Batching system utilizing digital-to-analog subtraction to denote the amount of batched material

Claim 2

A weighing system comprising a weighing hopper, means for providing a first analog voltage signal in accordance with the weight of said hopper and the material contained therein, means for producing a series of pulses, an electronic counter for registering the number of pulses forwarded from the pulse producing means, a digital-to-analog converter for converting the count registration of said counter to a second analog voltage signal having a value representative of said registration, and means for discontinuing the forwarding of pulses to said counter when the value of said second analog voltage signal has reached a predetermined relation with the value of said first analog voltage signal.

Claim 3

A weighing system as defined in claim 1 in which said predetermined relationship is reached when the value of said first analog signal is substantially equal to the value of said second analog signal.

Claim 4

A weighing system as defined in claim 2 in which said first analog signal is of one polarity and said second analog signal is of opposite polarity.

Claim 5

A weighing system as defined in claim 3 in which said pulse discontinuing means includes an operational amplifier having a pair of input terminals and an output terminal, said means for providing a first analog signal and said converter being connected to one of said input terminals so that when said first and second analog signals are equal the output signal at said output terminal is zero.

Claim 6

A weighing system as defined in claim 4 in which said pulse discontinuing means additionally includes a comparator having a first input terminal connected to the output terminal of said operational amplifier, a second input terminal connected to the other input terminal of said operational amplifier, and an output terminal connected to said pulse producing means.

Claim 7

A weighing system as defined in claim 5 including a first resistor connected between said means for providing a first analog signal and a second resistor connected between said converter and the said one input terminal of said operational amplifier.

Claim 8

A weighing system as defined in claim 5 in which said pulse producing means includes a controlled pulse generator, and a common switch means for starting said pulse generator and simultaneously resetting said counter.

Claim 9

A weighing system as defined in claim 5 in which said operational Amplifier has a gain greater than ''''one.''''

Claim 10

A weighing system as defined in claim 8, in which said gain is equal to ''''two.''''

Claim 11

In combination, a weighing hopper, a load cell having first and second output terminals providing an analog voltage signal in accordance with the weight of said hopper and the material contained in said hopper, an operational amplifier having first and second input terminals and an output terminal, a first resistor connected between the first output terminal of said load cell and the first input terminal of said operational amplifier, the second input terminal of said amplifier being connected to the second output terminal of said load cell, a comparator having first and second input terminals and an output terminal, the first input terminal of said comparator being connected to the output terminal of said operational amplifier and the second input terminal of said comparator being connected to the second output terminal of said load cell and also to the second input terminal of said amplifier, a pulse generator connected to the output terminal of said comparator and controlled thereby, an electronic counter connected to said pulse generator for counting the pulses received therefrom, a digital-to-analog converter for converting the count of said electronic counter to an analog signal representative of the count, and a second resistor connected between the output of said converter and said first input terminal of said operational amplifier.

Claim 12

In combination, a weighing hopper, a load cell having first and second output terminals providing an analog voltage signal in accordance with the weight of said hopper and the material contained in said hopper, an operational amplifier having first and second input terminals and an output terminal, a first resistor connected between the first output terminal of said load cell and the first input terminal of said operational amplifier, the second input terminal of said amplifier being connected to the second output terminal of said load cell, a comparator having first and second input terminals and an output terminal, the first input terminal of said comparator being connected to the output terminal of said operational amplifier and the second input terminal of said comparator being connected to the second output terminal of said load cell and also to the second input terminal of said amplifier, a pulse generator connected to the output terminal of said comparator and controlled thereby, an electronic counter connected to said pulse generator for counting the pulses received therefrom, a digital-to-analog converter for converting the count of said electronic counter to an analog signal representative of the count, and a second resistor connected between the output of said converter and said first input terminal of said operational amplifier.

Claim 13

The combination defined in claim 10 including switch means for resetting said counter to its zero state and also for simultaneously starting said pulse generator, said pulse generator providing pulses to said counter until a zero difference between the first and second input terminals of said comparator causes a signal to appear at its said output terminal which stops said pulse generator.