Patent GB-971625-A (GB)
Title: Currency identification
IPC: G07D7/00
Filed: 1960-10-27
Abstract: 971, 625. Testing paper currency. NATIONAL REJECTORS Inc. Oct. 27, 1960 [Oct. 27, 1959], No. 36987/60. Heading G1N. In an apparatus for identifying authentic paper currency that has a metallic face of predetermined pattern and comprising means for gripping the currency and a magnetic head with an air gap, which are relatively movable at a predetermined speed, the signals developed in the head as a result of the motion are used to authenticate the currency. The note to be identified is rested on platform 178, Fig. 1, and push button 520 Fig. 10 is depressed, the latter energizing a solenoid 116 and motor 164 to drive chain 314 and rotate rollers 290, 302. A pin 260 which is mounted on a further chain 262, and engages a slotted block 256 on a carriage 226, starts the carriage in motion and simultaneously therewith eccentric jaws 246 rotate, and a cork, rubber, or elastomeric plastic, flat face thereof clamps the leading edge of the note at both side edges to bearing plates 230, Fig. 4, on the carriage. Movement of the carriage disengages a bracket 252 from a resilient finger 158 which in the rest condition holds open switch contacts 154 and thus establishes a holding circuit for the solenoid 116 and a running circuit for the motor which is maintained until the carriage returns to its initial position. The note is moved at between 2 inches and 25 inches per second to produce an adequate signal strength, between a bed plate 188 and a confining plate 208 which has an aperture 218 into which plunger 118 of solenoid 116 may drop when the solenoid is deenergized to limit the extent by which a note can be introduced. Brushes 342 mounted on a bracket 338 are moved by a roller 236 on the carriage which engages and lifts a pivoted member 364 to press the note into intimate contact with magnetic heads 318, 344 spaced astride the centre-line of the note, the leading edge of the note having passed the air gap in'head 344 before the pressure is applied. The motor runs up to synchronous speed by the time the note is scrutinised by the head to produce voltage variations in response to the magnetic ink and if the note is genuine the output from unit 426 energizes relay 428. The energization i.e. by the phase, duration and repetition rate of voltage variations arising from grid lines on either 'side of a central portrait on a U.S. note and the relay is actuated twice during the passage of such a note, the first actuation setting up a circuit for actuation by the second release whereby solenoid 126 is energized and rollers 380 driven by bead chain 314 take over the forward feed of the note. At the end of the carriage forward movement, roller 236 rolls clear of member 364, and the bracket carrying the pressure brush and magnetic head rotates back to its rest position under the action of spring 352. The moving note strikes the , lower end of switch arm 400 which actuates a selfholding relay 494 in an associated vending machine and rollers 302, 390 which are eccentric, to prevent the note being pulled back, take over the feed of the note to deposit it in the cash box. When the trailing edge of the note clears switch arm 400, a relay 504 controlling the cycling device of the vending machine is also energized, and finally when the item sold is delivered, a delivery switch 512 de-energizes relays 494, 504. The carriage is returned and the clamps 246 are lifted by stops 60, 62, switch 154 being opened when the carriage returns to normal to reset all relays. A spurious note does not operate solenoid 126 and is stopped and returned by the carriage. The vending machine may be equipped with an electrically or mechanically operated change dispenser. A modified apparatus described with reference to Figs. 11-14 (not shown) checks the authenticity before a note passes completely into the machine, and if spurious solenoid 116 is de-energized and the motor comes to rest. The note may then be manually withdrawn, its withdrawal enables an additional switch to close and return the equipment to its normal rest condition. A modified arrangement conveying the note between two belts of inelastic material one wide and one narrow is described with reference to Figs. 15-23 and 29 (not shown) and in this arrangement the note is introduced by lifting a flap from a channel projecting from the front face of the machine, laying the note in the channel, dropping the flap back into position, and pushing the projecting channel forward to operate a motor start switch and feed the leading edge of the note into the point where the two belts run together. The motor is run for a period determined by the time constant of a capacitor in a relay circuit, and the note is accepted or rejected by a deflector controlling acceptance or rejection shoots. The vending machine may include an "empty" switch and an "empty" lamp the former interrupting the supply to the note scrutineer. The machine may scan a number of areas with a number of heads or a magnetic head may have a plurality of gaps or be mounted to move transversely of the note. Alternatively the note could also be given a transverse movement. Magnetic head Fig. 25 comprises a permanent magnet 916 united with a core 914 carrying a winding 918 and an alternative arrangement Fig. 26 has the permanent magnet 926 immediately adjacent the air gap of core 922. A D.C. or A.C. bias may be applied to the heads. The output from the heads. the coils of which may be connected series aiding is applied to terminal 1008 of a tuned amplifier, Fig. 30, D.C. bias being applied to the head over resistors 1016, 1010 from the voltage regulated power pack supplied over transformer primary winding 940. The signal after pre-amplification in double triode 1022, 1030, is limited in an overdriven amplifier comprising double triode 1038, 1046 and applied via a resonant circuit 1050, 1052, 1054 tuned to the repetition rate of the signal derived from the background grid lines of a U.S. Dollar note, to a thyratron trigger device 1064 which actuates the note acceptance relay. The thyratron 1064 is fired after the receipt of a predetermined number of grid.line variations of the right frequency unless an excessive input signal has fired a thyratron 1078 also connected to the output of the pre amplifier, this latter actuating a relay 1000 to change the bias arrangement of thyratron 1064 and thus prevent its response. In an alternative amplifier arrangement Fig. 31A, the heads are connected to terminal 1200 and are D.C. biased through a resistor 1204. The input signal from the heads is pre amplified in triode stages 1212, 1226 and 1238, clipped in clipper stages 1260, 1278 and applied to cascade stages of frequency selective amplifiers 1300, 1312, feedback to preamplifier 1238 being provided through a bufferamplifier cathode-follower stage 1358 and a non- selective amplifier 1350. The buffer 1358 feeds rectifiers 1416, 1418 through a cathode-follower stage 1374 to provide a firing voltage for a thyratron 1398 contolling vending relay 428, the firing of the thyratron being indicated in a magic-eye 1384. A thyratron 1330 for dealing with excessive signals short circuits the last pre-amplifier stage and gives an external indication by lighting a neon lamp 1266, operation of a push button switch being necessary to extinguish the neon. A voltage regulated power supply for the amplifier including the manner of heater connection is described with reference to Fig. 31B (not shown). A further amplifier arrangement described with reference to Fig. 34 (not shown) includes a pair of frequency spaced tuned circuits responsive to different denominations of currency to selectively fire one of a pair of output thyratrons. Components for discriminating between more than two signals may additionally be provided. Modifications of the note scrutinising apparatus referred to include the use of a reversible motor, the use of a spring motor, the use of a separate motor drive for shaft 300. the use of a curved bed plate in conjunction with the first described apparatus to straighten wrinkles, the connection of the resonant circuit in the anode or cathode circuit of the limiter, the provision of an inductive coupling between the limiter of Fig. 30 and the resonant circuit and the use of a stepping relay instead of relay chain.