Patent ID: 6202313
Filing Date: 2001-03-20
Classification: G01C,Y10S

Abstract:
A plumb-bob device, comprising:An elongated beam-casting housing having an upper end portion and a lower end portion and an axis extending therethrough;linear light beam generating means provided in the beam-casting housing, for generating a linear light beam cast from the lower end of the beam-casting housing onto a floor surface to indicate a floor reference point thereon and also generating a linear light beam cast from the upper end portion of the beam-casting housing onto a ceiling surface to indicate a ceiling reference point corresponding to the floor reference point;a plurality of legs each having an upper end portion rockably mounted through a gyroscope mechanism on and around the upper end portion of the beam-casting housing and a lower end portion extending from the upper end portion, the legs each having an inner surface substantially complementary to an outer periphery of the beam-casting housing, and each being rockable between a contracted position, at which the inner surface is in the vicinity of the outer periphery of the beam-casting housing, and a expanded position, at which the lower end portion is spaced apart from the outer periphery, the legs being capable, in the expanded positions thereof, of vertically supporting the beam-casting housing through the gyroscope mechanism; anda retaining member capable of being removably mounted on the lower end portions of the legs in the contracted positions thereof to retain the legs in the contracted position, wherein the outer periphery of the beam-casting housing is closed by the legs when the legs are in the contracted positions, and wherein the retaining member has a blind-nut shape having a bottom and has a string having one end attached to the bottom, whereby an inverted plumb-bob device function is provided by suspending the beam-casting housing, serving as a weight, with the string with the retaining member mounted on the lower end portions of the legs.