Patent GB-776034-A (GB)
Title: Letter conveyor system
IPC: B07C3/08
Filed: 1955-04-22
Abstract: 776,034. Sorting letters; shoots; endlessbelt conveyers. POSTMASTER GENERAL OF CANADA. April 22, 1955 [May 27, 1954], No. 11755/55. Class 78 (1). [Also in Group XL (b)] In a letter-sorting system the letters are pushed along a track on which they rest by uniformly-spaced projections on an endless belt or chain and each letter is removed automatically from the track by means controlled by pattern codes imposed on the letter. In one construction in which the letters are conveyed horizontally an endless belt 6, Fig. 3, provided with pushers 8 in the form of a comb 7, Fig. 1, is mounted above a series of metal or plastic strips 1 mounted between side walls 4, 5 with the teeth 7 disposed between the strips 1. A series of boxes 16 is disposed below the strips 1 access to which is provided by hinged doors 17 let into the strips 1. As shown, these doors move downwards, but since letters may jump the gap left by an open door, doors opening upwards against the direction of travel may be used. When the letters are conveyed on edge along a plate 10, Fig. 2, the plate supports the strips 1 and is integral with a backing plate 13 carrying rollers 14 which loosely retains the belt. The belt is reinforced by strips 11 of metal inserted in it immediately behind each comb 8. Doors 23, Fig. 5, when opened allow the letters to pass on to a horizontal belt conveyer 26 from which they are deflected by guides 27 to shoots 28 leading to boxes 29. Letters may be fed to the above-described conveyers by mechanism of the roller type such as is used in automatic cancelling machines or by the arrangement shown in Fig. 6. The strips 1 at the feeding section 30 are first bent so as to be nearer to the belt 6 and then discontinued so that a gap 30a is formed between their end and their continuation which is at the normal distance from the belt. The teeth 7 of the combs 8 protrude through spaces between the strips 1 at the section 30. A guide plate 32 disposed as shown is connected by a curved part to the continuation of the strips 1. A guide rail 33 is mounted between the parts 1, 32. The base plate 10a is inclined so that the letters on insertion lean on the plate 32 with their lower edges bearing against the guide rail 33. Cam-actuated plungers 35 mounted in the plate 32 are moved inwards to push the letters against the strips 1 when the spaces between adjacent pushers 8 are opposite to them. In the construction shown in Fig. 8 letters are directed to openings 37 in the strips 1 by sets of bands 36 which pass between the teeth 7. Each band terminates at a different opening and is attached there to a guide plate 38. Each band is attached to a different channel selection plate 40. These plates are supported between the strips 1 and the supporting surface 41 of the feed mechanism on a platform 44 carried by a rod 47 which rests on a rotatable cam 50. A plate 53 mounted above the plate 40 has a series of pins 57 slidably mounted in its sides 54. L-shaped hooks 58, Fig. 10, depend from the outer extremities of the pins. The pins are moved to their extreme positions by magnetic hammers 62 and relays 63, 64. In the innermost position the flukes 61 of the hooks pass beneath the sides of the plates 40 and retain all the plates above them when the platform 44 is lowered. If a pattern code is inposed upon each letter, the code is read by an electronic scanning device 66 and the requisite pair of hammers 62 is actuated thereby. As the platform descends, the letter is ejected into the space between the retained and the lowered plates to be conveyed by the combs 8 to the appropriate discharge point. The actuation of the doors 23, Fig. 5, is controlled by the following means. Pins 67a, 67b are pivoted to the back of the belt 6 opposite to each comb 8. The pins pass through longitudinal slots in the backing plate 13 towards curved plates 69a, 69b on which are formed L-shaped pin supporting guides 71a ... 71d and 72a ... 72d. Gates 82 ... 84 at one end of the guides are actuated by an electronic scanning device, similar to that shown in Fig. 8, in connection with a magnetic drum type memory to direct each pin into the appropriate guide. Pairs of coils 91, located at intervals along the plates 69a, 69b are disposed between the pin guides and the plates with room for the spatulate ends 70 of the pins to pass between them. Light-transmitting tubes 92 may be used instead of the coils. In the latter case light from a source 93 passes into one tube of a pair and out through the other member of the pair on to a photo-electric cell 94 when the space between their inner ends is not obstructed by a pin end 70. The coils or tubes 91, 92 are arranged as shown in Fig. 12 in groups of four so that when two pins 67a, 67b have been directed by the gates to the appropriate guides, there will be one position only at which they will pass simultaneously between two pairs of coils or tubes. When this occurs, two pulses are applied simultaneously to a circuit which only under such conditions can supply a pulse which is used to effect the opening of the appropriate gate (e.g. 23, Fig. 5) to divert a letter into the appropriate box 95. When a gate 23, Fig. 14, opens, a letter is deflected into a guide 106 and is carried by its momentum to the end 110. Pushers 113 are then actuated and push it off the bottom 109 through a gap into a shoot 111 which leads to a box 112. A blast of air may be used to transfer the letter to the shoot or this result may be achieved by attaching a strip of fur to the wall opposite to the gap. In a modification (not shown) the guide is divided into compartments by a central wall and a gate is provided to direct a letter into either compartment. Each compartment has a gate at the end in the bottom which when open allows a letter to fall on to a deflector which directs it into one of two receptacles. The deflector may be controlled by pins 119, Fig. 11. Branch guides 122, Fig. 16, may be arranged in pairs, the entrance to each of which is controlled by a gate 121<SP>1</SP>. These guides extend downwardly from the conveyer 120<SP>1</SP> and gradually lean away from each other. As a letter falls from the open 123, it moves about its lower edge into a substantially horizontal position and can be received by the tray 126, Fig. 18, of a stacker. This tray is hooked on to a drive chain 130. In initial position the bottom 133 of the tray is just below and opposed to the opening 123. A photo-electric cell (not shown) placed just below the opening 123 has the light falling on it obscured gradually as the letters fall into the tray. When light is cut off entirely, the cell effects the starting of the motor driving the chain 130 and the tray is lowered until light again reaches the cell whereupon the motor stops. The conveyer 135, Fig. 19, and its branch guides 136 are encircled by a multi-box type stacker consisting of boxes 144 suspended between endless chains 143 which travel between annular tracks 141, 142. The boxes are divided by a centre wall 145. The arrangement is such that when one half of a box is in position to receive letters falling from a right-hand shoot 140, the other half of another box will be in position further round the tracks to receive letters from the left-hand shoot.