Electrical pulse counters – pulse dividers – or shift registers: c – Applications – Counting animate or inanimate entities
Patent
1990-04-16
1991-08-13
Heyman, John S.
Electrical pulse counters, pulse dividers, or shift registers: c
Applications
Counting animate or inanimate entities
377 3, G06M 900
Patent
active
050401963
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an instrument for counting the number of sheets, panels or other elements in a stack.
There are various applications in which it is desirable to determine the number of sheets or panels in a stack of such elements. One example is for stock taking, another is for checking that the correct number of elements are delivered by a supplier to a customer. Manually counting the number of elements in a stack is time consuming and measuring the height of the stack does not necessarily yield an accurate indication of the number of elements in the stack.
A stack counting apparatus is disclosed in U.S. Pat. No. 4 298 790, in which apparatus a wheeled carriage moves along a track adjacent the stack and a photodetector on the carriage receives light reflected from the edges of the elements in the stack. The signal derived from the photocell is processed in conjunction with a train of pulses produced by an encoder coupled to an axle of the wheeled carriage, so that these pulses are synchronised with the movement of the carriage. Further, the signal processing system requires preprogramming with data representing the nominal thickness of the elements in the stack. The apparatus is therefore complex and requires a signal produced in synchronism with the travel of the carriage on which the photodetector is mounted, and requires information as to the nominal thickness of the elements in the stack.
A stack counting apparatus is also disclosed in European application No. 0 098 320, in which a photodetector is moved at a fixed velocity relative to the stack. The effective width of the photodetector must be adjusted in accordance with the thickness of the elements in the stack. The signal from the photodector is processed using a tapped analog delay line, so that the single photodector operates as the equivalent of a plurality of sensors spaced apart on the direction of its movement. The delay line requires a clock input the frequency of which is derived from a signal representing the fixed velocity of movement of the photodector relative to the stack. This apparatus also has the drawback of requiring a fixed velocity of movement which the processing circuit must know, and of requiring adjustment to match the thickness of the elements in the stack.
I have now devised an instrument which will provide an accurate count of the number of sheets, panels or other elements in a stack, whilst overcoming the drawbacks of the prior art apparatus.
In accordance with this invention there is provided an instrument for counting the number of elements in a stack, comprising means for scanning a side of the stack in a direction generally perpendicular to the edges of the elements in the stack to provide an electrical signal, and means for processing the electrical signal alone to determine a characteristic periodicity therein representing successive elements in the stack, and further counting the repeating cycles in said electrical signal to provide a count of the number of elements in said stack.
The instrument is preferably hand-held and arranged to be moved over the height of the stack whilst it repeatedly scans the portion of the stack which it is aligned with at each instant. The instrument preferably comprises an opto-electronic device such as a CCD (charge-coupled device) arranged to electronically scan an optical image projected onto it from the side of the stack. Preferably the instrument includes a light source for illuminating the portion of the stack with which it is aligned.
Preferably the instrument includes a digital read-out giving a count of the elements in the stack. In use, the instrument may be directed at for example the foot of the stack and the counter reset to zero, then moved up to the top of the stack. The read-out will give a count of the total number of elements in the stack. The instrument can also be used to count off a required number of elements from the top of the stack and for this purpose preferably the light source is arranged to project a datum line onto the side of the stack.
The si
REFERENCES:
patent: 3813523 (1974-05-01), Mohan et al.
patent: 3835306 (1974-09-01), Bills et al.
patent: 3971918 (1976-07-01), Saito
patent: 4225931 (1980-09-01), Schwefel
patent: 4298790 (1981-11-01), Decker et al.
patent: 4324195 (1983-05-01), Nosler
patent: 4442532 (1984-04-01), Takemura
Heyman John S.
Schindler Edwin D.
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