Patent Publication Number: US-2007107235-A1

Title: Light assembly for circular saw

Description:
BACKGROUND  
      The present invention relates to power tools, and in particular to a circular saw. Additionally, the present invention relates to a circular saw with a light source provided to illuminate the cutting line of the saw. The circular saw of the present invention improves on previous designs because it includes a light or a plurality of lights that illuminate the cutting line both in front of and behind the saw blade.  
     BRIEF SUMMARY  
      The present invention provides a light assembly for a circular saw. The circular saw includes a motor operatively connected to rotate a saw blade that forms a cutting plane and a fixed blade guard that surrounds a portion of the saw blade. The circular saw additionally includes at least one light source mounted to the fixed blade guard to emit a beam that forms a first linear optical alignment marker on a workpiece in a first direction and emits a beam that forms a second linear optical alignment marker on a workpiece in a second substantially opposite direction.  
      Advantages of the present invention will become more apparent to those skilled in the art from the following description of the preferred embodiments of the invention that have been shown and described by way of illustration. As will be realized, the invention is capable of other and different embodiments, and its details are capable of modification in various respects. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of one embodiment of a laser assembly of the present invention for a circular saw.  
       FIG. 2  is a second perspective view of the light assembly and circular saw of  FIG. 1 .  
       FIG. 3  is the view of the circular saw of  FIG. 1  with a portion of the fixed blade guard removed.  
       FIG. 4  is an exploded view of the circular saw of  FIG. 1  showing the components forming the light source.  
       FIG. 5  is an additional perspective view of the laser assembly of  FIG. 1 .  
       FIG. 6  is a perspective view of another embodiment of the laser assembly of the present invention mounted on a circular saw.  
       FIG. 7  is an exploded view of the circular saw of  FIG. 6  showing the components forming the rotatable light.  
       FIG. 8  is a cross-sectional view of another embodiment of the laser assembly of the present invention mounted on a circular saw. 
    
    
     DETAILED DESCRIPTION  
      Referring now to  FIGS. 1-5 , a first embodiment of a laser assembly mounted on a circular saw  10  is provided. The circular saw includes all of the components of conventional circular saws, including a motor (not shown) that is rotatably mounted to a saw blade  14  and surrounded by a housing  11 . As understood with reference to  FIG. 3 , a cutting plane  26  is formed that extends through the center plane of the saw blade  14 . The housing  11  includes a handle  16  and is preferably pivotably mounted to a base plate  12  to allow the cutting depth of the saw blade  14  to be adjusted. Additionally, a trunnion plate  24  may be provided that extends from the base plate  12  and receives a post (not shown) that is connected to the housing  11  to allow the saw blade  14  to be retained within a range of bevel angles with respect to the base plate  12 . The circular saw includes a motor switch  20  that operatively connects the motor to a source of electrical current, either from an external AC source, or with a DC source from a rechargeable battery  19  that may be releasably mounted to the circular saw  10 .  
      A fixed blade guard  30  is mounted to the housing  10  and positioned to enclose a portion of the saw blade  14 . As shown in  FIG. 3 , the fixed blade guard  30  is mounted to enclose a top portion  14   a  of the saw blade  14  to prevent the user from contacting the rotating saw blade  14  during operation of the circular saw. In some embodiments, a lower blade guard  18  may be pivotally attached to the fixed blade guard  30 . The lower blade guard  18  is normally slidably attached to the fixed blade guard  30  and biased to a position where the lower blade guard  18  encloses a bottom portion (not shown) of the saw blade. As is understood by those of skill in the art, the lower blade guard  18  normally covers the bottom portion of the saw blade  14  and retracts into the fixed blade guard  30  when the circular saw encounters a workpiece (not shown) to be cut at front end of the circular saw  10 .  
      Referring to  FIGS. 1 and 3 , the fixed blade guard  30  is preferably formed from two clam shell halves (with one of the two halves  30   a  shown in  FIG. 3 , and the assembled fixed blade guard  30  shown in  FIG. 1 ). In some embodiments, the fixed blade guard  30  is formed with a front cavity  32  and a rear cavity  34 . The front cavity  32  can receive a forward light source  50  and the rear cavity  34  can receive a rear light source  70 . Each of the front and the rear cavities  32 ,  34  include a window  38 ,  39  respectively, to provide an opening for a light beam emitted from the respective light source  50 ,  70 .  
      In some embodiments, the windows  38 ,  39  may be formed with an opening in the surface of the fixed blade guard  30  to allow the light beam to escape. In other embodiments, the windows  38 ,  39  may be formed from clear plastic, glass or other substantially transparent materials. In other embodiments, the lower blade guard  18  includes a slot (not shown) to allow the light beam to escape the lower blade guard  18 .  
      Each of the forward light source  50  and the rear light source  70  are formed with the same components and attached to the fixed blade guard  30  in the same manner. Therefore, only one of the light sources will be fully described with the element numbers being the same for the same components in both the front and rear light sources  50 ,  70 .  
      Each of the front and rear light sources  50 ,  70  are preferably provided with laser generators that emit a planar light or beam. The light sources  50 ,  70  include a laser that emits a beam that is converted to a planar laser source with a lens. In other embodiments, the light sources  50 ,  70  may be provided with LEDs or other types of lights from which a planar light can be emitted.  
      Each of the light sources  50 ,  70  includes a light emitter  60 , a housing  52  that surrounds a majority of the light emitter  60  and is movable with respect to the fixed blade guard  30 , and structure to allow for desired movement of the light sources  50 ,  70  with respect to the fixed blade guard  30 .  
      The light emitters  60  may be powered from the same power source as the circular saw motor (not shown) or may be powered from a power source different than that which powers the motor. The power source can be AC power with the current to operate the light emitters  60  being transformed and rectified to useable DC current as is understood by those of ordinary skill in the art. The power source can also be DC power from a variety of sources, including rechargeable batteries.  
      The front light source  50  and the rear light source  70  may be operated by a light switch  22  that is mounted to the housing  11  or may be operated upon actuation of the motor switch. In other words, the light sources  50 ,  70  can be operated independently from the operation of the saw blade  14  can be wired to be operated whenever the motor is operates.  
      The light emitter  60  is partially enclosed and supported within an internal cavity  52   b  within the housing  52 . The housing  52  surrounds a side circumference surface  60   a  of the light emitter  60  and includes the structure to rigidly support the light emitter  60  with respect to the housing  52 , as discussed below. The housing includes an opening  52   a  that allows the light emitted from the light emitter  60  to exit the respective light source  50 ,  70  and be directed toward the workpiece.  
      A lateral slot  54  extends from the housing  52  opposite from the opening  52   a . The slot is oriented perpendicular to the length of the housing  52 . The slot  54  receives a fastener  55  ( FIG. 4 ) that extends through the slot  54 . The fixed blade guard  30  includes a hole  56  that receives the fastener  55 . Because the fastener  55  is fixed to the fixed blade guard  30 , the length of the lateral slot  54  establishes the limits of movement of the respective light source  50 ,  70  in a direction substantially perpendicular to the cutting plane  26  of the saw blade  14 .  
      The light emitter  60  may be adjustably mounted to the housing  52  with at least one screw  62  as shown in  FIGS. 4 and 5 . The screw  62  is rotatably inserted into a tapped aperture  53  within the housing  52 . The screw  62  is accessible for rotation when the fixed blade guard  30  is assembled because the fixed blade guard  30  includes a plurality of apertures  35  positioned in-line with each of the screws  62  to allow the user to rotate each screw  62  without disassembling the fixed blade guard  30 .  
      In the embodiments shown in  FIGS. 4 and 5 , a first screw and a second screw  62 ,  62   a  are provided for each housing  52 . A first screw  62  is rotatably inserted into a first tapped aperture  53  that is in line with a tab  65  (best shown in  FIG. 4 ) in the light emitter  60 . The tab  65  extends from the bottom side of the light emitter  60  and extends downward into the housing  52  when the light emitter  60  is positioned within the housing  52 . An end of the first screw  62  engages the tab  65  when the first screw  62  is sufficiently inserted into the first tapped aperture  53 . A first spring  64  is positioned between the opposite side of the tab  65  and a wall of the housing  52  opposite the wall with the tapped aperture  53 . The first spring  64  is compressed with all positions of the tab  65  to constantly bias the tab  65  toward the first screw  62 .  
      Rotation of the first screw  62  in a first direction causes motion of the first screw  62  toward the tab  65 , which causes the light emitter  60  to rotate in a first direction about the longitudinal axis  60   b  of the light emitter  60  and further compresses the first spring  64 . Rotation of the first screw  62  in the opposite direction causes motion away from the tab  65 , which causes the light emitter  60  to rotate in the opposite direction and partially decompressing the first spring  64 . The threaded connection between the first screw  62  and the first tapped aperture  53  in the housing retains the light emitter  60  in the selected rotational position.  
      The housing  52  includes a second tapped aperture  53   a  that is positioned to receive a second screw  62   a . The second tapped aperture  53   a  is oriented rearward of the first tapped aperture  53  and preferably in-line with a longitudinal axis  60   b  of the light emitter  60 . A second screw  62   a  is inserted within the second tapped aperture  53   a  to contact the body section  60   a  of the light emitter  60  along its longitudinal axis  60   b  rearward of the tab  65 . A second spring  64   a  is provided within the housing  52  and positioned in-line with the second screw  62   a  and between the housing  52  and the light emitter  60  on the opposite side from where the second screw  62   a  contacts the light emitter  60 . The second spring  64   a  is compressed with all positions of the second screw  62   a  to urge the light source in the horizontal direction perpendicular for the longitudinal axis  60   b  of the light emitter  60 .  
      Rotation of the second screw  62   a  in a first direction causes motion of the second screw  62   a  toward the light emitter  60  causing lateral motion of the light emitter  60  away from the second tapped aperture and further compressing the second spring  64   a . Rotation of the second screw  62   a  in the opposite direction causes reverse motion of the second screw  62   a  and allows the biasing force of the second screw  64   a  to cause lateral motion of the light emitter  60  toward the second tapped aperture  53   a . The threaded connection between the second screw  62   a  and the second tapped aperture  53   a  retains the light emitter  60  in the selected lateral position.  
      Normally, the forward and rear light sources  50 ,  70  are aligned so that the linear optical alignment marker that is emitted from each of the light sources  50 ,  70  is coplanar with the cutting plane  36 . Often during use, the circular saw  10  is subjected to vibration and mechanical shock that may over time change the alignment of the forward and rear light sources  50 ,  70  so that the optical alignment marker that is emitted from each no longer is coplanar with the cutting plane  26 . When the light sources  50 ,  70  need to be adjusted, the first and second screws  62 ,  62   a  may be selectively rotated to maintain the planar light beam emitted form the light emitter  60  in parallel with the cutting plane  26 , and to finely adjust the lateral position of light beam emitted from the light emitter  60  to maintain the planar light beam within the cutting plane  26 , as discussed above.  
      As shown in  FIGS. 6 and 7  a second embodiment of a laser assembly mounted on a circular saw  10  is provided. The second embodiment includes all of the components of conventional circular saws, including a motor (not shown) that is rotatably mounted to a saw blade  14  that forms a cutting plane  26  and surrounded by a housing  11 . The housing  11  includes a handle  16  and is preferably pivotably mounted to a base plate  12  to allow the cutting depth of the saw blade  14  to be adjusted. Additionally, a trunnion plate  24  may be provided that extends from the base plate  12  and receives a post (not shown) that is connected to the housing  11  to allow the saw blade  14  to be retained within a range of bevel angles with respect to the base plate  12 . The circular saw includes a motor switch  20  that operatively connects the motor to a source of electrical current, either from an external AC source, or with a DC source from a rechargeable battery that may be releasably mounted to the circular saw  10 .  
      A fixed blade guard  130  is mounted to the housing  10  and positioned to enclose a portion of the saw blade  14 . As with the embodiment discussed above, the fixed blade guard  130  is mounted to enclose a top portion of the saw blade  14  to prevent the user from contacting the rotating saw blade  14  during operation of the circular saw. In some embodiments, a lower blade guard (shown in  FIG. 3 ) may be pivotally attached to the fixed blade guard  130  as discussed in the embodiment above.  
      Referring to  FIG. 3  of the previous embodiment, the fixed blade guard  130  (as shown as  30  in  FIG. 3 ) is formed from two clam shell halves. The fixed blade guard  130  includes a cavity  134 , which is constructed in the same manner as the cavity  32 ,  34  that are described in the above embodiment. Specifically, the cavity  134  encloses a light source  50  that emits a linear optical alignment marker through a window  39  and is positioned within a housing  52  that is adjustable with the use first and second screws  62 ,  62   a  and first and second springs  64 ,  64   a  as discussed above in the previous embodiment. The cavity  134  can be positioned on either the front end of the fixed blade guard  130  to provide light from the light source  50  in front of the circular saw  10 , or alternatively (as shown in  FIG. 6 ), the cavity  134  can be positioned on the rear end of the fixed blade guard  130  to provide a light from the light source  50  behind the circular saw  10 .  
      A rotatable light  150  that is mounted to the trunnion plate  24  can be secured in a selected orientation. The rotatable light  150  emits a planar light beam that forms a linear optical alignment marker when it contacts a workpiece. Because the rotatable light  150  is rotatably securable on the trunnion plate  24 , the rotatable light  150  can provide a plurality of different functions depending on its orientation. The figures show a rotatable light  150  that is mounted on the trunnion plate  24  to emit a light in front of the circular saw  10 . It should be understood that the rotatable light  150  and associated components, discussed below, for rotatably mounting the light source on the trunnion plate  24  can be oriented oppositely so the rotatable light  150  can emit a light behind the circular saw  10 .  
      For example, the rotatable light  150  can be rotated so that the linear optical alignment marker is along the same plane with the cutting plane  26  when the base  12  of the circular saw  10  is on the workpiece. Alternatively, the rotatable light  150  may be rotated such that the linear optical alignment marker is parallel but offset from the cutting plane by a predetermined distance, which allows the linear optical alignment marker to serve as a virtual edge guide, which is a substitute for a fence (not shown). Thus, if the user moves the saw along the workpiece such that the linear optical alignment marker is co-linear with an edge of the workpiece, the saw will precisely make the intended cut on the workpiece.  
      The rotatable light  150  may be constructed with a laser generator that emits a planar beam, or alternatively from an LED or other type of light source known to those of skill in the art. The rotatable light  150  and the rear light source  134  may be operated with a dedicated light switch  22  located on the housing to allow for operation of the lights independently of the motor. In other embodiments, the light may be operated with the motor.  
      The structure to mount the rotatable light  150  to the trunnion plate  24  is shown in  FIG. 7 . The rotatable light  150  includes a body section  152  that is inserted into an aperture  142  in the trunnion plate  24 . The aperture  142  is formed with a tapered surface  144 . The tapered surface  144  is conical in that the diameter of the aperture  142  on the rear side  146  of the trunnion  24  is greater than the diameter of the aperture  142  at the front side  145  of the trunnion  24 . The body section  152  includes a conical section  154  that corresponds to the tapered surface  144  of the aperture such that the body section  152  fits tightly within the aperture  142  when the body section  152  is inserted into the trunnion plate  24 .  
      The body section  152  of the rotatable light  150  may be maintained within the trunnion plate  24  with a plate  160  that is connected to the rear side  146  of the trunnion plate  24 . A spring  162  is positioned between the rear end  156  of the body section  152  and the plate  160  to bias the body section  152  such that the conical surface  154  of the body section  152  is inserted into the tapered surface  144  of the aperture in the trunnion plate  24 . The rotatable light  150  can be freely rotated with respect to the trunnion plate  24  by urging the body section  152  rearwardly with respect to the trunnion plate  24  against the biasing force of the spring  162  until the conical surface  154  no longer contacts the tapered surface  144 . When the rotatable light  150  is positioned such that the linear optical alignment marker is located on the desired position on the workpiece, the user releases the body section  152 , which moves through the trunnion plate  24  due to the biasing force of the spring  162  until the conical surface  154  of the body section  152  engages the tapered surface  144  of aperture  142 . In this position, the spring  162  remains compressed and exerts a forward force on the body section  152 , which frictionally engages body section  152  and the trunnion plate  24  that aids in retaining the rotatable light  150  in the selected position.  
      The front end of the rotatable light  150  is attached to a cap  170 . The cap  170  provides an ergonomic surface for the user to manipulate to precisely rotate the rotatable light  150  and change the position of the linear optical alignment marker with respect to the workpiece. The cap  170  also allows the user to move the rotatable light  150  rearwardly with respect to the trunnion plate  24 . As discussed above, this rearward motion against the forward biasing force of the spring  162  disengages the contact between the conical surface  154  of the body section  152  and the tapered surface  144  of the trunnion plate  24  and allows the rotatable light  150  to be rotated to a new position. When the rotatable light  150  is in the desired position, the user releases the cap  170  allowing the spring  162  to reposition the body section  152  with respect to the trunnion plate  24  to retain the rotatable light  150  in the desired position.  
      A third embodiment of a laser assembly mounted on a circular saw  10  is provided as shown in  FIG. 8 . The circular saw  10  includes the components that are found on a conventional circular saw, including a motor (not shown) that is enclosed within a housing  11  and rotates a saw blade  14  through a cutting plane  26 . The circular saw  10  includes a base  12  that is the surface that contacts the workpiece when it is being cut and a handle  16 .  
      The circular saw  10  includes a fixed blade guard  230  that encloses a top portion of the saw blade  14  during operation. Additionally, the circular saw includes a lower blade guard (not shown in  FIG. 8 , but is similar to that shown as  18  in  FIGS. 1 and 3 ) that surrounds the remainder of the saw blade  14  when the circular saw is not cutting a workpiece, and is retractable into the fixed blade guard  230  when performing a cutting operation to expose the lower portion of the saw blade  14 .  
      The circular saw  10  includes a light source  250  that emits a planer light beam, which preferably is a laser beam but can be other types of light sources in other embodiments. Similarly to the above embodiments, the light source  250  may include with a light switch  22  that allows for operation of the light independently from the motor. Alternatively, the light source  250  may be operated with the motor. The light source  250  is constructed and operates similarly to the light sources  50 ,  70  discussed in detail in the first embodiment above and is formed with a housing ( 52 ), a light emitter ( 60 ), a plurality of screws ( 62 ) and springs ( 64 ) that are adjustable to adjust the position of the light source  250  (and therefore the orientation of the linear optical alignment marker that is shined on the workpiece) with respect to the fixed blade guard  230 . The fixed blade guard  230  includes a plurality of apertures (similar to element  35  in  FIG. 1 ) that allow for the operation of the screws  62  to position the light source  250  within the fixed blade guard  230 .  
      The light source  250  is oriented within the fixed blade guard  230  such that the single light source  250  provides a linear optical alignment marker both in front of the circular saw and behind the circular saw, as is shown in  FIG. 8 . The light emitted from the light source  250  shines through each of a front window  238  and a rear window  239  to allow the light to exit the fixed blade guard  230  and contact the workpiece. As with the embodiments discussed above, the windows  238 ,  239  may be formed by an opening in the surface of the fixed blade guard  230  to allow the light beam to escape, while in other embodiments the windows  238 ,  239  may be formed from clear plastic, glass, or other substantially transparent, material. In other embodiments, the lower blade guard  18  forms a slot to allow the light beam to escape the lower blade guard.  
      The light source  250  is positioned within a cavity  236  in the fixed blade guard  230  that provides space for the light source  250  to be oriented to allow the light beam to reach the cutting line both in front of and behind the circular saw  10 . In other embodiments, the light source may be positioned differently within the fixed blade guard  230  and provide a linear optical alignment marker both in front of and behind the circular saw  10 . For example, the light source  250  may be positioned to emit a first portion of its light beam into a mirror which reflects the light toward the workpiece to provide a linear optical alignment marker either in front of or behind the circular saw, with the light source  250  emitting a second portion of the light beam directly to the workpiece on the opposite side of the circular saw  10 . In other embodiments, the light source may emit a first portion of its light beam into a first mirror that reflects the light to provide a linear optical alignment marker in front of the circular saw and emits a second portion of its light beam into a second mirror that reflects the light to provide a linear optical alignment marker behind the circular saw.  
      It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting, and that it be understood that it is the following claims, including all equivalents, that are intended to define the spirit and scope of this invention.