Abstract:
A hand-held laser pointer is disclosed that comprises a laser module that is isolated from unwanted hand tremor motions of the laser pointer housing. A passive inertial stabilizer is utilized for stabilizing the laser module to suppress laser dot jitter associated with hand tremor. To achieve the above object, a collimated laser diode module is mounted on a stage that is suspended by a low-friction gimbal that pivots with respect to the housing of the pointer on two intersecting and mutually perpendicular axes. The inertial stage is coupled to the housing via a spring and damper.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to laser pointers. More particularly, the present invention relates to hand-held laser pointers. Even more particularly, the present invention relates to a hand-held laser pointer stabilized against hand tremor.  
         [0003]     2. Prior Art  
         [0004]     Various hand-held laser pointers have been taught for visually pointing out a target on, for example, a whiteboard, chart, map, or projected display. Laser pointers typically include a laser diode module that produces a collimated laser beam. The laser diode module is packaged within a housing and is battery powered. A user holds the pointer in one hand and directs the laser beam towards a target, generally during a presentation or the like.  
         [0005]     The effectiveness of such hand-held laser pointers for particularly pointing out a target is reduced by the unintentional tremor of the user&#39;s hand. Human tremor is an involuntary trembling or shaking of the muscles of the body associated with physical weakness, emotional stress, or excitement. The small angular movements of the hand from tremor impart undesirable motion to the laser pointer and its corresponding laser beam and image, which is generally a small dot indicating where the beam is striking the target. This unwanted motion is amplified as the distance between the laser diode and the target increases and generally results in visibly shaky movements of the laser dot. The jitter of the laser dot limits the user&#39;s pointing resolution which may distract an audience, expose nervousness and may act to discredit the user.  
         [0006]     To address this problem, some hand-held laser pointer devices have been taught that blink on and off, or create a pulsed laser beam. These devices mask the problem and do not stabilize the orientation of the laser light beam. Uninterrupted siting of the laser dot is additionally not achieved by this type of laser pointer.  
         [0007]     Other suggested means for coping with hand tremor while pointing a hand-held laser pointer include turning the laser on only momentarily, holding the pointer with both hands to reduce tremor, resting the pointing hand, wrist, or arm on a stable object, or connecting the pointing device directly to a stable object such as a podium. The lack of an adequate solution to this problem has prompted many to suggest that hand-held laser pointers should not be used during presentations.  
         [0008]     Artisans have made attempts to provide a laser pointer wherein the pointer is protected from damage when subjected to high frequency vibration and shock. For example, LaCroix, in U.S. Pat. No. 4,357,649, disclosed a laser pointer wherein the laser is protected from shock by supporting it with a cushion material at each end within its housing. It can be shown mathematically that the construction disclosed by LaCroix is inoperable for isolating the laser from low-frequency tremor as occurs when hand-held. The required natural frequency of the suspended laser must be significantly lower than the frequency of hand tremor. Hand tremor is small in magnitude and slow in frequency, less than 0.1 degree at 4 Hz frequency. A cushion means to support the laser transmits the majority of the unwanted low frequency hand tremor motions of the housing to the laser.  
         [0009]     Artisans have disclosed laser devices that point in a direction relative to the direction of gravity irrespective of the housing orientation. WU, in U.S. Pat. No. 6,035,540, teaches an industrial laser level using a hanging mechanism. The invention of WU requires that the pivot for the laser be significantly offset from the center of mass of the counterweighted pivoting assembly in order that the laser always points in the direction of gravity. The invention of WU continues pointing in a direction relative to the direction of gravity when the housing is tilted. NG, in U.S. Pat. No. 6,792,685, teaches a damped bearing assembly for a laser plumb that includes a spinning mass affixed to the pivoting laser assembly. Similar to WU, NG&#39;s invention only points in a direction relative to the direction of the gravity and is structurally designed for that purpose. The inventions taught by WU and NG are not sufficient to enable a laser to be both arbitrarily aimed in an arbitrary desired direction by pointing the housing while at the same time attenuating motions due to hand tremor.  
         [0010]     There is a need in the art for an improved hand-held laser pointer that substantially eliminates the effect of hand tremor on the direction of the laser beam produced by a hand-held laser pointer.  
       SUMMARY  
       [0011]     It is a primary object of the present invention to provide a hand-held laser pointer that suppresses or minimizes laser dot jitter associated with hand tremor.  
         [0012]     To meet the above object of the invention, a hand-held laser pointer is disclosed that generally comprises: 
        (a) a housing having an interior chamber and a longitudinal axis;     (b) a power source disposed within the interior chamber of the housing; and     (c) a laser module disposed within the interior chamber of the housing, the laser module being in electrical communication with the power source and operable for producing a laser beam, 
 
 wherein the laser module is passively inertially stabilized with respect to motion of the housing about at least one axis perpendicular to the longitudinal axis of the housing. 
       
 
         [0016]     In a preferred embodiment of a hand-held laser pointer operable for providing a laser beam having a direction defining a longitudinal axis, the laser pointer comprises: (a) a housing; (b) a laser module enclosed within the housing; (c) a power supply enclosed within the housing and in electrical communication with the laser module; (d) a counterweight rigidly attached to the laser module by a bridge, the laser module, counterweight and bridge collectively forming an inertial mass having a center of gravity disposed on the bridge; (e) a gimbal affixed to said housing and said bridge at the center of gravity of said inertial mass, said gimbal pivoting on two intersecting and mutually perpendicular axes; and (f) means for biasing said gimbal-mounted inertial mass to a neutral position with respect to said housing, said biasing means being operable for damping angular vibration between said inertial mass and said housing while enabling said laser pointer to be panned. The counterweight is preferably adjustable towards and away from said mutually perpendicular pivot axes of said gimbal. The means for biasing the inertial mass to a neutral position preferably employs a magnetic field interaction between a magnetic or ferromagnetic first material disposed on the inertial mass, and a ferromagnetic or magnetic second material affixed to said housing. An electrically conductive non-magnetic material may be disposed on the inertial mass in proximity to a second magnetic material affixed to the housing. The magnetic interaction therebetween provides a damping effect by the generation of eddy currents therein. Preferably, the magnetic material is movably mounted to the housing and adjustable towards and away from the conductive non-magnetic material disposed on the inertial mass.  
         [0017]     The laser assembly is mounted to a pitch and yaw inertially stabilized frame disposed within the housing that provides for pivoting of the laser assembly with respect to the housing about two axes that are orthogonal to the longitudinal axis and to each other. The inertial stabilization is accomplished passively. The laser assembly serves as an inertial mass that is balanced to be substantially free from gravitational influence while gimballed to the housing. The inertial mass is spring biased to a neutral position with respect to the housing. A damping element may be positioned interior the housing and is provided to improve stabilization.  
         [0018]     Low frequency angular movements of the housing are transmitted to the laser assembly while angular movements of the housing substantially at or above a predetermined frequency and, preferably, in a range similar to the frequencies associated with hand tremor, are isolated from the laser assembly.  
         [0019]     The features of the invention believed to be novel are set forth with particularity in the appended claims. However the invention itself, both as to organization and method of operation, together with further objects and advantages thereof may be best understood by reference to the following description taken in conjunction with the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a perspective view of a tremor-stabilized, hand-held laser pointer in accordance with the present invention.  
         [0021]      FIG. 2  is a side plan view of the laser pointer of  FIG. 1 .  
         [0022]      FIG. 3  is a schematic view of a gimbal included in a laser pointer according to the present invention.  
         [0023]      FIG. 4  is a magnified view of the spring and damping means included in a laser pointer according to the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0024]     Referring to  FIGS. 1 and 2 , the preferred embodiment of a hand-held laser pointer in accordance with the present invention is shown at  10 . The laser pointer  10  generally includes a housing  12 , a laser assembly  14 , and a power source  16 . The housing  12  has a inner surface  26 . The housing  12  defines an open interior  28 .  
         [0025]     A transparent material  30  such as clear plastic, glass, or some well known optically transparent material separates the interior of the housing  12  from the external environment. The housing  12  includes a power supply access  32  for facilitating the mounting and dismounting of the power source  16 . The power source  16  is preferably a single battery or a plurality of batteries.  
         [0026]     The laser assembly  40  and laser assembly  41  each include a collimating lens, a laser element, and a driving circuit. The output of the laser element is preferably a laser diode that emits coherent light of a desired color such as red, green, blue, or infrared laser light. Suitable laser elements are produced by Nichia Corporation having a principle place of business at 491 Oka, Kaminaka-Cho, Anan-Shi, Tokushima 774-8601, Japan and by Cree, Inc., having a place of business at 4600 Silicon Drive, Durham, N.C. 27703.  
         [0027]     The laser assembly  40  and a counterweight  46  is mounted to a bridging element  50 . The weighted element  46  defines or comprises a counterweight so that the the laser assembly  40  is balanced about a centerpoint C of the bridging element  50 . The bridging element  50  is suspended in the housing  12  by a low friction gimbal  60  that pivots about substantially perpendicular first and second axes  62 ,  64  each of which is perpendicular to longitudinal axis x 1 . The gimbal  60  is pivotally mounted to the housing  12 . Such pivotal mounting may be accomplished via pairs of pin and cup mechanisms  74  or other low friction bearing elements.  
         [0028]     The laser module assembly  40 , the counterweight  46 , and the bridging element  50  act as a pivoting inertial mass suspended by the gimbal  60 . The laser module housing  40 , the counterweight  46 , and the bridging element  50  may be formed from synthetic resinous materials or metallic materials. A soft cylindrical component  48  is used to limit the allowable travel of the inertial mass. Moving  48  towards or away from the gimbal center C respectively increases or decreases the range of travel of the inertial mass.  
         [0029]     In a preferred embodiment of the stabilized laser pointer  10 , a threaded shaft  81  mounted to the housing  12  contains a magnet  80  and a ferromagnetic pin  82 . The magnetic field from magnet  80  is focused though the ferromagnetic pin  82 . A ferromagnetic pin  84  is mounted within a conductive non-magnetic material  83  mounted to the bridging element  50 . The magnetic field of magnet  80  is focused through pin  82  to interact with the ferromagnetic material  84  to provide a small magnetic spring coupling between the pivoting inertial mass and the housing  12 . The assembly comprising threaded element  81 , pin  82 , and magnet  80  can be adjusted towards or away from pin  84  to increase or decrease the magnetic restoring force.  
         [0030]     A conductive non-magnetic material  92  is mounted on bridging element  50 . A threaded shaft  91  contains a magnet  90  and serves to dampen the magnetic spring coupling between the pivoting inertial mass and the housing  12  by interaction with component  92 . The assembly comprising threaded element  91  and magnet  90  can be adjusted towards or away from conductive non-magnetic material  92  to respectively increase or increase the magnitude of the damping.  
         [0031]     Essential tremor and postural tremor frequencies are generally between 4 Hz and 12 Hz. As such, the spring (magnetic coupling) and damping characteristics are sized for effective isolation of angular motion imparted to the laser assembly  14  about axes  62 ,  64  within this frequency range, while providing adequate angular motion coupling about axes  62 ,  64  for effective panning and tilting of the laser assembly  14  during use. Various arrangements of these or other spring and damping materials may be employed to provide alternate or adjustable spring and damping characteristics.  
         [0032]     With reference now to  FIG. 2 , the laser assembly  40  is electronically connected to the power source  16  via two electrical paths  76  and  77 . At least one of these paths is electronically connected to a switch  58  on the housing  12 . Power is supplied to the laser assembly  14  by actuating the switch  58 . Electrical connections between the power source  16 , the switch  58 , and the laser assembly  14  may be comprised of flexible wiring. A second laser assembly  41  is directly mounted within the housing  12  and is electronically connected to the power source via electrical paths  78  and  79 . At least on of the paths is electronically connected to a switch  57 . A switch cover  59  protrudes through housing  12  and is direct contact with switches  57  and  58 . Switch cover  59  can be pressed to activate both switch  57  and switch  58  at the same time or pressed to activate only one of the switches at a time.  
         [0033]     When the user grasps the laser pointer  10  with his/her hand and switches on the switch  58 , the laser beam is emitted from the laser assembly  40  through the aperture  30  of the housing  12  towards a target. Low frequency angular movements of the housing will be transmitted to the laser assembly  40  and its emitted laser beam while angular movements of the housing  12  substantially at or above a predetermined frequency and, preferably, in a range similar to the frequencies associated with hand tremor, will be isolated from the laser assembly  14  and its emitted laser beam. The preferred embodiment of the present invention passively accomplishes stabilization of hand tremor that may be imparted to the laser pointer  10 . A power source is not required for stabilization and it is more cost effective to stabilize the laser assembly  14  in a passive fashion in accordance with the present invention. When the user activates switch  57 , a laser beam is emitted from the laser assembly  41  towards a target, said laser beam not stabilized from hand tremor.  
         [0034]     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. For example, the laser pointer may further include an elastically deformable material disposed within the interior  28  between the counterweight  46  and the inner surface  26  of the housing  12 . In addition, the laser pointer may be mounted on a transportable device, as, for example, on a vehicle, and still enjoy the advantages of the stabilization system. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.