Golf Ball

Abstract

This invention relates to an electronic golf ball comprising a central resilient sphere, a mass of elastic material surrounding the sphere and an outer casing, the central sphere including an electric squegging oscillator circuit, a battery therefor and a transmitting coil, all enclosed in a spherical mass of a set resin which forms a solid core, the spherical mass being located with close fit in a hollow spherical cavity formed in the central resilient sphere. The battery is a mercury cell located within the transmitting coil, as are the other components of the squegging oscillator circuit. The electrical circuit may include components which permit the oscillator to be turned on and off when the golf ball is brought into and then moved out of an A.C. magnetic field having a predetermined frequency.

Description

This invention relates to a golf ball containing an electric oscillator circuit which assists in the recovery of golf balls lost during a game of golf. It is a well known fact that many golf balls are lost due to the fact that during play the golf ball lands in a particularly overgrown area of the golf course. The loss can occur even though the ball may have been visible during its entire flight and the approximate region of the landing of the ball is known. The loss of a golf ball not only entails financial loss to the player it also means that the player is put at a disadvantage as far as that game is concerned. The present invention reduces the occurrence of lost golf balls and players employing golf balls which can be recovered are at an advantage both financially and by not losing unnecessary points over lost balls.

According to one aspect of the invention of golf ball comprises a central resilient sphere, a mass of elastic material surrounding the sphere and an outer casing, in which the sphere includes an electric oscillator circuit and a battery therefor, and is characterized in that the oscillator circuit, a transmitting coil and the battery are enclosed in a spherical mass of a set resin to form a solid core, the spherical mass being located with close fit in a hollow spherical cavity formed in the central resilient sphere.

Conveniently the oscillator circuit is tuned to a particular frequency and generates an induction field at that frequency, the oscillatory circuit squegging so that its output comprises bursts of oscillation at the desired frequency interspersed by longer periods of non-oscillation. The duty ratio (i.e. the ratio between the periods of non-oscillation (off periods) and the periods of oscillation (on periods)) can be chosen at will, but is preferably within the range 100:1 to 1,000:1. The bursts of oscillation can be kept stable and the repetition of these bursts appear in a detector unit (which may be a simple radio receiver tuned to the frequency of the oscillator circuit) as a modulation frequency characteristic of the oscillator circuit employed. By filtering this pulse repetition frequency the detector unit can respond to different frequencies making identification of different golf balls possible.

A suitable frequency range for the oscillator circuit is between 10 kilohertz and 10 megahertz since in this frequency band it is easy to arrange for there to be a negligible component of radiated energy.

The "on" period can be as long as a fraction of a second (e.g. 0.1 second) or as short as a few tens of micro-seconds, the only requirement being that the burst of oscillation should be sufficiently long to enable it to be reliably detected by the detector unit. By utilising a large duty ratio, it is possible to employ an oscillator operating at a carrier frequency as high as 10 megahertz (where a significant proportion of the energy will produce an induction field from a coil of only a few millimeters in diameter) and have a mean radiated power output of the order of microwatts.

Preferably the transmitting coil is wound into a short cylinder and is positioned in the spherical mass of resin so that a median plane of the coil normal to the axis of the coil lies in a diametric plane of the spherical mass. A cylindrical mercury cell makes a suitable battery and this may be positioned so that the axis of the coil is normal to the axis of the battery, the other component parts of the oscillator circuit being disposed on either side of the battery to lie within the transmitting coil.

The oscillator circuit may operate in the same manner from the time the circuit is completed until the battery is finally spent (it is not difficult to arrange for a lifetime of several years using conventionally available batteries) but a modified oscillator circuit can be used which can be switched on and off before and after playing a round of golf. With this latter arrangement it is possible to increase the strength of the induction field and still obtain acceptably long lifetimes for the battery .

Embodiments of golf balls in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a partially sectioned golf ball,

FIG. 2 is a perspective view of the spherical mass within the centre of the golf ball shown on an enlarged scale,

FIG. 3 is one form of circuit suitable for employment in the golf ball of FIG. 1, and

FIGS. 4 and 5 are two alternative forms of circuit.

Referring to FIGS. 1 and 2, the golf ball shown in the drawing comprises an outer casing 1, a wound mass of elastic filament 2 and a central core 3. In a normal golf ball the core 3 is a sphere of rubber with a liquid centre. In a golf ball in accordance with the invention the rubber core 3 contains a spherical recess 4 in which is located a spherical mass 5.

The mass 5 is of hard set resin material (catalytically hardened resin) of a diameter of 0.625 inch (15.9 mm) which with its electric components weighs 3.5 grammes. The outside diameter of the core 3 is 1.00 inch (25.4 mm), the core 3 being divided along a diametric plane to allow the mass 5 to be located within the recess 4 before the core 3 is incorporated in the mass 2 and casing 1 in a manner wholly conventional in the production of golf balls.

No alteration whatever is necessary in the components 1 and 2 shown in the drawings but the core 3, as well as having a solid centre rather than a liquid-filled centre, is fabricated from a softer rubber than normal, the hysteresis of the rubber being chosen so that the ball containing the mass 5 behaves in a similar manner to a ball having a liquid-filled centre.

A simple circuit for incorporation in the mass 5 is shown in FIG. 3 and includes a transistor T (a Texas Instrument 2N3708), a battery B (a mercury cell) a resistor R (560K ohms), two capacitors C1 (1,500 pS) and C2 (0.1.mu. F) and an intermediate-tapped coil L. The circuit components cause oscillation at a frequency determined by the natural frequency of the resonant circuit C1 L at a duty ratio determined by the components C2 and R. The coil L has a turns ratio 4:1 and is formed into a short cylindrical coil of diameter 0.60 inch (15.0mm).

The relative positioning of the components in the spherical mass 5 is important to ensure that the centre of gravity of the components is roughly at the centre of the spherical mass.

The components shown within the dotted line in FIG. 3 can be combined in an integrated circuit, to which are added the coil L, the battery B and the capacitor C2.

The circuit shown in FIG. 3 operates in the same manner from the moment of its completion to the moment the battery has run down. This means that in order to ensure a life of several years, the average power output must be exceedingly low and in turn this means either a limited range at which a simple radio receiver will detect the induction field or the use of a highly sensitive detector unit. FIGS. 4 and 5 show alternative circuits which although somewhat more complicated in their design do have the advantage of being able to be switched "on" and "off" so that higher means power outputs are obtainable during the "on" periods whilst still providing a useful working life from a small mercury-cell.

Referring to FIG. 4, under quiescent conditions the base of a transistor T2 is connected to its emitter via a resistor R2 so there is no collector current flowing, other than the negligibly small reverse current of the collector-base diode, hence there is no bias current to remove the transistor T1 from its cut-off condition. Also, the voltage developed across the dc. collector load of the transistor T2 (V*) is approximately zero.

The tapped resonant circuit in the collector of the transistor T1 resonates at a frequency f.sub.o = 1/2 .pi..sqroot.LC3 where L is the total inductance of the two primary sections of the coil, P1 and P2. If the golf ball is placed temporarily in the magnetic induction field of an external exciting coil fed from an oscillating source of frequency f.sub.o, an oscillating voltage will appear across the resonant circuit inductance P1 + P2 and a smaller voltage will appear across the secondary S. If the secondary voltage is large enough, it will turn the transistor T1 ON into a Class C mode of operation, the necessary negative voltage across the capacitor C4 being developed by the rectifying action of the base-emitter diode of the transistor T1. (The maximum peak-to-peak amplitude of the oscillation is limited to twice the battery voltage across the coil P1, and to about 9 volts across the secondary S, the 9 volts being the usual BE Zener breakdown voltage of most silicon transistors, and the lowest value of the voltage on the capacitor C4 is about half the 9 volts.) However, due to the large feedback ratio S/P1, and due to the fact that the time constant R1C4 of the base circuit is much larger than the oscillation period, the oscillator will start to squeg immediately, thereby turning itself off. The next burst of oscillation (in the absence of the external exciter) will occur when the voltage on the capacitor C4 is charged to about 0.6 volts through the resistor R1, but this can happen only when V* is large than 0.6 volts.

On the first turning on of the oscillator, the transient decreasing voltage on the capacitor C4 will pull down the base voltage of the transistor T2 via the capacitor C6, and this capacitor will supply a base current pulse if the transient voltage step exceeds 0.6 volts. The base current pulse, amplified by the current gain of the transistor T2, charges up the capacitor C5 to a voltage V* near the battery voltage. Hence the continual turning-on of the transistor T1 after the initial switch-on is assured.

If the exciter voltage is kept on for a time longer than necessary for start-up, the oscillator will start its successive bursts even before the voltage on the capacitor C4 exceeds 0.6 volts. Hence the transient step is reduced, and if it is reduced below a certain critical level it is not capable of driving the transistor T2 and V* drops to a negative value (approximately -4 volts). On the sudden removal of the exciter voltage the oscillator will not be able to start again and the golf ball therefore will be switched OFF.

Switching ON or OFF therefore uses the same exciter, which could be a part of the radio receiver used as the detector and could be activated by a push-button switch. The exciter could even be the ferrite aerial coil of the receiver, connected as an oscillator while the push-button is depressed. The actual ON or OFF operation would then be as follows:

Ball brought near (not too near) exciter and slowly removed = SWITCH ON

Ball brought very near the exciter and quickly removed = SWITCH OFF

FIG. 5 shows an alternative version of circuit. In this Figure a capacitor C7 stores the bias voltage for a transistor T3 which is charged up via a diode D. Squegging occurs with a time constant R3 C8 and bias current flows out of the capacitor C7 through the resistor R3. Switching ON and OFF is done with an exciter as before. On switching ON the capacitor C7 charges up to 41/2 volts during the first rf burst. On switching OFF, as the pulse repetition rate is increased, more current is drawn from the smoothed supply and the supply voltage V.sub.s is reduced, thereby reducing the oscillating voltage on P1 and therefore on S, which in turn does not keep V* at its previous high value of 41/2 volts, and the oscillator stops without the help from the external exciter.

In the circuit of FIG. 5, C9 must be a large capacitor, while in the circuit of FIG. 4 the values of the capacitors are small, enabling the circuit shown in FIG. 4 to be produced in Integrated Circuit form.

The circuit shown in FIG. 4 would conveniently employ components as shown in the following Table:

TABLE

B = 1.4 volts

P1 = 8 turns

P2 = 100 turns

S = 30 turns

C3 = 3,000 pF

C4 = 1,000pF

C6 = 200pF

R1 = 1,000k

R2 = 100k

T1 = n.p.n

T2 = p.n.p

The circuits shown in FIGS. 4 and 5 can be "potted" in a spherical mass of set resin in a similar manner to that employed with the circuit of FIG. 2, the component parts being positioned to give a centre of gravity as close to the centre of the mass 5 as possible.

The circuit of FIG. 5 can be modified by placing the coil S, the diode D and the resistor R4 in series with the emitter of the transistor T3 and connecting the resistor R3 and the capacitor C8 to the base line.

Claims

What is claimed is:

1. A golf ball comprising an outer spherical casing; an elastic spherical mass inwardly of said outer spherical casing; and squegging oscillator means accommodated within said elastic spherical mass and including an inductor serving as a transmitting coil, said oscillator means being operative for intermittently generating an oscillating electromagnetic field for periods of time which are shorter than the periods of time during which said field is not generated.

2. A golf ball as defined in claim 1, wherein said squegging oscillator means comprises a source of electrical energy.

3. A golf ball as defined in claim 2, wherein said source of electrical energy is a mercury cell.

4. A golf ball as defined in claim 1, and further including a resilient spherical central core inwardly of said eleastic spherical mass and having an internal spherical cavity, and further including a spherical mass of set resin material inwardly of said central core and tightly fitted within said cavity, said squegging oscillator means being embedded within said spherical mass of set resin material.

5. A golf ball as defined in claim 4, in which said transmitting coil is wound in the form of a cylinder and positioned in said spherical mass of resin material so that a median plane of said coil normal to the axis of said coil lies in a diametric plane of said spherical mass of resin material.

6. A golf ball as defined in claim 5, in which said squegging oscillator means comprises a mercury cell having a central axis of symmetry and serving for the supply of electrical energy and positioned in said spherical mass of resin material and inside said coil so that the axis of said coil is normal to the axis of said mercury cell, and wherein said squegging oscillator means includes a plurality of other electrical components located to either side of said mercury cell and also located within said coil.

7. A golf ball as defined in claim 1, wherein said inductor constitutes a transmitting coil, and wherein said squegging oscillator means comprises a npn transistor having an emitter, a collector and a base, a capacitor connected in parallel to said transmitting coil to form a parallel LC circuit having a predetermined resonance frequency, and a battery connected between an intermediate tap of said coil and said emitter, a parallel RC-circuit connected to said base, the ends of said parallel circuits not connected to said transistor being connected together and the resonant frequency of the RC circuit being a fraction of said predetermined resonance frequency.

8. A golf ball as defined in claim 1, wherein said squegging oscillator means includes magnetic-field responsive means operative for terminating operation of said oscillator means when the golf ball is brought into and then moved out of an A.C. magnetic field.

9. A golf ball as defined in claim 1, and wherein said squegging oscillator means includes magnetic-field-responsive means operative for terminating operation of said squegging oscillator means when the golf ball is brought into and then moved out of an A.C. magnetic field having a predetermined frequency.