SYSTEM AND METHOD FOR COUNT BY WEIGHT CORRECTION

• US 20090301791A1
• Filed: 09/20/2007
• Published: 12/10/2009
• Est. Priority Date: 09/20/2006
• Status: Active Grant

• Current Assignee: Duncan Mcphail, Neil James Hunter, William Wright Hamilton
• Original Assignee: Duncan Mcphail, Neil James Hunter, William Wright Hamilton
• Inventors: McPhail, Duncan, Hamilton, William Wright, Hunter, Neil James
• Granted Patent: US 8,283,580 B2
• Time in Patent Office: Days
• US Class Current: 177/25.170
• CPC Class Codes: G01G 19/42 for counting by weighing G01G19/387 takes precedence
• CPC Class Codes: G01G 23/10 by electric or magnetic means

Abstract

A method and apparatus for counting nominally identical articles employs weighing apparatus, which comprises a load hod (102) for holding a number of articles to be weighed and a load transducer (20) responsive to loading of the hod (102) to produce a derived electrical signal indicative of the apparent weight of articles in the hod (102). The signal is susceptible to fluctuation as a result of local air currents acting on the hod (102) or on the articles contained therein. The transducer derived signal is filtered to extract a component signal representative of such fluctuation. After further processing, the filtered component signal is used to correct the original transducer signal thereby to indicate the true weight of articles in the hod (102). The number of articles in the hod (102) is then determined by dividing the true weight indication by an expected average weight of an article. Fluctuations in the transducer signal due to air currents may also be removed by a system of validation of the signals depending on whether or not they are within range limits based on a running average.

Claims

1. A method of counting nominally identical articles by weighing them in weighing apparatus, which apparatus comprises a load hod for holding a number of articles to be weighed and a load transducer responsive to loading of the hod from which is derived an electrical signal indicative of the apparent weight of articles in the hod, said signal being susceptible to fluctuations acting on the hod or on the articles contained therein, the method comprising the steps of:

taking a series of samples of the transducer derived signal when a number of articles to be determined are loaded in the hod;

determining if each sample is within a predetermined broad range;

calculating a running average value for those samples falling within the broad range;

determining if these samples also fall within a narrower range of the running average value;

accepting samples falling within the narrower range as valid if a predetermined number of such samples occur in succession;

determining a fluctuation independent weight for the loaded articles from the accepted samples; and

determining the number of articles in the hod by dividing the fluctuation independent weight by an expected average weight of an article.

2. A method as claimed in claim 1 including the step of calculating the actual limits for each successive sample from the current running average and a predetermined tolerance value.

3. A method as claimed in claim 1 in which the predetermined number of samples within the narrower range necessary for them to be accepted as valid is three.

4. A method of counting nominally identical articles by weighing them in weighing apparatus, which apparatus comprises a load hod for holding a number of articles to be weighed and a load transducer responsive to loading of the hod from which is derived an electrical signal indicative of the apparent weight of articles in the hod, said signal being susceptible to fluctuation as a result of local air currents acting on the hod or on the articles contained therein, the method comprising the steps of:

filtering the transducer derived signal to extract a component signal representative of such fluctuation;

processing the filtered component signal;

using the processed component signal to correct the original transducer signal thereby to indicate the true weight of articles in the hod; and

determining the number of articles in the hod by dividing the true weight indication by an expected average weight of an article.

5. A method as claimed in claim 4 in which said processing step inverts the filtered component signal.

6. A method as claimed in claim 5 in which the transducer derived signal is delayed by a fixed amount and said using step subtracts the inverted filtered component signal from the delayed signal.

7. A method as claimed in claim 4 in which said processing step further includes the steps of scaling and phase adjusting the inverted filtered component signal and said using step subtracts the phase adjusted filtered component signal from the transducer derived signal.

8. A method as claimed in claim 7 which the transducer derived signal is analog and includes the step of converting the transducer derived signal to digital form, said filtering, inverting, scaling and phase adjusting steps all being performed digitally, and further includes the step of converting the phase adjusted digital signal to analog form for subtraction from the transducer derived signal.

9. Article counting apparatus for counting nominally identical articles comprising:

a load hod for holding a number of articles to be counted;

a load transducer responsive to loading of the hod to produce a derived electrical signal indicative of the apparent weight of articles in the hod, said signal being susceptible to fluctuation as a result of local air currents acting on the hod or on the articles contained therein;

filter means for filtering the transducer derived signal to extract a component signal representative of such fluctuation;

processing means for processing the filtered component signal;

correction means arranged to use the processed component signal to correct the original transducer derived signal thereby to indicate the true weight of articles in the hod; and

count computing means arranged to determine the number of articles in the hod by dividing the true weight indication by an expected average weight of an article.

10. Apparatus as claimed in claim 9 in which said processing means includes an inverter to invert the filtered component signal.

11. Apparatus as claimed in claim 10 including a delay means for delaying the transducer derived signal by a fixed amount and said correction means is arranged to subtract the inverted filtered component signal from the delayed signal.

12. Apparatus as claimed in claim 11 in which said processing means further includes scaling means and phase adjusting means for scaling and phase adjusting the inverted filtered component signal respectively and said correction means is arranged to subtract the phase adjusted filtered component signal from the transducer derived signal.

13. Apparatus as claimed in claim 12 which the transducer derived signal is analog and which includes an analog to digital converter for converting the transducer derived signal to digital form, said filter means, inverter and phase adjusting means all being digital, and which further includes a digital to analog converter for converting the phase adjusted digital signal to analog form for subtraction from the transducer derived signal by said correction means.

14. Apparatus as claimed in claim 9 in which the articles are bank notes, the load hod being adapted to hold a stack of such banknotes.