Patent GB-932479-A (GB)
Title: Letter feeder
IPC: B65H3/52
Filed: 1960-11-15
Abstract: 932,479. Feeding sheets. POSTMASTER GENERAL. Nov. 15, 1960 [Nov. 30, 1959], No. 39210/60. Class 100 (1). Letters or postcards L are separated sequentially from a stack by creating a vacuum in a chamber V to attract the top letter against a pair of rotating rollers F which feed the letter between a forwarding roller A and a reverselydriven roller C, the roller A having a surface of greater coefficient of friction than that of the roller C so that the latter is fed into the bite of a pair of feed rollers D1, D2 which rotate at a higher rate than the roller A and deliver the letter to a sorting &c. apparatus. The letters are of mixed sizes and thickness, and in the case of a long letter the front edge will be grasped by the rollers D1, D2 before the letter is released by the roller A, and the latter will thus be over-run for a short period: this ensures that the surface of the roller A will have a more even wear, and a longer life. To allow over-running, the roller A is driven continuously through a ratchet or like one-way drive. The vacuum chamber V can be connected either to a source of vacuum or to atmosphere by a rotary valve operated by a rotary type solenoid M2, and the top letter is sucked against a guide plate 54 into contact with the friction rollers F, provided a control lever G is in the raised position. The lever G is operated by links 41, 42 from a rotary type solenoid M1. The reversely rotated roller C is mounted in arms 13 pivoted at 14 and urged towards roller A by a spring 22 on a rod 19 connected to a yoke 18 on the arms 13. Roller C has three spaced peripheral portions fixed on a core, the middle portion being opposite the narrow roller A, and the two outer portions being engaged always by a pair of coaxial idler rollers B on a forked member 11 pivoted at 12. An extension 26 on the member 11 carries a rod 28, and is engaged by a coil spring 30 thereon to urge a follower roller 25 on the member 11 against a constantly-rotating control cam E. The rod 28 is extended at 28a to act on a plunger 32 of a switch S in an " and/or " electrical circuit. The feed rollers D1, D2 are urged together by a spring 23. Three photo-electric cells P1, P2, P3 and three associated lamps R1, R2, R3 are positioned as shown in Fig. 12. The letters are guided along the plate 54, a plate 33 carried by the arms 13, and a short fixed plate 55. In normal operation, with the reverselydriven roller C held away from the feed roller A by the idler rollers B, the energized cell P3 energizes the solenoid M2 to apply vacuum to chamber V, and the top letter L is sucked up and fed forward by the rollers F to the bite of the reversely-rotating rollers B, C and is held back, cutting off the cell P3, thus de-energizing solenoid M2 to release the vacuum in chamber V. The cam E now allows the rollers B, C to rise, and the latter is fed forward by the roller A: a second letter loosely attached to the first is returned by the roller C, and the rod extension 28a opens the switch S. If a letter L1 is not grasped by the rapidly-rotating feed rollers D1, D2, due to a double-feed or any other cause, as shown in Fig. 12, the cam E in its normal rotation will depress the rollers B, C so that the letter will be returned by these rollers to the input side. During this period, the letter obstructs the optical lines of cells P2, P3, but not that of P1. The, positive signal from cell P1, the negative signal from cell P2, and a positive signal from the closed switch S, are fed into the " And " gate of the " And/or " circuit to energize the solenoid M1 and cause the lever G to be lowered to hold the returned letter away from rollers F. In a modification (Figs. 15 and 16, not shown) an idler roller, which can only rotate clockwise, is urged by a spring towards the plate 54 and is positioned between the stack and the roller C. This idler roller is adjusted so that only one letter L can pass through the gap between it and the plate 54, and thus opposes the passage of a loosely attached second letter.