Apparatus for indicating that a chromatographic signal has ended

Claim 2

In an apparatus including a slope detector for detecting the slope of time-varying signals occurring at an apparatus input means with a baseline potential, a circuit for indicating that a time-varying signal has ended after its slope is substantially in the range of the slopes of some baseline potentials, comprising: storage means for storing a slope-time signal; first control means for causing the value of said slope-time signal in said storage means to be increased at least during a portion of the time that said slope detector detects a slope; and second control means for causing the value of said slope-time signal stored in said storage means to be decreased while said slope detector does not detect a slope; said storage means including means for providing a signal-end signal when the stored slope-time signal reaches a predetermined value, whereby said signal-end signal is provided by said storage means a period of time after said slope detector stops detecting the slope of the signal, which period of time is related to the time that said slope is detected.

Claim 3

A circuit for indicating that a time-varying signal has ended in accordance with claim 1 in which: said storage means includes an up-down counter having an up terminal, a down terminal, a clock pulse terminal and an output terminal; said first control means being electrically connected to said up terminal; said second control means being electrically connected to said down terminal; said circuit further including a source of clock pulses; said source of clock pulses being electrically connected to said clock pulse terminal, whereby said up-down counter counts said clock pulses up when said first control means applies a signal to said up terminal, counts said clock pulses down when said second control means applies a signal to said down terminaL and applies an output signal to said output terminal at a predetermined count.

Claim 4

A circuit for indicating that a time-varying signal has ended in accordance with claim 2 in which said means for providing a signal-end signal includes signal-end gating means, having inputs connected to said source of clock pluses, said output terminal of said up-down counter and said second control means and having a signal-end gating-means output terminal, for providing said signal-end signal when a clock pulse occurs, said predetermined count in said up-down counter is reached, and said slope detector does not detect a slope of the time-varying signal all at the same time.

Claim 5

A circuit for indicating that a time-varying signal has ended in accordance with claim 3 further including: classification means for recognizing different waveforms of said time-varying signals; said classification means including means for altering the amount by which said value of said slope-time signal must be decreased by said second control means before reaching said predetermined value when certain waveforms are detected.

Claim 6

A circuit for indicating that a time-varying signal has ended in accordance with claim 4 in which said means for altering the magnitude that said value of said slope-time signal must be decreased includes a means for resetting said up-down counter.

Claim 7

A circuit for indicating that a time-varying signal has ended in accordance with claim 4 in which said classification means further includes a means for generating a rejection signal when certain waveforms are detected.

Claim 8

A circuit for indicating that a time-varying signal has ended in accordance with claim 6 in which said means for generating a rejection signal includes means for generating a rejection signal when the duration between consecutive changes in the sign of the slope of any portion of the waveform is less than a predetermined time.

Claim 9

A circuit for indicating that a time-varying signal has ended in accordance with claim 3 further including classification means for resetting said up-down counter when said slope of said time-varying signal changes from a positive slope to a negative slope within a predetermined time, whereby said slope-time signal stored in said up-down counter is increased from said predetermined value only by the negative slope of said time-varying waveform before said second control means begins to decrease the value of the stored slope-time signal from the time that the slope detector ceases to detect a slope.

Claim 10

A circuit for indicating that a time-varying signal has ended in accordance with claim 8 in which: said up-down counter includes a reset terminal; said classification means includes a reset gating means for applying a reset signal to said reset terminal when enabled and a classification control circuit; said classification control circuit includes enabling means for enabling said reset gating means when said slope of said time-varying signal changes from positive to negative within a predetermined time; and said enabling means includes means for blocking said reset gating means when said slope of said time-varying signal changes to negative a period of time greater than said predetermined time after changing from a positive to a substantially zero slope.

Claim 11

A circuit for indicating that a time-varying signal has ended in accordance with claim 9 further comprising: slope, no-slope means, having a slope, no-slope output means, for applying a first potential to said slope, no-slope output means in response to the detection of a slope and for applying a second potential to said slope, no-slope output means in response to the detection of no slope by the slope detector; said slope, no-slope output means being electrically connected to said first and second control means; one of said first and second control means including an inverter, whereby said first and second potentials are applied to one of the up terminal and down terminal And an inverter first and second potential is applied to the other of the up and down terminals of the up-down counter by the first and second control means.

Claim 12

A circuit for indicating that a time-varying signal has ended in accordance with claim 10 further including means for resetting the up-down counter when the slope detected by said slope detector changes to a positive value.

Claim 13

A circuit for indicating that a time-varying signal has ended in accordance with claim 10 in which said enabling means includes: slope-memory means, having a positive-slope output means and a negative-slope output means, for storing a potential on the one of the positive-slope output means and negative-slope output means that corresponds to the sign of the last slope detected by the slope detector; and means, connecting said gating means to said slope-memory means and said slope, no-slope means, for applying enabling signals to said gating means when the potential on said one of said positive-slope output means and negative-slope output means changes polarity at any time during a period of time extending from the time that the first potential is being applied to said slope, no-slope output means to the end of a short period of time after said first potential is applied to said slope, no-slope output means.

Claim 14

In an apparatus having a measuring device for measuring one characteristic of a time-varying signal, a circuit for indicating a second characteristic of the time-varying signal, comprising: first means for providing the value of said one characteristic during at least a portion of the time-varying signal when said characteristic is of a first type; second means for providing the value of said one characteristic during at least a portion of the time-varying signal when said characteristic is of a second type; and third means for comparing said value of said one characteristic when said characteristic is of a first type when said value of said one characteristic when said characteristic is of a second type; said third means including indicator means for providing an indicator output signal when the difference between said value of said one characteristic when said characteristic is of a first type and said value of said one characteristic when said characteristic is of a second type reaches a predetermined value to indicate said second characteristic of said time-varying signal.

Claim 15

In an apparatus having a measuring device for measuring one characteristic of a time-varying signal, a circuit for indicating a second characteristic of the time-varying signal, comprising: first means for providing the value of said one characteristic during at least a portion of the time-varying signal when said characteristic is of a first type; second means for providing the value of said one characteristic during at least a portion of the time-varying signal when said characteristic is of a second type; and third means for comparing said value of said one characteristic when said characteristic is of a first type when said value of said one characteristic when said characteristic is of a second type; said third means including indicator means for providing an indicator output signal when the difference between said value of said one characteristic when said characteristic is of a first type and said value of said one characteristic when said characteristic is of a second type reaches a predetermined value to indicate said second characteristic of said time-varying signal.

Claim 16

A circuit according to claim 13 in which said third means includes an up-down counter and said indicator means includes the output signal generator of said up-down counter.

Claim 17

A circuit according to claim 14 in which: said up-down counter includes an up terminal, a down terminal and a clock pulse terminal; said clock pulse terminal being adapted to be electrically connected to a source of clock pulses; said measuring device includes a slope detector; said first means includes means for applying an enabling signal to said up terminal of said up-down counter when said slope detector detects a slope on a time-varying signal; said second means includes means for providing an enabling signal to said down terminal of said up-down counter when said slope detector detects no slope on a time-varying signal, whereby said indicator output signal indicates that the difference between the time that at least a portion of said time-varying signal has had a slope and the time that no slope has been detected has reached said predetermined value.

Claim 18

A circuit according to claim 13 in which said third means includes a storage means for storing the difference between the one value of said one characteristic during at least a portion of the time-varying signal when said characteristic is of a first type and the value of said one characteristic during at least a portion of the time-varying signal when said characteristic is of a second type.

Claim 19

A circuit according to claim 16 further comprising a reset means for resetting said storage means when said one characteristic changes from the first type to the second type within a predetermined period of time.