Geometrical instruments – Straight-line light ray type – Alignment device
Reexamination Certificate
2003-03-10
2004-09-28
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Straight-line light ray type
Alignment device
C473S490000
Reexamination Certificate
active
06796041
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the use of visible reference lines during sporting or entertainment events and, more particularly, to systems employing at least one laser light beam source to generate such visible reference lines.
2. Discussion of the Background Art
To accommodate a sporting event, a series of reference and/or boundary lines may be defined upon a grass-covered surface using, for example, paint, powders, dyes and the like. Such methods of marking are entirely satisfactory so long as the reference lines themselves are static during the entire event. Where the position of a boundary or other line of demarcation changes dynamically during the event, however, markings of the permanent type cannot be used.
In the game of football, for example, a key objective of the team in possession of the ball (i.e., the “offense”) is to retain possession of that ball by moving it far enough down the field. Specifically, the offense is given a set of four plays or “downs” to advance the ball by at least ten yards. Each time that distance is reached or exceeded, the offense is said to have crossed a “first down” line, a new set of downs is earned, and the offense is allowed to continue its advance toward the goal line of the opposing team (i.e., the “defense”). If the offense falls short, however, possession is lost and the two teams reverse their roles. A regulation football field has a length of 100 yards and 53 yards. Thus, by way of example, a team gaining possession of the ball at its own 20 yard line must move the ball a total of eighty yards in order to reach the end zone of the opposing team.
In numerous occasions throughout an average football game, the officials of the game must resort to sideline markers to establish whether the offense has advanced the ball by the required distance. The standard alignment system that is utilized is generally a pair of poles connected by a 30-foot long chain. The relative position of the football is measured by locating a first of these poles at the approximate location of the initial line of scrimmage and moving the second as far forward as possible. Each time this measurement is made, the game must be delayed and the yard markers must be carried from the sidelines to the place on the field where the official has “spotted” the ball. Although the game of football has become a relatively complex sport, involving literally hundreds of millions of invested dollars, this time consuming system has remained relatively the same since the conception of the sport.
A number of approaches intended to ameliorate the aforementioned deficiencies have been proposed over the years, but none of them has met with any degree of commercial success. U.S. Pat. No. 3,741,662, entitled “VISIBLE LINE MARKER” and issued to Pioch on Jun. 26, 1973, U.S. Pat. No. 3,752,588, entitled “LASER FOOTBALL FIRST DOWN MEASURING DEVICE” and issued to Chapman on Aug. 14, 1973, and U.S. Pat. No. 4,090,708 entitled “APPARATUS FOR MARKING FOOTBALL FIELDS” and issued to McPeak on May 23, 1978. Each of the aforementioned patents involves the use of lasers for the purpose of marking visible lines of demarcation on an athletic field. One of the principal drawbacks of these systems is the time-consuming and tedious method of operation.
Both Chapman and Pioch involve the use of track mounted, sliding projectors that are located at the sidelines and just a few feet above the field level. The lasers are mounted for oscillation in a vertical plane and the projected low intensity beam developed by each must strike the field at points of reference lying on an imaginary line of demarcation defined by the intersection of the vertical plane with the field surface. Accordingly, it is necessary for the operator to manually position the projector for each reference point established. Like Pioch and Chapman, McPeak discloses the use of a laser assemblies adapted to accommodate sliding movement along the sidelines of a football field. McPeak, however, teaches that two oppositely directed beams should be aimed at a level above (i.e., “adjacent and parallel to”) the field surface.
Another drawback associated with the aforementioned systems is that the low-intensity output of these lasers is far too low to be visible by the players, let alone by an audience in, for example, a stadium setting. Indeed, the aforementioned systems are intended for use only in making a first down measurement determination after each close play. As it turns out, players intent on getting the ball past the first yard line—and focused on the sideline markers long enough to be “blindsided” by the defense—have either fumbled the ball or suffered very serious neck and back injuries.
Television networks have recently implemented an image pre-processing system which allows viewers of televised football games to see a so-called “virtual” first down line that digitally projects, in real time, a visible line onto video frames recorded by the television camera, the line being displayed on a viewer's television set so that it appears to extend between the first down sideline markers. Unfortunately, neither the players, game officials, nor the fans attending such games can actually see this virtual line. It is thus reasonable to conclude that given the rapid and widespread adoption of a virtual visible line marking system—whose enjoyment is strictly limited to television viewers, it has heretofore been assumed that it would be impossible or impracticable to project a real, visible line onto surfaces like those of athletic fields. Although there are many possible explanations for this conclusion, it is believed by the inventors herein that the poor light scattering properties of grassy surfaces is at least partially to blame. Blades of grass are randomly oriented and tend to scatter incident light in several directions. The inventors herein have discovered that from distances in excess of one hundred feet or so, a single beam of even relatively high intensity (e.g., 40 joules/second) will be reflected in such a way that it cannot be seen from most camera or fan viewing angles within a stadium.
A continuing need therefore exists for a visible line marking system that is simple to operate, accurate enough to allow its use by officials at sporting events, and of sufficient intensity to be viewed by players, large audiences, and television viewers alike.
A need also exists for a system capable of projecting a variety of other images, onto surfaces having non-uniform light scattering properties, which can be seen from different perspectives and from considerable distances even in daylight conditions.
SUMMARY OF THE INVENTION
The aforementioned needs are addressed, and an advance is made in the art, by an apparatus for providing at least one temporary visible reference line on a surface, as for example, an athletic field, within the field of view of at least one video camera. An illustrative system constructed in accordance with the present invention comprises a first laser source disposed at a first elevated, stationary location relative to the surface, the first laser source being operative to emit a first laser beam having a wavelength of between 400 nm and 750 nm and to sweep the first laser beam along a selectable path upon the surface so as to form a temporary line thereon. The system further comprises a second laser source disposed at a second elevated, stationary location relative to the surface and different from the first stationary location, the second laser source being operative to emit a second laser beam having a wavelength of between 400 nm and 750 nm and to sweep the second laser beam across the selected path so as to form, with the first laser beam, a composite temporary visible line as, for example, a line of demarcation during a football game. A controller comprising a synchronization module is operatively associated with the first and second laser sources and is adapted to synchronize the sweep frequency rate—at which the first laser beam and the second laser
Amron Alan
Dinicola Brian K.
Bennett G. Bradley
Dinicola Brian K.
First Down Laser Systems, LLC
LandOfFree
System for operating one or more lasers to project a visible... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System for operating one or more lasers to project a visible..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System for operating one or more lasers to project a visible... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3243625