Games using tangible projectile – Golf – Moving projectile responsive sensor or indicator
Reexamination Certificate
1999-05-19
2001-06-12
Cheng, Joe H. (Department: 3713)
Games using tangible projectile
Golf
Moving projectile responsive sensor or indicator
C473S353000, C473S378000
Reexamination Certificate
active
06244971
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to determining of the spin characteristics of a rotating object. More particularly, the present invention relates to the determination of the rate of spin and the axis of rotation of a rotating object, such as, for example, a golf ball that has been struck with a golf club.
BACKGROUND OF THE INVENTION
In many applications it is desirable to determine the spin characteristics of a rotating object, including the object's total rate of spin (spin rate) and the axis about which the object is rotating (spin axis). For example, the spin characteristics of a golf ball in conjunction with other parameters such as ball velocity and launch angle may be used to accurately predict the trajectory followed by the golf ball after it as been struck with a golf club. Such information is useful in golf simulator applications as well as golf equipment research and development applications. The determination of spin characteristics is also useful in assessing the effects of changes in a golfer's technique or equipment on the spin characteristics of a struck golf ball as part of a training system or an equipment selection system.
Devices and methods that attempt to characterize the spin of a rotating object, such as a golf ball, are known. With some devices and methods, spin information is inferred from observations of the rebound path followed by the ball after striking a mechanical network or grid having known characteristics. In other devices and methods, permanent magnets are embedded in the ball resulting in rotating magnetic fields as the ball spins. The rotating magnetic fields may be detected by coils placed in close proximity to where the ball is struck. Other devices and methods utilize high-speed photographic or videographic techniques. Sequential images of a ball having markings on its surface are obtained. By analyzing the relative position of the markings in the sequential images either manually or with computer processing means, the spin characteristics of the ball over the time interval of the images may be obtained.
The approaches to determining the spin characteristics outlined above can present several disadvantages, particularly when utilized in golf simulation, training, equipment selection, or general research and development applications. Mechanical grids can be relatively bulky and may provide inconsistent results when different types of balls and/or ball cover compositions are used. Also, mechanical grids interrupt the flight path of the ball preventing a user from observing the actual flight path of the ball. Magnetic systems require specially manufactured balls with magnets embedded therein. The magnets can change the moment of inertia of the ball thereby reducing the suitability of such devices and methods in research and development or equipment selection applications. High-speed photographic and videographic techniques systems are typically complex and expensive. Furthermore, such systems require a high resolution image and therefore highly magnified view of the ball resulting in a spin determination over only a very limited portion of the flight path of the ball. Additionally the performance of such systems may be compromised in outdoor situations where bright sunlight can interfere with image quality.
The devices and methods outlined above also share the common disadvantage that the spin characteristics of the ball are typically measured or sampled over only a relatively short interval of time immediately after the ball is struck. However, due to drag forces, the spin rate of the ball decays over its flight path. Particularly in research and development applications where it may be desirable to characterize the aerodynamic properties of a particular ball design, the capability of monitoring the spin characteristics over a longer portion of the ball's flight path may be advantageous.
SUMMARY OF THE INVENTION
In view of the forgoing, one objective of the present invention is to provide for the efficient and accurate determination of the spin rate of a rotating object, such as a golf ball.
Another objective of the present invention is to provide for the efficient and accurate determination of the spin axis of a rotating object, such as a golf ball.
An additional objective of the present invention is to provide for the determination of the spin characteristics of a moving, rotating object such as a golf ball without interrupting its flight path.
A further objective of the present invention is to provide for the determination of the spin characteristics of a moving, rotating object such as a golf ball over selected portions of its flight path.
Yet another object of the present invention is to provide for the determination of the spin characteristics of a moving, rotating object such as a golf ball without substantially effecting the object's moment of inertia.
These and other objectives and advantages are achieved by various aspects of the present invention. According to one aspect of the present invention, an apparatus for use in determining spin characteristics of a rotating object includes a transmitter, a receiver, and a demodulator. The transmitter is positioned for transmitting electromagnetic radiation of at least a first frequency at the object. The object is appropriately configured for reflecting at least a portion of the radiation transmitted thereat such that the amplitude, frequency or phase of radiation reflected by the object is modulated in a manner corresponding to at least one spin characteristic of the object. In this regard, the object may, for example, be a golf ball including at least one contrast area having different reflectivity to the transmitted radiation than the rest of the ball so that as the ball spins, the reflected radiation is amplitude modulated. The receiver is positioned for receiving at least a portion of the modulated reflected radiation. The transmitter and receiver may comprise a single transceiver unit. The demodulator is coupled to the receiver for detecting the modulated nature of the reflected radiation received by the receiver and outputting a demodulated signal including information about at least one spin characteristic of the object.
According to another aspect of the present invention, an apparatus for use in determining spin characteristics of a golf ball moving over an expected flight path includes a transceiver, a pre-amplifier/filter, a demodulator and a comparator. The transceiver is positioned for transmitting electromagnetic radiation of at least a first frequency into the expected flight path of the ball. The ball is appropriately configured for reflecting at least a portion of the transmitted radiation in a modulated fashion corresponding to at least one spin characteristic of the ball. A portion of the reflected radiation is receivable by the transceiver and mixed therein with a signal at the same frequency as the transmitted radiation to generate a difference signal. The difference signal is correspondingly modulated with the reflected radiation. The pre-amplifier/filter amplifies and filters the difference signal. The demodulator detects the modulation characteristics of the amplified and filtered difference signal and outputs a demodulated analog signal corresponding to the modulated difference signal. The demodulated analog signal includes information about at least one spin characteristic of the object. The comparator converts the demodulated analog signal to a digital signal that includes information about at least one spin characteristic of the object.
According to a further aspect of the present invention, a ball adapted for determination of its spin characteristics includes at least one contrast area. The contrast area is comprised of a material having different reflectivity than the rest of the ball to electromagnetic radiation of a predetermined frequency. In this regard, the predetermined frequency to which the contrast area has different reflectivity is preferably in the Radar frequency or the near infra-red frequency ranges.
Cheng Joe H.
Kasick Julie
Marsh & Fischmann & Breyfogle LLP
The DistanceCaddy Company, LLC
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