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. 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  
       [0008]     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.  
         [0009]     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. 
       
 
         [0013]     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 material may be disposed between said first material and said second material to dampen the magnetic interaction therebetween by the generation of eddy currents therein. Preferably, the ferromagnetic or magnetic second material is movably mounted to the housing and adjustable towards and away from the magnetic or ferromagnetic first material.  
         [0014]     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.  
         [0015]     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.  
         [0016]     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  
       [0017]      FIG. 1  is a partially cutaway perspective view of a tremor-stabilized, hand-held laser pointer in accordance with the present invention.  
         [0018]      FIG. 2  is a side plan view of the laser pointer of  FIG. 1 .  
         [0019]      FIG. 3  is a schematic view of a gimbal included in a laser pointer according to the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0000]     Definitions  
         [0020]     The term “passive” or “passive stabilization”, as used herein to describe means for stabilizing a laser module, means a stabilization mechanism operable for damping low frequency vibrations of the laser module that does not require a source of power for its operability.  
         [0021]     The term “low frequency” as used herein means vibrations in the range of 2-10 Hertz.  
         [0022]     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 proximal end  20 , a distal end  22 , an outer surface  24  and an inner surface  26 . The housing  12  defines an open interior  28 . The housing has an aperture  30  formed therethrough, preferably at its distal end  22 .  
         [0023]     A transparent material  31  is seated within the aperture  30  such as clear plastic, glass, or some well known optically transparent material, to separate the interior of the housing  12  from the external environment. The aperture  30  defines an optical aperture. 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. Button-shaped batteries may be employed that meet the size and electrical requirements of the laser assembly  14 .  
         [0024]     The laser assembly  14  includes a collimating lens  53 , a laser element  42 , and a driving circuit  44  disposed within a module housing  40 . The laser element  42  is preferably a laser diode that emits coherent light of a desired color such as red, green, or blue laser light. The emitted light is collimated into a light beam via the collimating lens  53 . The driving circuit  44  is electronically connected to the laser element  42  and serves to regulate power from the power source  16  and cause the laser to emit light. Such components may include lenses, mounts, wiring, and other components well known to those skilled in the art to which the present invention relates. Suitable laser elements  42  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.  
         [0025]     The laser assembly housing  40  is mounted to counterweight  46  via a bridging element  50 . The weighted element  46  defines or comprises a counterweight to the laser assembly  14  and laser assembly housing  40  so that the counterweight  46  and the laser module housing  40 , including elements contained therein, are 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. The gimbal  60  is pivotally mounted to the housing  12  at the inner surface  26  thereof and to the bridging element  50 . Such pivotal mounting may be accomplished via pairs of pin and cup mechanisms  74  or other low friction bearing elements.  
         [0026]     The laser module housing  40  and the counterweight  46 , and the bridging element  50  therebetween act as a pivoting inertial mass suspended within the gimbal  60 . The laser module housing  40 , the counterweight  46 , and the bridging element  50  therebetween may be formed from synthetic resinous materials or metallic materials.  
         [0027]     In a preferred embodiment of the stabilized laser pointer  10 , a magnet  92  is rigidly mounted to the proximal end of the counterweight  46 . A body comprised of a ferromagnetic material  90  is disposed within the housing interior  28  intermediate the power source  16  and the magnet  92 . The magnet  92  interacts with the ferromagnetic material  90  to provide a magnetic spring coupling between the pivoting inertial mass and the housing  12 .  
         [0028]     A conductive non-magnetic material  94  is preferably disposed intermediate the magnet  92  and the ferromagnetic material  90  and serves to dampen the magnetic spring coupling between the pivoting inertial mass and the housing  12 . The materials and relative sizes of the magnet  92 , the ferromagnetic material  90 , and the conductive non-magnetic material  94  are selected so that angular motions of the housing  12  at low frequency, generally below 4 Hz, will be transmitted to the pivoting inertial mass comprising the laser assembly  14 , while higher frequency angular motions of the housing  12  will be isolated from the inertial mass comprising the laser assembly  14 .  
         [0029]     Essential tremor and postural tremor frequencies are generally between 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.  
         [0030]     With reference now to  FIGS. 2 and 3 , the laser assembly  14  is electronically connected to the power source  16  via two electrical paths  76  and  78 . 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. Alternatively, electrical paths between the switch  58 , the laser assembly  14 , and the power source  16  can be routed via isolated conductive pathways through the bearing elements of the gimbal  60  as shown in  FIG. 3 . This embodiment decouples wiring forces that may serve to degrade the performance of the inertially stabilized frame.  
         [0031]     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  14  through the aperture  30  formed at the distal end  22  of the housing  12  towards a target. Low frequency angular movements of the housing will be transmitted to the laser assembly  14  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.  
         [0032]     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.