Apparatus for comparing two dimensions

Claim 2

Apparatus for comparing two dimensions comprising, a single transducer having an output voltage whose amplitude varies with time, said amplitude having a maximum value representative of one of two dimensions and a minimum value representative of the other dimension, a peak value detector circuit for providing a first DC voltage corresponding to the maximum value of said amplitude, a minimum value detector circuit for providing a second DC voltage corresponding to the minimum value of said amplitude, threshold means having two input terminals and an output terminal which provides a first voltage output at its output terminal for all voltages applied to its input terminals whose difference is less than a threshold value, and which provides a second voltage output on said output terminal for all voltages applied to its input terminals whose difference is greater than said threshold value, means to apply said first and second DC voltages to the input terminals respectively of said threshold means, and indicator means coupled to the output terminal of said threshold device to provide an indication of the output voltage of said threshold device.

Claim 3

The invention as expressed in claim 1 in which a variable resistor is connected across the input terminals of said threshold means whereby the threshold of said threshold means in combination with said resistor may be varied.

Claim 4

Means for comparing two dimensions comprising means to store a voltage which is a measure of the smaller of the two dimeNsions, means to store a voltage which is a measure of the greater of the two dimensions, threshold means having two input terminals and an output terminal which provides a first voltage output at its output terminal for all voltages applied to its input terminals whose difference is less than said threshold value, and which provides a second voltage output on said output terminal for all voltages applied to its input terminals whose difference is greater than said threshold value, means to apply respective voltages which are measures of the voltages stored by said two storage means to the input terminals respectively of said threshold means, indicator means coupled to the output terminal of said threshold device to provide an indication of the output voltage of said threshold device, said first-mentioned voltage-storing means comprising a capacitor, means to charge said capacitor to a relatively high voltage, means to discharge said capacitor, a differential amplifier having a pair of input terminals and an output terminal, means to apply a voltage which is a measure of the smaller of said dimension to one input terminal of said differential amplifier, means to sense the voltage across said capacitor and means to apply a voltage to the other input terminal of said differential amplifier which is a measure of the voltage sensed by said voltage-sensing means, and means to connect the output terminal of said differential amplifier to said capacitor discharging means, whereby said capacitor is discharged until the voltage applied to one of the input terminals of said differential amplifier is equal to the minimum voltage applied to the other of said input terminals thereof.

Claim 5

Means for comparing two dimensions comprising means to store a voltage which is a measure of the smaller of the two dimeNsions, means to store a voltage which is a measure of the greater of the two dimensions, threshold means having two input terminals and an output terminal which provides a first voltage output at its output terminal for all voltages applied to its input terminals whose difference is less than said threshold value, and which provides a second voltage output on said output terminal for all voltages applied to its input terminals whose difference is greater than said threshold value, means to apply respective voltages which are measures of the voltages stored by said two storage means to the input terminals respectively of said threshold means, indicator means coupled to the output terminal of said threshold device to provide an indication of the output voltage of said threshold device, said first-mentioned voltage-storing means comprising a capacitor, means to charge said capacitor to a relatively high voltage, means to discharge said capacitor, a differential amplifier having a pair of input terminals and an output terminal, means to apply a voltage which is a measure of the smaller of said dimension to one input terminal of said differential amplifier, means to sense the voltage across said capacitor and means to apply a voltage to the other input terminal of said differential amplifier which is a measure of the voltage sensed by said voltage-sensing means, and means to connect the output terminal of said differential amplifier to said capacitor discharging means, whereby said capacitor is discharged until the voltage applied to one of the input terminals of said differential amplifier is equal to the minimum voltage applied to the other of said input terminals thereof.

Claim 6

Means for comparing two dimensions comprising means to store a voltage which is a measure of the smaller of the two dimensions, means to store a voltage which is a measure of the greater of the two dimensions, threshold means having two input terminals and an output terminal which provides a first voltage output at its output terminal for all voltages applied to its input terminals whose difference is less than said threshold value, and which provides a second voltage output on said output terminal for all voltages applied to its input terminals whose difference is greater than said threshold value, means to apply respective voltages which are measures of the voltages stored by said two storage means to the input terminals respectively of said threshold means, and indicator means coupled to the output terminal of said threshold device to provide an indication of the output voltage of said threshold device, said second voltage storage means comprising a capacitor, means to charge said capacitor, a differential amplifier having a pair of input terminals and an output terminal, means to apply a voltage which is a measure of said greater dimension to one input terminal of said differential amplifier, means to sense the voltage across said capacitor and means to apply a voltage to the other input terminal of said differential amplifier which is a measure of the voltage sensed by said voltage-sensing means, and means to connect the output terminal of said differential amplifier to said capacitor-charging means, whereby said capacitor is charged until the voltage applied to one of the input terminals of said differential amplifier is equal to the maximum voltage applied to the other of said input terminals.

Claim 7

Means for comparing two dimensions comprising means to store a voltage which is a measure of the smaller of the two dimensions, means to store a voltage which is a measure of the greater of the two dimensions, threshold means having two input terminals and an output terminal which provides a first voltage output at its output terminal for all voltages applied to its input terminals whose difference is less than said threshold value, and which provides a second voltage output on said output terminal for all voltages applied to its input terminals whose difference is greater than said threshold value, means to apply respective voltages which are measures of the voltages stored by said two storage means to the input terminals respectively of said threshold means, and indicator means coupled to the output terminal of said threshold device to provide an indication of the output voltage of said threshold device, said second voltage storage means comprising a capacitor, means to charge said capacitor, a differential amplifier having a pair of input terminals and an output terminal, means to apply a voltage which is a measure of said greater dimension to one input terminal of said differential amplifier, means to sense the voltage across said capacitor and means to apply a voltage to the other input terminal of said differential amplifier which is a measure of the voltage sensed by said voltage-sensing means, and means to connect the output terminal of said differential amplifier to said capacitor-charging means, whereby said capacitor is charged until the voltage applied to one of the input terminals of said differential amplifier is equal to the maximum voltage applied to the other of said input terminals.