Abstract:
A power tool includes a leveling device which includes a rotatable member which seeks an equilibrium position which corresponds to a level position. A rotating device includes a member which enables passage of a beam. An electrical circuit which includes an emitting device, a receiving device and an indicating device is electrically coupled such that upon activation, the emitting device emits a beam which passes through the beam passing member. The beam is received by the receiving device which, in turn, activates the indicator device. The indicator is generally a light emitting device which has a varying brightness so that the user may view the indicator from all sides of the power tool.

Description:
FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to power tools and, more particularly, to a leveling device that indicates when the power tool is in a level position. 
     In various types of power tools, especially drilling tools, it is desirable to know when the tool is in a horizontal or vertical plane. This is particularly useful when drilling holes for hanging doors or the like when it is desirable to have holes which are in plane with horizontal. 
     Bubble types of levels have been utilized in power tools. However, these types of leveling devices have various shortcomings. While the bubble level works satisfactorily for horizontal applications, it is still burdensome on the user to view the bubble in between the lines. Ordinarily, these bubble types of levels are not conducive for vertical drilling. Also, due to the vibration of the tool, frothing occurs inside the level, rendering the bubble level useless in many applications. 
     Another type of measuring device utilizes a simple pendulum with a rigid straight bar connecting the pivot point with a hanging weight together with a cross bar mounted at ninety (90°) degrees to a vertical bar. The cross bar can be disposed on either side of the pivot point when the pivot level is hung and the weight achieves equilibrium, the cross bar will be positioned in a horizontal plane. Accordingly, the ends may be aligned with two notches on a carrier board to align the board to the horizontal and thus measure the horizontal plane. 
     Both of these devices require the user to have an accurate view of the level during drilling to maintain the plane of the power tool. Also, while these types of devices may be satisfactory in horizontal drilling planes, they are not particularly useful when used in a vertical drilling arrangement. 
     Accordingly, it is an object of the present invention to provide a user with an easy to use leveling device. The device indicates to the user, usually by an illuminated light, that horizontal or vertical planes have been achieved. The present invention enables the user to readily establish visual contact to indicate that a desired level position has been achieved. 
     SUMMARY OF THE INVENTION 
     In accordance with a first embodiment of the present invention, a power tool leveling device comprises a housing with a cavity in the housing. A rotating member is positioned in the housing. The rotating member moves in the cavity such that the rotating member seeks an equilibrium position. The equilibrium position corresponds to a level position. At least one member is associated with the rotating member to enable passage of light through the rotating member. An electrical circuit is associated with the rotating member. The electrical circuit includes an emitting device, a receiving device, and an indicator device. These devices are electrically coupled such that upon activation, the emitting device emits a beam which passes through the at least one member. The beam is received by the receiving device which, in turn, activates the indicator device. The indicator device informs a user that the leveling device is in an equilibrium position. Also, a power source is coupled with the electrical circuit to energize the electrical circuit. The electrical circuit further includes a device for varying current to the indicator device such that as the beam intensity at the receiver device increases, the indicator device increases in intensity. This corresponds to leveling; e.g., as the tool becomes more level, the intensity increases. The device for varying the current is a PNP transistor. The indicator device is a light emitting device. The light emitting device has a variable intensity from off to full on. In the full on position the leveling device is in its level position. The at least one member in the rotating member is an aperture. In an alternate embodiment, the aperture includes a lens for refracting the beam. In a second alternate embodiment, a lens is positioned between the rotating member and the receiving device to refract the beam. Also, the at least one aperture may be an elongated slot. Further, the at least one member may be an optic fiber to transmit the beam. Also, a switch is coupled with the leveling device for activating and deactivating the electrical circuit. 
     In accordance with a second aspect of the invention, a power tool comprises a housing with a motor in the housing. An output is coupled with the motor. An activation member to energize the motor for rotating the output is coupled with the motor. A power source is electrically coupled with the motor and activation member. A leveling device is present in the housing. The leveling device comprises a housing with a cavity in the housing. A rotating member is positioned in the housing. The rotating member moves in the cavity such that the rotating member seeks an equilibrium position. The equilibrium position corresponds to a level position. At least one member is associated with the rotating member to enable passage of light through the rotating member. An electrical circuit is associated with the rotating member. The electrical circuit includes an emitting device, a receiving device, and an indicator device. These devices are electrically coupled such that upon activation, the emitting device emits a beam which passes through the at least one member. The beam is received by the receiving device which, in turn, activates the indicator device. The indicator device informs a user that the leveling device is in an equilibrium position. Also, a power source is coupled with the electrical circuit to energize the electrical circuit. The electrical circuit further includes a device for varying current to the indicator device such that as the beam intensity at the receiver device increases, the indicator device increases in intensity. This corresponds to leveling; e.g., as the tool becomes more level, the intensity increases. The device for varying the current is a PNP transistor. The indicator device is a light emitting device. The light emitting device has a variable intensity from off to full on. In the full on position the leveling device is in its level position. The at least one member in the rotating member is an aperture. In an alternate embodiment, the aperture includes a lens for refracting the beam. In a second alternate embodiment, a lens is positioned between the rotating member and the receiving device to refract the beam. Also, the at least one aperture may be an elongated slot. Further, the at least one member may be an optic fiber to transmit the beam. Also, a switch is coupled with the leveling device for activating and deactivating the electrical circuit. 
     In accordance with a third aspect of the invention, a power tool comprises a housing with a motor within the housing. An output is coupled with the motor. An activation member energizes the motor to rotate the output which is coupled with an output source and the motor. A leveling device is coupled with the power tool. The leveling device includes an indicator such that upon activation of the leveling device the indicator indicates to a user that the leveling device is in an equilibrium position. The leveling device is also coupled with the power source. The indicator is positioned on the housing such that a user may view the indicator from all sides of the housing when the power tool is in use. The indicator varies in intensity as the leveling position is reached. The indicator is ordinarily a light emitting device. Accordingly, the light emitting device varies in brightness, being brightest when the power tool is in the level position. Also, a switch is coupled with the activation member for activating the leveling device prior to activating the motor. 
     From the following detailed description, taken in conjunction with the drawings and subjoined claims, other objects and advantages of the present invention will become apparent to those skilled in the art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view partially in section of a drill with a leveling device in accordance with the present invention. 
     FIG. 1 a  is a partial rear perspective view of the drill of FIG.  1 . 
     FIG. 2 is a cross-section view of FIG. 1 along lines II—II thereof. 
     FIG. 3 is an exploded perspective view of a level indicator in accordance with the present invention. 
     FIG. 4 is a schematic view of the electrical circuit of the leveling device. 
     FIG. 5 is a section view of an alternate embodiment of a leveling device. 
     FIG. 6 is a cross-section view of an alternate embodiment of the present invention. 
     FIG. 7 is a perspective view of an alternate embodiment of the present invention. 
     FIG. 8 is a cross-section view of an alternate embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning to the figures, FIG. 1 illustrates a power tool in accordance with the present invention and is designated with the reference numeral  10 . The power tool  10  is illustrated as a drill; however, any type of power tool such as a screwdriver, sander, rotary tool, clippers, hedge trimmer, saw or the like may be utilized with the level indicator in accordance with the present invention. The power tool  10  includes a housing  12  which includes two halves  14  which surround a motor  18 . An activation member  20  is coupled with the motor as well as with a power source  22 . The power source  22  may be a power cord (AC current) or the power tool may have a battery (DC current) as shown. The motor  18  is coupled with an output  24  which may include a transmission  26  and a chuck  28  to retain the tool with the drill. 
     A level indicator  30  is positioned in the housing half  14 . The level indicator  30  includes a housing  32  and circuitry  34 . Turning to FIG. 3, the level indicator housing  32  includes two halves  36  and  38  which are secured together, preferably by a snap fit. A rotatable member  40  is rotatably positioned within the housing half  36 . The rotatable member  40  has an overall disc shape with an axle  42  extending through the center of the rotatable member  40 , and with the axle ends in blocks  43 . Also, apertures  44 , preferably four in number, are formed in the disc  40 . Also, a counter-weight  46  is coupled with the rotating member  40 . 
     The rotatable member  40  rotates within a cavity  48  in the housing halves  36  and  38  about the axle  42 . The counter-weight  46  provides a weighted side of the rotatable member  40  so that the rotatable member  40  is always seeking an equilibrium position. The apertures  44  are positioned about the rotatable member  40  at zero (0°) degrees, ninety (90°) degrees, one hundred eighty (180°) degrees, and two hundred seventy (270°) degrees about a three hundred sixty (360°) degree circle of the rotating member  40 . The apertures  44  have a desired size, preferably with a diameter of 0.5 mm. which enables sensing as will be described herein. The rotatable member  40  rotates throughout three hundred sixty (360°) degrees within the housing  32  as the power tool is manipulated. 
     Circuitry  34  is best defined in FIG.  4 . Broadly speaking, the circuitry includes a light emitter  50 , a light receiver  52  and an indicator  54 . Lead  56  extends from the power source  22  to switch  58 . Lead  60  leads from the switch  58  to the emitter  50 . Also, a resistor R 1  is electrically coupled in lead  60 . R 1  may have a value as illustrated in Chart 1 below, varying with the voltage of the power source. Lead  60  is coupled with lead  64  which electrically couples the switch with the receiver  52 . Lead  64  extends from lead  60  to the receiver  52 . A pair of resistors R 2  and R 3  are electrically coupled in lead  64  extending to the receiver  52 . Lead  60  is electrically coupled with lead  66 . Lead  66  is electrically coupled with the indicator  54 . Transistor Q 1  is electrically coupled in lead  66 . Transistor Q 1  is a PNP transistor. Thus, a base lead  68  is coupled with lead  64  between resistors R 2  and R 3 . A fourth resistor R 4  is coupled with lead  66  between the transistor Q 1  and the indicator  54 . Further, lead  70  is coupled with the power source  22 , leads  62 ,  64  and  66 . 
     The emitter  50  is preferably an infrared emitter generating a stream of light towards the receiver  52 . Preferably, the emitter  50  is axially positioned 2:1 mm. away from the rotatable member  40 . The receiver  52  is preferably a phototransistor to receive the light generated from the infrared LED  50 . Preferably, the phototransistor  52  is axially positioned 1.5 mm. away from the rotatable member  40 . The indicator  54  is preferably an LED having a desired color such as red. 
     The leveling device  30  operates as follows. The trigger  17  of the activation member  20  is pushed inward to contact switch  58 . As this occurs, the circuit is activated. However, the switch  58  is activated before the motor  14 . Upon activation of the switch  58 , the circuit is closed so that current moves through the lead  60 . As current moves through the lead  60 , current passes to the emitter  50  turning on the emitter  50  generating a light beam  72 . If the rotatable member  40  is in a non-level or non-equilibrium position, the apertures  44  do not align with the beam  72  and therefore light does not pass across the rotatable member  40  and light is not sensed by the receiver  52 . In this case, the indicator  54  does not illuminate. This is due to the fact that the current at lead  68  is blocked and therefore the transistor Q 1  does not allow current to pass to the indicator LED  54 . 
     Once the leveling device approaches an equilibrium or level position so that the power tool is on or near a horizontal or vertical plane, one of the apertures  44  is in alignment with the beam  72  from the infrared LED  50 . As this occurs, the beam  72  passes through the rotatable member  40 . The beam  72  is sensed by the phototransistor receiver  52 . As this occurs, the receiver phototransistor  52  is energized. As this occurs, current passes from lead  60  through lead  64  to lead  70  completing that circuit. As this happens, the current in base lead  68  is conductive. As the transducer Q 1  senses the change in current between the emitter and base, current begins to flow from the collector to the emitter along lead  66 . As this occurs, current flows to indicator LED  54  illuminating the indicator  54 . 
     Since small apertures  44  are used which may have a conical shape, the beam intensity increases through the rotatable member  40 , as the rotatable member  40  becomes more level and the apertures  44  are centered and directly in line with the beam  72 . As this occurs, the receiver phototransistor  52  senses a higher intensity in the beam  72 . Thus, more current passes through the phototransistor  52 . As this occurs, the current sensed by the base of the transistor Q 1  increases in lead  68 . As this occurs, the transistor Q 1  senses an increase in base current of the PNP transistor. As this occurs, the PNP transistor Q 1  enables more current to pass through it which, in turn, increases the intensity of the illumination of the indicator  54 . Thus, a variable output is established. The indicator  54  varies in intensity from off to its brightest point when the leveling device is in its most level position. 
     A plus or minus six (6°) degree range from level is present where the light goes on. When the tool is further than six (6°) degrees away from level, the light is in an off position. When the power tool comes within the six (6°) degrees of level range, the light begins to turn on. As the light hits the level position, the light at its brightest. As it approaches the other side of the six (6°) degrees (positive or negative), the light would again go off. Thus, the user can determine if he is high or low of the level position when the light is the brightest. 
     A chart is provided below which provides the values of R 1 , R 2 , R 3  and R 4  in the above circuit diagram. Note that the values of R 1  and R 4  vary depending upon the voltage of the power source. 
     
       
         
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
               
               
                 VOLTAGE 
                 R 1   
                 R 2   
                 R 3   
                 R 4   
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 9.6 
                 1.8 K 
                 10 K 
                 10 K 
                 1.8 K 
               
               
                 12.0 
                 3.3 K 
                 10 K 
                 10 K 
                 2.2 K 
               
               
                 14.4 
                 4.3 K 
                 10 K 
                 10 K 
                 2.7 K 
               
               
                 18.0 
                 6.8 K 
                 10 K 
                 10 K 
                 3.5 K 
               
               
                   
               
             
          
         
       
     
     The indicator LED  54  is positioned between the housings at a top rear position of the tool. When the tool is used by a user, the user ordinarily is positioned behind the tool. Also, as illustrated in FIGS. 1 and 1 a , the indicator LED is ordinarily positioned above the contour of the housing so that the LED can be viewed by the user from all sides and angles of use of the drill. Thus, the user can readily view whether or not the light is illuminated and the power tool is level. 
     As can be seen in FIG. 1, the activation member  20  includes trigger  80  for activating the motor. The trigger  80  includes a plunger shaft  82  as well as a leaf contact actuator  84 . The leaf contact actuator  84  contacts the micro-switch  58  for activating the leveling circuit. The leaf contact actuator  84  contacts the leaf contact  86  which pushes down the plunger  88  actuating the switch  58 . 
     Turning to FIG. 5, a second embodiment of the leveling device is shown. Here, the leveling device is substantially similar to that as previously described. The difference is that lenses  90  are positioned in apertures  44  to enhance the refractiveness of the beam  72 . 
     Turning to FIG. 6, an additional embodiment is shown. Here, the embodiment is the same as previously described. However, a lens  92  is positioned between the rotative member  40  and the receiver  52  to enhance the beam passing through the apertures  44 . 
     Turning to FIG. 7, an additional embodiment is shown. FIG. 7 illustrates a rotatable member  40 ′. Here, the apertures  44 ′ have an elongated shape enhancing the variable output of the indicator  54 . 
     Turning to FIG. 8, an additional embodiment is shown. In FIG. 8, optic fibers  96  and  98  are positioned in rotatable member  40 ′. The optical members extend like spokes across the rotating member  40 . Also, the emitter  50  and receiver  52  are positioned radially with respect to the rotatable member. 
     While the above detailed description describes the preferred embodiment of the present invention, the invention is susceptible to modification, variation and alteration without deviating from the scope and fair meaning of the subjoined claims.