Abstract A preset amount of weight change with respect to a load cell is monitored by a circuit which provides an alarm at an adjustable point prior to the weight change reaching the predetermined amount. A load cell and a phase detector circuit are driven by an oscillator which provides a pair of different phase signals. The phase detector is further provided with an output signal from the load cell indicative of the weight carried by the load cell and at the frequency and phase of one of the signals of the oscillator. The phase detector provides a direct current signal representative of weight carried on the load cell in response to its input alternating signals and the direct current signal is utilized for determining operation of an alarm device. An adjustable and switchable set point circuit is provided for developing an operating signal for the alarm device in response to the direct current signal from the phase detector, the switching function being effective to permit the direct current signal to approach a reference signal representative of the predetermined weight change unidirectionally regardless of whether the load cell is being loaded or unloaded.
Inventors
👤 W Jones
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-27 08:36
CPC Classifications
G; G01; G01G; G01G23/00; G01G23/18; G01G23/36
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
172 words
In a weighing system of the type wherein a detector circuit provides a signal across its output terminals which is indicative of a predetermined weight being applied on an associated load cell and a set point circuit is interposed between the detector and an alarm device for establishing a signal which will effect operation of the alarm device, the improvement wherein said set point circuit comprises a differential amplifier for operating said alarm device including a first input connected to a reference potential and a second input for receiving an input signal, a pair of interconnected impedance circuits connected to the output terminals of the detector circuit for developing said input signal, and switch means operable to selectively connect said impedance circuits to said second input of said differential amplifier so that said input signal may unidirectionally approach the reference potential to effect operation of the alarm device prior to said predetermined weight being applied to said load cell regardless of whether the weight on the load cell is increasing or decreasing.
Claim 2
Dependent Claim
172 words
In a weighing system of the type wherein a detector circuit provides a signal across its output terminals which is indicative of a predetermined weight being applied on an associated load cell and a set point circuit is interposed between the detector and an alarm device for establishing a signal which will effect operation of the alarm device, the improvement wherein said set point circuit comprises a differential amplifier for operating said alarm device including a first input connected to a reference potential and a second input for receiving an input signal, a pair of interconnected impedance circuits connected to the output terminals of the detector circuit for developing said input signal, and switch means operable to selectively connect said impedance circuits to said second input of said differential amplifier so that said input signal may unidirectionally approach the reference potential to effect operation of the alarm device prior to said predetermined weight being applied to said load cell regardless of whether the weight on the load cell is increasing or decreasing.
Claim 3
Dependent Claim
58 words
The improvement set forth in claim 1, wherein said impedance circuits are of equal value, and including a variable impedance connected between said impedance circuits for varying with respect to the output signal of the detector the point of development of an input signal equivalent of said reference level to provide an early warning alarm for an operator.
Claim 4
Dependent Claim
49 words
The improvement set forth in claim 2, wherein each of said impedance circuits comprises a resistor connected in series between a respective output terminal of the detector and said switch means, and comprising a variable resistor connected across the connection of said impedance circuit resistors to said switch means.
Claim 5
Dependent Claim
49 words
The improvement set forth in claim 3, wherein said switch means is a manually operable transfer switch having a movable contact connected to said second input of said differential amplifier and a pair of stationary contacts connected to said variable resistor and individually connected to said impedance circuit resistors.