Weighing scales – Computer – Electrical
Reexamination Certificate
2001-11-05
2002-10-29
Gibson, Randy W. (Department: 2841)
Weighing scales
Computer
Electrical
C177S025150, C705S407000, C705S415000
Reexamination Certificate
active
06472616
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to a method for controlling a dynamic scale and to a corresponding arrangement therefor, for use in a dynamic scale which weighs a piece of mail during a conveying event, particularly for a fast processing of mixed mail in a scale and franking system. The inventive method is suitable for users of mail-processing systems with a dynamic scale and postage-calculating postage meter machine as well as with dynamic postage calculating scales and franking devices.
Description of the Prior Art
“Mixed mail” means an unsorted stack of pieces of mail. The term “letters” is used below as a representative term for all other possible pieces of mail as well.
Dynamic letter scales are known. For example, Francotyp-Postalia AG & Co. distributes a dynamic letter scale as component of an automatic mail system Francopost 12.000. The letters are introduced as a stack and are first automatically separated. The separated letters are accepted by the dynamic weighing unit and their weight is identified. The weight determination must ensue with a precision that enables the allocation of the letters to the correct postage class. The postage is automatically transmitted to the connected franking unit, is billed and printed onto the letter. Upon placement of the letter onto the weighing pan and the transport thereof, mechanical vibrations are transmitted to the weighing cell, the amplitude thereof being approximately proportional to the absolute letter weight. These noise vibrations limit the precision of the measuring result. In general, a measuring precision of 1 g is specified in dynamic letter scales up to a letter weight of 1000 g. Letters that are heavier cannot be precisely weighed with this device, in manner which would enable an automatic postage setting of the franking unit. Such letters then must be separately weighed with a suitable, static scale. The corresponding postage must then be manually entered into the franking unit. The automatic execution is thus interrupted. Especially disadvantageous is the fact that the mail shipper cannot predict whether a specific letter that is introduced in common with the others as a stack will or will not exceed this weight limit.
U.S. Pat. No. 4,778,018 discloses a dynamic letter scale wherein the weighing pan is resiliently suspended relative to the conveying mechanism. The transmission of vibrations from the conveying mechanism to the weighing cell are intended to be attenuated by this arrangement. This damping, however, is adequate given high weights in order to assure an adequate measuring precision. Moreover, a resilient suspension produces an intrinsic oscillation of the weighing pan that lengthens the measuring time and thus reduces the letter throughput.
U.S. Pat. No. 5,014,797 discloses a non-modular apparatus for automatic mail processing wherein the dynamic weighing function is integrated in the franking unit. A shortening of the conveying paths and a letter throughput per time unit that is higher overall are thus achieved. Again, however, the maximum weight is limited given a prescribed measuring precision and processing speed. A product constructed according to this solution achieves a throughput of approximately 5,000 letters per hour given a maximum weight of 500 g. For pieces of mail having a higher weight, the manufacturer offers an additional static scale, thus an automatic processing of pieces of mail that one higher in weight is not possible.
U.S. Pat. No. 4,956,782 and British Specification 22 35 656 disclose semi-dynamic weighing. A user station arranged upstream in the processing chain can be a scale and a user station arranged downstream is a postage meter machine. A continuously moving piece of mail must be completely accepted by the scale for the measuring time required for weight identification. Given mixed mail, the probability is higher that the scale could determine an incorrect measured result. The measuring time is lengthened dependent on the dimensions of the letter. A complicated control that interprets the dimensions of the letter in advance and controllable motors are required for this purpose. Alternatively, the weighing path could be lengthened and a reject compartment could be provided, however, this would increase the length of the overall mail-processing system, which is not possible without more extensive retrofitting.
According to European Application 514 107, a control means interrupts transport given pieces of mail that are large and difficult to weigh until the measurement is stable. A detector is arranged in the scale close to the end of the conveyor belt at a downstream location, this detector only allowing a letter to pass whose weight has been identified before this point in time. Measuring errors occur given a short weighing path and unequally distributed mass in the letter or given a high conveying speed of high-mass letters. Given a stop, moreover, the letter can slide off the weighing pan due to its inertia. The dimensions of the weighing pan are therefore designed somewhat larger, or the conveying speed is fixed lower. The throughput given mixed mail is correspondingly reduced.
German Published Application 37 31 494 (U.S. Pat. No. 4,753,432) discloses that a resting time be provided in the weighing procedure, during which operation of the franking system and the transport system is interrupted because continued operation would otherwise produce too large a vibration. The transport time from the weighing module to the postage meter machine is selected short, however, the speed cannot be arbitrarily increased without increasing the risk of a jam of letters. The item output that can be achieved is limited by the pauses inserted into the executive sequence. The speed of weighing is limited by the speed of the weight identification, which causes a greater outlay given heavy pieces of mail when the measurement must be exact.
SUMMARY OF THE INVENTION
With the goal of increasing the throughput of pieces of mail per hour, an object of the invention is to achieve an automatic processing of pieces of mail even having higher weight, without a need for manual interventions during the mail processing. Alternative weighing means should be eliminated. An optimally high proportion of the outgoing mail of the mail shipper should be weighed in the dynamic mode.
The above object is achieved is achieved in accordance with the principles of the present invention in a method and an apparatus for controlling a dynamic scale which processes mixed mail, consisting of items having different weights, for use with a further processing station connected downstream from the dynamic scale, wherein the dynamic scale is set according to particular requirements for processing a mixed mail stack, this setting taking place through an input unit and ensuing on the basis of selected shipping parameters and/or operating parameters, and wherein operating parameters and data for the scale are modified according to the setting with the modified parameters and data being stored in a non-volatile memory, and wherein a supplied postal item from the stack of mixed mail is conveyed through the dynamic by a conveyor arrangement and is weighed therein and is transported from the dynamic scale to the further processing station dependent on the operating parameters and data which have been set.
The scale is basically composed of conveyor arrangement, weighing pan, a weighing cell as well as an electronic control and evaluation unit. The weighing pan preferably has a rectangular shape, with its dimension oriented transversely relative to the conveying direction minimally corresponding to the maximum letter format plus a tolerance allowing for admission of the letter to the weighing pan. The dimensioning of the weighing platform in the conveying direction must correspond to the maximum longitudinal format of the postal matter plus a distance that is traversed by the item being weighed during the weighing procedure. It is of no significance for the realization of the invention whether the pieces of
Francotyp-Postalia AG & Co.
Gibson Randy W.
Schiff & Hardin & Waite
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