the following discussion describes in detail one embodiment of the invention ( and several variations of that embodiment ). this discussion should not be construed , however , as limiting the invention to those particular embodiments , practitioners skilled in the art will recognize numerous other embodiments as well . for definition of the complete scope of the invention , the reader is directed to appended claims . fig1 is the present invention 10 , an extendable retractable screen 12 having motion sensors 14 responsive to projectiles for extending said barrier . shown is a ball 18 being hit by a batter in a line drive fashion . also shown is the screen 12 deflecting the ball 18 before it reaches the pitcher 16 thus insuring the functionality of said invention . further shown is the intended location for the proper use of the present invention 10 to further insure that its functionality is preserved . fig2 is the present invention 10 , an extendable retractable barrier having motion sensors responsive to projectiles for extending said barrier . shown is the typical location for the present invention 10 to insure that the proper functionality is maintained . also shown is the present invention 10 as it relates to a baseball diamond . further shown is the typical position of the present invention 10 as it correlates to the pitchers mound 22 , the pitchers rubber 24 and home plate 26 . the actual distance may vary due to the overall change in field size between leagues , shown is a visual representation of the present invention 10 intended location . fig3 shows a perspective view of the present invention 10 . shown are call outs of the items which comprise said invention . also shown is a visual representation of the present invention 10 as it may look at the time of manufacturing and assembly . also shown is the interrelation of the sensors 14 as they relate to the housing unit 13 of said invention 10 . further shown is the relation of the housing unit 10 as it relates to the protective screen 12 . shown is a plurality of sensors 14 that may comprise the present invention at the time of manufacturing . fig4 is shows a sectional view of the present invention 10 . shown are call outs of several items which comprise the present invention 10 . also shown is the intended interrelation of these parts in order to obtain the functionality of said invention 10 . shown is the screen 12 , and the screen mounting bracket 28 as they are furnished to the drive gear assembly 29 which will allow the screen to traverse its intended distance . also shown is the seal 32 which is housed within the ground of the field . further shown is the relationship between the housing 13 , the seal 32 and the screen 12 . a timer 40 included to retract the screen 12 after per - determined period of time once the screen 12 is extended and deployed . this sectional view is depicted to show how the present invention 10 may appear at time of assembly . fig5 shows a sectional view of the present invention 10 , an extendable retractable screen 10 having motion sensors responsive to projectiles for extending said barrier . shown is the drive mechanism 29 having raised the screen 12 to an elevated position . said barrier having impact resistant screen 12 movable by means of chain 30 drive between a seated and extended position . fig6 is a cross section view of the present invention 10 taken from fig4 as indicated . shown is the interrelation of the components which drive the screen into its intended functional position including the motor 36 and drive shaft 37 , the bearing block 34 and the chain 30 communicating therebetween . also shown is the sensor 14 location as it relates to the main drive motor 36 of the present invention 10 . further shown is an attempt to position all the functioning parts of the present invention 10 as they may appear during manufacturing and assembly . fig7 is a cross section view of the present invention 10 including a remote control actuator 38 . the device can be operated mechanically or by hand held remote control 38 as well as using the electronic sensors 14 . fig8 is a cross sectional view of the chain drive assembly 29 present invention . shown is the intricate workings of the chain drive assembly 29 as the chain 30 is affixed to the screen mounting bracket 28 that is further affixed to the screen 12 with fastening means in order to insure repairability due to stress or natural wear of parts . it will be understood that each of the elements described above , or two or more together may also find a useful application in other types of methods differing from the type described above . while certain novel features of this invention have been shown and described and are pointed out in the annexed claims , it is not intended to be limited to the details above , since it will be understood that various omissions , modifications , substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the spirit of the present invention . without further analysis , the foregoing will so fully reveal the gist of the present invention that others can , by applying current knowledge , readily adapt it for various application without omitting features that , from the standpoint of prior art , fairly constitute essential characteristics of the generic or specific aspects of this invention .
a protective barrier for use on a baseball field that is actuated by motion sensors that are housed within a structured base . the protective barrier is actuated when a projectile such as a baseball travels through the sensors line of sight . the barrier serves to sense when a line drive is hit towards a pitcher and will rapidly extend to block the baseball and greatly reduce the possibility of harm to the pitcher .