Weighing scales – With recorder – With recording of a factor additional to weight
Reexamination Certificate
2001-01-12
2003-10-07
Gibson, Randy (Department: 2841)
Weighing scales
With recorder
With recording of a factor additional to weight
C177S025150, C705S407000
Reexamination Certificate
active
06630632
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method and arrangement for the control of a dynamic scale system, referred to below as a dynamic scale, for weighing items during the transport thereof to a processing station, such as in a mail processing system.
2. Description of the Prior Art
“Mixed mail” means an unsorted stack of postal items that, with respect to a side to be printed. The item letters is used below as representative of all other possible pieces of mail that differ in format, thickness and weight. Methods and arrangements are suited for users of mail processing systems both with a dynamic scale and postage-calculating postage meter machine as well as with dynamic postage-calculating scales and franking devices.
In a known, automatic mail processor Francopost 12000 marketed by Francotyp-Postalia AG & Co., a dynamic weighing station is arranged following a separating station. The letters applied as a stack are first automatically separated and are then accepted by the dynamic weighing station, and their weight is determined. The weight determination ensues 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, and is debited and printed onto the letter. When the letter arrives on the weighing pan and during the transport thereof, mechanical oscillations, having an amplitude dependent on the letter weight, the transport direction and speed, the distribution of the letter mass as well as the letter stiffness, are transmitted onto the weight sensor. The unwanted oscillations limit the precision of the measured result. Generally, a measuring precision of ±1 g is indicated in dynamic letter scales up to a letter weight of 1000 g. Given transport of heavy pieces of mail having a weight above 1000 g, the transience of the dynamic scale requires more waiting time as a consequence of the vibratory influences on the weighing system. All letters that are even heavier are usually separately weighed with a suitable static scale. The corresponding weight or postage then can be manually entered into the franking unit. The automatic execution is thus interrupted. Especially disadvantageous is the fact that the mail handler cannot predict whether a specific letter that is introduced in the a stack in common with the others will exceed this weight limit.
U.S. Pat. No. 4,778,018 discloses a dynamic letter scale wherein the weighing cell is resiliently suspended with respect to the transport mechanism. The transmission of oscillations from the transport mechanism onto the weighing cell thus is damped. For high weights, however, this damping is not sufficient in order to assure an adequate measuring precision. Moreover, such a resilient suspension produces a transient behavior 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 device for automatic mail processing in which the dynamic weighing function is integrated. Shortening of the transport path and a letter throughput per time unit that is higher overall are intended to be achieved. In this solution, as well, however, the maximum weight is limited, given a predetermined measuring precision and processing speed. A product constructed according to this principle achieves a throughput of approximately 5000 an hour given a maximum weight of 500 g. For letters having a higher weight, the manufacturer offers an additional, static scale as an attachment. Thus, automatic processing of heavier letters is not possible.
U.S. Pat. No. 4,956,782 and British Specification 22 35 656 disclose a semi-dynamic weighing. The user station arranged upstream can be a scale and the user station arranged downstream is a postage meter machine. A continuously moving letter must be completely accepted by the scale for the measuring time required for the weight determination. The probability that the scale will determine an incorrect measured result is higher given mixed mail. The measuring time is increased dependent on the dimensions of the letter. A complicated control, which interprets the dimensions of the letter in advance, and control motors are required for this purpose. Alternatively, the weighing path could in fact be lengthened and a reject compartment could be provided. This, however, would increase the length of the overall mail processing system; which is not possible without extensive retrofitting.
According to European Application 514 107, a control means interrupts the transport given large letters and letters that are difficult to weigh until the measurement is stable. The measurement ensues in the static condition of the dynamic scale. A detector is arranged in the scale in the proximity of the downstream conveyor belt end, and only letters whose weight has been identified prior to this time pass through this detector. Measurement errors occur given a short weighing path and unevenly distributed mass in the letter or a high transport speed of high-mass letters. In the event of a sudden stoppage, moreover, the letter can slide from the weighing pan due to its mass inertia. The dimensions of the weighing pan are therefore designed somewhat larger or the transport speed is fixed lower. The throughput given mixed mail is correspondingly reduced.
German Published Patent 37 31 494 corresponding to U.S. Pat. No. 4,753,432 discloses weighing during a quiescent time, wherein the operation of the franking system and of the transport system are interrupted because the latter would otherwise produce an excessive vibration. The transport time from the weighing module to the postage meter machine is designed to be short. The speed cannot be arbitrarily increased, however, without increasing the risk of jams. The throughput performance that can be achieved is limited by pauses introduced into the executive sequence. The speed of the weighing is limited by the speed of the weight determination. This is particularly slowed for heavy letters, for which the measurement must be exact.
In contrast to semi-dynamic operation, dynamic operation is problematical for heavy letters. German OS 198 33 767 discloses a dynamic scale wherein the mass of the weighing pan is significantly decreased and its rigidity significantly enhanced. Short transient times for the overall measuring system result therefrom, as, consequently, do correspondingly higher letter transport speeds given dynamic operation.
With the goal of assuring an efficient mixed mail processing with a dynamic scale in conjunction with a newly developed postage meter machine, whereby the former implements a weight determination and the latter implements the calculation of the postage value, this known dynamic scale has a weighing pan for the letters that is implemented in lightweight structure but which is flexurally and torsionally rigid. This weighing pan is coupled to a weighing cell at the approximate location of the center of gravity of the weighing pan and of a letter with the highest allowed weight that is arranged centrally on the weighing pan. Negative effects of the load arm are minimized by the aforementioned coupling of the weighing pan to the weighing cell. An increase in the range of utilization is established by the improvement of the function properties of the dynamic scale.
A method for the control of a dynamic scale that can process mixed postal matter having different size and thickness and that can be operated in at least two operating modes is disclosed in German Patent Application DE 19860296.0. In the dynamic operating mode, a piece of mail is supplied, before the beginning of a first measuring time span, with a transport speed that is set to a predetermined value and independently of the letter format when the letter is located at the entry to the dynamic scale. Speed regulation is deactivated by the controller of the dynamic scale during the dynamic weighing in the measuring time span, so that a weight measurement ensues given a dea
Huebler Uwe
Kubatzki Ralf
Thiel Wolfgang
Francotyp-Postalia AG & Co. KG
Gibson Randy
Schiff & Hardin & Waite
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