GB2208439A - Projectile with speed measuring device - Google Patents

Abstract

A projectile 1 in the form of a ball comprises a shell 2 having a recess 4 housing a speed measuring device. The device comprises a first shock activated switch 6 for sensing when the ball is thrown and a second shock activated switch 7 for sensing when the ball hits a target. Switch 6 is more sensitive than switch 7. A counter 10 counts the time between the activation of the switches, and the speed as calculated by a calculator and based on a predetermined distance is displayed at 9. <IMAGE>

Description

PROJECTILE WITH SPEED MEASURING DEVICE The present invention relates to a projectile having a speed measuring device for measuring the speed of the projectile.

When practising ball games suc-h as baseball or tennis it is desirable to know how fast the ball is travelling after it has been thrown or hit. One system for determining the speed of the ball utilises radar to determine the speed of the ball. Another system provides a switch on the ball. The switch is released when the ball is thrown, thus triggering a counter, and a shock sensing device triggers a switch to turn off the counter when the ball hits a wall, for example, the speed of the ball can then be calculated from the elapsed time or count if the distance is known. The latter system has the drawback that the ball must be thrown from the hand.

The present invention provides a projectile incorporating a device for measuring the speed of the projectile when projected through a predetermined distance, the speed measuring device comprising sensing means for determining automatically when the projectile is accelerated from a substantially rest position and when the projectile is decelerated relatively rapidly, means for determining the time elapsed between said acceleration and relatively rapid deceleration and means for calculating the speed of the projectile from the elapsed time and the predetermined distance.

With the projectile of the invention, a first sensor may sense the shock applied to the ball when it is accelerated, for example thrown or hit, whilst a second may sense the shock applied to the ball when it is decelerated.

The sensors may be of comparable sensitivity, the second sensor being disabled until after the first sensor has been activated, and the first sensor being disabled once activated, until the second sensor has been activated. Preferably, however, the first sensor is more sensitive than the second.

Other preferred features and 5 advantages of the invention will be apparent from the following description and the accompanying claims.

The invention will be further described by way of exmaple with reference to the drawings, in which: Figure 1 is a diametrical cross sectional view through a ball embodying the invention; and Figure 2 is a schematic diagram of circuitry for a speed measuring device of the ball of Figure 1.

Figure 1 shows a projectile 1 in the form of a ball,such as a baseball. The projectile comprises a spherical elastic body 2, for example of rubber of plastics material, having an outer skin 3 of leather or hide. A recess 4 is formed in the body 2 for receiving a speed measuring device 5 of the invention.

The speed measuring device 5 comprises first and second shock sensitive switches 6, 7, electronic circuitry 8, a display 9 and a power supply 10 in the form of a small battery or cell.

Referring to Figure 2, the electronic circuitry 8 comprises a counter 10 which receives an input from the switch 6 via a control circuit 11 and an input direct from the switch 7, a count determined by the counter is output to a calculator 12 which displays a calculated speed on the display 9.

The switch 6 comprises a conducting wire 13 which is soldered at one end to a track on a printed circuit board 14 and carries at its other end an electrically conducting weight 15. Weight 15 rests inside a metal cylinder 16 which is also electrically connected to the circuit board 14. The weight 15 and cylinder 16 form contacts of a switch which is closed when the weight 15 contacts the cylinder 16. This will happen when a shock is applied to the ball. The degree of shock required will depend on the resilience of the wire 13, mass of the weight 15 and the relative sizes of the weight 15 and cylinder 16, and these parameters are chosen to suit the desired application.

The switch 7 comprises a coil spring 17 which is soldered at one end 18 to a track on a printed circuit board 19 and rests just above a second track on the board 19 at its other end. When a shock is applied to the ball the free end of the spring will move against the board to contact the second track.

The degree of shock required will depend on the resilience of the spring 17 and the separation of the spring 17 from the board 19 when in a rest position.

Referring to Figure 2, the switches 6 and 7 are set so that the switch 6 will be triggered by a relatively light shock, such as when the ball is thrown from the hand. This passes a signal to the control circuit 11 which in turn signals the counter 10 which starts counting. When the ball hits an object it decelerates rapidly, causing the switch 7 to send a signal to the counter 10. The counter 10 stops counting and the count is passed to the calculator 12 which calculates the speed of the ball according to a preprogrammed algorithm based on a predetermined distance of throw. The calculated speed is then displayed on the liquid crystal display 9. The control circuit resets the counter 10 after a predetermined time, for example 10 seconds, allowing the ball to be retrieved and the calculated speed read from the display before the sequence recommences.

The device as described requires the ball to be thrown over the predetermined distance used in the calculation by the calculator 12. A chart may be provided to allow conversion to other distances of throw, or means may be provided for entering a distance into the calcuator, using a switch (not shown), the entered distance being shown momentarily on the display.

To assemble the projectile the body 2 Is moo ?li''d fro rubber or plastics material. The device 5 is assembled and installed in the recess 4 and the outer covering 3 stitched on the body 2. The covering 3 has a window 20 for viewing of the display 9.

Various modifications may be made to the described embodiment and it is desired to include all such modifications as fall within the scope of the accompanying claims.

Claims (14)

1. A projectile incorporating a device for measuring the speed of the projectile when projected through a predetermined distance, the speed measuring device comprising sensing means for determing automatically when the projectile is accelerated from a substantially rest position and when the projectile is decelerated relatively rapidly, means for determining the time elapsed between said acceleration and relatively rapid deceleration and means for calculating the speed of the projectile from the elapsed time and the predetermined distance.

2. A projectile as claimed in claim 1, including display means for displaying the calculated speed.

3. A projectile as claimed in claim 1 or 2, wherein the sensing means comprises a first shock sensing device for determining automatically when said projectile is accelerated, and a second shock sensing device for determining automatically when said pojectile is decelerated relatively rapidly.

4. A projectile as claimed in claim 3, wherein said first shock!; sensing z-- is more sensitive than said second shock sensing device.

5. A projectile as claimed in claim 3 or 4, wherein said first shock sensing device comprises a pendulum.

6. A projectile as claimed in claim 5, wherein said first shock sensing device comprises a wire carrying a weight at one end and fixed at its other end.

7. A projectile as claimed in any one of claims 3 to 6, wherein said second shock sensing device comprises a resilient member.

8. A projectile as claimed in claim 7, wherein said resilient member is elongate and mounted at one end, said member moving transversely to its length under a shock to make or break an electrical contact.

9. A projectile as claimed in claim 8, wherein said member is a coil spring which is mounted at one end.

10. A projectile as claimed in any one of claims 1 to 9, comprising a casing, said casing housing the speed measuring device.

11. A projectile as claimed in claim 10, in the form of a ball.

12. A projectile as claimed in any one of claims I to 10, comprising means for storing said calculated speed for a minimum time.

13. A projectile incorporating a device for measuring the speed of the projectile when projected through a predetermined distance, substantially as hereinbefore described with reference to the accompanying drawings.

14. A speed measuring device for a projectile as defined in any one of claims 1 to 13.