Patent GB-519948-A (GB)
Title: Improvements in and relating to miniature-rifle ranges using cinematographic target images
IPC: F41J9/14
Filed: 1938-10-07
Abstract: 519,948. Kinematograph targets. PIMBLEY, J. P., and FIRTH, J. Oct 7, 1938, No. 29057. [Class 20 (i)] [Also in Group XX] Kinematograph target apparatus for use on miniature ranges and of the type wherein an electric circuit for controlling the projector-arresting device under the restraint of a retardation means for providing a time lag between the 'perforation,by the bullet of the screen and the stopping of of the moving picture thrown on the screen, has the circuit actuated by an electromagnet which is energized by the bullet striking the fixed target behind the film whereby the range conditions are simulated to actual conditions of firings at movable objects at distances greater than the length of the range. Account is taken, both of the distance the object on the screen would have moved, and the fall of the bullet due to gravity over the assumed distance of the object from the marksman. The system comprises a target 10 arranged behind a marking screen 22, a circuit closing device 12, 13 actuated when the target is struck, a projector 14 provided with an electromagnet arresting device 16, Fig. 4, an electromotor 20 for driving the projector, and a switch control panel 26 for controlling the movements of the parts. The target comprises target plates 28 suspended by knife edges, on rods 32 through which passes loosely a rod 34 pivoted at its lower end to a counterweighted pivoted rod 39 holding a contact 12 which makes contact with a mercury cup 13 each time the target is struck and so actuates the control system. The marking screen 22 is of known construction comprising a screen of three layers 44, 45, 46 of paper or the like capable of being moved in the same direction at different speeds from feed rollers 48, 49, 50 on to take-up rollers 52 53. 54 actuated through chain gearing from a ratchet-operated wheel 56 the pawl of which is connected to a solenoid 24 under the control of a circuit 197, 199 leading from the control panel 26. The projector 14 is carried by a platform 64 pivoted at 66 to swing in a vertical plane so that the picture thrown on the screen may be raised through the required height to allow for the fall of the bullet under gravity during its assumed trajectory. A graduated setting device 68. 80 is provided and an extension 76 of the platform is raised by a spring 78 after the release by its holding electric-magnet 88 also controlled from the control panel. Two low - voltage direct current terminals 106, 108 and two high-voltagepreferably alternating current-terminals 156, 158 are provided on the control panel; the former supply current to the control system, while the latter provide current through an automatically actuated switch to the illuminating lamps 173 and through leads 154, 170 to the projector-motor 20. The main controlling means comprises a solenoid 90, Fig. 2, the plunger 91 of which is connected by a pin 112 to a sliding plate 114 on which is mounted an automatic switch 96 connected by a wire 92 to the targetcontact and by a wire 100 through the solenoid winding, a resistance 102, and wire 104 to the low voltage terminal 106, the other wire 93 of the target contact being connected to the other low voltage terminal 108, so that each time the target is struck, the solenoid plunger is actuated. The switch 96 is so constructed that it is automatically actuated to be closed when rising and to be opened at the top of the upward stroke and closed at the bottom of the stroke. The sliding plate is connected by a rod 119 with a dash-pot 116, provided with valves 121, 123 at opposite ends which can be set according to the virtual distance of the target from the marksman. A shoulder on the rod 119 operates the lighting switch 180, 181, so that the illuminating lamps are on when the plunger is in its lowest position and off as soon as the plunger rises; a control arm 164 carried by the plate makes contact with fixed bars 166, 168 which lead to the projector motor, a resistance 172 being momentarily short-circuited when the arm contacts with both fixed bars, to provide an increased starting torque. Further moving contacts 186, 188, both connected to one low potential terminal 108 are fixed to the movable plate to coact with fixed contacts 190, 192, 224, 226, 228 to control the movement of the plunger, the release of the projector platform, the movement of the marking screen and the stopping and starting of the projector motor 20 through a friction coupling 16. The movement of the plunger 91 may be retarded by an electric induction brake 126, additional to or alternately to the dash-pot, the braking disc being rotated between the poles of an electro magnet 130 through gearing 146, 148 by the movement of the plunger, the current through the coil being varied according to the virtual distance between the target and the marksman by a bank of "plugin" resistances 140-145, connected to the contacts on the control panel. These resistances are graduated according to virtual ranges and times for the trajectories. The operation is as follows:-the marksman sets his sights according to the virtual range he is supposed to be firing, sights on the object on the screen and fires; the bullet perforates the marker 22 and strikes the fixed target 10 whereupon the contacts 12, 13 are actuated and the solenoid coil is energized through the automatic switch 96 thus raising the plunger. The solenoid remains energized through the " holding " circuit by contacts 188, 226 so that the plunger continues to move upwardly under the control of the retarding devices 116, 126 which are set to correspond with the " virtual" range, during this movement the lamp switch 180, 181 is in so that the rear of the screen is illuminated and the perforation is visible. On the initial movement of the plunger, the movable contact piece 164 leaves the fixed contact 168 thus placing a resistance 172 in the motor circuit, and the contacts 186, 190 separate, breaking the circuit of the projector retaining magnet 88 and so enabling the projector platform to be raised by its lifting spring through an amount controlled by the adjustable stop 80. On further movement of the plunger the contacts 188. 226 close the circuit of the screen coil 24 so that the perforation is masked, the lamp switch is thrown open, and the contacts 288, 228 close the energizing circuit of the brake coil 18 of the film of the projector so that the film is stopped. During this movement of the main solenoid plunger the contact 186 has been in contact separately with two contacts 192. 224 connected to the bank of resistances through plugs 206, 214 respectively and according to the sockets 208, 212. used, so the braking effect of the induction brake 126 is varied. When the plunger arrives at the top of its stroke, the automatic switch 96 is tripped, the solenoid circuit is broken, the plunger falls and the automatic switch is reset at the end of the downward movement. The film arresting device is of known construction and comprises an electromagnet 236 carrying the energizing coil 18 rotatably mounted on a shaft 238 from which the shutter disc of the projector is operated through a pulley 240 and a friction clutch 246, 248 of which the disc 246 is slidable on the shaft 238, the circuit for the coil being controlled from the control box and leads 232, 234 and completed through the shaft and a brush 250 in contact with the disc 246 ; when the film is stopped a full picture is projected on the screen and if the firing has been accurate, the hole in the screen coincides with the image thrown upon the screen.