Abstract:
A line generating device may include a housing having a bottom surface, a top surface, a front surface connecting the top and bottom surfaces, a rear surface connecting the top and bottom surfaces, and a side surface connecting the top and bottom surfaces, a support assembly mounted within the housing. In addition, the device may include a light source mounted on the support assembly, and a lens for receiving light and projecting the light in the shape of a fan within a plane. The light plane exits through the front surface. The device is disposable on a reference surface on the bottom, rear and side surfaces.

Description:
FIELD OF THE INVENTION 
   The present invention generally relates to line generating devices and more specifically to laser line generating devices. 
   BACKGROUND OF THE INVENTION 
   In the construction industry, it is well known to use laser levels for marking reference lines to be used in the layout of different features in a room or structure. Most of these laser levels are expensive due to the optics and electronics involved therein. 
   Less expensive laser levels that generate a laser line have recently entered the market. However, they typically have limited uses. Accordingly, it is an object of the invention to provide a line generating device that can be used in multiple situations. 
   SUMMARY OF THE INVENTION 
   In accordance with the present invention, an improved line generating device is employed. The line generating device may include a housing having a bottom surface, a top surface, a front surface connecting the top and bottom surfaces, a rear surface connecting the top and bottom surfaces, and a side surface connecting the top and bottom surfaces, a support assembly mounted within the housing, a light source mounted on the support assembly, and a lens mounted on at least one of the support assembly and the light source, the lens receiving light and projecting the light in the shape of a fan within a plane, said light exiting through the front surface, wherein the device is disposable on a reference surface on the bottom, rear and side surfaces. 
   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 left-side front perspective view of a line generating device constructed in accordance with the teachings of the present invention; 
       FIG. 2  is a right-side front perspective view of the line-generating device of  FIG. 1 ; 
       FIG. 3  is a right-side front perspective view of the line-generating device of  FIG. 1  disposed on its side; 
       FIG. 4  is a right-side rear perspective view of the line-generating device of  FIG. 1 ; 
       FIG. 5  is a perspective view of the line-generating device of  FIG. 1  disposed on its rear; 
       FIG. 6  is a perspective view of a laser support assembly according to the invention; 
       FIG. 7  is an exploded perspective view of a laser barrel assembly according to the invention; 
       FIG. 8  is an assembled perspective view of the laser barrel assembly of  FIG. 7 ; 
       FIG. 9  is a partial cross-section of the laser barrel assembly of  FIG. 7 ; 
       FIG. 10  illustrates the adjustment axes for adjusting a level vial in the line generating device, wherein  FIGS. 10A–10B  are front and top plan views of the line generating device, respectively; 
       FIG. 11  illustrates the means for adjusting the level line, wherein  FIGS. 11A–11B  show the adjustment assembly in assembled and exploded views, respectively; 
       FIG. 12  illustrates several lenses for generating a laser line with at least one bright spot, wherein  FIGS. 12A–12G  are the first, second, third, fourth, fifth, sixth and seventh embodiments of the invention; 
       FIG. 13  is a cross-section of the table assembly of  FIG. 1 , shown along a center plane thereof; 
       FIG. 14  is a side view of an alternate table assembly; 
       FIG. 15  is a perspective view of another alternate table assembly; 
       FIG. 16  illustrates a hanging assembly, wherein  FIGS. 16A–16B  show the hanging assembly in assembled and exploded views, respectively; 
       FIG. 17  illustrates a pin assembly, wherein  FIGS. 17A–17C  show the pin assembly in exploded, uninstalled and installed views, respectively; 
       FIG. 18  is a perspective view of a portion of an alternate pin assembly. 
   

   DETAILED DESCRIPTION 
   With reference to  FIGS. 1–6 , a line-generating device constructed in accordance with the teachings of the present invention is generally indicated by reference numeral  10 . Line generating device  10  may comprise a base assembly  11 , a housing assembly  12 , a support assembly  13  disposed on at least one of the base assembly  11  and housing assembly  12 , a laser barrel assembly  14  disposed on the support assembly  13 , a lens assembly  15  mounted onto the laser barrel assembly  14 , level vials  16 ,  17 ,  18  mounted on at least one of the base assembly  11 , housing assembly  12  and support assembly  13 , a printed circuit board (not shown) with a switch  20  mounted thereon, a battery (not shown) mounted on at least one of the base assembly  11 , housing assembly  12  and support assembly  13 . Persons skilled in the art are referred to U.S. Application No. 20020178596 and Ser. No. 10/822,626 (filed Apr. 12, 2004), both of which are wholly incorporated by reference, for further information on the elements of the line generating device  10 . 
   Base assembly  11  is preferably made of metal, such as aluminum. Base assembly  11  preferably has a substantially horizontal planar support  11 S. Planar support  11 S is preferably machined. 
   Support assembly  13  is preferably disposed or mounted on base assembly  11 . Support assembly  13  preferably supports laser barrel assembly  14 , lens assembly  15  and vials  16 ,  17 ,  18 . 
   Housing assembly  12  may be mounted onto base assembly  11  to substantially enclose support assembly  13 , laser barrel assembly  14 , lens assembly  15  and vials  16 ,  17 ,  18 . In particular, screws  12 S may extend through base assembly  11  and threadingly engage housing assembly  12 . 
   Housing assembly  12  may have a front surface  12 F, a rear surface  12 R, a top surface  12 T, and a side surface  12 SS. Front surface  12 F may have an opening  12 FO to allow a laser beam to exit through housing assembly  12 . Preferably, side surface  12 SS has a protrusion  12 SC, which may be a cylinder. Protrusion  12 SC may also have a magnet  12 M disposed therein. Rear surface  12 R may have a protrusion  12 RC, which may be a cylinder. 
   As will be discussed below, the line generating device  10  generates a planar laser beam LB, which generates a laser line LL on a reference surface, such as a wall, floor, etc. As shown in  FIG. 1 , when the line generating device  10  is disposed on surface  11 S of base assembly  11  and on a substantially horizontal reference surface, e.g., a floor, the line generating device  10  will generate a substantially horizontal laser beam LB. Such laser beam LB will create a substantially horizontal laser line LL on a second reference surface having a vertical component, e.g., such as a wall, whether the wall is vertical or inclined relative to the substantially horizontal reference surface. 
   In such orientation, it is preferable that level vial  17  indicate that the laser line LL is substantially level, i.e., horizontal. Persons skilled in the art will recognize that laser beam LB may not necessarily be substantially level when laser line LL is level. This is because laser beam LB may be inclined, for example, when line generating device  10  is disposed at a location higher than laser line LL. 
   Persons skilled in the art will also recognize that level vial  16  can be calibrated so that it can indicate when line generating device  10  is substantially level. Accordingly, a user can use both level vials  16 ,  17  to confirm that the laser line LL, the laser beam LB and line generating device  10  are substantially level. 
   As shown in FIGS.  1  and  3 – 5 , and as will be further discussed below, the line generating device  10  generates a laser beam LB which creates a laser line LL. It is also preferable that the laser beam LB create a bright spot LS on laser line LL. Preferably, the spot LS will be at the halfway point of laser line LL. Spot LS may be disposed on axis X, which may extend through the center of protrusion  12 RC. Accordingly, when the line generating device  10  is in the orientation of  FIGS. 1 and 4 , a user can use both level vials  16 ,  17  to confirm that the spot LS is within a horizontal plane which includes line generating device  10 . 
   As will be further detailed below, the line generating device  10  may be disposed on an adjustable table assembly  40 . Such table assembly  40  can be adjusted by the user to adjust the orientation of the line generating device  10  to ensure that laser line LL is substantially level. Such table assembly  40  may have an opening  40 P for receiving protrusions  12 SC and/or  12 RC. 
   As shown in  FIG. 3 , the line generating device  10  may be disposed on its side surface  12 S by inserting protrusion  12 SC into opening  40 P. When the line generating device  10  and table assembly  40  are disposed on a substantially horizontal reference surface, e.g., a floor, the line generating device  10  will generate a substantially vertical laser beam LB. Such laser beam LB will create a substantially vertical laser line LL on a second reference surface having a vertical component, e.g., such as a wall, whether the wall is vertical or inclined relative to the substantially horizontal reference surface. In addition, such laser beam LB will generate a laser line on the substantially horizontal reference surface. 
   In such orientation, it is preferable that level vial  18  indicate that the laser line LL is substantially plumb, i.e., vertical. 
   Persons skilled in the art will recognize that level vial  16  can be calibrated so that it can indicate when line generating device  10  is substantially level. Accordingly, a user can use both level vials  16 ,  18  to confirm that the spot LS is within a horizontal plane which includes line generating device  10 . 
   As shown in  FIG. 5 , the line generating device  10  may be disposed on its rear surface  12 R by inserting protrusion  12 RC into opening  40 P. When the line generating device  10  and table assembly  40  are disposed on a substantially horizontal reference surface, e.g., a floor, the line generating device  10  will generate a substantially vertical laser beam LB. Such laser beam LB will create a laser line LL on a second reference surface above the first reference surface, e.g., such as a ceiling or false ceiling. 
   In such orientation, it is preferable that level vials  17 ,  18  indicate that the line generating device  10  substantially plumb, i.e., vertical. When device  10  is substantially plumb, spot LS will be aligned with a point L disposed underneath device  10 . In such manner, a user can for example use line generating device to project unto a ceiling a spot that is substantially vertically aligned to a point on a floor. 
   Referring to  FIG. 1 , housing assembly  12  may have indicia  121  which are aligned to the laser beam LB and spot LS so that the user can know how laser beam LB and spot LS is aligned to the housing assembly  12 . 
   As mentioned above, laser barrel assembly  14  may be disposed on support assembly  13 . Referring to  FIGS. 6–9 , laser barrel assembly  14  has a body  14 B, which may carry laser diode  14 D (see  FIG. 12A ) and collimating lens  14 L (see  FIG. 12A ). 
   Body  14 B may have a screw  14 VS extending through body  14 B and threadingly engaging support assembly  13 . A spring  14 VB may be disposed between support assembly  13  and body  14 B. Preferably, spring  14 VB is disposed around screw  14 VS. 
   Body  14 B may have an ear  14 E with a hole  14 EH extending therethrough. A screw  14 RS may extend through hole  14  EH and threadingly engage support assembly  13 . The longitudinal axis of screw  14 RS is preferably substantially perpendicular to the longitudinal axis of screw  14 VS. A spring  14 RB may be disposed between support assembly  13  and ear  14 E. Preferably, spring  14 RB is disposed around screw  14 RS. 
   As mentioned above, lens assembly  15  may be rotationally attached to laser barrel assembly  14 . In particular, a lens  15 L (see  FIG. 12 ) may be disposed in (preferably glued to) a lens holder assembly  15 H. Lens holder assembly  15  may have two ears  15 HE with holes therethrough. Preferably one ear  15 HE is disposed at the top of lens holder assembly  15 H, whereas the other ear  15 HE is disposed at the bottom of lens holder assembly  15 H. 
   Lens holder assembly  15 H may be nested within lens barrel assembly  1  SR. In particular, two screws  15 HS may extend through ears  15 HE and threadingly engage lens barrel assembly  15 R. Springs  15 HB may be disposed between lens barrel assembly  15 R and ears  15 HE. Preferably, springs  15 HB are disposed around screws  15 HS. Lens barrel assembly  15 R may have ribs  15 RR on both sides of ears  15 HE to prevent rotation of the lens holder assembly  15 H. 
   Lens barrel assembly  15 R may be rotatably disposed on a flange  14 F of body  14 B. Body  14 B may have a shoulder  14 S to limit movement of lens barrel assembly  15 R along flange  14 F. 
   Lens barrel assembly  15 R may have an ear  15 E having a hole therethough. A screw  15 RS may extend through the ear  15 E and threadingly engage an ear  14 RE on body  14 B. A spring  15 RB may be disposed between ears  14 RE and  15 E. Preferably, spring  15 RB is disposed around screw  15 RS. 
   With such arrangement, the lens holder assembly  15 H can be adjusted to tilt lens  15 L for crowning by adjusting each screw  15 HS. Springs  15 HB bias lens holder assembly  15 H away from lens barrel assembly  15 R and into the heads of screws  15 HS to maintain lens holder assembly  15 H in the desired position. The screws  15 HS may be fixed by a locking compound, such as Loc-Tite. 
   The lens barrel assembly  15 R is preferably rotationally connected to body  14 B of laser barrel assembly  14 . The generated laser beam LB can be calibrated so that the resulting laser line LL is level (and/or parallel to surface  11 S) by rotating lens barrel assembly  15 R relative to body  14 B. This can be accomplished by rotating screw  15 RS. Spring  15 RB biases lens barrel assembly  15 R away from body  14 B and into the head of screw  15 RS to maintain lens barrel assembly  15 R in the desired position. The screw  15 RS may be fixed by a locking compound, such as Loc-Tite. 
   The laser barrel assembly  14  is preferably adjustable along two axes relative to support assembly  13 . First, the generated laser beam LB can be calibrated so that it is pararllel to surface  11 S by rotating body  14 B relative to support assembly  13  about a substantially horizontal axis. This can be accomplished by rotating screw  14 VS. Persons skilled in the art will recognize that, when screw  14 VS is rotated, body  14 B will rotate about the longitudinal axis of screw  14 RB. Spring  14 VB biases body  14 B away from support assembly  13  and into the head of screw  14 VS to maintain body  14 B in the desired position. The screw  14 VS may be fixed by a locking compound, such as Loc-Tite. 
   The laser barrel assembly  14  may also be adjusted sideways so that the spot LS is aligned to axis X. This can be accomplished by rotating screw  14 RS. Persons skilled in the art will recognize that, when screw  14 RS is rotated, body  14 B will rotate about the longitudinal axis of screw  14 VB. Spring  14 RB biases body  14 B away from support assembly  13  and into the head of screw  14 RS to maintain body  14 B in the desired position. The screw  14 RS may be fixed by a locking compound, such as Loc-Tite. 
   Persons skilled in the art may recognize that body  14 B may have clearances or cut-outs, such as channel  14 C, to increase the adjustment range of body  14 B relative to support assembly  13 . 
   Because of the multiple orientations that line generating device  10  can be placed, it is preferable to provide a means for adjusting the level vials  16 ,  17 ,  18  along several axes. For example, referring to  FIG. 10A , level vial  17  needs to be adjustable so that the vertical component of its longitudinal axis  17 A is zero, i.e., the longitudinal axis  17 A is substantially parallel to surface  11 S. Furthermore, level vial  17  needs to be adjustable so that the longitudinal axis  17 A is substantially perpendicular to axis X, as shown in  FIG. 10B . 
   Referring to  FIG. 11 , support assembly  13  has a post  13 P. Level vial  18  is disposed on a vial holder  18 A. A first screw  18 US preferably extends through a hole in vial holder  18 A and is threadingly engaged to post  13 P. A spring  18 UB may be disposed between vial holder  18 A and post  13 P. Preferably, spring  18 UB is disposed around screw  18 US. 
   A second screw  18 LS preferably extends through a hole in vial holder  18 A and is threadingly engaged to post  13 P. The longitudinal axis of second screw  18 LS is preferably substantially perpendicular to the longitudinal axis of first screw  18 US. A spring  18 LB may be disposed between vial holder  18 A and post  13 P. Preferably, spring  18 LB is disposed around screw  18 LS. 
   In order to adjust level vial  18  about the first axis, screw  18 US is rotated. Persons skilled in the art will recognize that, when screw  18 US is rotated, holder  18 A will rotate about the longitudinal axis of screw  18 LS. Spring  18 UB biases holder  18 A away from post  13 P and into the head of screw  18 US to maintain holder  18 A in the desired position. The screw  18 US may be fixed by a locking compound, such as Loc-Tite. 
   To adjust level vial  18  about the second axis, screw  18 LS is rotated. Persons skilled in the art will recognize that, when screw  18 LS is rotated, holder  18 A will rotate about the longitudinal axis of screw  18 US. Spring  18 LB biases holder  18 A away from post  13 P and into the head of screw  18 LS to maintain holder  18 A in the desired position. The screw  18 LS may be fixed by a locking compound, such as Loc-Tite. 
   Persons skilled in the art will recognize that level vials  16 ,  17  can be provided on assemblies similar to that used with level vial  18  and adjusted accordingly. 
     FIG. 12  illustrates several lenses  15 L to generate laser beam LB, laser line LL and spot LS. Referring to  FIG. 12A , the laser diode  14 D with or without a collimating lens  14 L generate a laser beam having a width LH. Lens  15 L is substantially cylindrical and having a diameter which is smaller than width LH. Accordingly, part of the beam goes through lens  15 L, generating laser beam LB and laser line LL. Two other parts of the beam bypass, i.e., do not go through, lens  15 L. These parts generate two bright spots LS. 
     FIG. 12B  illustrates another embodiment of lens  15 L, where like numerals refer to like parts, and all the teachings from the previous embodiments are incorporated herein. As before, lens  15 L is substantially cylindrical and has a diameter which is smaller than width LH. Accordingly, part of the beam goes through lens  15 L, generating laser beam LB and laser line LL. Another part of the beam bypasses, i.e., does not go through, lens  15 L. This part generates one bright spot LS. 
     FIG. 12C  illustrates a further embodiment of lens  15 L, where like numerals refer to like parts, and all the teachings from the previous embodiments are incorporated herein. Unlike before, lens  15 L has a width that is preferably larger than width LH. Lens  15 L may have a rectangular cross-section with two half-cylinders  15 LHC disposed thereon. The half-cylinders  15 LHC are preferably separated at portion  15 LS. Each half-cylinder  15 LHC may have a radius which is smaller than width LH. Accordingly, two parts of the beam goes through half-cylinders  15 LHC generating laser beam LB and laser line LL. Another part of the beam goes through portion  15 LS. Because such part is preferably not refracted, it goes straight through lens  15 L. This part generates one bright spot LS. 
     FIG. 12D  illustrates another embodiment of lens  15 L, where like numerals refer to like parts, and all the teachings from the previous embodiments are incorporated herein. As before, lens  15 L has a width that is preferably larger than width LH. Lens  15 L may have a rectangular cross-section with two half-cylinders  15 LHC disposed thereon. Unlike before, the half-cylinders  15 LHC are preferably separated by a channel  15 LC which extends through lens  15 L. Accordingly, each half-cylinder  15 LHC may have a radius which is smaller than width LH. With such arrangement, two parts of the beam goes through half-cylinders  15 LHC generating laser beam LB and laser line LL. Another part of the beam goes through lens  15 L via channel  15 LC. This part generates one bright spot LS. 
     FIG. 12E  illustrates yet another embodiment of lens  15 L, where like numerals refer to like parts, and all the teachings from the previous embodiments are incorporated herein. As before, lens  15 L has a width that is preferably larger than width LH and preferably has a channel  15 LC which extends through lens  15 L. Unlike before, lens  15 L may have a circular cross-section. Accordingly, part of the beam goes through lens  15 L, generating laser beam LB and laser line LL. Another part of the beam goes through lens  15 L via channel  15 LC. This part generates one bright spot LS. 
     FIG. 12F  illustrates another embodiment of lens  15 L, where like numerals refer to like parts, and all the teachings from the previous embodiments are incorporated herein. Lens  15 L has a semi-circular cross-section, with a flat surface  15 LFS being substantially parallel to the laser beam. Accordingly, part of the beam goes through lens  15 L, generating laser beam LB and laser line LL. Another part of the beam bypasses, i.e., does not go through, lens  15 L. This part generates one bright spot LS. 
     FIG. 12G  illustrates another embodiment of lens  15 L, where like numerals refer to like parts, and all the teachings from the previous embodiments are incorporated herein. Lens  15 L has a semi-circular cross-section, with flat surface  15 LFS being inclined relative to the laser beam. Accordingly, part of the beam goes through lens  15 L, generating laser beam LB and laser line LL. Another part of the beam bypasses, i.e., does not go through, lens  15 L. This part generates one bright spot LS. 
   Referring to  FIGS. 1 and 13 , and as discussed above, line generating device  10  may be disposed on table assembly  40 . Preferably, table assembly  40  has a base  43 , a deck  41  pivotably connected to base  43 , and feet  45  threadingly engaged to base  43 . Accordingly, a user can adjust the table assembly  40  (and thus line generating device  10 ) by moving deck  41  and/or rotating each foot  45 . 
   Deck  41  preferably has opening  40 P which receives protrusions  12 RC,  12 SC of line generating device. In addition, deck  41  may have a spherical portion  41 S which mates with spherical cavity  43 S of base  43  to allow rotation of deck  41  relative to base  43  along many different axes. Part of portion  41 S may extend through base  43  and terminate in snap hooks  41 SH to maintain the deck  41  connected to base  43 . It is also preferable to provide deck  41  with a bore  41 H therethrough, possibly with a peep hole  41 P near the snap hooks  41 SH. In this manner, the user can look through bore  41 H and peep hole  41 P to locate a point L (see  FIG. 5 ). The user can then project a spot on a ceiling right above point L, as discussed previously. 
   Persons skilled in the art will recognize that it is preferable to provide enough friction between the spherical portion  41 S and spherical cavity  43 S to maintain the deck  41  in a desired position when line generating device  10  is provided thereon. 
   It may also be preferable to provide deck  41  with a feature  41 C which receives a bump  12 B of line generating device  10 . Accordingly, when the bump  12 B is aligned with feature  41 C, the user can rotate both the line generating device  10  and deck  41  while touching only line generating device  10 . 
   Persons skilled in the art will recognize that deck  41  may have stops  41 TS provided thereunder to limit the adjustment range of deck  41  relative to base  43 . 
     FIG. 14  shows another embodiment of table assembly  40 , where like numerals refer to like parts, and all the teachings of the previous embodiment are wholly incorporated by reference. In this embodiment, feet  45  are not threadingly engaged to base  43  (though persons skilled in the art will recognize that such feet  45  can be provided thereon). In addition, the portion of deck  41  extending through base  43  may have outer threads  41 T for threadingly engaging a nut  46 . A user can rotate nut  46  to lock the position of deck  41  relative to base  43 . 
   It may be advantageous to provide a spherical cup  44  between a wall defining the spherical cavity  43 S and nut  46  to better hold deck  41  relative to base  43 . 
     FIG. 15  shows another embodiment of table assembly  40 , where like numerals refer to like parts, and all the teachings of the previous embodiments are wholly incorporated by reference. In this embodiment, deck  41  is integrated into base  43 . In other words, deck  41  cannot rotate relative to base  43 . 
   Referring to  FIG. 16 , a hanging assembly  50  is provided for hanging line generating device  10  from a nail or screw on a wall. Hanging assembly  50  may have a body  51  defining a cut-out  52  for receiving the head of the nail or screw. A washer  53  may be disposed on a shoulder  51 S of body  51  and held in place by snap hooks  54 . Washer  53  may have wings  53 W to better engage the snap hooks  54 . Preferably washer  53  is made of a ferromagnetic material. 
   To assemble such hanging assembly  50 , washer  53  just needs to be pushed into body  51 . Snap hooks  54  will preferably capture washer  53 . 
   With such arrangement, the user can hang the hanging assembly  50  from a nail or screw, then mount line generating device  10  thereon by inserting protrusion  12 SC into body  51 . Magnet  12 M will preferably magnetically engage washer  53  and keep line generating device  10  on hanging assembly  50 . 
   It is also preferable to provide a pin assembly  60  for hanging line generating device  10  on a vertical surface without any screws or nail. Referring to  FIG. 17 , pin assembly  60  may have a body  61  and a washer  62  rotatably captured within body  61  by snap hooks  61 SH and shoulder  61 S. Washer  62  may have a flange  62 F to better engage the snap hooks  61 SH. Preferably washer  62  is made of a ferromagnetic material. 
   Pin assembly  60  may also include a retractable pin assembly  63 , which in turn may have pin  63 P and a body  63 B molded over or attached to pin  63 P. Pin  63 P and part of body  63 B can extend through a hole  62 H in washer  62 . A torsion spring  64  may be attached to body  63 B and body  61  and disposed between washer  62  and body  61  to bias body  63 B away from body  61 . 
   Body  63 B may have a ramp  63 R to capture washer  62 . Preferably ramp  63 R has a low slope so that an assembler can slip washer  62  unto body  63 B past ramp  63 R without damaging ramp  63 R. On the other hand, if somebody tries to remove washer  62 , ramp  63 R should prevent such removal. 
   Preferably pin  63 P is movable between a retracted position where pin  63 P is covered by body  61  and an extended position where pin  63 P extends beyond body  61 . It may be desirable to provide a mechanism to prevent unintentional movement of pin  63 P from the retracted position to the extended position. 
   Body  61  may have a hole  61 H that allows part of body  63 B to extend therethrough when pin  63 P is in the extended position. Hole  61 W maybe shaped to receive the flanges  63 W of body  63 B. Spring  64  preferably torsionally rotates body  63 B so that flanges  63 W are not aligned with hole  61 H. Accordingly, the user would need to rotate the body  63 B so that flanges  63 W are aligned with hole  61 H. When flanges  63 W and hole  61 W are aligned, the user can push the body  63 B into body  61 , thus moving pin  63 P into the extended position. 
   With such arrangement, the user would place pin assembly  60  on a wall, as shown in  FIG. 17B . The user would then rotate the body  63 B so that flanges  63 W are aligned with hole  61 H. When flanges  63 W and hole  61 H are aligned, the user can push the body  63 B into body  61 , thus moving pin  63 P into the extended position and inserting pin  63 P in the wall, as shown in  FIG. 17C . 
   Persons skilled in the art will recognize that it is preferable that pin  63 P does not have a substantially circular cross-section, so that the pin  63 P does not rotate within the hole created in the wall. Instead, it would be preferable for the pin  63 P to have a polygonal cross-section, such as a triangle, or at least one flat surface. 
   It is preferable that the washer  62  has protrusions  62 P that extend through holes  63 H in body  63 B. Accordingly, when the pin  63 P is in the extended position, the protrusion  12 SC of line generating device can be inserted into body  61  and magnetically engage washer  62 . 
   Indicia  63 I and  61 I may be provided on bodies  63 B and  61 , respectively, to indicate the location of protrusions  63 W relative to hole  61 H, or in other words, the location where user can press body  63 B into body  61 . 
     FIG. 18  illustrates an alternate body  61 , where like numerals refer to like parts. All the teachings of the previous embodiment are hereby incorporated by reference. Body  61  has a cylinder  61 C disposed therein. Cylinder  61 C has the hole  61 H that allows pin  63 P to extend therethrough. Walls  61 CW extend between the cylinder  61 C and body  61  to support cylinder  61 C and/or act as a shoulder for washer  62 . 
   Cylinder  61  may have a stop protrusion  61 R for each flange  63 W, which contacts flanges  63 W when pin  63 P is in the retracted position. As before, the user may rotate pin  63 P until flanges  63 W align with channel  61 PO between stop protrusions  61 R, allowing the user to move pin  63 P to the extended position. It may be preferable to provide a ramp  61 R between stop protrusion  61 R and channel  61 PO so that, if the pin  63 P is rotated out of engagement with stop protrusion  61 R but not far enough to reach channel  61 PO, pressure on body  63 B will cause rotating of pin  63 P towards channel  61 PO. 
   Cylinder  61 C may have a slot  61 SS for receiving and/or capturing spring  64 . 
   While the invention has been described in this specification and illustrated in the drawings with reference to a preferred embodiment it would be understood by those skilled in the art that various changes may be made and equivalence may be substituted for elements thereof without departing for the scope of the invention as defined in the claims.