Patent Publication Number: US-2006013278-A1

Title: Laser level

Description:
This application is a continuation of copending U.S. patent application Ser. No. 10/277,474, filed Oct. 22, 2002, entitled “Laser Level”. The disclosure of the foregoing patent application is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION  
      This invention relates generally to laser instruments and specifically to laser levels.  
     BACKGROUND OF THE INVENTION  
      Laser levels have been used in construction for many years. They typically seek to produce a plane of light for a reference for construction projects. Laser levels have been used for large scale construction projects like commercial excavating, laying foundations, and installing drop ceilings. Laser levels save considerable time during initial layout of a construction job compared to other tools such as beam levels, chalk lines, or torpedo levels. Some examples of jobs where laser levels would be useful include laying tile, mounting cabinets, installing counter tops, and building outdoor decks.  
      It is an object of the present invention to provide a laser level that is inexpensive and usable by the general public.  
     SUMMARY OF THE INVENTION  
      In accordance with the present invention, an improved laser level is employed. The laser level disposable on a reference surface includes a housing, a pendulum pivotably connected to the housing, a first laser diode disposed on the pendulum for emitting a first laser beam along a first path, and a lens disposed on the pendulum in the first path for converting the first laser beam into a first planar beam, the first planar beam forming a line on the reference surface.  
      Additional features and benefits of the present invention are described, and will be apparent from, the accompanying drawings and the detailed description below. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The accompanying drawings illustrate preferred embodiments of the invention according to the practical application of the principles thereof, and in which:  
       FIG. 1  is a perspective view of a first embodiment of a laser level according to the invention;  
       FIG. 2  is a cross-sectional view of the laser level of  FIG. 1 ;  
       FIG. 3  illustrates different laser diode/lens arrangements, where  FIG. 3A  is a partial cross-sectional front view of an arrangement, and  FIGS. 3B-3E  are top views of alternate arrangements;  
       FIG. 4  illustrates another laser diode/lens arrangement, where  FIG. 4A  is a partial cross-sectional top view of such arrangement,  FIG. 4B  is an augmented view of  FIG. 4A ,  FIG. 4C  is a partial cross-sectional view along line IV-IV of  FIG. 4B ,  FIG. 4D  is an augmented top drawing of the lens in  FIG. 4A ,  FIG. 4E  is an augmented top drawing of a first alternate lens,  FIG. 4F  is a front view of a second alternate lens, and  FIG. 4G  is a cross-sectional view along line G-G of  FIG. 4F ;  
       FIG. 5  illustrates the laser level being used with a target, where  FIGS. 5A-5B  are front and top views, respectively;  
       FIG. 6  illustrates the target of  FIG. 5 , where  FIGS. 6A-6B  show the target independently and with the laser level, respectively;  
       FIG. 7  is a wall hanging assembly for the laser level;  
       FIG. 8  is a partial cross-section of a second embodiment of the laser level, where  FIGS. 8A-8B  show the laser level in vertical and inclined positions, respectively;  
       FIG. 9  illustrates a pendulum lock mechanism according to the invention;  
       FIG. 10  illustrates a third embodiment of the laser level, where  FIGS. 10A-10C  show a laser assembly disposed on right, top and left positions, respectively, and  FIG. 10D  is an exploded diagram of the laser level;  
       FIG. 11  is a block diagram of the components of the laser level;  
       FIG. 12  is an alternate block diagram of the components of the laser level;  
       FIG. 13  illustrates a fourth embodiment of the laser level, where  FIGS. 13A-13B  are perspective and cross-sectional views of the laser level, respectively; and  
       FIG. 14  illustrates another wall hanging assembly for the laser level. 
    
    
     DETAILED DESCRIPTION  
      The invention is now described with reference to the accompanying figures, wherein like numerals designate like parts. Referring to  FIGS. 1-2 , a laser level  10  may have a housing  11 . The housing  11  may have a top portion  11 T and a bottom portion  11 B. The housing may also have a hole  12  extending through the housing  11 . The hole  12  preferably extends through the top portion  11 T. The perimeter of the hole  12  may be defined by an inner wall  11 I.  
      The top portion  11 T may carry a pendulum assembly  30 . Preferably, the pendulum assembly  30  has a main body  31 , which may be made of metal or plastic. Main body  31  may be disposed on a knife edge  11 IK. Knife edge  11 IK may be connected to and/or supported by inner wall  11 I. Alternatively, knife edge  11 IK may be connected to and/or supported by housing  11 . Persons skilled in the art will recognize that pendulum assembly  30  may be supported by means other than knife edge  11 IK, such as a pin, bearing, point or other pendulous means.  
      The main body  31  may carry at least one laser assembly  40  and preferably two laser assemblies  40  disposed left and right of the knife edge  11 IK. Persons skilled in the art will recognize that a laser assembly  40  may disposed above knife edge  11 IK. Persons skilled in the art will also recognize that the laser assemblies  40  will emit laser beams. Accordingly, it is preferable to provide housing  11  with windows  13  to allow the laser beams to exit from housing  11 .  
      Persons skilled in the art will recognize that such arrangement will provide a self-leveling pendulum assembly that will emit substantially horizontal laser beams (and a substantially vertical laser beam if a laser assembly  40  is disposed above knife edge  11 IK and is directed upwardly) when laser level  10  is disposed against a wall. Persons skilled in the art will also recognize that it is preferable to allow laser assembly  40  to be angularly adjusted along a vertical plane relative to main body  31 , to ensure that the projected laser beam is substantially horizontal when the main body  31  is at its stationary position.  
      A possible adjustment arrangement is shown in  FIG. 8A , where laser assembly  40  has a barrel  41  carrying the laser diode and lens(es) (not shown). Barrel  41  may be disposed on a pin  38  supported by main body  31 . A spring  39  preferably disposed between barrel  41  and main body  31  may bias barrel  40  upwardly against set screw  37 . Set screw  37  is preferably disposed on main body  31  and contacts barrel  41  to stop rotation of barrel  41  about pin  38 , and set the position of barrel  41  (and thus of laser assembly  40 ). Persons skilled in the art will recognize that the set screw  37  is preferably locked in place using a locking compound such as Loc-Tite.  
      A second possible adjustment arrangement is also shown in  FIG. 8A , where like numerals refer to like parts. In this arrangement, barrel  41  may be disposed against a protrusion  31  P by main body  31 . A spring  39 ′ preferably disposed between barrel  41  and main body  31  may bias barrel  40  downwardly against set screw  37 . Set screw  37  is preferably disposed on main body  31  and contacts barrel  41  to stop rotation of barrel  41  about protrusion  31 P, and set the position of barrel  41  (and thus of laser assembly  40 ). Persons skilled in the art will recognize that the set screw  37  is preferably locked in place using a locking compound such as Loc-Tite.  
      Referring to  FIGS. 1-2 , main body  31  may also have weights  33  to provide a lower center of gravity, and enhance the performance of the pendulum assembly  30 . In addition, main body  31  may have at least one adjustment screw  33 A to adjust the center of gravity of pendulum assembly  30 , as necessary.  
      Main body  31  may also have a plaque  33 M, made of magnetic material, ferrous material or non-ferrous conductive material, such as zinc or copper. Plaque  33 M preferably is aligned with at least one magnet (and preferably two magnets) disposed in housing  11 , e.g., on the inside of the front and rear walls of housing  11 , for providing a damping action on pendulum assembly  30 . Basically, eddie currents are generated within plaque  33 M, as the plaque moves and interacts with the magnetic field supplied by the magnet(s).  
      Persons skilled in the art shall recognize that pendulum assembly  30  is preferably wholly contained within housing  11 . However, the pendulum assembly  30  may be at least partly, if not completely, disposed outside of housing  11 .  
      Persons skilled in the art shall recognize that a damping mechanism for damping the motion of pendulum assembly  30  may be provided. Persons skilled in the art are directed to the damping mechanism disclosed in U.S. Pat. No. 5,144,487, which is wholly incorporated by reference herein, as well as to its equivalents.  
      The bottom portion  11 B of housing  11  may carry a battery  50  for powering the laser assemblies  40 . In addition, the bottom portion  11 B may carry a stud sensor circuit  20 . The circuitry of the stud sensor circuit  20  is not illustrated herein. Persons skilled in the art are referred to U.S. Pat. Nos. 4,099,118 and 4,464,622, which are wholly incorporated herein by reference.  
      As is well known in the art, the stud sensor circuit  20  may include an on/off actuator or switch  21 , which can be a push-button type actuator. Stud sensor circuit  20  may also include light emitting diodes  22  to display the location of a stud.  
      It is preferable to align the sensors within stud sensor circuit  20  with the center of hole  12 , so that the center of hole  12  indicates the location of the stud.  
      Persons skilled in the art should recognize that detector circuits other than stud sensor circuit  20  may be provided in laser level  10 . Preferably, these detector circuits can detect features underneath a surface, such as a wall or floor. These features may include pipes or wires. Circuits for pipe and wire detectors, as well as other detector circuits, are well known in the art.  
      The housing  11  may be formed from a hard impact resistant, preferably moldable material such as a hard thermoplastic material such as ABS or polystyrene. It is preferable to provide a grip  14  on bottom portion  11 B. Grip  14  may be made of a soft or low durometer thermoplastic elastomer. In addition, grip  14  can be formed from any of the so-called “soft-touch” elastomer materials, such as those sold under the tradenames “Santoprene”, “Kraton” and “Monprene,” and are preferably adhered or overmolded to the housing  11 .  
      Referring to  FIGS. 2-3 , laser assemblies  40  are disposed on main body  31 . Laser assembly  40  may include a substantially cylindrical barrel  41 , which may be adjustably connected to main body  31 , laser diode  42  disposed in barrel  41 , and a line lens  43  disposed in barrel  41 . Persons skilled in the art will recognize that in the preferred embodiment, adjusting barrel  41  will result in moving laser diode  42  and line lens  43 . In addition, persons skilled in the art will recognize that a collimating lens may be disposed between laser diode  42  and line lens  43 .  
      Preferably, line lens  43  converts the laser beam exiting laser diode  42  into a planar beam. Line lens  43  may have different shapes to accomplish such purpose. For example, as shown in  FIG. 3B-3D , line lenses  43 A,  43 B,  43 C may have a substantially circular cross-section, half-circle cross-section or quarter-circle cross-section, respectively. Alternatively, line lens  43 D may have a compound cross-section, which includes a rectangle connected to a quarter-circle.  
      Accordingly, when laser level  10  is disposed against a wall, laser assembly  40  will preferably emit a laser plane that contacts the wall, forming a laser line on the wall. Persons skilled in the art will recognize that it is preferable to orient the laser assemblies  40  in such manner so that at least a portion of the laser plane will contact the wall. In addition, persons skilled in the art will recognize that providing laser assemblies  40  on the pendulum assembly  30  discussed above will preferably result in laser level  10  projecting substantially horizontal laser lines against the wall (and a substantially vertical laser beam if a laser assembly  40  is disposed above knife edge  11 IK and is directed upwardly).  
      Persons skilled in the art will recognize that line lenses  43 B,  43 C,  43 C will limit the angle of plane divergence. In other words, if a horizontal line HL is 0°, the plane exiting from line lens  43 A may extend from, for example, −30° to 30°, providing an angle of plane divergence DA of 60°. On the other hand, the plane exiting from line lenses  43 B,  43 C,  43 D may extend from, for example, 0° to 30°, providing an angle of plane divergence DA of 30°. This provides for a more efficient use of the laser beam, directing more energy towards the wall, rather than away from the wall. Persons skilled in the art will recognize that directing more energy towards the wall is preferable as it would result in a brighter laser line on the wall.  
      A preferred laser assembly  40 ′ is shown in  FIG. 4 , where like numerals refer to like parts. Such laser assembly  40 ′ has a collimating lens  44  disposed in the laser beam path, as well as a line lens  45  disposed in the laser beam path after the collimating lens  44 . Line lens  45  is preferably a prismatic lens that includes at least two cylindrical lens forms with significantly different focal distances to generate at least two superimposed laser planes with different divergence angles and trajectories.  
      With such arrangement, when laser assembly  40 ′ is placed near a wall W, two or more lines are projected onto wall W. At least one of these lines (L 1 ) may be directed to strike the wall W at a short distance along the wall surface, while another of these lines (L 2 ) may be directed to strike the wall W at a longer distance. This preferably increases the overall length and/or apparent brightness of the laser line shown on the wall W. Lines L 1 , L 2  may partially overlap or may be separated to further increase the length of the resulting laser line on wall W.  
      As mentioned above, line lens  45  may have two portions. One portion has a long focal distance for generating the high density line L 2 , i.e., having a small divergence angle. The brightness of line L 2  along wall W will depend of the divergence angle H, as the smaller the divergence angle, the brighter the line at a given distance.  
      But a small divergence angle H will result in a laser line gap on the wall W between the laser assembly  40 ′ (and thus laser level  10 ) and the beginning of line L 2 . Accordingly, it is preferable to provide line lens  45  with a second portion with a short focal distance for generating a line L 1  with lower density than the line L 2 , and thus having a larger divergence angle L. The larger divergence angle L will create a low density line L 1  that will contact wall W closer to the laser assembly  40 ′, thus reducing the laser line gap left by line L 2 .  
      Persons skilled in the art will recognize that the first and second portions will have a first and second radii R 1 , R 2 , respectively. Preferably, radius R 1  is substantially larger than radius R 2 . Persons skilled in the art will know how to select the appropriate radii, as they must be selected based on the distance from the wall W to laser assembly  40 ′, the desired length of laser line gap to fill up, etc.  
      Persons skilled in the art will recognize that the laser beam LB created by the collimating lens  42  has a generally oval cross-section. The use of the long axis of the oval allows easier positioning of the beam to pass the two portions of line lens  45 . It is desirable to orient the laser beam LB so that the short axis of the oval is aligned in the axis of the line lens  45  that offers no or minimal magnification. Accordingly, the short axis preferably provides the width of laser lines L 1 , L 2 . Persons skilled in the art will recognize that a narrower width is preferable as it increases accuracy and intensity of the laser lines. In a preferred embodiment, the short and long axes are about 3 mm and about 7 mm respectively.  
      Persons skilled in the art will also recognize that the above discussion is preferably applicable to line lens  45 , as well as to alternate line lens  45 ′ ( FIGS. 4E-4G ), except that the second portion with R 2  is concave, i.e., extending into the lens, rather convex, i.e., extending out of the lens. In the embodiment of  FIGS. 4F-4G , line lens  45 ′ has radii R 1 , R 2  of about 12.70 mm and about 0.75 mm, respectively.  
      It may also be preferable to provide line lens  45 ′ with protrusions  45 P to engage barrel  41 .  
      Furthermore, it is preferable to provide a means of line lens  45 ′ to delimit the width of the laser plane generated by laser assembly  40 ′. One such means is by providing a screen  45 S on the wall  45 F closest to laser diode  42 . With such screen  45 S, the shape or width of the emitted laser plane can be controlled. For example, screen  45 S can define an unscreened line through which the laser beam is transmitted.  
      In the present embodiment, screen  45 S is basically a texture molded onto wall  45 F. However, persons skilled in the art will recognize that screen  45 S can be an opaque material, such as paint, metal or fabric, which is disposed on or adjacent to line lens  45 ′. Furthermore, screen  45 S could be disposed on or adjacent to wall  45 R, or within line lens  45 ′. Alternatively, screen  45 S can be disposed ahead of lens  44 .  
      Referring to  FIG. 5 , regardless of the type of line lens used, it is likely that the laser line will fade as it gets farther from laser level  10 . As shown in  FIG. 5B , the emitted laser plane LP still has a component that does not contact the wall W. This component will form a laser line when it contacts another surface.  
      Accordingly, it is preferable to provide a surface that can intersect this component of the laser plane LP. This surface can be provided on a movable target  60 . Target  60  may have a main body  61 , and a cylinder  62  disposed on the body  61 . Preferably, the inside of cylinder  62  is carved out, forming a hollow cone  62 C ending in a central bore  63 . Target  60  may have cross-hair indicia, such as grooves  65  or ribs, intersecting at the center of bore  63 .  
      Persons skilled in the art will recognize that target  60 , main body  61  and/or cylinder  62  may be made of a translucent material to facilitate location of a mark. This could facilitate placing the laser level  10  on a specifically desired location.  
      A ramp  64  may be provided on cylinder  62 . Preferably the ramp  64  has some reflective material. (Alternatively, textured areas can be disposed on cylinder  62  or ramp  64  to enhance the visibility of the laser line.) Accordingly, the user can disposed the laser level  10  on wall W and move target  60  until ramp  64  is aligned with the laser line.  
      The user can then use a pencil to mark the center of target  60 . Alternatively, the user can push a pin  66 P or expanding mandrel  66 M through bore  63  to maintain the target  60  in place. Persons skilled in the art will recognize that an expanding mandrel has at least two metal strips along its longitudinal axis meeting at a front tip. The mandrel is inserted into a pre-drilled hole. The steel strips can be then expanded within the hole in order to fix the mandrel.  
      Persons skilled in the art will recognize that target  60  may be removably disposed in hole  12  of laser level  10 . Thus, laser level  10  provides on-board storage for target  60 . To this end, it is preferable to provide target  60  with detent protrusions  67 , which engage the laser level  10 .  
      Persons skilled in the art will recognize that, if the center of hole  12  is aligned with the horizontal lines emitted by the laser assemblies  40 , the bore  63  of target  60  will be placed at the intersection of the vertical centerline of laser level  10  with the horizontal lines. In addition, the laser level  10  may be hung by pushing a pin through bore  63  and nesting laser level  10  unto target  60 .  
      It may also be preferable to provide a hanger assembly  70  for laser level  10 . Hanger assembly  70  may have a main body  71  with a central hole  72  for receiving the head of a nail hammered into a wall. Main body  71  may be made of a translucent material to facilitate location of a mark or nail.  
      Hanger assembly  70  may also have a ramp  73 , as cross-hair indicia, such as grooves  74  or ribs, intersecting at the center of hole  72 . Textured areas can be disposed on main body  71  or ramp  73  to enhance the visibility of the laser line.  
      Hanger assembly  70  may be removably disposed in hole  12  of laser level  10 . To this end, it is preferable to provide hanger assembly  70  with detent protrusions  77 , which engage the laser level  10 .  
      Persons skilled in the art will recognize that housing  11  may be provided with holes for receiving nail heads or screw heads, for hanging laser level  10  thereon.  
      It may also be preferable to provide a separable hanger assembly  90  for laser level  10 . Hanger assembly  90  may have a main body  91 , a magnet  93  disposed on the main body  91 , and a ramp  92 . Main body  91  may also have cross-hair indicia, such as grooves or ribs, intersecting at its center. Hanger assembly  90  may be removably disposed in hole  12  of laser level  10 . To this end, it is preferable to provide hanger assembly  90  with detent protrusions  94 , which engage the laser level  10 .  
      Main body  91  may magnetically engage another assembly, such as wall assembly  95 , pin assembly  96  and/or mandrel assembly  97 . Wall assembly  95  preferably has a body  95 B, a magnetically-responsive metal plate  95 MP supported by body  95 B, and a hole  95 H. Basically, the user can dispose wall assembly  95  on a nail or screw on a wall. The user can then dispose main body  91  unto wall assembly  95 , which will stay together because of the magnet/metal plate combination.  
      Pin assembly  96  preferably has a body  96 B, a magnetically-responsive metal plate  96 MP supported by body  96 B, and a pin  96 P. Basically, the user can dispose pin assembly  96  unto a wall. The user can then dispose main body  91  unto pin assembly  96 , which will stay together because of the magnet/metal plate combination.  
      Mandrel assembly  97  preferably has a body  97 B, a magnetically-responsive metal plate  97 MP supported by body  97 B, and a mandrel  97 M. Basically, the user can dispose mandrel assembly  97  within a pre-drilled hole on a wall. The user can then dispose main body  91  unto mandrel assembly  97 , which will stay together because of the magnet/metal plate combination.  
      Persons skilled in the art will recognize that it is also preferable to provide a rib  98  on main body  91  that receives wall assembly  95 , pin assembly  96  and/or mandrel assembly  97 , or a portion thereof. Preferably, the rib  98  is designed so that, when main body  91  is disposed on wall assembly  95 , pin assembly  96  and/or mandrel assembly  97 , the main body  91  is centered relative to the opposite assembly. Rib  98  may also support main body  91  (and thus laser level  10 ). Persons skilled in the art will recognize that the rib  98  may be disposed on wall assembly  95 , pin assembly  96  and/or mandrel assembly  97 . Alternatively, rib  98  may be received within a slot or groove of wall assembly  95 , pin assembly  96  and/or mandrel assembly  97 .  
      A second embodiment of laser level  10  is shown in  FIG. 8 , where like numerals refer to like parts. The teachings of the first embodiment above are wholly incorporated by reference in the present embodiment. One difference from the previous embodiment is that the pendulum assembly  30  has a knife edge  36  disposed therein, which engages a notch  11 N in housing  11 . In addition, pendulum assembly  30  may have a lower curved area  35 .  
      It is preferable to dispose laser assemblies  40  within protrusions  15  of top portion  11 T. With such arrangement, when the laser level  10  is disposed substantially vertically against a wall, laser beams emitted by laser assemblies  40  can exit housing  11  through windows  13 . As discussed above, the laser level  10  has a certain angle range, where the laser level  10  can be disposed at an angle relative to the vertical centerline V and the pendulum assembly  30  will self-level and emit substantially horizontal (or vertical) laser beams.  
      If the laser level  10  is disposed at an angle beyond the angle range, laser assemblies  40  may contact the inner walls of protrusions  15 . Alternatively, pendulum assembly  30  may contact a component disposed within housing  11 . When this occurs, the laser level  10  will no longer provide an accurate leveling function.  
      Preferably, the windows  13  are sized to prevent the emitted laser beams to project out of housing  11  when the laser assemblies  40  contact the inner walls of protrusions  15  or pendulum assembly  30  contacts a component disposed within housing  11 . This prevents the user from believing that the emitted laser beams are substantially horizontal (or vertical).  
      Preferably, the windows  13  prevent the laser beams from exiting the housing when the pendulum assembly  30  approach the limits of the angle range. In other words, assuming an angle range being between about −10° to about 10° from vertical centerline V where pendulum assembly  30  will self-level, and where the laser assemblies  40  contact the inner walls of protrusions  15  or pendulum assembly  30  contact a component disposed within housing  11  at any angle beyond this angle range, it may be preferable to size and/or shape the windows  13  to begin blocking the laser beams at about −8° and/or about 8° from vertical centerline V.  
      It may be preferable to provide a pendulum lock mechanism  80  for locking pendulum assembly  30  at a certain position. For example, pendulum assembly  30  may be locked in place in order to safely transport laser level. Pendulum lock mechanism  80  may include a lock  84  that has a locking surface  84 LR which contacts a portion of pendulum assembly  30 , such as curved area  35 . Lock  84  is preferably movable along its axis between locked and unlocked positions. A spring  86  may be trapped between housing  11  (via boss  11 B) and lock  84  for biasing lock  84  towards the locked position.  
      Lock  84  may be moved between the locked and unlocked positions by an actuator  83 . The longitudinal axis of actuator  83  is preferably substantially perpendicular to the longitudinal axis of lock  84 . Actuator  83  may be moved along its axis between a first position that moves lock  84  into the locked position and a second position that moves lock  84  into the unlocked position. Preferably, actuator  83  and lock  84  have ramps  83 R,  84 R, respectively, for contacting therebetween.  
      As shown in  FIG. 9 , actuator  83  is shown in the first and second positions with solid and broken lines, respectively. As actuator  83  is moved upwardly, ramp  83 R contacts ramp  84 R, and moves lock  84  towards the unlocked position. Actuator  83  may have a plateau  83 P disposed at the end of ramp  83 R for maintain lock  84  in the unlocked position.  
      Actuator  83  may have an actuator button  81  to enable the user to move the actuator  83  between the first and second positions (and thus to move the lock  84  between the locked and unlocked positions).  
      Persons skilled in the art will recognize that actuator  83  may be connected to a switch  82 , so that when actuator  83  is moved, switch  82  is activated. Preferably, switch  82  turns laser assemblies  40  on and off.  
      Persons skilled in the art should also recognize that the spatial relationship between actuator ramp  83 R, lock ramp  84  and the travel distance of switch  82  can be manipulated so that the switch  82  will turn on laser assemblies  40  only when lock  84  is moved to the unlocked position. Alternatively, the spatial relationship between actuator ramp  83 R, lock ramp  84  and the travel distance of switch  82  can be manipulated so that the switch  82  will turn on laser assemblies  40  before lock  84  is moved to the unlocked position. This allows the user to use the laser level  10  to emit straight laser lines, even though these lines are not necessarily level.  
      A third embodiment of laser level  100  is shown in  FIG. 10 , where like numerals refer to like parts. The teachings of the embodiments discussed above are incorporated herein by reference.  
      Laser level  100  basically has three assemblies: base assembly  110 , pendulum assembly  120  and laser housing assembly  130 . These three assemblies may be designed so that they cannot be separated during operation. Alternatively these three assemblies may be designed so that they can be separated during operation and/or storage.  
      Base assembly  110  has a main body  111 , which has a substantially flat rear wall to ensure that laser level  100  can be disposed substantially flush against a wall. Main body  111  may a central hollow cylinder  112 . In addition, main body  111  may carry the stud sensor circuit  20 .  
      Pendulum assembly  120  preferably has a main body  121  and a hole  121 H on body  121  for nesting pendulum assembly  120  on cylinder  112 . Preferably, main body  121  (and thus pendulum assembly  120 ) can rotate about cylinder  112 . Accordingly, it is preferable to dispose bearings  123  therebetween to facilitate such rotation.  
      Main body  121  may have a compartment for receiving battery  50 . In addition, main body  121  may have an annular protrusion  122 .  
      Laser housing assembly  130  may have a housing  131  and at least one laser assembly  40  disposed within the housing  131 . Housing  131  may have a hole  131 H for nesting laser housing assembly  130  onto protrusion  122 . Preferably housing  131  (and thus laser housing assembly  130 ) can rotate about protrusion  122 . Accordingly, it is preferable to dispose bearings  126  therebetween to facilitate such rotation.  
      A detent mechanism  140  may be disposed between pendulum assembly  120  and laser housing assembly  130  for fixing the rotational position of laser housing assembly  130  (and thus of laser assembly  40 ) relative to the pendulum assembly  120 . Detent mechanism  140  may comprise a detent ball  144  which engages a notch (not shown) on housing  131 . A spring  145  is preferably disposed between body  121  and ball  144  to bias ball  144  towards the notch. Persons skilled in the art will recognize that the spring  145  and ball  144  may alternatively be disposed on housing  131 , whereas the notch can alternatively be disposed on body  121 .  
      Preferably, the notches are disposed in such locations so that the laser assembly  40  will emit a laser beam that is at 90° of the vertical axis of pendulum assembly  120  (i.e., emitting a laser beam towards the right of laser level  100 , as shown in  FIG. 10A ), at 0° of the vertical axis of pendulum assembly  120  (i.e., emitting a laser beam upwardly, as shown in  FIG. 10B ), or at −90° of the vertical axis of pendulum assembly  120  (i.e., emitting a laser beam towards the left of laser level  100 , as shown in  FIG. 10C ). Persons skilled in the art will recognize that the notches may be disposed on other positions.  
      With such arrangement, the user can dispose laser level  100  against a wall. The user can move laser level  100  along the wall until a stud is detected by stud sensor circuit  20 . While holding on to main body  111 , the user can let pendulum assembly  120  and laser housing assembly  130  self-level, so that the emitted laser beam will be substantially horizontal or vertical. The user can also rotate laser housing assembly  130  to the different desired positions.  
      In all three embodiments, the battery  50  preferably provides power to both stud sensor circuit  20  and laser diode(s)  42 , as shown in  FIG. 11 , so that the stud sensor circuit  20  and laser diode(s)  42  operate independently from each other. Persons skilled in the art will recognize that it may be desirable to enable the stud sensor  20  to control the laser diode(s)  42 , so that the laser diode(s)  42  only turn on when a stud is detected by stud sensor  20 .  
      Another embodiment of the novel laser level is shown in  FIG. 13 , where like numerals refer to like parts. The teachings of the embodiments above are wholly incorporated by reference in the present embodiment. Like before, laser level  10  has laser assemblies  40  for projecting laser beams, preferably in the form of planes. Furthermore, laser level  10  has a stud sensor circuit  20 .  
      In this embodiment, the main difference is that the laser assemblies  40  are not disposed on a pendulum. Instead, they are fixedly connected to housing  11 . Accordingly, the user can disposed housing  11  at any position against a wall or floor, and two laser lines will be emitted unto the wall or floor.  
      A horizontal bubble vial  11 HV may be provided on housing  11  to indicate to the user when the laser beams are level, i.e., substantially horizontal. Similarly, a vertical bubble vial  11 VV may be provided on housing  11  to indicate to the user when the laser beams are plumb, i.e., substantially vertical. Persons skilled in the art will recognize that other means for detecting and indicating whether the laser beams are plumb or level can be used. In addition, persons skilled in the art will recognize that it may be preferable to dispose at least one laser assembly  40  at 90° from another laser assembly  40 , to emit a perpendicular laser beam or line.  
      Persons skilled in the art may recognize other additions or alternatives to the means disclosed herein. However, all these additions and/or alterations are considered to be equivalents of the present invention.