Abstract:
An apparatus and method for generating two or more visible lines of light on a floor for the purpose of facilitating the layout process used in construction. The apparatus comprises a light beam generator producing two or more beams of light at 90° to each other and in a plane parallel to the plane of the floor. Subsequently cylinder lenses on the apparatus spread the beams and position them on the floor or target providing visible reference lines.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to hand tools, and in particular the invention is concerned with a hand tool for projecting two or more reference beams of visible light for precise alignment on floors. 
     For some time laser beams have been used in construction for level reference, vertical references and layout on floors. The subject invention pertains to the last application, floor layout. It allows the user to project visible lines on the floor at precise angles for the purpose of marking the floor or to direct positions of objects or installations on the floor. Typically a construction worker marks the floor indicating the location of walls or other building elements to be constructed. In a like manner a tile layer marks the floor with reference lines. This is often done using a tape measure and a 3-4-5 triangle as shown in FIG. 1 of the drawings. This method is inaccurate and often requires two men. In an alternate method a transit equipped with a calibrated turntable is often used as shown in FIG.  2 . In this case the operator sets the tripod over the first point with the aid of a plumb bob. Then the telescope of the transit is used to sight a known second point and the turntable angle is noted. Subsequently the turntable is turned to the required angle and the needed third point is marked by a second person communicating with the transit operator. This method can be very accurate but requires two men and is time consuming. 
     Many existing methods use small battery operated lasers to aid in the job of construction layout. For example, laying out 90° reference lines can be done using a visible laser beam generator such as the LeveLite manufactured by the assignee of this application. With that tool on its side, the self-leveling feature of the tool is disabled and visible light beams at 90° to each other can be used to project two lines at 90° to each other. FIG. 3 shows such a LeveLite tool  2  on an adjustable trivet  8 . The light beams  4  and  6  may be pointed on a target or on the floor using knobs  10 . The floor is subsequently marked for later use. In this case the lines are relatively short and difficult to position. To make the line on the floor longer a cylinder lens may be used as is shown in FIG. 4 depicting a system of U.S. Pat. No. 5,864,956. In this case a number of individual units project individual fan beams, with the beams fixed in their orientation to each base. The operator is unable to move the fan beam to position it on the floor where it is needed. Because the blocks are fastened together, tipping one axis to move the fan beam up or down causes the fan beam at 90° to rotate causing it to be no longer vertical. 
     In U.S. Pat. No. 5,539,990, as shown in FIG. 5, a self-leveling platform with two fan beams at 90° to each other is used. It uses a weight  11  and a bearing not shown to level the platform  13 . In this case the beam location is not controlled by the operator and, therefore, a wide beam must be used spreading the light over a wide angle making it difficult to see. 
     Rotating lasers with a special transmitting penta prism are often used in this application, as shown in FIG.  6 . In this case the rotating laser beam is visible on the floor or may be detected using a handheld detector. A portion of the beam is transmitted through the penta prism providing a 90° reference. This technique is expensive and it is difficult to see the beam because the light is spread over 360°. 
     An instrument using two rotating lasers is described in U.S. Pat. No. 5,218,770 and shown in FIG.  7 . Again, the laser beams from this unit are difficult to see because the light is spread over a large area. In U.S. Pat. No. 5,218,770 two planes of light at 90° to each other are generated using a mirrored cone and two mirrors. The beams are so weak in this case that a special detector must be used to find the beam and in addition, two men may be required. 
     The subject invention is designed to overcome the limitations of the prior art by making the light-generated reference lines more visible and also adjustable as to height of projection, allowing layout by a single operator. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-7 show various systems and devices according to the prior art for laying out two lines at 90° to each other. Some of these involve laser beams. 
     FIG. 8 shows, somewhat schematically, a device and system according to the invention. 
     FIGS. 9 and 10 schematically show the device of the invention in elevation, partially in section, with an adjustable beam steering lens in different positions. 
     FIG. 11 is a schematic perspective view illustrating a three-lens system according to the invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The system of the invention is shown in FIG.  8 . It comprises a beam generator  20  which produces two laser beams of visible laser light at precisely 90° to each other and in a plane parallel to the floor on which the unit is resting. Such beam generators are described in U.S. Pat. No. 5,617,202 and U.S. Pat. No. 5,500,524, belonging to the same assignee as this application, and incorporated by reference herein. The point of intersection of the two beams is indicated for positioning or marking. A cylinder lens in the path of each beam is used to direct the beams onto the floor by the operator for the purpose of positioning the beam on a target area. The axis of the cylinder lens is in a plane parallel to the floor plane in order to produce a fan beam perpendicular to the floor. The focal lengths of the lenses are chosen to spread the beam a minimal amount to place the light where it is needed thus producing the maximum visibility for the laser power available. For example, a focal length in the range of 60 mm works well with a laser diode collimated with a 10 mm focal length, providing a beam of appropriate height. However, the beam from the laser may be only collimated on one axis, to provide a beam which does not diverge horizontally. The natural spread of the beam in the generally vertical direction then combines with the effect of the cylinder lens, which can be less strong in this case. 
     A third lens and beam may be used to project three reference lines. The device allows for up/down adjustment of each lens to concentrate the beams and resulting lines where needed. 
     In FIG. 8 the light beam generator  20  produces two collimated beams of light at precisely 90° to each other. A base plate or housing or platform  22  supports the light beam generator  20  in secure and fixed position. The base plate preferably rests directly on the floor and thus provides the reference surface for the apparatus. A fixed vertical slide mount  24  supports an adjustable slider  26  which holds a cylinder lens  28 . The slide mount  24  preferably is an extension of the platform or housing  22 , molded of plastic material as part of the platform. A collimated beam of visible light  30  passes through the cylinder lens  28  and forms a narrow generally vertical fan beam  32  which can be directed onto the floor as desired by moving the slider  26  up and down. In addition the cylinder lens can be slid out of the way completely, preferably in the up direction, allowing a collimated beam of light to be projected parallel to the floor when needed. Such a concentrated beam of light would be the most visible. A reference mark  34  on the base plate  22  provides a means for marking the floor under the beam  30 , or for aligning the tool with a mark on the floor or elsewhere. 
     Features identical to the features  24 - 34  are located on the base plate  22  at 90° from the first light beam  30 , for a second beam  30   a , as shown in FIG.  8 . The two reference marks  34  on the tool locate the intersection of the two beams. 
     FIGS. 9 and 10 show a cross section through one slider  26 . In FIG. 10 the slider is moved down, steering the beam to the floor. The slider motion allows the operator to steer the beam along the floor, to a wall or to the ceiling. The slider may also be moved out of the way to produce a beam of maximum visibility. 
     The slider  26  fits tightly and securely on the slide mount  24  to establish constant orientation of the lens as the slider is moved up and down. This is achieved preferably by use of a small leaf spring (not shown) acting between the slider and the outer edge of the slide mount, at one side of each slider. 
     FIG. 11 shows the cylinder lenses and their relation to the floor  38 . A light beam generator  40  produces three beams of light  42 ,  44 , and  46 , each at 90° to the adjacent beam. A coordinate system with the floor  38  in the xy plane is shown in FIG.  11 . To ensure that the fan beams generated by cylinder lenses  50 ,  52 , and  54  are in essentially vertical planes (perpendicular to the floor or surface  38 ) the axes of the lenses must be in a plane parallel to the xy plane, i.e. the floor. Those axes should also be perpendicular to the incoming beam to provide a symmetrical beam. The slider  26  of FIG. 8 ensures the correct orientation of each lens as it moves on the slider. 
     The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit its scope. Other embodiments and variations to this preferred embodiment will be apparent to those skilled in the art and may be made without departing from the spirit and scope of the invention.