Patent Publication Number: US-11656062-B2

Title: Apparatus and method for indicating whether a target has been impacted by a projectile

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of, and claims priority to, co-pending U.S. patent application Ser. No. 16/787,413, filed Feb. 11, 2020, which is a divisional of U.S. patent application Serial No. D, filed Jan. 16, 2018, and also claims the benefit of U.S. provisional patent application Ser. No. 62/446,122, filed Jan. 13, 2017. 
     The disclosures of each of the foregoing applications are hereby expressly incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to shooting sports. More particularly, the disclosure relates to target hit indicators. Even more specifically, the present disclosure relates to unitary target-mounted target hit indicators. 
     BACKGROUND 
     Shooting targets are commonly used for recreation or in competition and are often made of metal so that the target can withstand the impact of multiple bullets. When metallic targets are shot at close range, the sound of the bullet hitting the target can often be heard. However, if the target is far away, the user has hearing difficulties, or is wearing hearing protection, it may be difficult or impossible to hear the sound. In such instances, a viewer (e.g., the shooter, spotter, etc.) must look for the movement of the target due to the bullet impact. Detecting an impact using this method may be difficult or impossible, even with a scope or binoculars. 
     Currently, several systems are available that are designed to detect an impact on a target and inform a viewer that the target has been impacted. In these systems, multiple disparate components are connected together to form an indicating system. For example, a sensor unit is attached to the rear of the target or to the target support structure to sense impact. A light-producing indicating unit is placed a distance away from the target to reduce the chance of damage to the indicating unit by unintentional bullet strikes. The sensor is then connected to the light unit by wired or wireless means. Existing systems suffer various problems and deficiencies. Thus, it would be desirable to have a target hit indicator that would avoid at least some of the drawbacks of currently available systems. 
     SUMMARY OF THE INVENTION 
     Detecting an impact on a shooting target can often be difficult. Several systems are currently available that can detect a bullet impact and signal the impact to a viewer. Such systems have several problems, however. These systems can be cumbersome to set up, may not be weather resistant, or may not have long standby life, thus requiring the user to travel to the target to install and set up the system each time it is used. In the case of a target 1,000 yards away, a user may need to travel a significant distance to the target and back to set up and take down the system. Subject matter disclosed herein may overcome, eliminate, reduce or solve the aforementioned problems. 
     Additionally, even though the light-producing unit is placed a distance from the target, it may still be prone to damage and if a wired connection is used between the sensor and the light-producing unit, the wires themselves may be damaged. Wireless connections, on the other hand, may be costly or unreliable and may add significant power drain, resulting in the need for large batteries or frequent battery changes. Subject matter disclosed herein may overcome, eliminate, reduce or solve the aforementioned problems. 
     One of the challenges of a target-mounted target hit indicator is the harsh shooting environment on and around the target. Bullets by their nature are destructive on impact. Even collateral impacts from rocks or shrapnel can cause significant damage. Therefore, it is advantageous to shield the target hit indicator from such conditions. Currently available systems use a sensor mounted to the rear of the target or to the structure holding the target. Mounting to the rear of a target provides protection from direct bullet strikes but also presents a problem in that there is no direct line of sight from behind the target to the user (e.g., shooter, spotter, etc.). Current systems solve this problem by providing a separate signaling unit which is placed a distance from the target to reduce (but not eliminate) the likelihood of damage. A wired or wireless connection is then used to communicate between the sensor unit and the signaling unit. These wired connections may themselves be prone to damage while wireless systems may be unreliable and consume a lot of power. Additionally, many systems may not be weather resistant. Consequently, such systems may be cumbersome, prone to damage, have short battery life, and require setup and take-down with each use. Subject matter disclosed herein may overcome, eliminate, reduce or solve the aforementioned problems. 
     It is one object of embodiments to provide a unitary target hit indicator by consolidating disparate components of current systems to form a single integrated device. It is also an object of this disclosure to provide a target hit indicator that consumes very little power but is still visible at long distances (e.g., 1,000 yards or more). 
     In embodiments, the unitary design of the target hit indicator may eliminate the need for a separate sensor unit and indicator unit which simplifies the packaging and setup of the device. Necessarily, the need for a wired or wireless connection also may be eliminated, resulting in increased reliability and reduced power consumption. 
     Additionally, it is an object of this disclosure to provide a target hit indicator that is weather resistant and has a long standby time, allowing the target hit indicator to be left on a target outdoors for an extended period of time and thus eliminating the need to set up and take down the target hit indicator each time it is used. It is a further object of this disclosure to provide a target hit indicator that can differentiate between an impact and a miss and signal to a user accordingly. 
     In embodiments, power consumption may be reduced by incorporating a low-power standby mode. Unnecessary components can be powered down in a low-power standby mode while the target hit indicator “listens” for an event generating one or both of initial vibration information and initial acoustic information above one of the vibration standby wake threshold and the acoustic standby wake threshold. 
     To these ends, a unitary target hit indicator is provided that may be mounted to the rear of a target and detect an impact and signal to a viewer that an impact and/or a miss has occurred. 
     In embodiments, a unitary target hit indicator may include a microcontroller unit, an impact sensor, and an impact indicator. The target hit indicator may further include an acoustic sensor. The target hit indicator may receive impact information from the impact sensor, determine whether a projectile impacted the target, and trigger the impact indicator to signal a successful impact based on the determination. Acoustic information may be further received from the acoustic sensor. If the target hit indicator determines that a miss has occurred, the impact indicator may be triggered to signal a miss based on the determination. A unitary target hit indicator may further include a light redirection element to allow the target hit indicator to be placed behind a target and reflect light from the impact indicator around the edge of the target toward a user. 
     The impact indicator may comprise the light redirection element and a light source. In embodiments the impact indicator may comprise a miss indicator, which may be configured to be activated responsive to the determination that a shot has been fired, but the projectile has not directly impacted the target. The light redirection element may be made of a flexible or rigid material and may have a light entrance area for receiving light from the light source, and a light exit area. The light redirection element may comprise one or more materials that are transparent, translucent, opaque, or reflective. Thus, at least a portion of the light received from the light source via the light entrance area, may be redirected, and be transmitted towards the user via the light exit area. One or more collimators substantially aligned with the impact indicator may be used to collect light from the light source to help direct the light toward the user. 
     In an embodiment, a method of indicating whether a target has been impacted may include receiving, from the impact sensor by the microcontroller unit, initial vibration information, determining whether the initial vibration information is above a vibration standby wake threshold and if the initial vibration information is above the vibration standby wake threshold: receiving, from an impact sensor by a microcontroller unit, vibration information, processing the vibration information (e.g. by integration), determining whether the vibration information is above a vibration impact threshold, and if the vibration information is above a vibration impact threshold, indicating a hit via the impact indicator. The method may further include indicating a miss via the impact indicator if the vibration information is not above the vibration impact threshold. 
     Alternatively, in an embodiment, such a method may include receiving, from an acoustic sensor by the microcontroller unit, initial acoustic information, determining whether the acoustic information is above an acoustic standby wake threshold and if the initial acoustic information is above the acoustic standby wake threshold, receiving, from an impact sensor by a microcontroller unit, vibration information; processing the vibration information (e.g. by integration); determining whether the vibration information is above a vibration impact threshold; and, if the vibration information is above a vibration impact threshold, indicating a hit via the impact indicator. The method may further include indicating a miss via the impact indicator if the vibration information is not above the vibration impact threshold. 
     The target hit indicator may utilize a low-power standby mode to conserve battery life when not in use. However, upon detection of an event above one of the standby wake thresholds, full power to some or all of the components can be restored. 
     Generally, the narrower the beam of light from the light redirection element to the viewer, the less intense the light source must be to be observable at distance. Collimators help collect light and direct the light into a narrow beam. Therefore, the use of collimators may allow for the use of a lower intensity light source which, among other advantages, ultimately results in increased battery life for the target hit indicator. 
     Similarly, a narrower beam also has a smaller field of view. Therefore, adjustable housing positions allow a narrow beam of light to reach a user and thus reduce the intensity of the light source (and resulting power consumption) required for the target hit indicator to be effective. 
     By eliminating the need to transmit a signal from one piece of a target hit indicator to another across a significant distance, by optimizing the transmission of light to the user, and further by incorporating a low-power standby mode, a unitary target hit indicator may have very low power requirement. In embodiments, such a target hit indicator that may have a battery life of months or even years. In embodiments, a target hit indicator may have a power demand that is a minor fraction of power demand of other target hit indicators, with accompanying increased battery life. 
     In embodiments, the unitary design of the target hit indicator also may allow it to be sealed, providing environmental protection for the electronics, thereby contributing to the devices&#39; ability to be left on a target exposed to uncontrolled weather for extended periods of time. Advantageously, a user need not remove the target hit indicator after a shooting session, nor does the user need to travel to the target to turn the unit off. 
     The target hit indicator, in embodiments, may perform an integration or other processing of data received from its sensor(s) and use the integrated data to more accurately differentiate between a hit and a miss. 
     In an embodiment, a target hit indicator may include, or may be in communication with, an acoustic sensor which may also be used to sense a projectile that passes nearby but does not impact the target. Such information may be used to trigger the impact indicator to indicate a miss. By indicating a miss in this manner, the target hit indicator may provide a user with confirmation that the target hit indicator is functioning whether or not the target is impacted. 
     These and other advantages will become apparent in the following disclosure with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The exemplary embodiments are illustrated by way of example and not limitation in the accompanying figures. 
         FIGS.  1 A-B  show one embodiment of a target hit indicator. 
         FIGS.  2 A-D  show one embodiment of a target hit indicator with a rectangular target. 
         FIGS.  3 A-D  show one embodiment of a target hit indicator with a circular target. 
         FIG.  4    shows an exploded view of a target hit indicator according to one embodiment. 
         FIGS.  5 A-B  show an exploded view of some components of a target hit indicator according to one embodiment. 
         FIGS.  6 A-B  show an unexploded view of the components of  FIGS.  5 A- 5 B . 
         FIG.  7    shows an electrical schematic for a target hit indicator according to one embodiment. 
         FIG.  8    shows an electrical schematic of a system having an acoustic sensor according to one embodiment. 
         FIG.  9    shows an electrical schematic of an indicator circuit for a target hit indicator according to one embodiment. 
         FIGS.  10 A-B  show one embodiment of a target hit indicator having a mounting plate. 
         FIGS.  11 A-F  shows an embodiment of an adjustable target hit indicator having multiple light pipes. 
         FIGS.  12 A-B  show an exemplary embodiment of a target hit indicator. 
         FIGS.  13 A-D  show an alternate embodiment of a target hit indicator, wherein the target hit indicator is integrally connected with the target. 
         FIG.  14    depicts an exemplary embodiment of a method for operation of a target hit indicator. 
         FIG.  15    depicts an exemplary embodiment of a method for identifying the impact location of a projectile using a plurality of sensors. 
     
    
    
     DETAILED DESCRIPTION 
     Although the description herein is directed to indicating the impact of a bullet on a target, one of ordinary skill in the art would recognize that such a device may be used to indicate an impact on any object. Further, such an apparatus may be used to indicate vibration, acceleration, movement, etc. 
     A target may refer to any object that a user wishes to detect vibration in or movement of (e.g., as a result of a projectile impact). For the purposes of this disclosure, the front of a target may be any portion of the target which is intended to be impacted with a projectile and the rear (or back or “behind”) of a target is any portion which is not intended to be impacted with a projectile (although impact may occur due to ricochet, etc.). 
     Within this disclosure, the term “or” refers to the conjunctive and not just the alternative unless expressly stated otherwise. For example, “a or b” may refer to “a” only, “b” only, or “a” and “b”. 
     Turning now to  FIGS.  1 A- 1 B , an embodiment of a target hit indicator  100  is shown. A housing  110  defining an interior volume  112  for holding components of the target hit indicator (e.g., the electronic components). Housing  110  comprises a mounting surface  114  for attaching the target hit indicator  100  to a target. Mounting surface  114  may have any suitable shape or orientation. Housing  110  and endcaps  120  may provide protection for the components of the target hit indicator and may provide protection from environmental conditions such as dust, dirt, etc., or debris such as flying rocks or shrapnel produced by a nearby bullet strike. 
     Components held within the housing  110  may include sensors for sensing an impact as well as indicators for indicating an impact, a miss, or other information. The indicators in the embodiment shown in  FIGS.  1 A- 1 B  are light sources in the form of a plurality of light emitting diodes (LEDs). Generally, a light source within the visual spectrum of light may provide the most easily detectible signals; however, in some embodiments it may be advantageous to use an infrared or other non-visible light source for signaling hits/misses. Furthermore, in embodiments the light source may comprise other types of light sources, including one or more of: light emitting diode, laser, incandescent light bulb, arc lamp, gas-discharge lamp, or flash tube. Target hit indicator  100  may further comprise a light redirection element  130  positioned so as to reflect light from the impact indicator light source(s) to a viewer. As depicted in the embodiment shown in  FIGS.  1 A- 1 B , light redirection element  130  may be made of a transparent or translucent material for directing the light produced by the plurality of light emitting diodes (LEDs) which function as the impact indicators. Light redirection element  130  may allow the target hit indicator to be placed on the rear of a target to protect the components of the target hit indicator from damage by a direct bullet strike yet still make the light output from the indicators visible to viewers of the target. Thus, light redirection element  130  may direct light from the indicators around the edge of the target toward a viewer. This can be seen more clearly with reference to  FIGS.  2 A- 2 D and  3 A- 3 D . 
     In embodiments, the light source may comprise one or a plurality of light sources capable of emitting different colored lights or different flash patterns responsive to different determinations made by the microcontroller. For example, a determination of a hit may trigger a red light, while the detection of a miss may trigger a yellow light. In another example, a first hit may trigger a green light, a second subsequent hit may trigger a blue light, and a third consecutive hit may trigger a purple light. In such multi-hit configurations, a determination of a miss, a signal from the user, or the passing of a predetermined time period between hits may reset the hit count. 
       FIGS.  2 A- 2 D  show one embodiment of a target hit indicator  200  attached to the rear of a rectangular target  290 . In the illustrated embodiment, only light redirection element  230  extends beyond the top edge  292  of target  290  while the remainder of the target hit indicator  200  remains within the periphery of the target  290 . Because of this placement, target  290  protects all but light redirection element  230  of target hit indicator  200  from damage due to direct impact. Light from the target hit indicator  200  passes through light redirection element  230  and is reflected around the edge of the target  290  and back up-range and may thus be visible to one or more viewers despite the indicator being positioned behind the target. 
     Light redirection element  230  may be adjustable relative to the housing  210  so as to allow the light to be aimed towards the viewers. For example, light redirection element  230  may be rotated within housing  210  to aim light to a viewer at lower or higher elevation than the target. Endcaps  220  may hold light redirection element  230  from freely rotating during use. Endcaps  220  may be configured to allow for little or no rotation of the endcaps  220  within or about housing  210 . One embodiment of such a configuration based on an asymmetric shape of endcaps  220  may be seen in  FIG.  2 C . Friction between end caps  220  and light redirection element  230  may thus be used to hold light redirection element  230  from moving with respect to housing  210 . Friction may be created by applying a force on the endcaps  220  such as by an elastic material stretched around the endcaps  220  or by manually-applied pressure, threaded fasteners, springs, or any other means. Additionally, end caps  220  may have bumps, ridges, or other features that interface with the light redirection element  230  and increase the friction between the end caps  220  and the light redirection element  230 . 
     Light redirection element  230  may be formed of a flexible or “self-healing” polymer such that direct impact by a bullet causes minimal damage to the light redirection element  230 . Additionally, light redirection element  230  may be replaceable in the event the light redirection element  230  becomes excessively damaged. Alternatively, in embodiments, a plurality of smaller light redirection elements, such as a plurality of light pipes, may be used in place of a single larger light redirection element. (See e.g.,  FIGS.  11 A-F ). In alternate embodiments, a rigid material may be used for the one or more light redirection elements  230  which may break away from the target hit indicator in the event of an impact. (See e.g.,  FIGS.  11 A-F ). 
     Turning now to  FIGS.  3 A- 3 D , target hit indicator  300  may be attached to the rear of a circular target  394 . Despite the curvature of the edge of circular target  394 , only light redirection element  330  of target hit indicator  300  may be visible from a position facing the front side of the target (See, e.g.,  FIG.  3 D ), while the remaining portions of the target hit indicator  300  remain protected behind target  394 . 
       FIG.  4    shows an exploded view of a target hit indicator  400  according to one embodiment. In this depiction, end cap  420  has been removed from housing  410  while the other end cap  420  remains installed in the housing  410 . Light redirection element  430  and other components of the target hit indicator  400  are shown as removed from interior volume  412  of housing  410 . This helps demonstrate one potential structure wherein target hit indicator  400  may be disassembled to replace light redirection element  430  or other components, and then reassembled for continued use. 
     Turning now to  FIGS.  5 A and  5 B , electronics holder  540  and electronics module  550  have been removed from pocket  532  of light redirection element  530 . Electronics module  550  may comprise a printed circuit board  552 , one or more light sources  558 , and battery holder  554 . One or more batteries  556  may provide power to the target hit indicator  500 . Electronics module  550  may additionally comprise sensors, a microcontroller unit (MCU), a processor, and other electrical components (not shown). 
     Electronics module  550  may be held within electronics holder  540 , which may be positioned to hold light source  558  against light entrance area  534  of light redirection element  530 . Light redirection element  530  thus may provide protection for electronics module  550  from dirt, water, etc. 
     In operation, light from one or more light sources  558  passes into light redirection element  530  via light entrance area  534 . The light is redirected by light redirection area  538 , and exits the light redirection element  530  at light exit area  536 . Light redirection area  538  of light redirection element  530  may redirect light by use of a reflective coating or by partial or total internal reflection. In one embodiment, light entrance area  534  may comprise one or more collimators  535  for collecting and focusing light produced by the one or more light sources  558 . 
       FIGS.  6 A and  6 B  show an unexploded view of the components of  FIGS.  5 A and  5 B , including light sources  658  and collimators  635 . As can be seen in  FIG.  6 B , each collimator  635  of light redirection element  630  may be substantially aligned with each of light sources  658 . Thus, light from each of light sources  658  may be collected by a collimator and directed around the edge of a target toward a viewer. 
       FIG.  7    shows an electrical schematic  700  of a target hit indicator according to one embodiment. A power source  790  such as a battery may provide electrical power to various components of the target hit indicator, including microcontroller unit (MCU)  710 , powering light sources  720  and  730 , which may operate as impact and/or miss indicators. A dc/dc converter  740  may be used to provide power to the light sources  720  and  730 , or other components. In another embodiment, the light sources  720  and  730  may be powered directly from power source  790 , rather than by dc/dc converter  740 . The dc/dc converter  740  may also be used to power MCU  710  in the event that the current draw from the light sources  720  and  730  causes the voltage from power source  790  to drop below the acceptable operating voltage of MCU  710 . Diode  770  may prevent power from the dc/dc converter  740  from feeding back into power source  790  while diode  780  may allow MCU  710  to be powered by the dc/dc converter  740  without power source  790  continuously powering light sources  720  and  730 . 
     In embodiments, a photovoltaic cell may be used as power source  790  or may be used in conjunction with power source  790 , for example, to recharge a battery or a capacitor acting as power source  790 . 
     In embodiments, one or more of an impact sensor  750  and an acoustic sensor  760  may be connected to MCU  710 . The impact sensor  750  may be connected by a digital interface and the acoustic sensor  760  may be connected to a digital pin on the MCU  710 . The impact sensor  750  may comprise an accelerometer and a comparator, and the acoustic sensor  760  may comprise a microphone and a comparator. In embodiments, a unitary target hit indicator may comprise a microcontroller, an impact sensor, and an impact indicator and may further include an acoustic sensor. In operation, acoustic information, impact information, or both is received by the microcontroller unit (MCU  710 ). Analysis by the MCU  710  using the acoustic information, impact information, or both, may enable a determination to be made regarding whether a target associated with the target hit indicator has been impacted. The impact indicator may be activated and signal a hit or a miss based on the determination. In embodiments, a light redirection element may include one or more light pipes which may be used to direct light from the impact indicator around the edge of a target towards a user, thus allowing a single unitary device to be mounted behind a target for protection from damage, but allowing light from the indicator to reach a user viewing the front of the target. 
     The MCU  710  may control power to the various components, such as the impact sensor  750  (e.g., accelerometer) and acoustic sensor  760  (e.g., microphone). Power to various components may be provided through a general purpose digital input/output pins from the MCU  710 . 
     In various embodiments, impact sensor  750  may be one or more of a micro electrical machine (MEMS) sensor having programmable digital interrupt outputs, a piezo sensor, or an induction circuit. Impact information (e.g. acceleration values) from impact sensor  750  may be communicated to MCU  710  via a digital interface. 
     Turning now to  FIG.  8   , an electrical schematic  800  of a target hit indicator system having an acoustic sensor according to one embodiment is shown. One skilled in the art will understand that there are many potentially suitable designs for a low-power acoustic input such as the one referenced herein. The embodiment shown in  FIG.  8    uses an acoustic sensor comprising a micro-electrical-mechanical system (MEMS) microphone and a comparator to provide acoustic information in the form of a digital signal to the MCU. Generally, an external amplifier circuit may be used to increase the signal strength of a MEMS microphone. In the embodiment shown in  FIG.  8   , the target hit indicator is not concerned with acoustic fidelity, such that the analog signal from the microphone may be provided directly into a comparator. The comparator may determine whether the acoustic information exceeds a threshold, and this determination may be communicated to the MCU. In response, the MCU may wake the system from low-power standby mode and may activate a light source to indicate a hit or a miss, or take another action. 
       FIG.  9    depicts an electrical schematic of an indicator circuit  900  for a target hit indicator according to one embodiment. In the embodiment shown, dc/dc converter  940  may be used to supply power to components of the target hit indicator via dc/dc converter output  912 . For example, dc/dc converter  940  may be used to power the microcontroller unit, light sources  920  and  930 , which may operate as impact and/or miss indicators, as well as the impact sensor and acoustic sensor. A voltage regulator  950  may be used to reduce the voltage from dc/dc converter output  912  to an appropriate voltage for some components. 
     Activation of the light sources  920  and  930 , which may operate as impact and/or miss indicators, may be controlled by a microcontroller unit  190  via transistors  922 ,  924 ,  932 , and  934 . In the embodiment shown in  FIG.  9   , transistors  922  and  932  may be used to activate light sources  920  and  930  at full brightness. Alternatively, transistors  924  and  934  may be used to activate light sources  920  and  930  at a reduced brightness level. The brightness level may be user selectable or may be automatically selected (e.g., in the event that the power source is unable to supply the necessary current). 
     In an embodiment, a resistive divider network may also be used to drop the dc/dc converter output  912 , such that the MCU may use an analog-to-digital converter to determine if the dc/dc converter  940  is performing correctly. 
     Turning now to  FIGS.  10 A-B , an alternative embodiment of a target hit indicator  1000  is shown. Similar to embodiments shown in  FIGS.  1 - 5   , electronics holder  1040  and a portion of light redirection element  1030  are held within the interior volume  1012  defined by housing  1010 . Rather than attaching directly to a target, however, housing  1010  may be attached to mounting plate  1016  via elastic members  1018 . Mounting plate  1016  in turn may be attached permanently or semi-permanently to a target or may be formed integrally with a target. For example, mounting plate  1016  may be attached to a target via adhesive tape  1019 . Elastic member  1018  may rest in a groove in mounting plate  1016  and housing  1010  to hold the two together. Thus, housing  1010  may be quickly and easily attached to or removed from a target by installing or removing elastic members  1018 . In one embodiment, elastic member  1018  may be a rubber O-ring. 
     Such a mounting system may provide other advantages in addition to ease of installation and removal of the target hit indicator  1000 . When a projectile such as a bullet impacts a target, the target may experience a large acceleration both in the direction of bullet travel and also in the opposite direction. If the target accelerates away from the target hit indicator  1000 , inertial forces are generated that act to pull the target hit indicator  1000  away from the target. Such forces may stress adhesive tape  1019  (or other attachment means) beyond its operational limit, thus undesirably causing the target hit indicator  1000  to detach from the target. Therefore, incorporating a means for dampening such large forces may help keep the target hit indicator  1000  attached to the target. In the embodiment shown in  FIGS.  10 A-B , elastic members  1018  may stretch, thus helping to decouple housing  1010  (and contents of housing  1010 ) from mounting plate  1016 . Decoupling may result in lower peak stress on adhesive tape  1019 , thus resulting in better adhesion of the target hit indicator  1000  to the target. 
     Additionally, as the inertial forces increase with the mass of the target hit indicator  1000 , minimizing the mass adhered to the target also reduces the peak stress on the attachment means, such as adhesive tape  1019 , and resulting in better adhesion. Minimizing the mass may be accomplished through the use of lightweight materials or compact design. For example, housing  1010  may be made of aluminum while electronics holder  1040  may be made of plastic. Additionally, electronics holder  1040  may have a shape that minimizes volume, such as by the triangular shape seen in  FIGS.  10 A and  10 B  that leaves open space between electronics holder  1040  and housing  1010 . 
     In embodiments comprising a circular shaped housing (see  FIG.  10 A ), the circular shape of housing  1010  may allow electronics holder  1040  and light redirection element  1030  to be rotated within housing  1010  to allow a user to adjust the direction of light output. Embodiments of the housing  1010  may contain a plurality of grooves  1011  into which electronics holder projection  1041  may be coupled. A user may align electronics holder projection  1041  with the desired groove  1011  and slide electronics holder  1040  and light redirection element  1030  laterally into housing  1010 . Such an arrangement may provide a positive engagement, preventing electronics holder  1040  (and thus light redirection element  1030 ) from rotating due to vibration, impact, etc. 
     Turning now to  FIGS.  11 A-F , an alternative embodiment of a target hit indicator  1100  having a multiple light redirection elements in the form of light pipes  1130  is shown.  FIG.  11 C  shows a front view of target  1190 . As can be seen, target hit indicator  1100  may be positioned behind target  1190  so that only light pipes  1130  are visible. 
     Light pipes  1130  may be made of a rigid transparent or translucent material and may be designed to break away if impacted so as to not damage the rest of the target hit indicator  1100 . Light pipes  1130  may be inexpensive and easy to replace when broken. Alternatively, light pipes  1130  may be deformable and/or self-healing so as to reduce the damage caused by impacts. 
     Each light pipe  1130  may be associated with a light source (such as an LED) contained within housing  1110 . Thus, in the embodiment in  FIGS.  11 A-F , housing  1110  contains a light source consisting of nine LEDs, each substantially aligned with one of the nine light pipes  1130 . Each light pipe  1130  may comprise a light entrance area (hidden by housing  1110 ) a light redirection area  1138 , and a light exit area  1136 . 
     Additionally, each light pipe  1130  may comprise a collimator to collect the light emitted by a light source substantially aligned with the collimator associated with each light pipe  1130  to produce a substantially parallel beam of light. When total internal reflection is used to reflect light, having a substantially parallel beam of light allows more light to strike the light redirection area  1138  at an angle greater than the critical angle, and thus more light may be reflected off the light redirection area  1138  and directed around the edge of the target  1190  and less light may be lost through the light pipe  1130 . 
     Light from a light source of the may travel into a light pipe  1130  via a light entrance area (hidden by housing  1110 ). Light may reflect off a light redirection area  1138  of light pipe  1130  and then exit light pipe  1130  via a light exit area  1136 . Thus, at least a portion of the light received from the light source via the light entrance area (hidden by housing  1110 ) may reflect off the light redirection area  1138  and exit the light pipe  1130  via the light exit area  1136 . In this way, light produced by the light source from a protected location behind the target  1190  may be directed around the edge of the target toward a viewer. 
     In embodiments, target hit indicator  1100  may be attached to target  1190  via mounting arms  1117 . Endcaps  1120  may attach to housing  1110  and may have gear-shaped shafts that fit in a correspondingly-shaped opening in mounting arms  1117 . Such a configuration may provide for different positioning of housing  1110  with respect to target  1190 , allowing a user to aim the light exiting the light exit area  1136  of light pipes  1130  toward an intended viewer.  FIGS.  11 D,  11 E, and  11 F  show a target hit indicator  1100  in a horizontal position, a below-horizontal position, and an above-horizontal position, respectively. 
       FIGS.  12 A and  12 B  show an additional embodiment of a target hit indicator  1200 .  FIG.  12 A  illustrates target hit indictor  1200  in a fully assembled state while  FIG.  12 B  is an exploded view of some components of target hit indicator  1200 . In embodiments, an electronics module  1250  may be protected from the elements by electronics holder  1252 , and lens  1254 , either of which may be made of a rigid polymer. A seal  1256  prevents dust and liquids from reaching electronics module  1250 . Lens  1254  may be made of a transparent or translucent material and may contain collimators for collimating light emitted by light sources of electronics module  1250 . Light redirection element  1230  may comprise light entrance area  1234 , light redirection area  1238 , and light exit area  1236 , and may be made of a flexible material and may be designed to rest against lens  1254 . Housing  1210  comprises an interior volume  1212  shaped to hold lens  1254  against light redirection element  1230  thereby preventing dirt or other materials from interfering with light transmission between lens  1254  and light redirection element  1230 . Interior volume  1212  also may be shaped to hold lens  1254  and electronics holder  1252  together and to compress seal  1256  sandwiched therebetween, thus creating a weather-resistant enclosure for electronics module  1250 . 
     By integrating collimators into lens  1254 , light redirection element  1230  is less complex than if the collimators were incorporated into lens  1254  in design. This allows for the benefit of making the article less expensive to manufacture. Additionally, as light redirection element  1230  may be a consumable part (in embodiments it may be the only consumable part in the device), this design may result in significantly reducing overall operating costs over the life of the target hit indicator  1200 . 
     While electronics holder  1252  and lens  1254  provide mostly elemental protection for electronics module  1250  (e.g., water, dirt), housing  1210  provides mechanical protection for electronics module  1250  (e.g., impact). To this end, housing  1210  may be made of extruded metal such as aluminum or durable polymer such as glass filled nylon. 
     End caps  1220  may be made of a flexible material such as rubber and may provide additional weather and impact protection for electronics module  1250  in addition to retaining components  1250 ,  1252 ,  1254 ,  1256 , and  1230  in housing  1210 . Discs  1226  may be made of metal and may be placed inside end caps  1220  to provide additional impact protection. 
     Flexible straps  1260  may wrap around end caps  1220  to hold end caps  1220  against base plate  1270 . End caps  1220  may therefore be prevented from sliding off of housing  1210 , thereby maintaining all components of the target hit indicator together as a single unit. Housing  1210  may be rotated around the longitudinal axis with respect to base plate  1270  in order to aim emitted light toward intended viewer(s). Flexible straps  1260  may be loosened to allow housing  1210  to rotate to the desired position and then tightened in order to prevent rotation and otherwise secure the components to the base plate  1270 . 
     Base plate  1270  may be attached to a target by means of, for example, hook and loop fasters. Hook and loop fasteners may be attached to base plate  1270  or may be molded integrally with base plate  1270 . 
     Several features of target hit indicator  1200  facilitate secure attachment of the target hit indicator  1200  to a target, for example, by decoupling a substantial portion of the mass from the target. Hook and loop fasteners between base plate  1270  and the target may provide a strong yet flexible bond which may be able to remain attached during the intense vibrations caused by a bullet impacting a steel target. Flexible straps  1260  and end caps  1224  may operate as means for decoupling the target hit indicator  1200  from the target, further isolating the housing  1210  (and components held within) from impact and vibration. Such decoupling between housing  1210  and base plate  1270  significantly reduces the peak forces on hook and loop fastener  1270 . In at least some instances, the peak forces on hook and loop fastener may be reduced below the maximum strength of the hook and loop fastener, thus providing a secure attachment method using commercially available hook and loop fasteners. Hook and loop fasteners are desirable because they provide inexpensive, easy, tool-less attachment and removal to nearly all existing target designs. 
     In certain embodiments, however, other attachments may be desired. In an embodiment, for example, a base plate may be attached to a secondary plate, with the secondary plate being attached using an existing mounting hole. Such a secondary plate may be made of metal, be pivotally attached to the base plate, and may have a hole for aligning with a preexisting hole in the target (e.g., a hole for mounting the target). 
     In embodiments, a base plate  1270  may also have one or more holes for fastening to a specially designed target. For example, a target may have appropriately placed holes for inserting one or more fasteners therethrough. The fastener(s) may pass through the one or more holes in the base plate. A nut or other fastening means may be placed on the fastener, thus holding the base plate onto the target. 
     Rather than attaching to a steel target, a target hit indicator may be formed integrally with a target, as shown in  FIGS.  13 A-D .  FIG.  13 A  is a side view of a target hit indicator formed integrally with a target while  FIG.  13 B  is an oblique projection of the same. With reference to  FIGS.  13 A-D , target hit indicator target  1300  (hereinafter “THI target”) may be made from a flexible transparent material which is designed to be impacted by a bullet. Material selection for the target is such that a bullet will pass through the THI target  1300  with minimal damage to the THI target  1300 . Sensors (not shown) may detect whether the THI target  1300  has been impacted and may also detect the location of the impact. One or more light sources (not shown) along the top and bottom edges  1312  introduce light into the THI target  1300  which passes perpendicular to the thickness of THI target  1300  until the light reaches reflective surface element  1314 . Reflective surface element  1314  reflects the light toward the shooter to indicate an impact (or miss) as shown by the arrows in  FIGS.  13 A  and B. Thus, THI target  1300  acts similarly to the light redirection element of the other target hit indicator embodiments shown herein. 
     In the embodiment shown in  FIG.  13   , reflective surface elements  1314  form an “X” shape.  FIG.  13 C  shows target  1300  with none of reflective elements  1314  illuminated, while  FIG.  13 D  shows all elements illuminated. In operation, any one or more reflective surface elements  1314  may be illuminated to convey desired information. For example, specific elements may be illuminated to indicate the point of impact or the direction of a miss. Still further patterns could be used to indicate the number of hits or misses or even the battery condition. 
       FIG.  14    depicts an embodiment of a method  1400  of indicating whether a target has been impacted that may include operating  1410  a target hit indicator system in a low-power mode. While operating  1410  in low-power receiving  1420 , from the impact sensor by the microcontroller unit, initial vibration information, and determining  1425  whether the initial vibration information is above a vibration standby wake threshold. Alternatively or in combination, method  1400  may include receiving  1430 , from an acoustic sensor by the microcontroller unit, initial acoustic information, and determining  1435  whether the initial acoustic information is above an acoustic standby wake threshold. If either the initial vibration information is above the vibration standby wake threshold or the initial acoustic information is above the acoustic standby wake threshold waking the target hit indicator system, such that it is operating  1440  at standard power. Once the system has gone through the step of waking and is operating  1440  at standard power method  1400  may further include receiving  1450 , from an impact sensor by a microcontroller unit, vibration information, processing  1460  the vibration information (e.g. by integration), determining  1470  whether the processed vibration information is above a vibration impact threshold, and if the processed vibration information is above a vibration impact threshold (a positive determination), indicating  1480  a hit via the impact indicator. The method  1400  may further include indicating  1490  a miss via the impact indicator if the processed vibration information is not above the vibration impact threshold (a negative determination). 
     The system may remain operating  1410  in a low-power mode responsive to its determining  1425  that the initial vibration information is less than the vibration standby wake threshold (a negative determination) and determining  1435  that the initial acoustic information is less than the acoustic standby wake threshold (a negative determination). The system may also revert back into operating  1410  in a low-power mode upon the expiring  1495  of a sufficient amount of time after determining  1425 / 1435  either of the standby wake thresholds have been surpassed and the system has indicated  1480 / 1490  either a hit or a miss. 
     Referring back to  FIG.  7   , in operation, MCU  710  may receive information from one or more of the impact sensor  750  and the acoustic sensor  760  and make a determination as to whether the target has been impacted. If it is determined  1470  that the target has been impacted (e.g., impact information is determined to be above a vibration impact threshold), MCU  710  may activate a light source  720 , which may operate as an impact indicator, to signal an impact. In some embodiments, the target hit indicator may comprise an additional light source  730 , which may output a different color light to operate as a miss indicator, to indicate that a projectile passed near the target hit indicator but did not impact the target. If MCU  710  determines  1470  that a miss occurred, light source  730  may be activated. 
     In some embodiments, the MCU  710  may be always powered on, while power to other components (e.g., impact sensor  750 , acoustic sensor  760 , dc/dc converter  740 , etc.) may be selectively controlled and reduced when the MCU  710  determines that power to some components is unnecessary. The MCU  710  may be configured to manage the system such that components default to a low-power “standby” mode after a period of time in which no hits or misses are detected. In the low-power standby mode, some components (including a clock, which may be integrated into the MCU  710 ) may not be powered, so as to minimize the target hit indicator&#39;s power consumption and thereby increase its operational battery life. 
     In some embodiments, in a standby mode, the system may “listen” for impact information from the impact sensor  750  and acoustic information from the acoustic sensor  760 . If impact information or acoustic information is received, the system may “wake up” from standby mode and resume an “active” mode in which power may be restored to more or all of the components under control of the MCU. In some embodiments, the MCU may receive an interrupt from the impact sensor  750  or acoustic sensor  760 . In embodiments, the MCU may be configured to wake up one or more components of the system upon receiving impact information or acoustic information that exceeds an associated standby wake threshold. 
     In one embodiment, if the target hit indicator system is woken up by the acoustic sensor  760 , the system may monitor only the acoustic sensor  760 . If, after being awakened by acoustic sensor  760 , vibration above a threshold (e.g. the vibration standby wake threshold) is detected by impact sensor  750 , the system may ignore the acoustic information and monitor the impact sensor  750  only. 
     In embodiments as shown in  FIGS.  7  and  14   , when MCU  710  receives  1420  initial impact information from the impact sensor  750  that is determined  1425  to exceed a vibration standby wake threshold, MCU  710  may communicate with impact sensor  750  to receive  1450  additional impact information for some time interval (e.g., 100 milliseconds). MCU  710  may add, integrate, or otherwise process  1460  additional impact information to obtain a total amount of acceleration for the time interval. If the total amount of acceleration is determined  1470  to exceed a specified value (i.e. vibration impact threshold) during the time interval, the system may determine  1470  that the target has been impacted and indicate  1480  a hit via light source  720 . If the total amount of acceleration is determined  1470  to not exceed the vibration impact wake threshold during the time period, the MCU  710  may determine  1470  that the target has not been impacted and may perform no action or may indicate  1490  a miss via light source  730 . 
     In embodiments, the unitary target hit indicator may utilize a two-factor detection system. A two-factor detection system may combine acoustic and acceleration information to determine if target is struck and filter out non-hit events such as hitting support structure or kicked up rocks. In such embodiments, acoustic data and acceleration data may be combined to provide more accurate hit/miss determination. There are several methods in which a two-factor detection system may be used. In some embodimoents, the target hit indicator may use a two-factor detection system that may require both acoustic information and acceleration-based impact information to count as a hit. This may reduce the number of false hits a user may experience and may prevent false indications of hits/misses while the user is mounting or handling a target hit indicator, especially if the target hit indicator is set to a very sensitive mode. In an alternate embodiment, the target hit indicator may utilize a two-factor detection system that may require that any acceleration “hit” be accompanied by the sound of about the frequency of the target being struck. 
     Some embodiments of the target hit indicator system may require that the relative time-of-arrival of the sound received by the acoustic sensor and the vibration of the target received by the impact sensor fall within a designated range in order to determine a hit. 
     In some embodiments, the vibration and/or acoustic standby wake thresholds or the vibration and/or acoustic impact thresholds may be set or modified by the user. For example, preset values may be selectable by a switch or a user may be able to program specific values into the target hit indicator. In some embodiments, the programing of the thresholds, or other programing information (e.g. resetting the target hit indicator when programmed to determine and indicate successive hits), may be achieved by the target hit indicator receiving audio signals from the user. Such audio signals may be encoded to provide the target hit indicator with particular programming instructions, which may be decoded and interpreted by the MCU via the acoustic sensor. One particular advantage of this acoustic method of programming, especially with regard to the resetting of target hit indicators, is that it may allow for the programming of multiple target hit indicator systems with a single signal. This could be useful in situations such as use on a multi-target course, where the entire course, consisting of multiple targets each equipped with a separate target hit indicator, may be reset (or otherwise programmed) via a single audio signal. 
     In embodiments a target hit indicator may include a receiver, such as an infrared receiver, for sending programming information to the target hit indicator, or otherwise controlling the target hit indicator (e.g. turning the system on/off, etc.). 
     In alternate embodiments, these thresholds may be set by a “learning” mode. In such learning mode embodiments a user may place the target hit indicator system into the learning mode (e.g. by the actuation of a switch or by the transmission of a specific acoustic signal to the device) after which the system may register the next set of impact and/or acoustic information received by the target hit indicator may be used 2 l as either a hit or miss baseline against which subsequent information is compared in order to make the hit/miss determination. This may allow for the target hit indicator system to tailor its sensor thresholds to the particular target to which it has been attached as targets of different sizes, shapes, thicknesses, and materials can produce significantly different acoustic signatures when impacted by a bullet. 
     The use of collimators and adjustable housing positions may result in increased battery life for the target hit indicator, among other advantages. In the case of a target hit indicator using total internal reflection to direct light, collimators allow more light to be reflected and correspondingly less light lost to the environment. Additionally, the narrower the beam of light from the target hit indicator to the viewer, the less intense the light source must be to be viewable at a given distance. The collimator may help collect light and direct the light into a narrow beam. Necessarily, a narrower beam of light also has a smaller field of view. Therefore, adjustable housing positions allow a narrow beam of light to reach an intended viewer and thus minimize the necessary intensity of the light source (and resulting power draw) of the target hit indicator. 
     In embodiments, the unitary design of the target hit indicator may provide environmental protection for the electronics while the low-power standby mode facilitates a very low power draw of the system that may extend battery life to months or even years, thus resulting in a target hit indicator that can be left on a target in uncontrolled weather for extended periods of time. These features provide for an advantage in that a user need not remove the target hit indicator after a shooting session, nor does the user need to travel to the target to turn the unit off. The target hit indicator may remain in a low-power standby mode for months or even years before the batteries are depleted. 
     Because portions of a target hit indicator may be sealed for protection against dust and the weather, controlling the target hit indicator may require means other than traditional switches and buttons. Controlling a target hit indicator may entail changing operating modes, flashing sequences, turning the unit on or off, etc. Embodiments of target hit indicators may be controlled using acoustic sounds received by the microphone. Embodiments may also be controlled through the use of sensors that detect magnetic fields, or radio frequency transmissions (including Wi-Fi, Bluetooth, etc.). Control may also be achieved by holding the target hit indicator unit in a particular orientation or by tapping the unit a specified number of times. For example, a target hit indicator may be turned off and on by holding a unit roughly orthogonal to the orientation it would be on a target and tapping the unit quickly three times. Confirmation of a mode change can be relayed to the user, such as by flashing lights in a particular pattern. 
     In embodiments, a target hit indicator may be attached to a target using any suitable attachment structure now known or hereinafter discovered including, but not limited to, adhesives, straps, magnets, welding, brazing, soldering, fasteners including screws or bolts, and hook and loop type fasteners. Alternatively, rather than being separate from and mechanically attached to a target, a target hit indicator may be formed integrally with a target. 
     In embodiments, a light pipe may be a particular embodiment of a light redirection element. In alternate embodiments, rather than passing through a light pipe, light may pass through air or another suitably transparent medium until it contacts a light redirection element at which point the light may reflect off the light redirection element before continuing to the viewer. Such embodiments, for example, may be similar to the embodiment shown in  FIG.  5 A , except omitting the light pipe, with a light redirection element being included in a position coplanar with where light redirection element would have been. The light redirection element may be any of a number of materials or types of light redirection elements, such as a mirror, glass, polymer (e.g., acrylic), metal, biaxially-oriented polyethylene terephthalate, or any other element capable of redirecting incident light to a new direction, and may have any structural configuration that functions to redirect light from the impact indicator light sources. 
     Other embodiments of an impact indicator may include signaling subsystems other than light and light redirection elements for notifying a user of a hit or a miss. For example, the hit indicator and miss indicator may be include any device having capability to convey information to a user over a distance, such as a flag, colored object, or moving object. Furthermore, a hit indicator comprising a light source may not require a light redirection element. In embodiments, the light sources may be exposed around the edge of the target, and may be replaceable in the event of a bullet strike. In embodiments, for example, a hit indicator light source may be located on a movable arm which may extend or rotate from a retracted position behind a target to a visible position outside the edge of the target, thus placing it in view of a user. Such a movable arm may move from behind the target upon detection of an impact or miss and may retract after a period of time, allowing a user to take another shot yet still prevent damage to the hit indicator light source in the retracted position. Such a system may provide the additional advantage of having no portion of the target hit indicator light source exposed from behind the target, except during a brief period of time after the detection of a hit or a miss, in which it signals said hit or miss. This may reduce likelihood of damage to the hit indicator light source due to impact with a subsequently fired projectile. 
     In embodiments, patterns of light flashes or other indicator methods may be used to convey types of information other than a binary hit/miss indication. In one embodiment, for example, a count of the total number of hits or misses may be conveyed. In an embodiment, a low battery indication may be conveyed via the use of different colors of light, different numbers of flashes, etc. 
     Embodiments of a target hit indicator may comprise a plurality of acoustic sensors spaced apart from each other in at least one axis. Such a configuration of a target hit indicator may provide for the capability of acoustically determining the location of an impact or miss. In such embodiments the target hit indicator may determine a horizontal location of a miss based on the order, time difference, or intensity between the sound being received at each acoustic sensor. The impact indicator may then use a signaling methodology to indicate the direction of the hit/miss to the user, for example, by flashing lights on one side only or by a sweeping motion. Any suitable number of impact sensors or acoustic sensors may be used to locate an impact or miss and different configurations of indicators may be used to indicate direction. With reference to  FIG.  15   , such embodiments may determine the location of an impact by a method such as method  1500 , in which the target hit indicator is receiving  1510  acoustic info from a first acoustic sensor, and receiving 1520 second acoustic info from a second acoustic sensor, and uses the acoustic info and the second acoustic info to make a determining  1530  of where the projectile made impact. In embodiments, n number of acoustic sensors may be used to receive n number of sets of acoustic info to inform the determining  1530  of the projectile impact location. Method  1500  may further include indicating  1540  the location of the projectile&#39;s impact based on the determining  1530 . Such an indicating  1530  may be achieved by, for example, activating lights on only the half of the target hit indicator corresponding to the location of the impact. Method  1500  may be most useful for indicating to the shooter to which side they missed the target. 
     One of ordinary skill in the art would recognize that many features disclosed herein may provide advantages over the prior art either alone or in combination with other features and therefore subject matter disclosed herein should not be taken as dependent on the inclusion of any other subject matter herein, unless expressly stated otherwise. For example, the use of integration or other processing of impact information to determine whether a projectile has impacted a target may be useful for unitary as well as non-unitary target hit indicators. 
     One or ordinary skill in the art will also recognize that many suitable materials may be used in constructing a target hit indicator, including metals, plastics or other polymers, glass, rubber, wood, etc. One would also recognize that material choice for a part is dependent on the desired properties of the part and that use of heavier materials may have additional advantages that outweigh the disadvantage of the increased weight. Further, one of ordinary skill in the art will also recognize that many variations of the systems and methods disclosed herein are possible without departing from the scope of embodiments.