Patent GB-1439082-A (GB)
Title: System for controlling the feed of documents into and along a document transport path
IPC: B65H5/00
Filed: 1974-06-03
Abstract: 1439082 Feeding sheets BURROUGHS CORP 3 June 1974 [2 July 1973] 24445/74 Heading B8R [Also in Division G3] A control system for a document feeding device includes a pressure actuator which is intermittently forced into engagement with a feed wheel when the speed of the feed wheel is sensed as excessive so as to slow the feed wheel and thus keep the velocity of the documents constant. The system described also includes a provision for stopping the feed wheel at least for a fixed time whenever the end of a document is sensed so that the documents pass down a transport system spaced from each other and this is described with reference to Fig. 2. The documents from a hopper pass between belt 70 and feed wheel 27 which are driven where they touch in the same direction but the belt moves more slowly so that only single documents pass into guide 16 where they are propelled by high speed rollers 25. Feed wheel 26 is driven by a low inertia motor 60, e.g. a.d.c. printed circuit motor, which is capable of rapid stopping and starting and in use would accelerate to a high speed without the braking action imposed by a pressure actuator 22 whose operation is described in connection with Fig. 5. In the drive circuit shown in Fig. 2, the counter 104 will count up for 95 ms. and will then reset or hold depending on whether a document trailing edge has been sensed by sensor 24 or not. The trailing edge pulse additionally always triggers flipflop 136 to its off state which terminates a driving signal to the delayed monostable multivibrator DMV which causes reverse power to be applied to motor 60 which stops and remains stopped for a minimum period of 5 ms. to ensure a minimum document spacing in the guide 16. This mode of operation results in documents 6 inches long or less being fed at a constant 600 d.p.m. rate with counter 104 reset after 95 ms. but documents longer than 6 inches will themselves reset the counter so the throughput rate is variable but less than 600 per minute. In an alternative mode of operation the counter 104 can be set to count up to 150 ms., when, irrespective of the length of the document, it will reset and start the feed which was stopped when the document trailing edge was sensed. This connection gives a slower feed rate of 400 d.p.m. The speed of the feed wheel drive motor is controlled by the braking action imposed by pressure actuator 22 operated by the circuit shown in Fig. 5. The actual speed of motor 60 is sensed by the transducer 66, 68 co-operating with disc 65 which produces pulses for resetting binary counter 190. In operation counter 190 counts up during the period between reset pulses and thus defines a time period corresponding to the actual speed of the motor. The counter 194 counts up to its Y6 stage in a time representing the desired speed of the motor. The AND gates 204, 208 act on the set and reset terminals of flip-flop 212 to control the supply of power to the pulse actuator solenoid 80. If the motor overspeeds AND gate 204 will conduct because counter 190 will show less than the set time and flip-flop 212 will be set to energize the solenoid 80. The energizing signal will be fed back to delayed multivibrator 214 which delays for 10 ms. before putting an output signal on line 218 for 10 ms. to reset flip-flop 212 and de-energize solenoid 80. The intermittent energization of solenoid 80 provides a braking action on feed wheel 26 to control its speed. It is stated that by using this method of controlling the speed of the feed wheel by intermittently increasing the pressure on belt 70 any tendency for documents to adhere is reduced to remove overlapping.