CN1845772A - Method and apparatus to locate lost golf balls - Google Patents

Abstract

A method is disclosed that assists a golf player in finding golf balls that have been lost. The method relies on the presence of materials in the golf ball that emit light at a second wavelength with illuminated by light at a first wavelength. Implementations of such a ball-finding device are disclosed that use blue or near-UV illumination light to create emission at somewhat longer wavelengths. Unlike prior art that uses UV illumination the disclosed devices do not require proximity to the ball to enhance visual detection of the same.

Description

Method and apparatus for determining the location of a lost golf ball

technical field

This invention relates to determining the location of lost objects, and in particular to the location of lost golf balls.

Background technique

During golf tournaments, it is a common occurrence for players, especially beginners, to lose golf balls. This firstly pays the cost of replenishing a large number of lost balls, and secondly, if the ball cannot be found, then it is annoying for a competitor to lose a shot that could result in losing a game.

Several methods and devices have been planned to overcome the problems described above by making golf balls easy to spot. Usually these methods involve some kind of marking of the golf ball with an easily detectable tag. For example US 6482108 McLaughlin teaches the use of holograms applied to golf balls and US 6353386 Castonguay teaches the use of scented compounds. A disadvantage of these systems is that the competitor must either modify the ball by inserting a tag, or must use a specially developed ball.

Another approach employs the practice of coating many golf balls with brighteners that absorb near-UV light and then fluoresce at longer wavelengths, usually in the blue portion of the spectrum. Thus by shining UV light on the golf balls, they will fluoresce and will be easier to spot. Several devices for generating relevant UV light are commercially available. However, these devices are generally intended for nighttime use in order to distinguish the fluorescent emission from ambient background light caused by daytime. Furthermore, since the light must shine directly on the golf ball, it is necessary to operate the device in close proximity to the ball in order to achieve some effect to be seen.

Contents of the invention

It is an object of the present invention to provide an improved method and apparatus for locating lost objects.

According to the present invention there is provided an apparatus for finding an object comprising:

Light sources suitable for emitting beams of light at wavelengths absorbed by objects or coverings on them;

· detectors suitable for detecting light in the wavelength range in which objects or coverings on them fluoresce; and

• A processor adapted to determine the presence of an object based on the light detected by the detector.

It is preferred that the device further comprises an oscillator for modulating the light source. Usually an oscillator will modulate the light source via a driver circuit.

It is preferred that the processor comprises a mixer which receives the modulated signal from the oscillator and receives the signal from the detector. Typically the processor further includes a low pass filter adapted to pass signals of significant magnitude so long as a time averaged coherent signal is produced.

Advantageously the processor will further comprise a threshold detector which compares the signal from the low pass filter to a predetermined threshold and sends a signal to the pointer which exceeds the threshold significantly in order to indicate the presence of a ball.

Typically this modulation will be in the frequency range of 10 Hz to 100 Hz.

Description of drawings

In order to facilitate the understanding of the present invention, its specific implementation will now be described by way of example and with reference to the accompanying drawings, in which:

1 is a plan view of an apparatus for finding a lost golf ball according to the present invention; and

FIG. 2 is a block diagram of the electronic components in FIG. 1 .

Detailed ways

Referring to FIG. 1 , the device shown in FIG. 1 comprises an oscillator 101 adapted to generate a signal 102 for modulating a light source 103 . The light source as shown is a light emitting diode (LED), although other light sources could be used. The modulation can be sinusoidal or another type like a square wave, and can be an amplitude modulation or a phase modulation. A light source 103 produces a light beam 106 that emits in the blue or ultraviolet (UV) portion of the spectrum. Basically steer the beam to a wide angle in front of the light source. Lenses or other optical systems 104 may be used to steer and expand the beam to produce a desired emission pattern, depending on the light source.

As the covering is applied to the golf ball, the ball absorbs light in the UV and blue range and re-emits (fluoresces) at longer wavelengths. The exact wavelength of fluorescence depends on the specific covering applied to the sphere, but a wavelength shift of tens of nanometers is generally found.

Other materials like grass where the golf ball's position can be determined also fluoresce, but at such a low efficiency that when the fluorescence is detected it is likely emanating from the golf ball.

The device also contains a detector 109 . The detector 109 is equipped with a lens 108 which enables light emerging from a wide angle to be collected by the detector. In addition, in order to filter out light of wavelengths other than the fluorescent wavelengths previously considered according to the golf ball, and to allow as much of the above-mentioned light as possible to be received by the detector 109, an optical filter 110 is installed in an appropriate position in front of the detector. Location. In addition, light shields 111 , 112 are provided around the light source 103 and/or the detector 109 since the fluorescence will be several orders of magnitude weaker than the light emitted from the light source 103 .

Detector 109 sends photocurrent 114 to processor 116 for determination when a golf ball is present. To facilitate signal processing, a copy of the oscillator signal 113 may also be input to the processor. If a ball is detected, a signal 115 is sent to an indicator 117 to alert the user to the presence of a ball.

The detector is only sensitive to and receives a small portion of the light propagating in the direction of the detector. When the detector is not specifically designed to filter out unwanted light, sunlight can easily overwhelm the detector, rendering the device nearly worthless. For this reason, the above-mentioned detectors are generally used at night and are only effective in very low ambient light intensities. However, even with filter 110 sunlight may still be strong enough to swamp weak fluorescent signals at the relevant wavelengths.

In accordance with the present invention, the weak fluorescent signal from the golf ball is detected from the intense ambient light using simultaneous detection. The light source and the detection circuit are modulated. The signal is thus coherently integrated over the modulation period T. However, ambient light does not have a specific phase relationship to the modulation. Thus the contribution of light or noise like this to signal detection does not increase linearly with time, but increases with the square root of the period T. For example, for sufficiently long integration times, the true signal will eventually grow faster than the noise will contribute to provide unambiguous detection.

Typically the device will be used in slow scan mode. Therefore it is reasonable to assume that a signal integration time of the order of T=0.1S is more appropriate. This is equivalent to only allowing noise within a bandwidth B of approximately B=1/T=10 Hz.

Referring now to Figure 2, Figure 2 illustrates the execution of synchronization detection. The oscillator 201 applies modulation 202 to the driving circuit 203 so that the driving circuit 203 provides a driving signal to the LED 204, and at the same time sends the modulation signal 205 to the mixer 206. The frequency of the modulating signal has no precise meaning and can be kept in the range of 10Hz~100MHz. The output light 207 is converted by a golf ball or the like to fluorescent light 208 which is received by a detector 209 which sends (210) to amplifier 211 and from there sends (212) to another input of mixer 206 port. The output 213 of the mixer 206 is sent to a low pass filter (LPF) 214 . The filter is designed to cut off frequencies above a predetermined bandwidth B, thus passing only signals of significant magnitude as long as a coherent signal averaged over time T=1/B is produced. The output 215 of the LPF is passed to a threshold detector 216 which compares the LPF signal to a predetermined threshold. If the signal exceeds a predetermined threshold, a signal 217 is sent to an indicator 218 to indicate the presence of a ball.

It is not intended that the invention be limited to the details of the embodiments described above. For example, embodiments with multiple light sources, ie multiple light sources arranged in a hexagonal pattern, may be used to increase the optical power applied to the golf ball. Furthermore, the light source can be modulated at a high frequency like 10-100 MHz so that detection of the received signal phase relative to the applied modulation phase can also be used to determine the distance to the golf ball. Finally for some options, the device can be constructed using plastic lenses, including plastic Fresnel lenses.

Claims (8)

1. A device for detecting objects, the device comprising: Light sources suitable for emitting beams of light at wavelengths absorbed by objects or coverings on them; · detectors suitable for detecting light in the wavelength range in which the object or covering on it fluoresces; and • A processor adapted to determine the presence of an object based on the light detected by the detector. 2. The apparatus of claim 1, further comprising an oscillator to modulate the light source. 3. The apparatus of claim 2, further comprising a driver circuit. 4. Apparatus as claimed in claim 2 or 3, wherein the processor comprises a mixer which receives the modulated signal from the oscillator and which receives the signal from the detector. 5. The apparatus of claim 4, wherein the processor further includes a low pass filter adapted to pass signals of significant magnitude whenever a coherent signal averaged over time is present. 6. The apparatus of claim 5, wherein the processor further comprises a threshold detector that compares the signal from the low pass filter with a predetermined threshold and sends a signal to the indicator that the threshold is exceeded, indicating the presence of a ball . 7. Apparatus as claimed in claim 2 or any one of claims 3 to 6 when dependent on claim 2, wherein the modulation is in the frequency range 10 Hz to 100 MHz. 8. A method for determining the location of a lost object comprising a covering that absorbs light at a first wavelength and fluoresces at a second wavelength; the method consisting essentially of the following steps: providing beads containing wavelengths absorbed by the covering on the object; detecting light in the wavelength range in which the object to be located fluoresces; and • Determining the presence or absence of an object based on the detected light.

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