GB2348489A

GB2348489A - Location of arrows in a target

Info

Publication number: GB2348489A
Application number: GB0012506A
Authority: GB
Inventors: Russell Thrall Butts
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-07-23
Filing date: 1996-07-23
Publication date: 2000-10-04
Anticipated expiration: 2016-07-23
Also published as: GB2317225A9; GB2348489B; GB0012506D0; GB9615485D0; GB2317225A

Abstract

The position of a dart is determined using an optical source and sensor, 50, positioned on one side of a target, 12 (having a first centre, T). On the opposite side of the target a number of corner cube reflectors, 52, disposed on an arc with a second centre, reflect light pulses back to the detector. A fixed half prism may be used as a beam splitter, and a reflector mounted on a motor so as to scan across the target. The light source may be a semi-conductor laser diode producing a repeating rectangular wave. The system may be controlled by a computer, programmed with the rules of the game and linked to a score display. Another form described locates the position, (see Fig. 2A) using a number of optical sources arranged in an arc. A number of photo-detectors, on the opposite side of the target, are turned on and off to scan across the target.

Description

ARROW LOCATION APPARATUS TECHNICAL FIELD The invention relates to an apparatus to precisely locate an arrow embedded in a target, such as a dart in a game of darts.

Dart games are popular in England and are gaining in popularity in the United States. Traditionally, after an arrow or dart has been thrown into the target, a person has to visually inspect the target to determine where the arrow landed. That person has to then calculate the score according to the rules of the game being played. The applications for such devices include use in places of entertainment and in dart leagues and dart tournaments.

OBJECTS AND SUMMARY OF THE INVENTION The prior art includes various complex apparatus. The apparatus shown in United States Patent 4,845,346 Touch Panel Having Parallax Compensation and Intermediate Coordinate Determination uses light sources and light receiving elements in sequentially driven pairs to accomplish a scan operation, and uses an interrupted signal to determine position.

United States Patent 4,187,545 Article Orientation Determining Apparatus employs a column of sequentially pulsed radiation emitters and corresponding detectors and develops binary data indicative of the number of emitters that are unblocked during each scan.

United States Patent 4, 243, 877 Electro-Optical Target For an Electro-Optical Alignment Measuring System describes a reflective target that includes a photoelectric sensor for producing an electric signal indicative of the lateral displacement of the reflective target and a reflective surface (mirror) for returning a portion of the optical reference beam to a photo sensor positioned adjacent the reference beam source to provide information relative to the angular position of the reflective target.

United States Patent 4,346,994 Secondary Alignment Target For An Electro-Optical Alignment Measuring System employs a beam splitter in which the refracted sub-portion furnishes optical information regarding transverse orientation of the target, while the reflected sub-portion is re-reflected by the beam splitter to furnish a return beam containing optical information regarding rotational orientation of the target.

The apparatus shown in United States Patent 4,052,066 Light-Emission Gun Amusement Machine for Home Use comprises of a light source, screen, and mirror as disposed between the screen and light source.

The apparatus shown in United States Patent 4,281,926 Method and Means For Analyzing Sphero-Cylindrical Optical Systems utilizes a beam splitter and mirror for finding the refractive properties of lenses.

The apparatus shown in 5,154,404 Jam Detector For Inserter utilizes horizontal and vertical photo sensors and associated retro-reflective targets to detect jams by sensing an interruption of the horizontal beam and an uninterrupted retro-reflection of the vertical beam.

United States Patent 5,154,002 Probe, Motion Guiding Device, Position Sensing Apparatus, and Position Sensing Method has a differential optical transducer which has two light source elements which emit light beams and two light sensor elements which receive these beams and an electronic circuit that compares the signal from light sensor elements and provides an output signal which indicates the position of the second member relative to the first member.

The apparatus shown in United States Patent 3,877,816 Remote-Angle-of-Rotation Measurement Device Using Light Modulation and Electro-Optical Sensors includes a rotating disc-type linear polarizer in combination with a reference linear polarizer and a target linear polarizer. The photo sensors are arranged to receive modulated light separately from the target and reference polarizer and sinusoidal output signals representative of the modulated light received by the photo sensors are generated.

While such apparatus are suitable for some applications, they are not wholly satisfactory. The noted patented inventions apply to a myriad of diverse inventions, having only a casual relationship to the present apparatus.

It is an object of the invention to provide apparatus to precisely locate an arrow in a target.

It is an object of the invention to display the score of a dart game.

Another object of the invention is to provide apparatus that will function with a standard, unmodified bristle board target and standard unmodified darts.

Still another objectof the invention is to be able to program different game rules into the apparatus and to calculate the score.

It is yet another object of the present invention to provide apparatus that is reliable.

It is an object of the invention to provide apparatus which is inexpensive to manufacture.

It is also an object of the invention to enable the apparatus to be used with targets of various diameters.

It has now been found that these and other objects of the invention may be attained in an apparatus for precisely locating an associated arrow embedded in an associated target having a first center which includes a plurality of light sources positioned in an arc having a second center. The first center may be offset 6.03cm (i. e. 2.375) inches from the second center, which was empirically derived. A plurality of photo sensors are arrayed opposite the light sources with the target intermediate the light sources and photo sensors. The apparatus includes a means for turning on and off each light source sequentially to produce a scan of the target. The apparatus also includes a means for detecting when an arrow embedded in the target interrupts any light beam from any of the light sources to any of the photo sensors and a means for determining the exact location of an arrow embedded in the target, the means for determining utilizing the means for detecting.

In some forms of the invention, a plurality of photo sensors comprises three photo sensors and the means for determining the arrow's location includes a multiplexer and the multiplexer controls the scan of the light sources. The multiplexer may be controlled by a microprocessor which turns the light sources on in sequence so that only one light source's light is projected across the target to the photo sensors. The photo sensors may be located in relation to the target and the light sources so that the photo sensors'cones of operation have azimuth angles of approximately 60 degrees each and the azimuth angles overlap in order to receive the beam of light from any light source. In some forms of the invention, the microprocessor receives the output signals from the photo sensors and performs the required mathematical functions to calculate the location coordinates. The apparatus' microprocessor may be connected to a Read Only Memory (ROM) in which the rules of the game being played can be programmed and the score calculated according to the game rules programmed into the ROM. The microprocessor may display the score on a display. In some forms of the invention, the light sources are light emitting diodes (LEDs). The number of LEDs in the arcuate array may be 512. The LEDs may be rectangular in shape with one side being the actual emitter, emitting light in approximately 120 degrees of azimuth angle. The photo sensors and plurality of LEDs may be covered by an optional light shield. The arcuate array of light sources may have an angular sector of 177.6 degrees and a radius of 29.37cm (i. e.

11.562 inches).

The apparatus may include a multiplexer that controls the scan of the LEDs. In some forms of the invention, the multiplexer is controlled by a microprocessor which turns the LEDs on in sequence so that only one of the LEDs'light is projected across the target's face to the photo sensors. The apparatus may include a microprocessor that receives the output signal from the photo sensors and performs the required mathematical functions to calculate the location coordinates for the arrow, and display the score on the apparatus'display.

It has also been found that these and other objects of the invention may also be attained in another form of the apparatus for precisely locating an arrow embedded in an associated target having a first center. The apparatus includes a plurality of corner cube reflectors arrayed in semi-circle having a second center with the plurality of corner cube reflectors being arrayed generally around a first side of the target. The apparatus includes a light detection and transmitting module which is disposed on a side of the target generally opposite the plurality of corner cube reflectors with the light detection and transmitting module generating pulses of light and receiving the pulses of light after the light has been reflected off one of the plurality of corner cube reflectors. The first and second mirrors of the apparatus are positioned generally opposite to the first side and respectively on each side of the light detection and transmitting module with the mirrors disposed to reflect light beams originating from the light detection and transmitting module to cause light pulses to scan across the entire face of the target. The apparatus includes a means for determining when an arrow embedded in the target interrupts a light pulse emitted from the light detection and transmitting module and a means for determining the exact location of an arrow embedded in the target. In some forms of the invention, the light detection and transmitting module includes a light source, a fixed half prism which functions as a beam splitter, a motor with a reflector mounted on the motor's rotating shaft, a photo sensor, a light shield, and two lenses. The light source of the light detection and transmitting module may be a semi-conductor diode laser with a power rating of approximately three milliwatts. The light source may produce an output waveform in the form of a repetitious rectangular wave. In some forms of the invention, the microprocessor generates a train of rectangular pulses, each rectangular pulses accurately timed and electronically identified, which alternately turn the laser on and off. Simultaneously, the motor's rotating shaft causes the light path to scan across the target. The motor rotation is synchronized with the laser pulse train such that the light pulses which are accurately generated are closely and equally spaced in a radial pattern encompassing the entire target face.

In some forms of the invention, the microprocessor contains digital circuits which process the rectangular waveforms received by the photo sensor, perform the required mathematical functions and produce location coordinates for each arrow. The digital circuits may contain a Read Only Memory (ROM) in which the rules of the game being played can be programmed and the game score calculated according to the programmed game rules. A microprocessor may be connected to a display with the display used to show the score of the game being played. The arcuate array of plurality of corner cube reflectors may have an angular sector of 177.6 degrees and a radius of 29.37cm (i. e. 11.562 inches).

BRIEF DESCRIPTION OF THE DRAWING The invention will be better understood by reference to the accompanying drawing in which: Figures 1A and 1B are respectively top view and side elevational view of the relationship between a single light source, an arrow, and a single photo sensor in a first embodiment.

Figures 2A and 2B are respectively top and side elevational views of the apparatus for determining the precise location of an arrow embedded in a target in the first embodiment.

Figure 3 is a block diagram of the apparatus in the first embodiment.

Figure 4 and 4A are the mathematical definitions and relationships used to precisely locate an arrow embedded in the target together with a diagrammatic view in Figure 4A.

Figure 5 is a diagrammatic view illustrating the geometric relationships.

Figure 6 includes equations used to translate the coordinates of the arrow to the symmetrical center of the target.

Figure 7 is a portion of the computer program listing which shows the mathematical calculations necessary to precisely locate the arrow in the target in the first embodiment.

Figure 8 is a top view showing the relationship of elements of the apparatus that is in accordance with the preferred form of the invention in a second embodiment.

Figure 9 is a partial side view of the elements of the light detection and transmitting module and the relationship of the light detection and transmitting module to an arrow and the plurality of corner cube reflectors in accordance with the second embodiment.

Figure 10 is a block diagram of the elements of the preferred form of the invention in the second embodiment.

Figure 11 is a diagram of the rectangular pulses emitted from the light detection and transmitting module and demonstrate how an arrow interferes with the laser pulses in the second embodiment.

Figure 12 is a portion of the computer program listing which shows the mathematical calculations necessary to precisely locate the arrow in the target in the second embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figures 1-5 there is shown a preferred form of the detection apparatus 10 for precisely locating an associated arrow 26 in an associated target 12. The apparatus 10 includes an arcuate array 14 of light sources, and photo sensors 18,20 and 22. The apparatus is shown in greatest detail in Figures 1-2 and the means for precisely locating an associated arrow 26 in associated target 12 is shown in Figures 3-7.

An associated target 12 having a first center T is partially surrounded by an array 14 of a plurality of light sources 16 disposed in an arc 14 having a second center C. Referring to Figure 5, there is shown an offset F of 6.03cm (i. e. 2. 375 inches) from the first center T of the associated target 12 and the center C of the plurality of light sources 16. This offset is empirically derived. Each light source 16 is a light emitting diode (LED). Accordingly, the reference numeral 16 will be used for either an LED or a light source. Except for the LEDs at the ends of the arcuate array each LED is disposed in side abutting relation to two other LEDs in the arcuate way. The arcuate array 14 of the plurality of light sources has an angular sector of 177.6 degrees and a radius of 29.37cm (i. e.

11.562 inches) in the preferred embodiment. The number of LEDs 16 in the arcuate array 14 number 512. In the preferred embodiment the LEDs 16 are rectangular in shape with one side being the actual emitter, having an emitting azimuth range of approximately 120 degrees.

Photo sensors 18,20,22 are arrayed outside target 12 and located opposite the plurality of light sources 16 so that photo sensors'18,20,22 functional cone of operation's azimuth angles X, Y, and Z are approximately 60 degrees each and overlap to receive the beam of light 28 emitted from any one of the plurality of LEDs 16. This is illustrated in Figure 2.

The output power of each LED 16 is approximately 1.2 milliwatts.

Each LED 16 is normally off, producing no light 28 output until a relatively high voltage pulse is applied to LED 16 producing a brief and intense pulse of light.

The LEDs 16 are powered by multiplexer 34 and controlled by microprocessor 38 and are turned on in sequence such that only one LED 16 emanates a light beam 28 at any given time. The collective beams 28 produce a scan of the associated target 12. The light beam 28 is projected across the face of target 12 to either photo sensors 18,20 or 22. Suitable light shields 24 may be provided to eliminate the effects from ambient light. With no associated arrow 26 present, photo sensor 18,20 or 22 detects the light 28 output from the light source 16 and produces an output voltage. With an arrow 26 embedded in the target and interposed between the LED 16 and photo sensor 18,20, or 22, the light beam 28 is interrupted, producing a change in the photo sensor's 18,20 or 22 output voltage. The output voltage is fed into an amplifier circuit 48 which amplifies and shapes the voltage so as to be suitable for processing by the digital electronics circuitry of microprocessor 38 used for calculating and displaying scores. This is shown in Figures 2-3.

The position of each LED 16 is identified electronically in the microprocessor 38 such that when an identified LED 16 is momentarily turned on and light sensors 18,20 or 22 receive no light pulse due to an interposing arrow 26, that arrow 26 can be precisely located using the mathematical definitions and relationships shown in Figures 4-5. These mathematical relationships provide X and Y rectangular coordinates in terms of identified LEDs 16 to locate each arrow 26. These coordinates are then translated to the symmetrical center T of target 12. This is demonstrated in Figures 5-6. The X and Y coordinates are then translated into polar coordinates which use the reference angles and line vectors according to the equations shown in Figure 6. The polar coordinate system is appropriate and compatible with the pattern of scoring in the face of target 12. An example of this is the scoring of various dart games. The individual LED's 16 identification and photo sensors' 18,20, and 22 output are used by the microprocessor circuits 38 which perform the mathematical functions, calculate the score according to game rules programmed into the Read Only Memory (ROM) 40 and display the score on display 44. Figure 7 is a portion of a computer program listing which shows the mathematical calculations and Figure 3 is a block diagram of the essential elements of this method.

Referring now to Figures 8-11 there is shown another preferred form of the detection apparatus 10 for precisely locating an associated arrow 26 in an associated target 12. The apparatus 10 includes an associated target 12, light detection and transmitting . module 50, two mirrors 54 and 56, and a plurality of corner cube reflectors 52. The light detection and transmitting module 50 is made up of light source 14, photo sensor 18, a fixed half prism 58, lens 6 intermediate light source 14 and fixed half prism 58, lens 8 intermediate photo sensor 18 and fixed half prism 58, light shield 24, reflector 60 mounted on a motor's rotating shaft, and a motor 62. The apparatus is shown in greatest detail in Figures 8-10 and the means for precisely locating an arrow 26 in a target 12 is shown in Figures 6,8,12 and 13.

An associated target 12 having a first center T is partially surrounded by a plurality of corner cube reflectors 52 disposed having a second center C with the plurality of corner cube reflectors 52 being arrayed generally around a first side of target 12.

Referring to Figure 8, there is shown an offset of 6.03cm (i. e. 2.375 inches) from the first center T of associated target 12 and the second center C of the plurality of corner cube reflectors 52 which was empirically derived. The plurality of corner cube reflectors 52 has an angular sector of 177.6 degrees and a radius of 29.37cm (i. e. 11.562 inches). The light detection and transmitting module 50 is disposed on a side of the associated target 12 which is generally opposite the plurality of corner cube reflectors 52. This is illustrated in detail in Figure 8. The mirrors 54 and 56 are 15.88cm (i. e. 6.25 inches) long in the preferred embodiment and are positioned on either side of the light detection and transmitting module 50 in such a manner so that a beam of light 28 originating from the light detection and transmitting module 50 is reflected to the plurality of corner cube reflectors 52, producing a scan of the face of target 12. The light beam 28 is then reflected back along its original path, or a path closely parallel to it, through reflector 60, fixed half prism 58 and lens 8 to sensor 18. The light source 14 is a semi-conductor diode laser with a power rating of approximately 3 milliwatts. Microprocessor 38 generates a train of pulses, each one accurately timed and electronically identified, which alternately turn the laser 14 on and off, producing a series of pulses of light 28.

Simultaneously the motor's 62 rotating shaft causes the light path to scan across the face of target 12. The motor's 62 rotation is synchronized with the laser 14 pulse train such that the light pulses, which are accurately generated, are closely and equally spaced in a radial pattern. This is shown in detail in Figure 9.

The photo sensor's 18 output waveform is in the form of a repetitious rectangular wave. Where light is blocked by an associated arrow 26 embedded in an associated target 12, notches appear in the output waveform. The notches indicate missing pulses from the waveform.

This is shown in Figure 11. The missing pulses and remaining waveform are processed by digital circuits to produce location coordinates for each arrow 28. The output signals are then sent to microprocessor 38 which performs the mathematical functions shown in Figures 6 and 13 and then displays the score on display 44 by using the mathematical definitions and relationships shown in Figures 5,6 and 13. These mathematical relationships provide X and Y rectangular coordinates in terms of identified notches in the rectangular waveform to locate each associated arrow 26. These coordinates are then translated to the symmetrical center T of target 12. This is demonstrated in Figures 5-6. The X and Y coordinates are then translated into polar coordinates which use the reference angles and line vectors according to the equations shown in Figure 6. The polar coordinate system is appropriate and compatible with the pattern of scoring in the face of target 12. An example of this is the scoring of various dart games. Figure 12 is a portion of a computer program listing which shows the mathematical calculations and Figure 10 is a block diagram of the essential elements of this method.

It will be understood that the dimensions provided are to accommodate an associated target 12 having a diameter of 45.72cm (i. e. 18 inches). The same principles described herein can be used for an associated target 12 of any diameter. The apparatus will thus be seen to work with an unmodified bristle board and other targets off the shelf and do not require any special requirements as do other systems.

The invention has been described with reference to its illustrated preferred embodiment. Persons skilled in the art of such devices may upon exposure to teachings herein, conceive other variations. Such variations are deemed to be encompassing by the disclosure, the invention being delimited only by the following claims. For example, the invention has general applicability to determining the location of a projectile embedded in a target.

Claims

CLAIMS 1. An apparatus for precisely locating an associated arrow embedded in an associated unmodified standard board target having a first center which includes: a plurality of corner cube reflectors disposed having a second center, said plurality of corner cube reflectors being arrayed generally around a first side of the target; a light detection and transmitting module, said light detection and transmitting module being disposed on a side of the target which is generally opposite said plurality of corner cube reflectors, said light detection and transmitting module generating pulses of light and receiving the pulses of light after said light has been reflected off one of said plurality of corner cube reflectors; first and second mirrors positioned generally opposite to said first side and respectively on each side of said light detection and transmitting module, said mirrors disposed to reflect light beams originating from said light detection and transmitting module to cause light pulses to scan across the entire face of the target; means for detecting when an arrow embedded in the target interrupts a light pulse emitted from said light detection and transmitting module; and means for determining the exact location of an arrow embedded in the target.
2. The apparatus as described in claim 1 wherein: said light detection and transmitting module includes a light source, a fixed half prism which functions as a beam splitter, a motor with a reflector mounted on said motor's rotating shaft, a photo sensor, and a light shield.
3. The apparatus as described in claim 2 wherein: said light source produces an output waveform in the form of a repetitious rectangular wave.
4. The apparatus as described in claim 3 wherein: said light source of said light detection and transmitting module is a semi-conductor diode laser with a power rating of approximately three milliwatts.
5. The apparatus as described in claim 4 wherein: said microprocessor contains digital circuits which process said rectangular waveforms received by said photo sensor and produce location coordinates for each arrow.
6. The apparatus as described in claim 5 wherein: said digital circuits contain a Read Only Memory (ROM) in which the rules of the game being played can be programmed and the game score calculated.
7. The apparatus as described in claim 6 wherein: said apparatus further includes a display and said microprocessor is connected to said display, said display being used to display the score of the game being played.
8. The apparatus as described in claim 7 wherein: said arcuate array of said plurality of corner cube reflectors has an angular sector of 177.6 degrees.
9. The apparatus as described in claim 8 wherein: said arcuate array of said plurality of corner cube reflectors has a radius of 29. 37cm (i. e. 11.562 inches).
10. Apparatus as claimed in claim 1 for determining the location of a projectile embedded in a target, and substantially as hereinbefore described with reference to the accompanying drawings.