Patent Publication Number: US-10323903-B2

Title: Auto on gun accessory

Description:
RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 15/600,596, entitled AUTO ON GUN ACCESSORY, filed on May 19, 2017, now U.S. Pat. No. 10,060,701, which is a continuation application of U.S. patent application Ser. No. 13/720,083, entitled AUTO ON GREEN LASER SIGHT, filed on Dec. 19, 2012, now U.S. Pat. No. 9,658,031, which claims the benefit of U.S. Provisional Application Ser. No. 61/577,433, entitled AUTO ON GREEN LASER SIGHT, filed Dec. 19, 2011, which applications are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present invention relates to accessories used with firearms, and more particularly to laser sighting devices and other accessories designed for removable attachment to a barrel of a handgun. 
     BACKGROUND 
     A wide variety of accessories have been developed for users of firearms, to facilitate target visualization and improve targeting accuracy. Among these are laser sighting devices configured to generate a coherent energy beam parallel or nearly parallel to the extension of a gun barrel, with the precise alignment depending largely on the distance to the target and windage. When activated, the coherent energy beam forms a spot of light on the target, to indicate the expected point of impact of the firearm projectile. These devices can enhance the experience of any firearm user, and have considerable importance in certain law enforcement and military operations. 
     Typical laser sighting devices employ visible red or infrared laser frequencies, as energy at the desired frequency can be generated directly, e.g. with a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal. More recently, it has been discovered that visible light in the “green” range, e.g. having a wavelength in the 490-570 nanometer range, has much higher visibility than visible red laser energy. The more visible beam, while enhancing utility of a sighting device in general, is particularly effective for daytime use. 
     A difficulty that has limited the use of green laser energy in sighting devices is the need for additional components not required by visible red and infrared lasers. To generate coherent energy in the green region of the spectrum, an Nd:YAG crystal is used to generate energy at a wavelength outside the visible spectrum, e.g. 1064 nm, that is then provided to a frequency doubler, e.g. a potassium titanium oxide phosphate (KTP) or lithium triborate (LBO) crystal to generate the desired wavelength, in this case 532 nm. The additional components require a larger laser drive circuit, typically a printed circuit board, and a larger power supply to meet a higher power requirement. The resulting sighting device is larger and difficult to use with handguns, either because the handgun barrel is not long enough to accommodate the device, or because the device protrudes ahead of the barrel an excessive amount. In accessory devices incorporating green laser sighting and white light (multichromatic energy) illumination, this difficulty is magnified. 
     Another problem encountered with the green laser is the higher power requirement and the accompanying reduction in useful life of the power source, typically one or more batteries. A larger battery of course contributes to the size of the device; all the more so in devices that combine laser and multichromatic illumination as they typically employ separate voltage level power sources for the separate light sources. 
     While sighting devices and other accessories can be mounted to firearms in a variety of ways, one approach gaining increasing acceptance involves forming longitudinally extending rails on opposite sides below the barrel of a handgun ahead of the trigger guard, for example as shown in U.S. Pat. No. 6,185,854 (Solinsky et al.). The accessory or auxiliary device is provided with opposed projections, each slidable relative to one of the rails to guide the accessory for longitudinal travel relative to the barrel. The accessory also carries a transverse spring loaded bar that fits into a transverse groove formed in the barrel to secure the accessory against longitudinal travel. While this approach has proven useful for attaching a variety of accessories including laser sights and illumination devices, problems are encountered due to the differences in locations for the transverse grooves among different brands of firearms. 
     SUMMARY 
     The disclosure pertains generally to laser sighting devices such as green laser gun sights that are configured to be easily attached to a variety of different hand guns. In some embodiments, the laser gun sights are configured to permit elevation and windage adjustment without requiring movement of an entire laser module, thereby affording use of a more compact device housing. In some embodiments, the laser gun sights are configured such that the gun sight shuts off when a gun equipped with the laser gun sight is holstered, and turns itself back on when the gun is drawn from the holster. 
     While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a perspective view of an illustrative green laser gun sight secured to a handgun in accordance with an embodiment of the present invention. 
         FIGS. 2A and 2B  are perspective views of a housing forming a portion of the green laser gun sight of  FIG. 1 . 
         FIG. 3  is a perspective view of a green laser module. 
         FIG. 4  is a perspective view of the green laser gun sight of  FIG. 1 . 
         FIG. 5  is a perspective view of the green laser gun sight of  FIG. 4 , with a front plate removed to illustrate internal components. 
         FIG. 6  is a perspective view of a portion of the handgun of  FIG. 1 . 
         FIG. 7  is an exploded perspective view illustrating attachment of the green laser gun sight to the handgun. 
         FIG. 8  is a front perspective view of an illustrative green laser gun sight in accordance with an embodiment of the present invention. 
         FIG. 9  is a rear perspective view of the green laser gun sight of  FIG. 8 , shown mounted on a gun having a long rail system. 
         FIG. 10  is a schematic illustration of a remote switch that may be used with the green laser gun sight of  FIG. 8 . 
         FIG. 11  is a perspective view of the handgun and green laser gun sight of  FIG. 1  disposed within a holster. 
         FIG. 12  is an upper perspective view of the holster of  FIG. 11 . 
         FIG. 13  is a lower perspective view of the holster of  FIG. 11 . 
         FIG. 14  is a partially cutaway perspective view of the holster of  FIG. 11 . 
         FIG. 15  is a view of a portion of the holster of  FIG. 11 , showing the primary retention feature engaging a component of the green laser gun sight. 
         FIG. 16  is a schematic view of a green laser module used in the green laser gun sight of  FIG. 1 . 
         FIG. 17  is a simplified schematic view of electrical circuitry in the green laser gun sight of  FIG. 1 . 
         FIG. 18  is a simplified schematic view of electrical circuitry in the green laser gun sight of  FIG. 1 . 
         FIG. 19  is a perspective view of the handgun and green laser gun sight of  FIG. 1  disposed within a holster. 
         FIG. 20  is a partially cutaway perspective view of the holster of  FIG. 19 . 
         FIG. 21  is an upper perspective view of the holster of  FIG. 19 . 
     
    
    
     While the disclosure is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the disclosure to the particular embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives thereof. 
     DETAILED DESCRIPTION 
     The disclosure pertains generally to laser gun sights such as green laser gun sights that are configured to be easily attached to a variety of different hand guns. In some embodiments, the green laser gun sights are configured to permit elevation and windage adjustment without requiring movement of an entire laser module, thereby affording use of a more compact device housing. In some embodiments, the laser module can be in direct contact with the housing. Because the housing can then function as a heat sink, a smaller laser module may be used. 
     The green laser gun sights described herein may be used with a variety of different gun styles and sizes, including handguns, rifles, shotguns and the like. For purposes of illustration,  FIGS. 1 through 7  illustrate an embodiment of a green laser gun sight attached to a small handgun while  FIGS. 8 through 10  illustrate an embodiment of a green laser gun sight secured to a larger gun such as a rifle.  FIGS. 11 through 14  illustrate an embodiment of a holster that is configured to be used in combination with a handgun to which a green laser gun sight has been attached. Embodiments of the holster are configured to engage various portions of the green laser gun sight to releasably secure the gun within the holster without engaging the trigger guard. In some embodiments, the green laser gun sight and the holster are configured, in combination, to automatically shut off the green laser gun sight when a gun is holstered and to automatically turn on the green laser gun sight when the holstered gun is drawn, or removed from the holster. 
     Turning to  FIG. 1 , a handgun  10  is illustrated. The handgun  10  includes, among other elements and features, a barrel  12  and a trigger guard  14 . The barrel  12  includes a rail system  16  that is configured to accommodate a variety of different accessories and other attachments. In some embodiments, a laser gun sight  18  may be attached. In some embodiments, as illustrated, the green laser gun sight  18  is secured to the rail system  16  ahead of the trigger guard  14 . In some embodiments, the green laser gun sight  18  is configured such that the green laser gun sight  18  does not extend beyond a muzzle end  20  of the barrel  12 . It will be appreciated that the rail system  16  may vary somewhat, depending on the identity of the handgun  10 . Further details of the green laser gun sight  18 , as well as details of how the green laser gun sight  18  attaches to the handgun  10 , will be discussed with respect to subsequent Figures. 
       FIGS. 2A and 2B  are perspective views of a housing  22  that forms a part of the green laser gun sight  18 .  FIG. 2A  is a right rear perspective view while  FIG. 2B  is a left front perspective view. The housing  22  may be formed of any suitable material. In some embodiments, the housing  22  is formed of a strong, lightweight metal such as aluminum. It will be appreciated that the housing  22 , particularly if formed of a highly heat conductive material such as aluminum, will function as a heat sink. The housing  22  includes several apertures such as a green laser module aperture  24 , a visible light module aperture  26  and a larger aperture  28  that may be configured to accommodate a battery (not illustrated) as well as at least some of the laser circuitry. In some embodiments, the visible light module may include an LED light source. 
     The housing  22  also includes features that facilitate attachment of the green laser gun sight  18  to the handgun  10 . A pair of grooves  30  are formed, one on each side of the housing  22  (only one visible in this illustration). As will be explained subsequently, the grooves  30  accommodate a rail set that connects the green laser gun sight  18  to the handgun  10 . The housing  22  also includes a through aperture  32  that also helps to connect the green laser gun sight  18  to the handgun  10 . 
       FIG. 3  is a perspective view illustrating a green laser module  34  that is aligned to slide into the laser module aperture  24 . In some embodiments, the green laser module  34  has a cylindrical shape that fits snugly into the laser module aperture  24 . As a result, the housing  22  may serve as a heat sink for the green laser module  34 . This may be especially beneficial, as green lasers tend to produce more heat than a correspondingly-powered red laser. 
       FIG. 4  is a front perspective view of the green laser gun sight  18 . Rail sets  36  and  38  are disposed on either side, respectively, of the green laser gun sight  18  and fit into the grooves  30  disposed on either side of the green laser gun sight  18 . It will be appreciated that the rail sets  36  and  38  slide downward into the grooves  30 . A cross pin  40  extends between the rail sets  36  and  38  and secures the rail sets  36  and  38 . In some embodiments, for example, the cross pin  40  may slide through an aperture formed in the rail set  36  and may be threadedly engaged in a corresponding threaded aperture formed within the rail set  38 . The cross pin  40  may be considered as including a head  41  that may be used in advancing or withdrawing the cross pin  40  as well as a threaded portion  43  (shown in  FIG. 7 ). As will be discussed, the head  41  may also be used to help secure the green laser gun sight  18  (and hence the handgun  1 ) within a holster. 
     As will be illustrated with respect to a subsequent drawing, the cross pin  40  also helps to secure the rail sets  36  and  38 , and hence the green laser gun sight  18 , to the handgun  10 . It can be seen that the rail set  36  includes a mounting surface  42  and the rail set  38  includes a mounting surface  44 . The mounting surfaces  42  and  44  may be configured to interact with the rail system ( FIG. 1 ) and may be modified to fit a particular handgun  10 . 
     The green laser gun sight  18  includes a front cover  52  that in some embodiments may be formed of a suitable polymeric material. The front cover  52  includes a portion  46  that is configured to permit laser light to emerge as well as a portion  48  that is configured to accommodate a visible light. A cover  50  seals off the larger aperture  28  ( FIG. 2 ). In some embodiments, the cover  50  may be threadedly engaged with the housing  22 , but this is not required. An elevation screw  54  and a windage screw  56  are arranged along one side of the portion  46 . 
     In some embodiments, the green laser gun sight  18  includes one or more switches  80  that can be used, for example, to program the green laser gun sight  18 , to turn the green laser module  34  on or off, to turn the visible light module on or off, or to vary a pulse rate for the green laser module  34  and/or vary a strobe rate for the visible light module. In some embodiments, there are a pair of switches  80 , with one switch  80  arranged on each side of the green laser gun sight  18 . In some embodiments, as will be discussed subsequently, the switch(es)  80  may be disposed at a remote location. 
     In some embodiments, the switch  80  on the right side of the green laser gun sight  18  and the switch  80  on the left side of the green laser gun sight  18  may be used interchangeably. For example, it may be more natural for a right-handed user to use their thumb to operate the switch  80  on the left side of the green laser gun sight  18  while a left-handed user may use their thumb to operate the switch  80  on the right side of the green laser gun sight  18 . In some cases, a user may prefer to turn the green laser gun sight  18  on or off using a different finger, before they are holding the gun  10  in a ready-to-fire position. In some embodiments, the green laser gun sight  18  includes circuitry that enables either switch  80  to be used. 
       FIG. 5  is similar to  FIG. 4 , except that the front cover  52  has been removed to better illustrate internal components. A light assembly  62  is disposed in alignment with the portion  48  of the front cover  52  ( FIG. 4 ). It can be seen that the elevation screw  54  and the windage screw  56  are arranged in opposition to a spring  60  and thus can be used to alter a position of a laser collimating lens  58  as the force applied to the laser collimating lens  58  by the spring  60  includes a component aligned with (in opposition to) the elevation screw  54  as well as a component that is aligned with (in opposition to) the windage screw  56 . An elevation screw spacer  54   a  extends between the elevation screw  54  and the laser collimating lens  58 . In some embodiments, the laser collimating lens  58  may rest on a ribbed or otherwise textured surface to reduce friction. 
     An individual can adjust the aim of the laser beam emitted by the green laser sighting device  18  by turning the elevation screw  54  and/or the windage screw  56 . As a result of turning the elevation screw  54  and/or the windage screw  56 , the laser collimating lens  58  may slide radially or perpendicularly with respect to the green laser module  34 . In some embodiments, the elevation screw  54  and the windage screw  56  may be configured to permit the laser collimating lens  58  to pivot relative to the green laser module  34 . In some embodiments, the laser collimating lens  58  may be stationary, and the elevation screw  54  and/or the windage screw  56  may be used to alter the position of an additional lens or other optical component (not illustrated) in order to fine tune aiming of the green laser module  34 . 
       FIGS. 6 and 7  illustrate in greater detail how the green laser gun sight  18  is attached to the handgun  10 .  FIG. 6  illustrates an enlarged end portion of the handgun  10  in which the rail system  16  may be seen as including a left (in the illustrated orientation) profile  64  and a corresponding right profile  66 .  FIG. 7  illustrates the green laser gun sight  18  in combination with the rail set  36  and the rail set  38 . It will be appreciated that the mounting surface  42  of the rail set  36  is configured to fit into or otherwise interact with the left profile  64  of the rail system  16  and that the mounting surface  44  of the rail set  38  is configured to fit into or otherwise interact with the right profile  66  of the rail system  16 . The left profile  64  and/or the right profile  66  may be configured to provide a key and lock arrangement between the rail sets  36  and  38  and the rail system  16  such that when the rail sets  36  and  38  are held together via the cross pin  40 , the green laser gun sight  18  is held in place on the handgun  10 . 
     In some embodiments, the rail system  16  also includes a horizontal cross slot  68 . In some embodiments, as illustrated, the rail set  36  and the rail set  38  may include, respectively, mounting apertures  70  and  72  that permit the cross pin  40  to extend through the rail set  36  and the rail set  38 . In some embodiments, the horizontal cross slot  68  is sized and positioned to accommodate the cross pin  40  and thereby prevent or at least substantially prevent lateral movement of the laser sighting device  18  relative to the handgun  10 . In some embodiments, each of the rail sets  36  and  38  may include several different mounting apertures to accommodate particular handguns  10  having different positions for the horizontal cross slot  68 . 
     In some embodiments, the rail sets  36  and  38  may include an aperture  35  (only one visible in  FIG. 7 ) that is configured to accommodate a threaded rod or screw  33 . The screw  33  may extend through the aperture  35  and thread into the aperture  32  formed in the housing  22  at or near the top of the groove  30 . In some embodiments, instead of a screw  33 , a pin may extend through the apertures  35  to secure the first and second rail sets  36 ,  38  to the green laser gun sight  18 . In some embodiments, a single pin may extend through both rail sets  36 ,  38  and may form a frictional or compressive fit with the apertures  35  formed in each of the rail sets  36 ,  38 . 
     It will be appreciated, therefore, that the green laser gun sight  18  may be attached to a variety of different handguns  10  without requiring alteration of the housing  22 . Rather, the rail sets  36  and  38  may be configured to have mounting surfaces  42  and  44 , respectively, that are configured to interact with the particular rail system  16  of a particular handgun  10 . 
     The green laser gun sight  18  described with respect to  FIGS. 1 through 7  may be considered in some cases as being designed for use with smaller handguns such as compact and subcompact handguns.  FIGS. 8 through 10  illustrate a green laser gun sight  82  that shares many features with the green laser gun sight  18 , but in some cases may be considered as being designed for use with larger guns such as full size handguns, rifles, shotguns and the like. 
     The green laser gun sight  82  includes a portion  84  that is configured to accommodate the green laser module  34 . In some embodiments, the portion  84  may include a glass plate that permits the green laser light to pass through. The green laser gun sight  82  also includes a visible light module  86 . In some embodiments, as illustrated, the visible light module  86  may be configured to provide substantially more visible light than that provided by the visible light module  62  ( FIG. 5 ) and may extend outward relative to the portion  84 . In some embodiments, the visible light module  86  may be considered as being positioned in front of a battery aperture formed within the green laser gun sight  82 . In some embodiments, the visible light module  86  may be user-removable in order to permit battery installation and/or replacement. In some embodiments, the green laser gun sight  82  includes an elevation screw  88  and a windage screw  90  that can be used to adjust the aim of the green laser module by moving a laser collimation lens (as discussed previously with respect to the green laser gun sight  18 ). 
     The green laser gun sight  82  includes a first rail set  92  and a second rail set  94  that may be attached to the green laser gun sight  82  in a manner similar to that described previously with respect to the green laser gun sight  18 . In some embodiments, a screw  96  attaches the first rail set  92  to the green laser gun sight  82 , while a similar screw (not visible) attaches the second rail  94  to the opposing side of the green laser gun sight  82 . In some embodiments, as illustrated, a pair of cross pins  98  secure the first rail set  92  to the second rail set  94  and thus secure the green laser gun sight  82  to a gun rail system. In some embodiments, it will be appreciated that larger guns have longer rail systems  102  and thus can accommodate more than one cross pin  98 . In some embodiments, the green laser gun sight  82  may be physically larger and longer than, for example, the green laser gun sight  18  and thus may benefit from using more than one cross pin  98 . 
     In some embodiments, the green laser gun sight  82  includes one or more switches  100  that can be used, for example, to program the green laser gun sight  82 , to turn the green laser module  34  on or off, to turn the visible light module  86  on or off, to vary a pulse rate for the green laser module  34  and/or to vary a strobe rate for the visible light module. In some embodiments, there are a pair of switches  100 , with one switch  100  arranged on each side of the green laser gun sight  82 . In some embodiments, as illustrated for example in  FIG. 9 , the green laser gun sight  82  may not include the switch  100 . 
       FIG. 9  is a rear perspective view of a green laser gun sight  104  secured to a long rail system  102 . In some embodiments, the green laser gun sight  104 , however, does not include the switch  100 . Instead, the green laser gun sight  104  includes a rotary switch  106  and a lead  108  that extends to a remote switch (not illustrated). In some embodiments, the rotary switch  106  may be used to select a particular lighting program, i.e., solid or strobing visible light, solid or pulsing green laser, and the like, while the remote switch may be used to turn either the visible light module  86  and/or the green laser module  34  on or off. 
     As an illustrative but non-limiting example, the settings “A”, “B”, “C” and “D” may each be used to designate a particular function such as constant laser only, constant light only, or constant laser with constant light. In some embodiments, each of these functions may be momentary only. In some embodiments, on or more of the aforementioned settings may be used to designate independent activation between the two separate buttons  112  and  114  (discussed below with respect to  FIG. 10 ). In some embodiments, the settings “1”, “2”, “3” and “4” may be used in a similar manner. In some embodiments, the setting labeled “P” may be used for a program setting that allows the user to change settings according to their preferences, such as the pulse rate for the laser and/or the strobe rate for the visible light. For example, one of the buttons  112  and  114  may be used to increase the laser pulse rate while the other of the buttons  112  and  114  may be used to decrease the laser pulse rate. 
       FIG. 10  is a schematic illustration of a remote switch  110  that includes a first switch button  112  and a second switch button  114 . In some embodiments, the first switch  112  and the second switch button  114  may be individually pressed to turn the green laser gun sight  104  on or off. In some embodiments, the first switch  112  and the second switch  114  may be pressed together and/or in combination with rotating the rotary switch  106  to select between different program modes. The remote switch  110  may be located at any convenient location along the gun. In some embodiments, the remote switch  110  may be placed at a location proximate where the user holds the rifle or shotgun with their non-trigger hand, such as at or near the magazine. In some embodiments, the remote switch  110  may be mechanically or adhesively secured to the gun. 
       FIGS. 11 through 14  provide various views of a holster that is configured to accommodate a handgun  10  to which a green laser gun sight  18  has been attached. In some embodiments, the holster described herein is configured to interact with the green laser gun sight  18  to releasably secure the handgun  10  within the holster without engaging the trigger guard  14 . 
       FIG. 11  is a perspective view of the handgun  10  disposed within a holster  120 .  FIG. 12  provides a view down into the holster  120  while  FIG. 13  provides a lower perspective view. As seen in  FIGS. 11-13 , the holster  120  includes a pocket  122  that is formed between an outer panel  124  and an inner panel  126 . In this, inner and outer may be considered as being relative to a user who has the holster  120  secured to their belt. The inner panel  126  is closest to a securement portion  128  that is configured to be secured to a user&#39;s belt. 
     In some embodiments, the outer panel  124  and the inner panel  126  may be distinct portions that are screwed, bolted, riveted or otherwise secured together. In some embodiments, as illustrated, the outer panel  124  and the inner panel  126  may instead be outer and inner portions, respectively, of a unitary structure. In some embodiments, the outer panel  124  and the inner panel  126  are molded as a unitary structure. The holster  120  may be formed of any suitable material. In some embodiments, the holster  120  is largely molded from a relatively rigid polymer such as KYDEX® or a similar material. 
     The holster  120  includes a primary retention device  130  and a secondary retention device  132 . In some embodiments, the primary retention device  130  is configured to releasably engage with an external component of the green laser gun sight  18 . In some embodiments, as illustrated, the primary retention device  130  includes a moveable lever  134  that includes an engagement portion  136 , a finger button portion  138  and an intervening pivot point  140 . In some embodiments, the moveable lever  134  is movable between an engagement position in which the engagement portion  136  interacts with a portion of the green laser gun sight  18  and a disengagement position in which the engagement portion  136  is moved out of engagement with the green laser gun sight  18 . In some embodiments, the moveable lever  134  is biased into the engagement portion by a spring or similarly resilient element (not illustrated). In some embodiments, the primary retention device  130  is configured such that a user may easily draw the handgun  10  from the holster  120  by depressing the finger portion with their finger to move the primary retention device  130  to a disengagement position and wherein the primary retention device  130  is positioned relative to the pocket  122  such that the gun  10  may be withdrawn from the holster  122  with the user&#39;s finger proximate a switch  80  ( FIG. 4 ) on the green laser gun sight  18 . 
     In some embodiments, the secondary retention device  132  includes a resilient member  142  that forms a frictional fit with the housing  22  of the green laser gun sight  18 . It will be appreciated that the secondary retention device  132  is configured to resist accidental removal of the gun  10  from the holster  120  but permits removal of the gun  10  from the holster  120  when the finger portion  138  is depressed and the gun  10  is withdrawn. 
       FIGS. 14 and 15  illustrate how the primary retention device  130  interacts with the green laser gun sight  18 . In particular, the primary retention device  130  interacts with a component of the green laser gun sight  18 . In some embodiments, the engagement portion  136  of the primary retention device  130  engages with the head  141  of the cross pin  140 . By comparing  FIG. 14  with, for example,  FIG. 4 , it will be appreciated that the engagement portion  136  is positioned to oppose movement of the head  141  of the cross pin  140  and thus prevent withdrawal of the green laser gun sight  18  and the gun  10  to which the green laser gun sight  18  is attached.  FIG. 15  also illustrates the relative position of the head  141  and the engagement portion  136  of the primary retention device  130  when the gun  10  is secured within the holster  120 . It can be seen that the engagement portion  136  blocks movement of the head  141  when in an engagement position but permits movement when the user depresses the finger portion  138  and thus pivots the engagement portion  136  out of the way of the head  141 . 
       FIG. 16  is a schematic illustration of a green laser module  154  that may be considered as representative of the green laser module  34  previously discussed. The green laser module  154  is configured to produce coherent energy in the green (490-570 nm) range of a visible spectrum. Laser module components include a semiconductor chip  166  that emits radiation when receiving battery power, a lasing medium or crystal  168  provided for light amplification at the fundamental frequency corresponding to a wavelength of 1064 nm and a frequency doubler or crystal  170  for converting the energy to the desired wavelength of 532 nm. In some embodiments, beam collimating optics  172  are positioned to receive the light emitted by the frequency doubler or crystal  170 . In some embodiments, the beam collimating optics  172  include the collimating lens  58  discussed previously. In some embodiments, the green laser module  154  may incorporate an infrared blocking filter. 
       FIG. 17  provides a simplified schematic view of electrical circuitry in the green laser gun sight  18 . In some embodiments, a printed circuit board  174  may be separated from the green laser module  154 . A printed circuit board  176  that incorporates a microprocessor for a variety of functions including providing battery power to the printed circuit board  174  pulsed at a variety of predetermined pulsing frequencies, and interrupting power to the laser drive circuit after a predetermined time of laser operation with no user input, to prevent overheating and prolong battery life. A flexible or pliant conductor  178  electrically couples the battery  162  to the pulsing circuit  176 , a conductor  180  couples the pulsing circuit  176  to the laser drive circuit  174 , and a conductor  182  couples the laser drive circuit  174  to the laser module  154 . A switch  184  is coupled to the pulsing circuit  176  and is operable to select one of several desired pulsing frequencies. In one version, the predetermined frequencies are 5 Hz, 7 Hz, and 10 Hz. 
     The pulsed input to laser drive circuit  174  causes the drive circuit  174  to generate a laser beam at substantially the same pulsing frequency, so that users visually perceive the beam as pulsed. Moreover, at the relatively low pulsing frequencies involved, the separate pulsing frequencies are readily visually distinguishable from one another. Consequently, in a situation in which sighting beams from several different firearms may be directed towards the same target, for example in certain law enforcement or military operations, the different pulsing rates allow each user to distinguish his or her sighting beam from the others. 
     More generally, the pulsing circuit  176  can be configured to provide power to the laser drive circuit  174  at several distinct pulsing frequencies, and further to provide power at several different pulsing circuit duty cycles, each associated with a different one of the pulsing frequencies. In each case, the laser drive circuit  174  provides power to the laser module according to a duty cycle controlled by its corresponding pulsing circuit duty cycle. 
     In some embodiments, the operator selects the desired pulsing frequency by operating the switch  184  to cycle through five distinct modes: continuous wave, pulse frequency number  1 , pulse frequency number  2 , pulse frequency number  3 , and off. The switch  184  also is operable to control the light source  164 . With further reference to  FIG. 9 , a conductor  190  couples the battery  162  to a voltage conversion circuit  192 , which in turn is electrically coupled to the light source  164  by a conductor  194 . Thus, the green laser module  154  and the light source  164  may be powered by the same power source. 
       FIG. 18  provides a simplified schematic view of electrical circuitry in the green laser gun sight  18 . While the laser gun sight  18  has been described as being a green laser gun sight, in some embodiments the laser gun sight  18  may instead be a red laser gun sight, a blue laser gun sight or an infrared laser gun sight. In some embodiments, the laser gun sight  18  is a green laser gun sight  18 . 
     In some embodiments, the printed circuit board  176  may include a sensing circuit  184  that includes a Hall effect sensor  186 . In some embodiments, as will be described, the holster  120  may include one or more magnets that are sized to produce a magnetic field that can be detected by the Hall effect sensor  186 . In some embodiments, one or more magnets may be placed in a soft holster such as a pocket gun holster. In some embodiments, one or more magnets may instead be disposed on or in a flat surface such as the floor of a safe, a nightstand drawer, an automobile glove box, or the like. If the sensing circuit  184  detects a magnetic field of a particular strength, the microprocessor  185  decides that a gun  10  to which the green laser gun sight  18  has been mounted has been holstered. When the sensing circuit  184  no longer detects the magnetic field, the microprocessor  185  decides that the gun  10  has been drawn from the holster  120  or picked up from the aforementioned flat surface. 
     In some embodiments, the microprocessor  185  is configured to turn off the green laser gun sight  18  when detection of a magnetic field indicates that the gun  10  has been holstered or otherwise put away. In some embodiments, the microprocessor  185  is configured to turn on the green laser gun sight  18  when a lack of detection of a magnetic field indicates that the gun  10  has been drawn or picked up. In some embodiments, the microprocessor  185  is configured to turn on the green laser gun sight  18  upon removal from the holster  120  if the green laser gun sight  18  was turned on when holstered, and is configured to keep the green laser gun sight  18  turned off upon removal from the holster  120  if the green laser gun sight  18  was turned off when holstered. 
     In some embodiments, turning the green laser gun sight  18  on and off refers to completely shutting off the green laser gun sight  18  in order to conserve battery power. In some embodiments, this refers to turning portions of the aforementioned circuitry on or off. For example, turning off the green laser gun sight  18  may refer to stopping power to the laser module  154  and/or the LED module  164  to conserve battery power and/or prevent inadvertent detection of the gun  10  while other portions of the circuitry remain powered. 
     In some embodiments, the green laser gun sight  18  may be programmed using the one or more buttons  80  to automatically turn on the laser module  154  and/or the LED module  164  when the gun is drawn from the holster  120 . In some embodiments, the green laser gun sight  18  may be programmed to automatically turn on the laser module  154  and/or the LED module  164  after a user programmable time delay should the user wish a short delay to, for example, better position the gun before providing a visual indication of the gun&#39;s presence. 
       FIGS. 19-21  are similar to  FIGS. 11, 12 and 14  described previously, but have been annotated to indicate an embodiment in which the green laser gun sight  18  and the holster  120  have been configured, in combination, to provide an instant-on feature. In  FIG. 19 , a region  190  has been indicated in phantom to show the relative position of the Hall effect sensor  186  in the sensing circuit  184  as well as a magnet disposed within the holster  120 .  FIG. 20  shows an embodiment in which a magnet  192  has been embedded in the resilient member  142 . In some embodiments, the magnet  192  is a rare earth metal and may be adhesively fixed within a pocket formed in the resilient member  142 . In  FIG. 21 , it can be seen that the magnet  192  is positioned relatively close to a region  194  of the green laser gun sight  18  that includes the sensing circuit  184  and the Hall effect sensor  186 . 
     Various modifications and additions can be made to the exemplary embodiments discussed. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the disclosure is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the disclosure, together with all equivalents thereof.