Geometrical instruments – Straight-line light ray type – Rod or target
Reexamination Certificate
2003-04-29
2004-07-13
Bennett, G. Bradley (Department: 2859)
Geometrical instruments
Straight-line light ray type
Rod or target
C033S228000, C033S526000
Reexamination Certificate
active
06760974
ABSTRACT:
The present invention relates to a height-indicating instrument and method enabling the production of poured cementitious floors upon uneven sub flooring, the poured flooring having a flat, level top surface and a thickness not less than a predetermined minimum thickness.
BACKGROUND OF THE INVENTION
Old apartment buildings, houses and other structures commonly have floors that are uneven, due to a variety of causes. When such buildings are renovated, it is desirable to pour new cementitious flooring over old, uneven sub floors to provide level, horizontal, flat flooring having at least a minimum thickness. Although pourable cementitious slurries generally are self-leveling to some extent, high spots and low spots nonetheless can result if care is not taken to distribute the slurry in such a manner that its top surface is flat and level.
Moreover, it is generally desired to maintain a minimum cementitious flooring thickness, and this may be difficult to accomplish when pouring a slurry upon a floor that is quite uneven and that has high spots and low spots, inasmuch as the poured flooring may be too thin at the high spots of the sub floor. If one can measure the elevation of a sub floor in different spots, and place markers on the floor designating heights all lying in a level, horizontal plane, then the slurry can be worked so that its upper surface coincides with the heights designated by the markers. This, however, requires substantial time-consuming work in determining the exact elevation of different flooring areas so that accurate height markers can be placed.
It would be desirable to provide an instrument and method for enabling a cementitious slurry to be quickly and easily poured on a floor to a predetermined elevation with the slurry at the highest point of the sub floor being at a minimum predetermined thickness.
SUMMARY OF THE INVENTION
In one embodiment, the invention relates to a height indicating instrument that comprises a first rod assembly that has a foot engagable with the surface of a sub floor and a second rod assembly that is operatively attached to and moveable axially with respect to the first assembly. The second rod assembly includes a height indicator to indicate the desired underlayment height above a sub floor, and carries a laser beam detector. A laser beam generator is provided to generate a horizontal laser beam detectable by the laser beam detector. Vertical movement of the second rod assembly with respect to the first rod assembly to horizontally align the laser detector with the laser generator simultaneously moves the height indicator to adjust the elevation of the latter with respect to the sub floor.
In a preferred embodiment, the height indicating instrument as thus described employs inner and outer tubes in respective sliding, telescoping engagement, and a lock is provided for releasably locking the inner and outer tubes against relative axial movement. The instrument desirably is devoid of structure, other than the foot, that extends downwardly beyond the height indicator, that is, below the elevation of the height indicator.
The invention, in another embodiment, provides a method for pouring a cementitious slurry to a desired elevation in a given sub floor area, e.g., a room, while ensuring that the slurry at the perceived or approximate point of highest elevation of the sub floor will be not have less than a predetermined thickness. The method comprises providing a first rod assembly having a lower foot that is engageable with the surface of the sub floor, and a second rod assembly operatively attached to and moveable axially with respect to the first rod assembly. The second rod assembly has a height indicator to indicate the desired underlayment height, and carries a laser beam detector. The foot of the first rod assembly is placed upon the sub floor at a first location which is a point of high elevation, desirably the point of highest elevation, of the sub floor, and the height indicator is adjusted to a given elevation which will be the elevation of the entire poured floor, the height indicator being spaced a predetermined distance above the sub floor, this distance being not less than the desired minimum thickness of the cementitious floor underlayment. While maintaining that predetermined distance, the laser beam detector is adjusted to detect a horizontal laser beam emitted from a laser beam generator. As the cementitious slurry is poured, the foot of the device is moved from one position to another over the sub floor area. At each position, while maintaining constant the separation between the height indicator and the laser beam detector, the detector is adjusted to detect the horizontal laser beam, thereby adjusting the height indicator upwardly or downwardly to the given elevation. Once the slurry at that point has reached the predetermined elevation, the device is moved to another point on the sub floor, and the process is repeated as many times as needed to provide a level floor.
If desired, a height marker may be applied to the sub floor at the first location to indicate the height of the height indicator at that location, and another marker is applied to the sub floor at other locations to indicate the height of the height indicator at that location. By repeating the process several times, a series of markers is applied to the floor at locations spaced from one another, with the height indicated by the markers defining a horizontal, flat plane to which the upper surface of a cementitious slurry should reach, the resulting flooring having a minimum thickness at the first location.
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Bennett G. Bradley
Fredrikson & Byron , P.A.
Maxxon Corporation
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