stylus force to said pickup.

wherein said central pin supporting said turntable extends outside said casing to form an external shaft for driving an external attachment.

The invention will now be described with reference to the drawings, in which:~ Figure 1 is a plan view of a preferred embodiment of sound reproducer, with parts of the housing removed; and Figure 2 is a partially sectioned side view.

The embodiment of a sound reproducer 1 shown in Figure 1 consists of a chassis 1 a and a housing 1 b. A turn-table 3 is carried within the chassis 1 a on a central pin 2 that is mounted for free rotation.

The central pin 2 in this embodiment is constructed as an integral part of the turn-table 3, and rotates in the direction of playing. The peripheral edge of the turn-table 3 is formed to constitute a pulley groove 15, and the turn-table carries a record disc 5 which rotates with the turntable in the direction of rotation for playing.

The record disc 5 may be formed as an integral part of the turn-table 3.

The central pin 2 is journalled in the base plate of the chassis 1 a, and extends outwardly to form an output shaft 12 for driving any external attachment.

This external output shaft may be coupled to its attachment via reducing gears 13, as shown in the drawing, if necessary for a given apparatus, but the degree of reduction required is minimal, and such reducing gears can be dispensed with in most embodiments of the invention.

A motor 4 has an output shaft 14 (Figure 2) which extends past the side of the turn-table 3 parallel to the central pin 2. A belt B extends around the pulley groove 1 5 of the turn-table 3 and the shaft 14. Since the belt B is extended about the output shaft 14 of relatively small diameter and the turn-table 3 of relatively large diameter, there is an inherent adequate reduction of speed and increase in torque imparted to the central pin 2, and consequently, the external output shaft 12 formed as an extension of the central pin 2 can readily be used as an output shaft for any external attachment (not shown).

As an alternative to a belt drive, it is possible to use rim-type drive means (not shown), wherein the output shaft of the motor directly contacts the peripheral edge of the turn-table 3 via a driving rim.

On the chassis 1 a there is mounted a speaker unit 8 consisting of a sound transmitting member 6 and a speaker diaphragm 7 carried by the sound transmitting member 6. As shown in Figure 1, the sound transmitting member 6 can be bifurcated at one end, and is supported at each of the two ends of the bifurcated portion by respective supporting posts 1 6.

A stylus pressure spring 11, which can be adjusted by a screw 17, urges said transmitting member 6 against the record disc 5.

In Figure 1 there is shown a tone arm 10 which is attached at its rear end to a swivel post 19 provided on the chassis 1 a, such that it can swing in two directions, both across the recorded face of the record disc 5 and closer to or further away from the record disc.

At the front tip of the tone arm 10 there is a pickup 9 having a sound reproducing stylus at the side facing the record disc 5.

The tone arm 10 is urged by a coil spring 20 wound around the swivel post 19 at its rear end such that the pickup 9 moves toward the starting point of sound reproduction and away from the recorded face of the record disc 5, when free.

The pickup 9 is interposed between the sound transmitting member 6 and the recorded face of the record groove 5, and the pickup 9 is constructed to travel toward the end point of sound reproduction of the record face, against the resilient force of the coil spring 20, when the record disc 5 rotates under stylus pressure imparted by a sound transmitting member 6.

A return cam 21 and a turn arm 18 is swingably disposed on the chassis 1 a with its rear end journalled on a swivel post 22 projecting upwardly from the top plate of the chassis 1 a adjacent to the return cam 21.

The foremost end of the turn arm 1 8 is positioned such that it can ride on the return cam 21 under the force given by the pickup, while the swivel post 22 at the rearmost end thereof has a coil spring 23 so wound around that the foremost end is urged to move away from contact with the return cam 21 toward the starting point of sound reproduction. The foremost end of the turn arm is disposed between the return cam 21 and the sound transmitting member 6.

Stoppers 24 and 25 are positioned for the tone arm 10 and the turn arm 18, respectively. A magazine 27 is provided for housing a battery and a main switch 28 enables power to be fed to the motor 4.

A stop switch 29 which is disposed such that it is supported by the pickup 9 when the pickup 9 is positioned at the starting point of sound reproduction on the recorded face of the record disc, and maintains and "OFF" position.

These switches 28 and 29, as shown in the drawing, are incorporated in parallel in the electric circuit between the battery and the motor 4 so that closing of the main switch 28 initiates rotation of the motor 4, which rotates the turntable 3 and the record disc 5 and causes the pickup 9 to move toward the point of sound reproduction, thereby the stop switch 29 is released by the pickup 9, to become "ON". Now, an electric circuit to the motor has been established, so the motor 4 will continue to rotate even if the operator releases the main switch 28.

When the pickup 9 arrives at the end point of sound reproduction, it urges the tone arm to move and ride on the turn arm 18. The turn arm, then acts by virtue of the return cam 21, to raise the speaker unit 8 upward to move away from the face of the record disc and so release the stylus pressure applied to the pickup 9.

The pickup 9 is then allowed to return, under the influence of the turn spring 20, to the stopper 24 at the starting point of sound reproduction, and at the same time, the turn arm 18 is also returned under the influence of the turn spring 23 to the stopper 25. At this position, the pickup 9 causes the stop switch 29 to be set to the "OFF" position and the supply of electric current to the motor 4 is cut off, to stop the motor 4.

In this manner, one complete cycle of sound reproduction is completed.

In this simple sound reproducer rotation of the turn-table 3 and the record disc 5 accompanies rotation of the central pin 2, including the output shaft 12 as the extension of the central pin.

Since the rotation of the output shaft 14 of the motor 4 of relatively small diameter is transmitted through the belt B of the turn-table 3 of relatively large diameter, the output shaft 12 rotates with reduced speed and increased torque, and accordingly any additional means for reducing the speed or increasing the torque may not be required, or if required, may be compact in size, and quiet in use.

Claims (4)

1. A sound reproducer comprising: a turn-table supported in a casing on a central pin; a motor for driving said turn-table; a record disc disposed on or integral with said turn-table; a speaker unit composed of a sound transmitting member positioned to extend over said record disc, facing away therefrom, and having a speaker diaphragm carried by said sound transmitting member; a tone arm, having at its foremost end a pickup which extends between said record disc and said sound transmitting member, and swingably mounted at its rear end so that said pickup can be reciprocally swung between the starting point and end point of sound reproduction; and a stylus pressure spring for imparting necessary stylus force to said pickup; wherein said central pin supporting said turntable extends outside said casing to form an external shaft for driving an external attachment.

2. A sound reproducer as claimed in Claim 1, wherein said central pin extends outside said casing at the side of the turn-table remote from the side where said sound transmitting member is disposed.

3. A sound reproducer as claimed in Claim 1 or Claim 2, in which said turn-table and said motor are connected by belt drive means, said output shaft rotation being thus reduced in speed and increased in torque due to the effect of said belt drive transmission.

4. A sound reproducer substantially as described with reference to Figures 1 and 2.