GB1310681A - of flat items - Google Patents

Abstract

1310681 Feeding or delivering sheets POST OFFICE 25 June 1970 [25 June 1969] 32059/69 Heading B8R In order to detect when two or more flat items, for example envelopes being fed to a sorting machine, are being fed in superposed or partly superposed relationship instead of singly as is desired, each envelope such as 3, Fig. 1, is first aligned by one of its edges with a reference line 13, for example by gravity while being fed on edge on a conveyer belt, and is then, when it reaches a given point 21, rotated about one of its corners present at that point until a second of its edges lies in the line 13. A pair of detectors, e.g. photo-electric detectors 22, 23 is arranged so that in normal operation both detectors are never obscured at the same time during the rotation. If a second envelope 4 is present beneath the envelope 3, it will normally be spaced somewhat backwardly of the latter, so that will reach the point 21 and begin its rotation later. On the completion of the rotation of the envelope 3, the two envelopes together will subtend an angle greater than a right-angle at the point 21 and will obscure both detectors, whereupon a signal will be given and the envelopes diverted or rejected. The means for rotating the envelopes may comprise two conical or frusto-conical rollers, between which the envelopes pass and at least one of which has a resilient surface, contacting each other along the line 26 and with their axes intersecting at 21. One roller may be replaced by a series of spaced cylindrical discs, 36, Fig. 8, while the other may be replaced by second series of such discs 30 contacting the first series and driven through belts 32 by rollers 33 of varying diameter so as to be mechanically equivalent to a conical roller. The spacing between the envelopes 3, 4 if insufficient can be increased by transferring the envelopes from a faster to a slower conveyer before reaching the point 21. The detectors may also be utilized to control a timing device by means of which they can detect if the space between successive envelopes in the stream is too small.