GB2124405A - Sound reproducing devices - Google Patents

Abstract

A simple sound reproducing device, comprises a turntable (3) is coupled to a governor by a belt drive (8), and the angle of the V-groove of the governor pulley is defined to be at least 60 DEG and not more than 90 DEG , the resilient belt 8 having a round cross- section. One or more brake members 6 are each normally urged by an associated spring 10 to move away from engagement with the inner face of a cylindrical chamber (4) formed in the casing. By virtue of this construction, the control function of the governor has been rendered exact, and slippage of the belt between the turn-table and the governor avoided when the device is incorporated into toys which may be used in dry conditions, in wet conditions, or actually in water. This construction allows use of a heavier brake member, which is necessary to avoid insufficient frictional engagement of a brake member with the inner face of the cylindrical chamber due to resistance given by water being present in the chamber between the brake member and the chamber wall. <IMAGE>

Description

SPECIFICATION Sound reproducing devices This invention relates to sound reproducing devices having a governor arranged to ensure precise speed control in normal ambient conditions, and also when operated in conditions where a device is liable to be wettened or actually dipped into water, and is able to effectively prevent any loss of smooth running due to slippage of a record disc or the like.

Heretofore, there have been provided simple sound reproducing devices comprising a turn table supported on a central pin disposed upright within a casing in a manner to permit both axial movement and rotation, a governor having one brake or more brake members pivotally supported on a bracket by a pin being housed in a cylindrical chamber disposed to one side of the turn table, and having a free portion frictionally engageable with the internal face of the chamber by the rotation of the bracket, the turn-table and the governor being connected by a combination of V-grooves and a resilient drive belt.

However, these devices have been intended for use in ordinary dolls or toys requiring no particular measure to prevent water from entering. Recently there has arisen some demands to incorporate sound reproducing devices into toys which can be used with water, or operated in a swimming pool or bath room, and which are able to speak, sing or generate sound. Any conventional device, when used in such conditions, allows water to flow into the device, and this may adversely influence the governor mechanism, or the drive transmission means between the governor and the turn-table, thereby obstructing satisfactory speed regulation.

It has been found that such troubles can be attributed to unfavourable slippage between the belt and the pulley groove, or to delay in timing of the frictional contact of the brake member with the internal face of the chamber caused by resistance imparted by the water, thus also lowering frictional engagement.

Such toys are also required for normal operation in places where there is no fear of contact with water, so the sound reproducing devices to be incorporated in such toys must be capable of use in normal ambient conditions.

It was initially found preferable to make the brake member or members of the governor heavier than that used in a conventional toy in order that the governor acts precisely, even when the device is used under water, but the use of such a heavier brake member results in an earlier operation of the governor control function, and excessively lowers the rotational speed of the turn-table, causing other undesirable malfunctions.

The inventor intended to accomplish the present invention to solve such pending problems which have been encountered when conventional sound reproducing devices were to be incorporated into toys which are desired to be used in a place near the water or even on and under the water. Accordingly, one object of the present invention is to provide a simplified sound reproducing device which performs with a correct and precise governor action, even when used under water, so that it is free from slippage and fully usable in both normal ambient conditions, in conditions susceptible to contact with water, or even to be used when immersed in water, In accordance with the present invention there is provided a sound reproducing device in which the rotational speed of a turn-table around a central support pin 2 in a casing 1 is regulated by a governor 7 disposed on a bracket 5 journalled within a cylindrical chamber 4 to one side of said turn-table and having at least one brake member pivotally mounted on said bracket 5 such that said or each brake member frictionally engages the inner face of said cylindrical chamber in dependance upon the rotational speed of said bracket, a resilient belt drive extending between a V-groove formed on said governor and a V-groove on the rim of the turn-table, the angle of said V-groove on said governor being not less than 600 and not more than 900, said resilient belt having a round cross section, and the or each said brake member being urged by an associated spring to move away from said inner face of said cylindrical chamber.

With this configuration, when the belt tightly engages the V-groove of the governor there is no fear that the belt can be gripped in the groove to such an extent that the belt is restrained from smoothly leaving at the end of its contact path with the pulley. This construction eliminates any irregular rotation of the turn-table due to inconstant or excessive tensioning of the drive belt, and enables the belt to be firmly extended without allowing any slippage.

By thus permitting the incorporation of a heavier brake member or members in the governor, it has become possible to maintain the speed of the turn-table at a desired number of revolutions per minute in water, and by incorporating a suitable spring means for the brake system any excessive or premature brake action is prevented when the device is used under normal conditions.

The invention will now be described with reference to the drawings, in which: Figure 1 is a graph showing the brake characteristic of various governor constructions, for explanatory comparison, in general; Figure 2 is a cross-section of one exemplary embodiment; Figure 3 is a plan view showing a record disc, the governor and a belt with the upper part of the casing of the embodiment shown in Figure 2 removed; and Figure 4 is a partially sectional fragmentary front view showing details of the relation between the governor and the turn-table.

In Figure 1 , the characteristics of a governor and turn-table with belt drive are shown for a known construction, curve A being its characteristic when operating in a normal environment and curve V being the characteristic when heavier brake members are fitted for working under water. The characteristic with an embodiment of the present invention is shown as curve C.

A preferred embodiment of a simple sound reconstructed producing device in accordance with the invention is shown in Figure 2, in which a turn-table 3 is driven by a constant-torque spring motor M.

As can be seen in Figure 2 a central pin 2 is disposed upright in a casing 1, within which the turn-table 3 is supported in such a manner that it is capable of being axially movable and yet freely rotatable.

A boss 1 a serves for retaining the central pin 2, and is crowned by a cap shaped washer 1 b.

On the rim of the turn-table 3 there is formed a pulley groove 3a defined by a flat between upper and lower shoulders. A record disc 3b is secured on the upper face of the turn-table 3, at the centre of which a sleeve 3c for attaching the record disc is disposed via a coii-shaped spring clutch 20.

Inside the spring clutch 20, a rotary member 21 comprising an integrally formed driven reel 3d is disposed. Near the bottom centre of the rotary member 21 and around the central pin an annular groove 12 is defined, with its opening end directed downwards. A coil spring 1 3 for imparting stylus force is inserted into the groove 12, the lowermost end of this spring being received on the washer 1 b on the boss 1 a, so that the turn-table 3 is resiliently supported.

At the lower face of the turn-table 3, the aforesaid driven reel 3d is urged by a spring clutch 20 such that the rotary member can be engaged with the turn-table for driving only in a required direction of rotation of the rotary member 21.

The constant torque spring motor M has a constant torque spring 14 whose free end is fixed to the driven reel 3d. On the upper part of the sleeve 3c at a position above the turn-table 3 a reel 3e for taking up a string is disposed, this reel being integral with the rotary member 21 and the sleeve 3c. The reel 3e for taking up the string is constructed such that it can be rotated together with the sleeve 3c, the rotary member 21 and the driven reel 3d by the string, as will be explained later. One end of the string 15 is fixed to the reel 3e, for winding up the motor while the free end of the string 1 5 extends outward through an opening 16 formed in the casing 1, and is attached to a pull ring (not shown).

A pickup 1 6 has at its lower end-face a downwardly projecting sound reproducing stylus 17, engageable with a record groove on the record disc 3b carried on the turn-table 3. The pickup 1 6 is mounted on a tone arm (not shown) and is capable of being swung in both the upward and downward directions, as well as laterally in the forward and rearward directions, and is normally urged toward the starting point of sound recording by a coil spring (not shown).

A speaker cone 1 8 is housed within the casing at its upper portion, with the head of the speaker cone being faced downward. On the head portion of the speaker cone 18, a sound-transmitting disc 1 8a is attached, the lower face of which is slidably engageable with the top of the pickup 1 6. The upper face of the transmitting-disc 1 8a of the speaker cone receives a coil spring 1 9 resiliently placed between this upper face and the overlying inner face of the casing 1, so that the speaker cone is resiliently urged as a whole toward the record disc 3b.The string is stretched under tension during the time of winding up the constant torque motor, and passes beneath the tone arm such that the pickup 1 6 can be supported by the sound-transmitting disc 1 8 while the turn-table 3 can be urged to move away from the sound reproduction stylus against the force imparted by the stylus force spring 1 3.

During the time of sound reproduction, the pickup 1 6 travels across the record disc 3b, guided by the recorded groove and pressed by the sound-transmitting disc 1 boa.

The governor 7 is disposed within the casing 1 to one side of the turn-table 3, and comprises a rotary shaft 22 disposed at the axial centre of a cylindrical chamber 4 formed partly by a flange wall integral with the casing 1 that stands up from the bottom of the casing 1 to surround a bracket 5 and a pulley 23, both fixed to the rotary shaft 22.

A pair of brake members 6 are positioned symmetrically with respect to the rotary shaft 22 and swingably supported about a pair of associated pins 1 , such that the outer face of free end portion of the brake member can frictionally contact the internal wall of the cylindrical chamber 4 when an excessive centrifugal force is imparted by the rotation of the bracket.

The construction of the governor 7 can be more clearly seen in Figure 3, where the cylindrical chamber 4 is shown in plan view, and the bracket 5 is shown to have a smaller circular shape, whilst the brake members 6 each have a semicircular outer configuration and is positioned to lie flush with the outer margin of the bracket 5. These brake members 6 are each pivotally attached to the bracket at one end about an associated pin 11, and they are resiliently urged by respective springs 10, such that their outer forward ends will normally move away from the inner face of the chamber 4. Each of the springs 10 is fabricated of thin wire, and is wound at its mid-portion about the head of the associated pin 11, one end being secured to an associated projection 24 on the upper face of the respective brake member 6, while the other end of each spring is secured to a respective projection 25 on the bracket 5.

A brake pad 26 fabricated of a soft material such as felt is adhesively attached to the outer peripheral face of the free end portion of each brake member 6, and thus the brake members frictionally engage the inner face of the cylinder 4 through the respective brake pads 26.

As can be seen from Figure 2, the pulley 23 is fixedly attached to the rotary shaft 22 at the same level as the turn-table 3. As is clearly shown in Figure 4, the pulley 23 has a pulley groove with a V-shaped cross section and the groove angle a is at least 600 and not more than 90". A drive belt 8 having a round cross-section extends between the pulley and the turn-table 3. By adopting the defined groove angle of 600 -- 900, and using a belt of round cross-section the belt can be extended with sufficient force without causing any excessive seizure by the pulley groove.

Accordingly, the belt 8 does not disturb smooth rotation of the turn-table 3, but can be extended with sufficient force, so any slippage during reproduction when dipped into or moistened by water or the like can be entirely avoided.

Figures 2 and 3, show a pair of brake member holders 27, formed integrally on the top of a bracket sleeve 28 integral with the bracket 5 to rotate together with the bracket and prevent the associated brake member 6 from escaping upwardly during rotation.

Owing to the constructions of the governor 7 and the pulley groove 9, a simplified sound reproducing device constructed in accordance with the present invention assures correct and exact speed control both in normal running, and when operating in water or a place where it may be susceptible to wetting. The problem of irregular running of the turn-table 3 due to the connection between the governor 7 and the turn-table 3 is avoided, and it should particularly be noted that the speed control when running in water and when playing in dry conditions is very precise and satisfactory, as will be explained in detail with reference to Figure 1.

Assuming that the governor of a simplified sound reproducing device of the kind described operates with a brake effect value of 10 to maintain rotation of the turn-table at 200 R.P.M.

in normal operation, using a brake member having a weight capable of displaying the braking characteristic shown by curve A. If this device is used when wet or when submerged in water, sufficient brake effect cannot be obtained unless the or each brake member is replaced by a heavier one than normally used, to obtain the braking characteristic shown by curve B. However, as the curve B shows, the heavier brake itself naturally displays a braking effect value of 50, in dry conditions, so it will result in excessive braking force in normal, dry operation, and it will take a much much longer time for the turn-table to build up rotation to the speed necessary for sound reproduction, so it is not acceptable as a dualpurpose device.In order to solve this problem, it is necessary, to use heavier brake member or members, but resiliently hold the or each brake member against centrifugal force, by means such that the or each brake member will not engage the inner face of the chamber 4 until rotation, of the turn-table reaches its desired rate. The means for holding a brake member against the centrifugal force is the associated spring 10 shown in Figure 3. Resilient support of the brake member by the spring 10 gives rise to a shift of brake characteristic to that shown by curve C in Figure 1. This manner of shifting assures rotation of 200 R.P.M. not only in both normal dry conditions and in water, running with a brake effect value of 10, but braking action only being initiated as the rotation of the turn-table approaches 200 R.P.M. accordingly the problem of long period of build-up time necessary to attain the desired speed of 200 R.P.M. is avoided.

As explained above, a simplified sound reproducing device constructed in accordance with the present invention guarantees smooth rotation and exact speed control both in normal dry conditions, in wet conditions, and when immersed in water.

In the following claims reference numerais have been included where it is thought this will be helpful to the reader, but these are not intended to have any specific limiting effect upon the language

Claims (4)

of the claims. CLAIMS

1. A sound reproducing device in which the rotational speed of a turn-table around a central support pin 2 in a casing 1 is regulated by a governor 7 disposed on a bracket 5 journalled within a cylindrical chamber 4 to one side of said turn-table and having at least one brake member pivotally mounted on said bracket 5 such that said or each brake member frictionally engages the inner face of said cylindrical chamber in dependence upon the rotational speed of said bracket, a resilient belt drive extending between a V-groove formed on said governor and a V-groove on the rim of the turn-table, the angle of said V-groove on said governor being not less than 600 and not more than 90 , said resilient belt having a round cross section, and the or each said brake member being urged by an associated spring to move away from said inner face of said cylindrical chamber.

2. A sound reproducing device as claimed in Claim 1, in which said bracket is a circular disc smaller than the internal diameter of said cylindrical chamber and said or each said brake member is pivotally supported at one end of said associated spring, which is wound around a respective pin on said bracket and has its other end secured to said bracket.

3. A sound reproducing device substantially as described with reference to Figures 2 to

4.