723,609. Sorting letters; endless-belt conveyers; screw conveyers. STAATSBEDRIJF DER POSTERIJEN EN TELEFONIE. Sept. 16, 1952 [Oct. 1, 1951], No. 23281/52. Class 78 (1). [Also in Groups XXXVIII and XL (b)] In a letter-sorting system the unsorted letters are divided into a number of batches each of which is conveyed past an operator who registers electrically particulars of each letter to control facing, stamp cancelling and sorting operations after the performance of which the batches are recombined on a conveyer which delivers each letter to the receptacle corresponding to the address thereon. Photo-electric arrangements are used to ensure that the operations of the control apparatus keep in step with movement of the letters and also for controlling a lamp indicator to show the operator's progress in relation to the letters passing him. The selection of the receptacle is controlled by five operators, each of whom has a separate key strip for each of the three digits of a number which he sets up in accordance with the address of each letter that passes. The thousand possible numbers are translated by a control circuit common to all the operators into three hundred sorting destinations, the translation being adjustable, e.g. in accordance with the time of day. The letters are delivered to the apparatus at I, Fig. 1, and are sorted according to size, thickness, &c., at II. They then pass to stacking places IIIa ... IIIf at the ends of narrow belts A ... F, each of which carries them past stations, e.g. IVf, V, VII and VI, to a chain conveyer VIII provided with containers 11, 12, &c. The conveyer VIII carries and delivers each letter to the receptacle of the series G, H, J, &c., corresponding to the address. Each letter passes from II through an inclined guide 5, Fig. 3, to between the turns of a rotating spring 2 which forwards it to a compartment 1. As this compartment fills, the shaft 3 carrying the spring moves to the right against the resistance of a spring 7 until a contact 8 on the shaft engages a contact 9 on the abutment 11 and closes a circuit which gives an indication that the compartment is full. The letters pass through a guide 15 to the belt at regular' intervals determined by the rotation of cam mechanism 13, 14. In a modification, Fig. 5, each letter passes through a guide 1 to a rotary member 2 which deposits it on top of a pile supported by a platform 3. A rotary cam 5 moves through a slot in the platform to transfer the bottom letter to a guide 4 leading to the belt. In a further modification, Fig. 7, the letters are transferred by a rotary wheel provided with suction heads 3, 7 which are connected by channels 4, 5 respectively to suction at 6 and to atmosphere at 10 as the wheel rotates. Each head has two openings 10. 11, Fig..7a, in the plane of which is the face of a stud 12 resiliently mounted in the centre of the bottom 14. This device prevents sagging of a letter in the middle. Each belt A ... F has transparent side walls to support the letters and may have transverse ridges. At the operator's station V there is a viewing apparatus W1 by means of which each letter is viewed in two of four different aspects one above the other, keys PT by the depression of the appropriate one of which the facing apparatus at station VII is set to turn the letter so that the stamp is in the correct position -for cancellation by the machine at station VI, and a group of ten keys BT for determining the receptacle to which the letter is to be sent. The cancellation machine at station VI can be rendered inoperative by depressing a foot contact VC at station V. The viewing apparatus W1 comprises mirrors Sp1, Sp2 and Sp3 arranged as in Fig. 6. The operator sets in respect of each letter a two-relay register to indicate whether or how the letter is to be faced and three four-relay registers to indicate by a three-digit number its sorting destination. Subsequently, as each letter passes photo-cell 1, an impulse is sent to a counting chain, Fig. 9c, the function of which is to render the register groups effective in turn at the times appropriate for the letters concerned. The chain is also built up when a letter is missing, but in this case the registered instructions are not carried out. If the relay AQ (not shown) of the first register is operated, VD, Fig. 9d, pulls up and causes the letter to be rotated about one axis when it reaches a further photo-cell 5. When the third counting relay CL pulls up the letter is diverted for rotation, if necessary, about another axis when it reaches photo-cell 6 by the operation of HD if AP (not shown) is operated. After each rotation the letter is restored to the main stream and on reaching photo-cell 3 has the stamp cancelled unless a special " no cancellation " relay is operated in the register group. Subsequently the destination registers are made effective when the chain has built up to the appropriate point for the letter concerned. Normally the chain is built up by impulses from relay P which operates each time a letter passes the photo-cell 1, but, if no photo-electric impulse is received, the grid of valve B2, after a time determined by the values of capacitors C and resistor R1, reaches a potential at which anode relay Q operates, gives an impulse to the chain and discharges C rapidly. To make it possible for the operator to gain and lose slightly on the conveyer, four letters are made visible to him and a lamp indicator shows his progress in relation to the letters visible at any time. A group of eight lamps and three groups of three as shown in Fig. 9e are associated respectively with the four positions of the letters on which the operator is working. Each time a letter enters the position, a photo-cell A controls the application of an impulse by a relay M1 (not shown) to a counting chain MA ... MN, which thus tends to build up. As each registration is completed, however, a short impulse is given with the aid of relay MT to one of a set of four relays MC, MF, MK, MO according to the condition of the counting chain, and that relay locks up, deenergizes the most recently energized pair in the counting chain and then falls back. The lamps of the indicator are controlled by the counting chain relays as shown via contacts on the conveyer sections so that the letter next to be attended to is constantly indicated. The operator's positions I-V are shown in Fig. 16, only position I being shown in detail. The positions are associated with the common control circuit in turn by a distributer C1 ... C5. The hundreds and tens digits operate respectively the select and hold magnets of a cross-bar switch 1700, Fig. 17, to select ten of the outlets 1724 and the units digit applies potential to one of these outlets. This potential is extended via a jumpering frame 1725 to one of three hundred terminals which are connected, in a manner variable by a drum controller 1723, to a corresponding number of input terminals of a translator 1722 shown in part in detail in Fig. 18. According to the terminal marked, one or more relays 1820 ... 1880 and 1822 ... 1859 become energized and apply potential to one or more wires 1811 ... 1813 and 1815 ... 1819 which are connected momentarily by relay 1615, Fig. 16, controlled by distributer cam C3, to a corresponding number of relays 1621 ... 1629. The selected relays lock up temporarily and energize. corresponding magnets 1631 ... 1639 which effect a mechanical registration of the sorting destination of the letter concerned. When the contacts controlled by C4 and C5 open, the operator's equipment is released, the common equipment having been released previously at contact 1605. Specification 680,798, [Group XL (b)], is referred to.