Geometrical instruments – Straight-line light ray type – Rod or target
Reexamination Certificate
2002-02-08
2003-12-16
Fulton, Christopher W. (Department: 2859)
Geometrical instruments
Straight-line light ray type
Rod or target
C033S296000
Reexamination Certificate
active
06662458
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to grade measurement devices, also referred to as leveling or surveying rods, and their uses, and more particularly to direct read-type leveling rods, such as are used in conjunction with laser beam or optical-sight type leveling instruments in construction applications, including excavation, setting and checking grades, measuring, and the like.
BACKGROUND OF THE INVENTION
Construction projects, including for instance road construction, home building, general excavating, etc., often require leveling tasks to be carried out by unskilled workers. Such tasks include, but are not limited to, checking pavement and concrete grades, setting concrete forms, erecting building components at varying elevations, etc.
In conventional construction projects, it has previously been known to employ leveling instruments, such as optical sights or laser-beam leveling instruments, to take elevation measurements of existing elevations, and to establish measurements for desired elevations, at various locations on the construction site. According to this methodology, the leveling apparatus is initially set up and adjusted to a level position, and the elevation of the sighting portion of the leveling apparatus is determined relative to some assumed base, sea level for instance. A leveling rod is provided, usually having a graduated measuring scale. A reading made from the thus-adjusted leveling instrument to the vertically oriented leveling rod as a lower end thereof rests on the ground at a desired location will yield a measure of the vertical distance from the elevation of the leveling instrument to the base of the leveling rod. Subtracting from this distance the height of the leveling instrument above the assumed base (e.g., sea level) yields a measure of the elevation of the ground, relative to the assumed base, at the lower end of the leveling rod. The disclosure of Martin, U.S. Pat. No. 1,220,358, is exemplary in these regards, and is incorporated herein by reference in its entirety.
Oftentimes, survey stakes or like markers are employed in construction projects to provide benchmark elevations following elevation measurements conducted in the manner discussed above. The survey stakes are provided at selected locations on the construction site where ground elevations have been previously determined. Taking the predetermined, desired elevation for that location, and a measurement of the height of the survey stake relative to the existing ground elevation, a measurement is provided on the stake that reflects the requisite change in the existing ground elevation to achieve the desired elevation.
While initial elevation surveys are commonly carried out by skilled professionals, subsequent leveling tasks (e.g., altering existing elevations to correspond to desired elevations, making subsequent elevation measurements, etc.), are carried out by relatively unskilled laborers, also using leveling rods and leveling instruments.
According to the use of conventional leveling instruments in establishing desired elevations at one or more locations for example, it is necessary for a worker to place a lower end of the leveling rod on a previously-identified benchmark, such as the aforementioned survey stake, having identified in relation thereto a known measurement for establishing the desired elevation at each location. The worker is first required to calibrate the leveling rod to the benchmark by placing the lower end of the leveling rod on the benchmark elevation and thereafter aligning the leveling instrument with a “zero” or other established starting point on the graduated measuring scale. The leveling rod is thereafter adjusted so that the known measurement reflecting the adjustment necessary to establish the desired elevation is identified on the graduated measuring scale, and necessary modifications to the elevation at the location until the measurement reflecting the desired elevation on the leveling instrument is aligned with the leveling instrument.
In the past, optical-sight type leveling instruments were employed to take visual sightings of leveling rods in conjunction with efforts to determine desired elevations such as in the manner described above. In modern construction projects, however, laser-beam leveling instruments are more frequently employed instead of optical sights. One such apparatus is described in U.S. Pat. No. 4,221,483, issued to Spectra-Physics, Inc., the disclosure of which is incorporated herein in its entirety. These laser-beam leveling instruments transmit a (usually) horizontal laser-beam across the construction site, which laser beam is detected by a laser-beam detector provided on the leveling rod carried by a construction worker. The detector is typically mounted to a bracket that is slidingly positionable along the length of the leveling rod, and is further operative to provide audible and/or visual signals indicating when the detector is positioned along the leveling rod at a height corresponding to elevation of the laser-beam. By selectively positioning the detector on the leveling rod at given measurements for establishing desired elevations, it is possible for a construction worker to use the leveling rod, for example, to determine elevations at various locations on the construction site.
One particularly common use of a leveling rod with leveling apparatus is in excavating operations, where existing terrain on a construction site is modified, either by cutting or filling as necessary, to achieve desired elevations. As indicated, the construction site is typically initially surveyed by skilled personnel who establish desired grade elevations for various locations throughout the site, and who identify these desired elevations on survey stakes or the like as measures of the amount of cut or fill necessary relative to the elevation of the stake, or as measures of the amount of cut or fill relative to some other benchmark elevation. “Cutting” or “cut” refers to the process of removing material from the existing terrain, for instance by machine or manually, until an elevation is reached that is lower than the existing elevations of the terrain; “filling” or “fill,” in contrast, refers to the addition of material to the existing terrain until an elevation is reached that is higher than the existing elevation of the terrain. According to the method described above, the construction worker calibrates the measuring scale of the leveling rod to “zero” or some other starting position relative to the benchmark elevation, determines the amount of cut or fill necessary at a given location, for instance as directed by a stake measurement, identifies a position along the measuring scale of the leveling rod corresponding to the amount of cut or fill (either by positioning a visual sighting indicator, when using optical-sight type leveling instruments, or, when laser-beam leveling instruments are employed, by adjusting the position of the laser beam detector), and adjusts the elevation of the terrain as necessary until the position on the leveling rod corresponding to the amount of cut or fill (and hence the desired elevation) is aligned with the leveling instrument.
For relatively unskilled laborers, conventional methods for employing leveling rods and leveling instruments such as described above are unduly complicated, since the determination of one or more desired elevations relative to a previously sighted measurement commonly requires mathematical computation. In the exemplary circumstance of grading the front porch and steps of a residential construction, the task of checking elevations for each step relative to a sighted elevation measurement made for the top of the porch would necessitate adding to that measurement the predetermined height of each step relative to the top of the porch. If any of these calculations is made in error, subsequent measurements made of the step elevations will be incorrect. And in excavating operations, a construction worker may improperly add or subtract one or more cut or fill measurements in
Fulton Christopher W.
Young & Basile P.C.
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