Slope error compensating apparatus for use with profile measuring equipment

Claim 2

Circuit apparatus for treating a composite signal having high frequency data on a low frequency slope or drift to remove said slope or drift, comprising: a low-pass filter having an input and an output; a sample and hold circuit interconnected with said filter to receive the filtered signal therefrom as a first input; a ramp generator interconnected to provide a second input to said sample and hold circuit; a timer for providing a control signal to said sample and hold circuit for obtaining readout at the end of a predetermined time after actuation of said timer of first and second signals having values corresponding to the orthogonal components of the composite signal slope; a switch selectively actuatable to simultaneously energize the ramp generator, the timer and the sample and hold circuit and to interconnect the low-pass filter circuit input with the composite signal; means fed by said first and second output signals of said sample and hold circuit to provide a further signal corresponding to the ratio of said first and second signals; means fed by the ratio signal and the ramp generator output to provide a further ramp signal of slope corresponding to the ramp generator output multiplied by said ratio signal; and means interconnected with said further ramp signal and said composite signal for providing the difference thereof.

Claim 3

Circuit apparatus as in claim 1, in which said means to Provide a ratio signal includes a divider providing a ratio signal corresponding to the tangent of the composite signal low frequency.

Claim 4

Circuit apparatus as in claim 1, in which said means for providing a further ramp includes a multiplier.

Claim 5

Circuit apparatus for removing the low frequency slope component from a composite signal including high frequency data comprising: a filter having an input an an output and selectively connectable to said composite signal for blocking passage of the high frequency data; a sample and hold circuit interconnected with said filter output as a first input; a selectively actuatable ramp generator for providing a second input to said sample and hold circuit; means for actuating said sample and hold circuit to obtain readout a predetermined time after providing said first and second inputs to said sample and hold circuit, said readout including the instantaneous value (Vz) of the filter signal as a first signal and as a second signal (Vx) the instantaneous value of the ramp base; means selectively actuatable to simultaneously energize the ramp generator and the means for actuating the sample and hold circuit, and to interconnect the filter input with the composite signal; means fed by said first and second readout signals of said sample and hold circuit to provide a further signal corresponding to the ration Vz/Vx; means fed by the ratio signal and the ramp generator output to provide a further ramp signal of slope corresponding to the ramp generator output multiplied by said ratio signal; means interconnecting said further ramp signal and said composite signal in subtractive relation.

Claim 6

Circuit apparatus for removing the low frequency slope component from a composite signal including high frequency data comprising: a filter having an input an an output and selectively connectable to said composite signal for blocking passage of the high frequency data; a sample and hold circuit interconnected with said filter output as a first input; a selectively actuatable ramp generator for providing a second input to said sample and hold circuit; means for actuating said sample and hold circuit to obtain readout a predetermined time after providing said first and second inputs to said sample and hold circuit, said readout including the instantaneous value (Vz) of the filter signal as a first signal and as a second signal (Vx) the instantaneous value of the ramp base; means selectively actuatable to simultaneously energize the ramp generator and the means for actuating the sample and hold circuit, and to interconnect the filter input with the composite signal; means fed by said first and second readout signals of said sample and hold circuit to provide a further signal corresponding to the ration Vz/Vx; means fed by the ratio signal and the ramp generator output to provide a further ramp signal of slope corresponding to the ramp generator output multiplied by said ratio signal; means interconnecting said further ramp signal and said composite signal in subtractive relation.

Claim 7

Circuit apparatus for treating a composite signal having high frequency data on a low frequency slope or drift to remove said slope or drift, said composite signal being alternately generated in reverse order, comprising: a filter having an input and an output of characteristics passing the drift and blocking the data; a sample and hold circuit interconnected with said filter to receive the filtered drift signal therefrom as a first input; a selectively energizable ramp generator interconnected with said sample and hold circuit as a second input thereto; a timer for providing a control signal to said sample and hold circuit for obtaining readout at the end of a predetermined time after actuation of said timer of first and second signals having values corresponding to the orthogonal components of the composite signal slope; a switch selectively actuatable to simultaneously energize the ramp generator, the timer and the sample and hold circuit and to interconnect the filter input with the composite signal; means fed by said first and second output signals of said sample and hold circuit to provide a further signal corresponding to the ratio of said first and second signals; means interconnected with the ratio signal and the ramp generator output as separate inputs to provide a further ramp signal of slope corresponding to the ramp generator output multiplied by said ratio signal; means interconnected with said further ramp signal and said composite signal for providing the difference thereof; means for generating a signal each time the composite signal reverses order; and means responsive to said reversal signal for activating an alarm indication whenever said reversal signal occurs within the predetermined time after actuation of the timer.

Claim 8

Circuit apparatus for treating a composite signal having high frequency data on a low frequency slope or drift to remove said slope or drift, said composite signal being alternately generated in reverse order, comprising: a filter having an input and an output of characteristics passing the drift and blocking the data; a sample and hold circuit interconnected with said filter to receive the filtered drift signal therefrom as a first input; a selectively energizable ramp generator interconnected with said sample and hold circuit as a second input thereto; a timer for providing a control signal to said sample and hold circuit for obtaining readout at the end of a predetermined time after actuation of said timer of first and second signals having values corresponding to the orthogonal components of the composite signal slope; a switch selectively actuatable to simultaneously energize the ramp generator, the timer and the sample and hold circuit and to interconnect the filter input with the composite signal; means fed by said first and second output signals of said sample and hold circuit to provide a further signal corresponding to the ratio of said first and second signals; means interconnected with the ratio signal and the ramp generator output as separate inputs to provide a further ramp signal of slope corresponding to the ramp generator output multiplied by said ratio signal; means interconnected with said further ramp signal and said composite signal for providing the difference thereof; means for generating a signal each time the composite signal reverses order; and means responsive to said reversal signal for activating an alarm indication whenever said reversal signal occurs within the predetermined time after actuation of the timer.

Claim 9

Circuit apparatus as in claim 5, in which said means responsive to said reversal signal includes an AND-gate, inputs to which are the reversal signal and a signal coextensive with the timer operation during the predetermined period of time, and the output of said gate being connected to an electrically actuated indicator.

Claim 10

Circuit apparatus as in claim 5, in which there are provided further means interconnected with said ramp generator for reversing the ramp generator slope whenever a reversal in traverse direction occurs, to correspond with the reversal in profile data being generated.

Claim 13

Circuit apparatus for treating a composite signal having high frequency data on a low frequency slope or drift to remove said slope or drift, comprising: a low-pass filter having an input and an output, said input being fed by the composite signal; a sample and hold circuit interconnected with said filter output to receive the filtered signal therefrom as a first input; a first ramp generator providing a second input to said sample and hold circuit; a timer providing a control signal to said sample and hold circuit for obtaining readout of first and second signals having values corresponding to the orthogonal components of the composite signal slope at the end of a predetermined time after actuation of said timer; means fed by said first and second output signals of said sample and hold circuit to provide a further signal corresponding to the ratio of said first and second signals; means fed by the ratio signal and the first ramp generator output to provide a second ramp signal of slope corresponding to the first ramp generator output multiplied by said ratio signal; and means interconnected with said second ramp signal and said composite signal for providing the difference thereof corresponding substantially entirely to the high frequency data with the low frequency slope removed.

Claim 14

Circuit apparatus for treating a composite signal having high frequency data on a low frequency slope or drift to remove said slope or drift, comprising: a low-pass filter having an input and an output, said input being fed by the composite signal; a sample and hold circuit interconnected with said filter output to receive the filtered signal therefrom as a first input; a first ramp generator providing a second input to said sample and hold circuit; a timer providing a control signal to said sample and hold circuit for obtaining readout of first and second signals having values corresponding to the orthogonal components of the composite signal slope at the end of a predetermined time after actuation of said timer; means fed by said first and second output signals of said sample and hold circuit to provide a further signal corresponding to the ratio of said first and second signals; means fed by the ratio signal and the first ramp generator output to provide a second ramp signal of slope corresponding to the first ramp generator output multiplied by said ratio signal; and means interconnected with said second ramp signal and said composite signal for providing the difference thereof corresponding substantially entirely to the high frequency data with the low frequency slope removed.

Claim 15

Circuit apparatus as in claim 9, in which said means to provide a ratio signal includes a divider providing a ratio signal corresponding to the tangent of the composite signal low frequency.

Claim 16

Circuit apparatus as in claim 9, in which said means for providing the second ramp includes a multiplier.