Sheet feeding or delivering – Feeding – Separator and conveyor
Reexamination Certificate
2001-03-26
2003-06-17
Walsh, Donald P. (Department: 3653)
Sheet feeding or delivering
Feeding
Separator and conveyor
C271S265020, C271S270000, C271S202000, C271S034000
Reexamination Certificate
active
06578839
ABSTRACT:
DESCRIPTION
The invention pertains to a method and a device for removing flat mail pieces from a pile according to the preamble of the independent claims.
The removal of the frontmost mail pieces from a pile of mail pieces must be done while maintaining a certain minimum gap [between mail pieces]. It is not desirable to fall below this minimum gap in order to permit downstream system components to process the individual mail pieces. At the same time, the mean gap which is achieved should exceed the minimum gap by as little as possible in order to achieve a high mail piece throughput.
Devices for removing flat mail pieces from a pile are known from EP 0 167 091 A1 and DE 196 07 304 C1. These devices have a controlled removal element that removes the frontmost mail piece of a pile and pushes it forward into the capture range of a pair of driven conveyor rollers, with a measurement section located between the pile outlet and the conveyor rollers in the form of a light barrier row whose output signals are fed to a control circuit. In EP 0 167 091 A1, the driving of the removal element for the removal of a mail piece takes place such that the spacing between the mail piece to be removed and a mail piece that has already been removed is ascertained and the respective spacing measurement result is corrected by a specified value that is dependent on the acceleration travel of an object to be removed and wherein the removal is initiated whenever the size of the thus corrected spacing measurement result matches a set spacing value.
The use of the specified value here permits only a global consideration of the transfer behavior of the removal drive units and their effect on the acceleration process.
Differing behavior of the mail pieces in the removal process also results from the differing positions of the mail pieces in the pile from which the mail pieces are removed. This likewise results in differing gaps, whereby throughput losses are created.
According to DE 197 07 304, therefore, the mail piece to be removed is first accelerated to an intermediate velocity which is lower than a prescribed final velocity, for a more precise control of gaps. As soon as the actual spacing is equal to the set spacing, the mail piece is accelerated to the final velocity.
These known solutions require an elaborate measurement section in the form of a light barrier row, with which both the position of the removed mail piece (back edge, as long as it is still located inside the measurement section) and that of the next mail piece to be removed (front edge) are continually detected in order to ascertain the correct points in time for the acceleration of the mail piece to be removed. Transfer characteristics of the removal drive unit are taken into account only globally.
The invention specified in the independent claims is thus based on the problem of creating a method and a device for removal of flat mail pieces from a pile with a defined final velocity in which a measurement section of linked sensors for detecting the mail pieces is not necessary and the deviations of the established gaps between the mail pieces are kept small with little effort.
The invention is based on the concept of associating gap differences from the set gap value with certain profiles of set velocity values. Since these waveforms are selectable, the drive conditions can be taken into account with them. The association of the set velocity value curves of the drive unit with the actual gaps in order to achieve the set gap at the takeover point of the conveyor belts takes place in previous measurements. The nonlinearities of the transfer function are covered empirically on the basis of the measurements, not algebraically, by a tabular association of the set and actual profiles. Thus there is no necessity for algorithmic description and the corresponding computational treatment. Arbitrarily complicated nonlinearities thus become easily manageable with a reproducible behavior. The run-time computational conditions during real-time operation are thus alleviated by virtue of the fact that the above associations are detected offline and represented in the tables.
Advantageous embodiments of the invention are specified in the subordinate claims.
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patent: 4691912 (1987-09-01), Gillmann
patent: 4893804 (1990-01-01), Sasage et al.
patent: 5056771 (1991-10-01), Beck et al.
patent: 5423527 (1995-06-01), Tranquilla
patent: 5461468 (1995-10-01), Dempsey et al.
patent: 5692742 (1997-12-01), Tranquilla
patent: 5813327 (1998-09-01), Freeman et al.
patent: 6076821 (2000-06-01), Embry et al.
patent: 196 07 304 (1997-07-01), None
patent: 6-183602 (1994-05-01), None
patent: WO 98/24719 (1998-06-01), None
Gerstenberg Frank
Luebben Hauke
Meyers Philip G.
Miller Jonathan R.
Siemens Aktiengesellschaft
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