Detector for sensing and/or measuring passing objects
First Claim
1. A detector intended for sensing and/or measuring objects passing the detector measuring path, where at one defining surface of which a detector element is disposed for catching radiation sent from a beam source, said detector element being connected to an electrical amplifier and filter circuit and the signal from said circuit being taken to two integration circuits having mutually different time constants (τ
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S, τ
L), the output signals of which are taken to a comparator for obtaining of an output signal at an object alarm circuit which indicates the possible presence of an object irrespective of long duration fluctuations in the operating conditions of the detector, said detector being characterized in that the output from the integration circuit with the long time constant (τ
L) also is connected to a reference level means included in the object alarm circuit and being connected to the output of the comparator for determination of the threshold level to be reached before indicating presence of an object, and to an amplifier within a function alarm circuit which sends an analogue output signal indicating the long duration operational conditions of the detector, such that when the signal falls below a threshold level an alarm signal is triggered.
1 Assignment
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Accused Products
Abstract
A detector for sensing or measuring objects passing a measurement path (5) has a detection element (6), the output signal of which is a function of objects discovered in the measurement path. The output signal is fed to an amplifier and filter circuit (7-9), the output of which is connected to two parallel integration cirucits (11, 12). The integration circuits have time constant (τSH, τL) of different magnitudes, and their output signals are fed to a comparator (13) for obtaining an operative signal indicating the presence of an object in the measurement path, this signal being unresponsive to long-duration fluctuations in the detector'"'"'s operating conditions, e.g., dirtying of the detection element. The detector includes a dirtiness alarm with the threshold response adjustable to a long-time-constant integrator output.
15 Citations
10 Claims
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1. A detector intended for sensing and/or measuring objects passing the detector measuring path, where at one defining surface of which a detector element is disposed for catching radiation sent from a beam source, said detector element being connected to an electrical amplifier and filter circuit and the signal from said circuit being taken to two integration circuits having mutually different time constants (τ
-
S, τ
L), the output signals of which are taken to a comparator for obtaining of an output signal at an object alarm circuit which indicates the possible presence of an object irrespective of long duration fluctuations in the operating conditions of the detector, said detector being characterized in that the output from the integration circuit with the long time constant (τ
L) also is connected to a reference level means included in the object alarm circuit and being connected to the output of the comparator for determination of the threshold level to be reached before indicating presence of an object, and to an amplifier within a function alarm circuit which sends an analogue output signal indicating the long duration operational conditions of the detector, such that when the signal falls below a threshold level an alarm signal is triggered. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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S, τ
Specification