Baseline projection apparatus for use with baseline drift correction circuits

Claim 2

Baseline projection apparatus for use with a readout system which is used with analytical measuring instruments which produce measurement signals having recurrent data fluctuations which extend from a baseline value and wherein the readout system includes drift correction circuit means operative during the nonoccurrence of data fluctuations for modifying the measurement signal to minimize baseline drift components therein, the baseline projection apparatus comprising: first circuit means responsive to the readout system for developing a signal indicative of the slope of the unmodified measurement signal; second circuit means responsive to the slope-indicative signal for storing the slope-indicative signal occuring during the nonoccurrence of a data fluctuation; and third circuit means coupled to the readout system and responsive to The stored slope-indicative signal for continuing the modification of the measurement signal during the occurrence of a data fluctuation at a rate dependent on the value of the slope-indicative signal stored immediately preceding the occurrence of the data fluctuation.

Claim 3

Baseline projection apparatus in accordance with claim 1 wherein the first circuit means for developing the slope-indicative signal is coupled to the output of the drift correction circuit means.

Claim 4

Baseline projection apparatus in accordance with claim 1 wherein the first circuit means for developing a slope-indicative signal includes a differentiating circuit.

Claim 5

Baseline projection apparatus in accordance with claim 1 wherein the second circuit means includes a storage capacitor for providing the storage function.

Claim 6

Baseline projection apparatus in accordance with claim 1 wherein the second circuit means includes a storage capacitor, adjustable resistance means for feeding the slope-indicative signal to the storage capacitor and high input impedance buffer circuit means coupled to the storage capacitor for supplying the slope-indicative signal to the circuit means which continues the modification of the measurement signal during the occurrence of a data fluctuation, the adjustable resistance means enabling adjustment of the time constant of the slope signal storage process for adjusting the time interval over which the slope-indicative signal is averaged.

Claim 7

Baseline projection apparatus in accordance with claim 1 wherein the drift correction circuit means in the readout system includes analog signal storage means for enabling a constant modification to be applied to the measurement signal during the occurrence of a data fluctuation and wherein the first circuit means which develops the slope-indicative signal includes a differentiating circuit coupled in cascade with an amplifier with the input of the differentiating circuit being coupled to the output of the drift correction circuit means and wherein the third circuit means which continues the modification of the measurement signal during the occurrence of a data fluctuation includes means for coupling the signal storing circuit means of the baseline projection apparatus to the input of the amplifier during the occurrence of a data fluctuation and means for coupling the output of the amplifier to the analog signal storage means in the drift correction circuit means during the occurrence of a data fluctuation.

Claim 8

Baseline projection apparatus for use with a readout system which is used with analytical measuring instruments which produce measurement signals having recurrent data fluctuations which extend from a baseline value and wherein the readout system includes drift correction circuit means operative during the nonoccurrence of data fluctuations for modifying the measurement signal to minimize baseline drift components therein and wherein drift correction circuit means includes analog signal storage means for enabling a constant modification to be applied to the measurement signal during the occurrence of a data fluctuation, the baseline projection apparatus comprising: a signal amplifier; differentiating circuit means having one side coupled to the input of said amplifier and adapted to have the other side coupled to the output of the drift correction circuit means; impedance means having a first point at one end, a second point at the other end, and an intermediate point therebetween, such first point being coupled to the input of the amplifier; analog signal storage means; first switch means for coupling the intermediate point to the output of the amplifier during the nonoccurrence of a data fluctuation and to the projection apparatus signal storage means during the occurrence of a data fluctuation; second switch means for coupling the second point to the projection apparatus signal storage means during the nonoccurrence of a data fluctuation; signal transfer means adapted to be coupled to the analog signal storage means in the drift correction circuit means; and third switch means for coupling the output of the amplifier to the signal transfer means during the occurrence of a data fluctuation.

Claim 9

Baseline projection apparatus for use with a readout system which is used with analytical measuring instruments which produce measurement signals having recurrent data fluctuations which extend from a baseline value and wherein the readout system includes drift correction circuit means operative during the nonoccurrence of data fluctuations for modifying the measurement signal to minimize baseline drift components therein and wherein drift correction circuit means includes analog signal storage means for enabling a constant modification to be applied to the measurement signal during the occurrence of a data fluctuation, the baseline projection apparatus comprising: a signal amplifier; differentiating circuit means having one side coupled to the input of said amplifier and adapted to have the other side coupled to the output of the drift correction circuit means; impedance means having a first point at one end, a second point at the other end, and an intermediate point therebetween, such first point being coupled to the input of the amplifier; analog signal storage means; first switch means for coupling the intermediate point to the output of the amplifier during the nonoccurrence of a data fluctuation and to the projection apparatus signal storage means during the occurrence of a data fluctuation; second switch means for coupling the second point to the projection apparatus signal storage means during the nonoccurrence of a data fluctuation; signal transfer means adapted to be coupled to the analog signal storage means in the drift correction circuit means; and third switch means for coupling the output of the amplifier to the signal transfer means during the occurrence of a data fluctuation.

Claim 10

Baseline projection apparatus in accordance with claim 7 wherein the differentiating circuit means comprises a capacitor having one side coupled to the input of the amplifier and the other side coupled to the output of the drift correction circuit means.

Claim 11

Baseline projection apparatus in accordance with claim 7 wherein the impedance means comprises a pair of resistors connected in series with the intermediate point therebetween being the intermediate point of the impedance means.

Claim 12

Baseline projection apparatus in accordance with claim 9 wherein the resistor located between the intermediate point and the second point is an adjustable resistor for enabling adjustment of the time constant for the signal storage process which occurs when the amplifier output signal is being fed to the projection apparatus analog signal storage means for adjusting the time interval over which the differentiated signal is averaged.

Claim 13

Baseline projection apparatus in accordance with claim 7 wherein the analog signal storage means in the baseline projection apparatus includes a storage capacitor for providing the storage function.

Claim 14

Baseline projection apparatus in accordance with claim 11 wherein the analog signal storage means in the projection apparatus further includes a high input impedance buffer circuit having its input connected to the storage capacitor and having its output coupled to the first switch means.

Claim 15

Baseline projection apparatus in accordance with claim 7 wherein the readout system includes recognition circuit means for recognizing the occurrence of data fluctuations in the measurement signal and wherein the first, second, and third switch means of the baseline projection apparatus are coupled to and controlled by such recognition circuit means.