Abstract:
A method of preventing trigger bounce during the launching of a projectile by a projectile launcher includes the step of first providing a projectile launcher having a trigger capable of actuating between a full non-firing position and a full firing position. An amount of time is determined for the trigger to normally transition from a full non-firing position to a full firing position. A sensor, such as an analog optical sensor, is used to sense position of the trigger. If the time for the trigger to transition from a non-firing position to a firing position exceeds the time for the trigger to normally transition from a full non-firing position to a full firing position, launch of the projectile is delayed period of time requiring the trigger to be release to a full non-firing position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is related to and claims priority from earlier filed provisional patent application Ser. No. 60/534,563, filed Jan. 6, 2004. 

   BACKGROUND OF THE INVENTION 
   The invention relates generally to paintball markers and other projectile launching devices. The present invention relates to the assembly, operation and control of a trigger of a projectile launcher, such as a paintball marker, and the firing of projectiles therefrom. The present invention particularly relates to the launching of a projectiles in an electronic paintball marker and other such devices. 
   The present invention relates to any type of projectile launcher, such as a paintball marker or firearm. For ease of discussion herein, this description relates solely to paintball markers and the control of triggers therein. However, it should be understood that the present invention is applicable to any type of projectile launcher and the scope of the present invention and the claims herein are intended to cover such projectile launchers other than paintball launchers. 
   However, it is also well known that it is possible, on only one pull or a partial pull of the trigger, a marker can operate automatically, i.e. firing multiple paintballs without fully releasing the trigger or fully pulling the trigger. This is known as “trigger bounce” in the paintball and weapon industries. Trigger bounce can occur in markers that have mechanical or electrical triggers. 
   In markers that have mechanical triggers, a trigger is pulled to open a pneumatic valve via a mechanical linkage to release a burst of air from an air supply to launch the paintball through the marker barrel. Such operation is well known in the art and need not be discussed in further detail herein. 
   As seen in the prior art paintball marker  10  of  FIG. 1 , main body  12  is provided with a barrel  14  for launching the paintball  16 . A trigger  18  typically is positioned in the grip frame portion  20  of the marker  10 . When the trigger  18  is pulled just enough to launch the paintball  16  and the trigger  18  is held in such a position, the mechanical recoil of the marker  10  can force the trigger  18  back into the finger of the user without another pull of the trigger  18  resulting in the immediate launching of another paintball  16 . As long as the trigger  18  is held in the partially pulled positioned and the marker  10  is balanced appropriated, the marker  10  can be easily be operated in automatic launching mode to launch paintballs  16  in successive fashion. 
   Such trigger bounce can also occur in triggers  18  that use electronic sensors or electronic switches to determine trigger position. Such electronic sensors (not shown in  FIG. 1 ) can be analog or digital. For example, an analog sensor can be an optical sensor that passes a portion of the trigger in front of a light emitter and light receiver or a Hall Effect inductive device that uses magnet or ferrous material and a coil to measure distance of trigger travel. 
   By way of example, a trigger equipped with an optical sensor  22  is shown in  FIG. 2  to illustrate trigger bounce in such an electronic environment. Trigger  18  pivots on a pin  24  that passes through the body of the grip frame  20 . The trigger  18  is held onto the pin  24  by means of a set screw  26 . A second set screw  28  is positioned in a threaded hole  30  through the front of the trigger  18  and acts as a trigger stop. This set screw  28  can be screwed into or out from the hole  30  in order to vary the maximum travel of the trigger  18 . A third set screw  32  locates in a threaded hole  34  through the top of the trigger  18  and also acts as a trigger stop. This set screw  32  can be screwed into or out from the hole  34  in order to vary the rest position of the trigger  18 . A small magnet  36  is located in the grip frame  20  above a fourth set screw  38 . This magnet  36  attracts the set screw  38 , ensuring that the trigger  18  returns to its rest position when released. 
   Most importantly, a prong  40  protrudes from the rear of the trigger  18  passing through a slot in the grip frame  20 . When the trigger  18  is operated the prong  40  passes through a slotted optical sensor  22 , having a light emitter  22   a  and a light receiver  22   b . More specifically, light emitter  22   a  emits light toward light receiver  22   b . When the light receiver  22   b  senses the full strength of the light emitted from light emitter  22   a , a non-firing position can be indicated. When the prong  40  completely blocks the light receiver  22   b , a firing position can be indicated. 
   A typical optical sensor  22  used in a paintball marker  10  has a 1.2 millimeters diameter view. Thus, a trigger stroke length of 1.2 millimeters can be monitored. Different optical sensors with different diameters can be used and still be within the scope of the present invention. It should also be understood that the trigger construction of  FIG. 2  is just one example of how a an optical sensor  22  can be used to monitor trigger position. 
   Also, a threshold level can be set so that when the trigger  18  blocks a certain amount of light to the light receiver  35   b , a firing position can also be indicated. Such a threshold can be set anywhere from 0 to 100 percent light blockage but it is typically in the range of 40–60 percent light blockage to indicate a firing condition. Therefore, the optical sensor  22  can detect trigger position along its path of travel. 
   In this example that employs an optical sensor  22  to sense trigger position, trigger bounce occurs when the trigger  18  is partially pulled and cycles slowly between a position just above and just below the threshold level for triggering. The resultant recoil of the marker  10  during the physical firing and movement of the bolt therein (not shown) causes the trigger  18  to move between the two aforementioned positions resulting in the marker  10  operating in a simulated automatic mode of operation. 
   Thus, it is very common in the use of paintball markers  10  to exploit the recoil of the marker during firing while holding the trigger  18  down to enable the marker  10  to fire automatically without pulling the trigger  18  again. The firing of multiple paintballs  16  from only a single pull of the trigger  18  is highly undesirable as it contravenes typical paintball competition rules. While players are penalized for such rules infractions, trigger bounce is still exploited during game play. 
   In view of the foregoing, there is a need for a way to enforce paintball rules that prohibit automatic firing by exploiting trigger bounce. There is a further need to control the operation of the paintball marker itself to ensure that a single trigger pull results in only one paintball being fired. 
   SUMMARY OF THE INVENTION 
   The present invention preserves the advantages of prior art trigger systems for paintball markers. In addition, it provides new advantages not found in currently available trigger systems and overcomes many disadvantages of such currently available systems. 
   The invention is generally directed to the novel and unique method of preventing trigger bounce during the launching of a projectile by a projectile launcher, such as a paintball marker. The method of the present invention includes the step of first providing a projectile launcher having a trigger capable of actuating between a full non-firing position and a full firing position. An amount of time is determined for the trigger to normally transition from a full non-firing position to a full firing position. A sensor, such as an analog optical sensor, is used to sense position of the trigger. If the time for the trigger to transition from a non-firing position to a firing position exceeds the time for the trigger to normally transition from a full non-firing position to a full firing position, launch of the projectile is followed by an enforced time delay during which no subsequent projectile launches can occur while requiring that the trigger be released to a full non-firing position. 
   It is therefore an object of the present invention to provide a method of controlling the firing operation of a paintball marker. 
   It is an object of the present invention to provide a method for controlling the operation of the trigger in a paintball marker. 
   It is a further object of the present invention to provide a method of monitoring the position of the trigger in a paintball marker. 
   Another object of the present invention is to provide a method for preventing trigger bounce in a paintball marker that employs an analog sensor to monitor trigger position. 
   It is a further object of the present invention to provide a method to prevent trigger bounce from permitting a non-automatic paintball marker from operating in an automatic firing mode. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features which are characteristic of the present invention are set forth in the appended claims. However, the invention&#39;s preferred embodiments, together with further objects and attendant advantages, will be best understood by reference to the following detailed description taken in connection with the accompanying drawings in which: 
       FIG. 1  is side view of a prior art paintball marker; 
       FIG. 2  is a side view of a prior art trigger assembly that uses an analog optical sensor to monitor trigger position; 
       FIG. 3  is a flowchart illustrating the method of the present invention; 
       FIG. 4  is a graph of trigger position against time during a typical trigger pull and release using an analog sensor; 
       FIG. 5  is a table of the data graphed in  FIG. 3 ; 
       FIG. 6  is a comparative graph of trigger position against time for a valid trigger pull and an invalid trigger pull based on transition time; 
       FIG. 7  is comparative graph of trigger position against time for a valid trigger pull and an invalid trigger pull based on stroke length; and 
       FIG. 8  is a graph of an invalid trigger pull based on oscillatory characteristics. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The prior art operation of an analog sensor  22 , such as an optical sensor, to control triggering in a paintball marker  10  is discussed in detail in connection with  FIGS. 1 and 2  above.  FIGS. 3–7  below discuss in detail the monitoring and filtering of such an analog sensor  22  to prevent unwanted automatic mode firing due to trigger bounce exploitation. In the prior art, analog sensors  22  are merely used as ON/OFF sensors where a certain threshold is met to indicate a given position of the trigger  18 . As will be discussed in detail below, the present invention uses the analog sensor  22  and all of the analog data supplied by it, including partial measurement of trigger  18  travel, to detect and then stop a trigger  18  bounce operation of a marker  10 . 
   Referring first to  FIG. 3 , a flow chart of the general operation of the method of present invention is shown. Known paintball markers  10  include operating systems that control the entire operation of the marker  10 , including firing timing, air pressure timing, bolt movement and paintball loading rates. The analog sensor  22  of the type shown in  FIG. 2  sends a real-time analog signal to its output which is fed into a microprocessor  42 , which typically runs the operating system of the marker  10 . The analog signal is digitally sampled periodically at  44 , such as at a rate of once every 120 microseconds. The digital sampling  44  is analyzed at  46  and if it appears to be a valid trigger profile, the marker  10  is permitted to operate normally at  48 . However, if an abnormality is detected in the sampled signal, it is considered to be an invalid signal based on impermissible trigger bounce at  50  which could result in the marker  10  operating in an automatic mode. In this later case, a delay  52  after firing can be caused. Details of the operation of the method of present invention are set forth below. 
   To understand the appearance of invalid trigger bounce signal, a valid signal must first be understood.  FIG. 4  illustrates a graphical representation of a trigger position versus time resulting from a typical and valid trigger pull, which would not generate trigger bounce, is shown. At time t 0 , the trigger  18  is in a fully released, non-firing position so that the analog electrical signal of the sensor is at a low level  52 . As the trigger is depressed at about t 2 , the signal rises at  54  as the trigger passes through the optical sensor  22  as more light is blocked by the prong  40  from reaching the light receiver  22   b . When the trigger  18  reaches a trigger activation point or level  56  as it moves from LOW (at  52 ) to HIGH (at  58 ), the firing sequence can be initiated and a paintball  16  launched. By way of example, the trigger LOW level  52  can be 0 volts while the HIGH level  58  can be 5 volts. Of course, this depends on the sensor  22  used for a given marker  10 . 
   Also, the trigger activation point  56  can be 50% (equating to about 2.5 volts, for example) of the overall travel or stroke of the trigger  18 . The actual trigger activation point  56  can be programmed and set as desired. 
   Initiating a firing sequence based on the sensor  22  reaching a given point  56  is well known in the art and need not be further discussed herein. It should also be understood that a typical sensor  22  has a LOW signal  52  when the trigger is released and a HIGH signal  58  when the trigger is depressed. Certain sensors and the appropriate circuitry therefor can be designed for the opposite arrangement where a HIGH signal represents a trigger released condition and a LOW signal represents a trigger depressed condition. The method of the present invention can be modified to accommodate such a sensor. 
   Still referring to  FIG. 4 , when the trigger  18  is fully depressed representing a full firing position at about t 10 , the sensor  22  reaches a HIGH position  58 . As the trigger  18  is released, the signal received by the sensor falls at  60  at a later position in time representing reversal of the position of the trigger  18 . Typical marker software requires that the trigger  18  be released and then re-pulled to effectuate a another firing cycle. 
   As shown in the chart in  FIG. 5 , the microprocessor maintains a running log of the digitized sensor output over time which is analyzed in real-time. This is created by a real-time software loop which is constantly storing the value of the trigger position. A short time after the preset trigger activation point  56  is reached, a snapshot of the log of the sensor output is taken and then analyzed. During this analysis, the data from this table is passed through a trigger transition filter algorithm, which compares how the trigger has been pulled against user defined parameters to determine whether it is a valid signal or an invalid signal thereby representing a trigger bounce mode of operation. 
   In  FIG. 6 , the parameter of transition time from the trigger being fully released to the trigger being fully depressed is measured as a way to determine if trigger bounce is occurring. Line A represents a normal transition signal resulting from a normal trigger pull, such as the one shown in  FIG. 4 . Line A represents a trigger pull where the user intends to pull the trigger fully for the purpose of firing a single projectile. A valid trigger pull typically transitions via  64  from LOW  62  to HIGH  66  state in less than 5 milliseconds, such as in the range of 1–2 milliseconds. 
   In contrast, Line B represents a signal received from a trigger pull that has an unusually long transition time  68  from LOW  62  to HIGH state  66 . A transition time that exceeds a preferred time of 10 milliseconds, indicates that the user is intentionally only partially pulling the trigger  18  for the purposes of exploiting the trigger bounce effect. This transition tolerance specifies the amount of time that the trigger can take to move past the optical sensor  22 . The transition tolerance parameter can be set within the filtering software to be a given amount. If that amount is exceeded, the filtering software senses a trigger bounce condition. Thus, the present invention provides a HIGH pass-type filter to detect a trigger bounce condition. 
   Turning now to  FIG. 7 , another filtering parameter is shown in detail. The band parameter defines how far the trigger  18  must be depressed and how far it must be released before a trigger pull is considered a valid pull. In the example of  FIG. 7 , a the band parameter is set with 15% (at reference line  70 ) being a minimum release point and 85% (at reference line  72 ) being a minimum pull point. Pull represented by A is valid because the trigger  18  was released more than 15% (at reference line  70 ) and then depressed more than 85% (at reference line  72 ) thereby representing a full, valid trigger pull. On the other hand, trigger pull represented by B in  FIG. 7  is invalid because although it starts below the release minimum  70  it fails to be depressed enough at  74  to exceed the minimum depression point at 85% (at reference line  72 ). 
   Still further, the method of the present can employ additional parameters for the purpose of setting forth a benchmark for determining when there is a trigger bounce operation. For example, minimum times can be set for the trigger to remain released or depressed. Referring back to  FIG. 7 , signal (at reference line  62 ) may be required to be LOW for a given period of time while the signal (at reference line  66 ) may be required to be HIGH for a period of time. For example, it may be required that the trigger  18  may have to be released or depressed for at least 10 milliseconds before another firing sequence can be initiated. 
   Turning now to  FIG. 8 , a typical signal of a trigger sensor  22 , that is not being monitored and filtered by the method of present invention, is shown. This is a common trigger bounce signature, although, as can be understood, these signatures vary from marker to marker. As can be seen, the position of trigger  18  is hovering above and below the trigger activation line. Each time the line  76  passes above the activation line  56 , another firing sequence is initiated. In the example shown in  FIG. 8 , three paintballs are launched, corresponding to transition points  78 ,  80  and  82  for only a single full pull of the trigger which occurred from LOW level  62  to HIGH level  66 . 
   As the trigger bounce is allowed to continue over time, the more the trigger pulls resemble valid trigger pulls. However, if the signal of  FIG. 8  was monitored and filtered using the method of the present invention, the signal would have been quickly determined to be invalid as a clear trigger bounce operation. For example, the signal of  FIG. 8  transitions too slowly from a fully released condition at  62  to a trigger depressed condition at  66 . Also, the stroke length of the trigger  18  is far too short as it hovers about the trigger activation line  56 . Also, the signal does not remain long enough above and below the trigger activation line  56 . When combined as desired, the various parameters can be set to eliminate the effect of recoil and trigger bounce on a paintball marker  10 . 
   The trigger transition filter of the present invention can be easily incorporated into an existing operating system of a marker  10 . Any algorithm can be employed to carry out the method of the present invention. Further, the filter at  46  of  FIG. 3  of the present invention can be written in any language known in the art for easy incorporation into a marker operating system. The software that embodies the trigger transition filter of the present invention can be easily installed on a marker  10  by an upgrade. Moreover, once the software is installed on a marker  10 , the parameters of the software, as described above, can be easily set for all competitors during a competition. For example, before a competition, the parameters for the match can be uploaded to the markers of the competitors to dictate the constraints on trigger bounce operation. Thus, the parameters of trigger bounce control and monitoring can be customized according the players and match at hand. 
   It would be appreciated by those skilled in the art that various changes and modifications can be made to the illustrated embodiments without departing from the spirit of the present invention. All such modifications and changes are intended to be covered by the appended claims.