Geometrical instruments – Straight-line light ray type – Alignment device
Reexamination Certificate
1998-12-21
2001-03-20
Gibson, Randy W. (Department: 2859)
Geometrical instruments
Straight-line light ray type
Alignment device
C033S392000, C033S666000, C033SDIG002, C362S410000, C362S413000, C362S414000
Reexamination Certificate
active
06202313
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plumb-bob device used on construction cites for a level pointing operation, i.e., indicating the positional relation between a floor surface and a ceiling surface.
2. Description of the Prior Art
A well-known plumb-bob device of the pertaining type indicates a leveling reference point by emitting a light beam, such as a laser beam. This plumb-bob device comprises a beam-emitting housing, which emits a linear light beam indicating a floor reference point from its lower end and also emits a linear light beam indicating a ceiling reference point from its upper end toward a ceiling surface, and a plurality of legs mounted by a gyroscope mechanism on and around the beam-emitting housing. The beam-emitting housing accommodates as light sources a high light intensity LED and a visible semiconductor laser, for instance. In the level pointing operation, a linear light beam is cast from the lower end of the beam-emitting housing closet onto a floor surface, thus indicating a floor reference point. Also, a liner laser beam is cast from the upper end of the beam-emitting housing onto a ceiling surface, thus indicating a ceiling reference point.
In the above prior art plumb-bob device, however, the legs are made from pipes or bars, and greatly project from the beam-emitting housing when they are held in an expanded state. Besides, the beam-emitting housing has a considerably large size. Therefore, even a plumb-bob device of reduced size is insufficient for being freely carried on the construction site.
Furthermore, the construction site is usually occupied by various machines and apparatuses, and therefore it may be difficult to secure sufficient space for storing the plumb-bob device. Accordingly, a plumb-bob device which is smaller in size and can be quickly and conveniently handled in use has been demanded.
SUMMARY OF THE INVENTION
It is thus an object of the present invention to provide a small-in-size and conveniently portable plumb-bob device, which permits a vertical level pointing operation on a construction site to be done more efficiently, and also can be made compact when it is not used for the vertical level pointing operation.
To attain the above object, according to the present invention a pencil-type plumb-bob device is provided, which comprises a beam-casting housing for casting, from the lower end, a linear light beam indicating a floor reference point on a floor surface and also casting, from the upper end, a linear light beam indicating a ceiling reference point on a ceiling surface corresponding to the floor surface, and a plurality of legs mounted for expanding and contracting by a gyroscopic mechanism on and around the upper end of the beam casting housing such as to be able to support the beam-casting housing vertically for the vertical level pointing operation and also extend in the longitudinal direction of the beam-casting housing, the legs each having a curved or concave inner surface substantially complementary to the outer periphery of the beam-casting housing, so that the legs can wrap the beam-casting housing so as to close the housing when they are contracted.
According to the present invention, the pencil-type plumb-bob device further comprises a retaining member mounted on the lower ends of the legs in the contracted state thereof to retain the legs in this state.
The plumb-bob device having the above construction according to the present invention, thus permits a vertical level pointing operation to indicate the positional relation between a floor surface and a ceiling surface to be done by expanding the legs after removing the retaining member and setting the legs on the floor surface. Since the legs each have the concave inner surface substantially complementary to the outer periphery of the beam-casting housing, when not doing the vertical pointing operation they can be brought, by contacting them, into close contact with the outer periphery of the beam casting housing such that they wrap the same, thus providing a pencil-like elongate overall shape. By mounting the retaining member on the lower ends of the legs in this state, the legs can be held in the contracted state, and the device thus can be freely carried.
According to the present invention, the retaining member has a blind-nut-like shape, and has a string attached to it. The beam-casting housing thus can be suspended in the inverted state by the string of the retaining member mounted on the ends of the contracted legs, and in this state a linear light beam can be cast on the floor surface or the like to effect a suspended plumb-bob device function.
According to the present invention, the pencil-type plumb-bob device further comprises a cap, which can open and close the upper end of the beam-casting housing and protect an upper end beam-casting part thereof, and a device retainer provided on the outer periphery of one of the legs.
With this structure, when not doing the vertical level pointing operation, the beam-casting part can be protected by closing the cap. In addition, with the device retainer provided on one of the legs, the device can be accommodated and held in a chest pocket or the like, and can be freely carried. Furthermore, by opening the cap the device can be used as a pointer as well.
According to the present invention, the pencil-type plumb-bob device further comprises a switch, which is provided on the outer periphery of the beam-casting housing for controlling the emission of the liner light be cast from the upper end of the beam-casting housing onto a ceiling reference point, and a window provided in one of the legs at a position thereof correspond to the position of the switch.
With this structure, the switch can be operated from the outside through the window for operation even in the contracted state of the legs.
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Gibson Randy W.
Jones Tullar & Cooper P.C.
Masato Co., Ltd.
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