US3730627A
Expired / Lapsed
US
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Signal processor
Assignee: Damon Corp
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Filing: 1971-09-22
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Granted: 1973-05-01
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Expires: 1991-09-22
Abstract
Abstract The absorbance measuring signal processor disclosed herein operates to generate a signal representing the absorbance of an unknown sample in relation to the absorbance of a previously measured standard sample. In measuring the absorbance of each sample, standard or unknown, the apparatus generates a signal corresponding to the log ratio of two signals, representing, respectively, the optical transmission of the sample channel and the optical transmission of a reference channel. The use of the ratio of the two transmission characteristics compensates for source and detector sensitivity variations while the logarithmic characteristic provides a signal which corresponds with the absorption characteristic. In accordance with the invention, a controlled attenuation factor is applied to one of the transmission signals and this attenuation factor is adjusted, during measurement of the standard sample, so as to produce an absorbance output signal of predetermined level. A signal level representing this particular attenuation factor is sampled and stored and this same attenuation factor is then applied during the measurement of subsequent unknown samples. Accordingly, the absorbancerepresenting output signals obtained with unknown samples vary in relation to the predetermined standard absorbance output signal level as their absorbances vary in relation to the absorbance of the standard sample.
Inventors
- 👤 R Kent
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:59
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/255; G01J; G01J1/00; G01J1/10; G01J1/16
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
265 words
In an absorbance measuring system in which the transmission of a sample channel is compared with the transmission of a reference channel and signals representing the respective transmission characteristics are generated; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comprising: means for attenuating one of said transmission signals by a factor which is variable as a function of the amplitude of a control signal applied thereto; means for generating an output signal which varies as a function of the ratio of the attenuated transmission signal and the other transmission signal; means operative in a first state to generate and apply to said attenuating means a control signal having an amplitude which varies as a function of said output signal thereby forming a feedback loop which adjusts said output signal to a predetermined level and operative in a second state to store and continue to apply to said attenuating means a control signal at the existing control signal amplitude level, the system being operated in a sequence in which said control signal applying means is in said first state during measuring of a standard sample, is switched to said second state to store the control signal amplitude level produced in response to said standard sample, and is left in said second state during the subsequent measurement of unknown samples whereby the output signal varies in relation to said predetermined level as a function of the relation of the absorptions of subsequent unknown samples to the absorption of the previous standard sample.
Claim 2
Dependent Claim
265 words
In an absorbance measuring system in which the transmission of a sample channel is compared with the transmission of a reference channel and signals representing the respective transmission characteristics are generated; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comprising: means for attenuating one of said transmission signals by a factor which is variable as a function of the amplitude of a control signal applied thereto; means for generating an output signal which varies as a function of the ratio of the attenuated transmission signal and the other transmission signal; means operative in a first state to generate and apply to said attenuating means a control signal having an amplitude which varies as a function of said output signal thereby forming a feedback loop which adjusts said output signal to a predetermined level and operative in a second state to store and continue to apply to said attenuating means a control signal at the existing control signal amplitude level, the system being operated in a sequence in which said control signal applying means is in said first state during measuring of a standard sample, is switched to said second state to store the control signal amplitude level produced in response to said standard sample, and is left in said second state during the subsequent measurement of unknown samples whereby the output signal varies in relation to said predetermined level as a function of the relation of the absorptions of subsequent unknown samples to the absorption of the previous standard sample.
Claim 3
Dependent Claim
268 words
In an absorbance measuring system in which the transmission of a sample channel is compared with the transmission of a reference channel and signals representing the respective transmission characteristics are generated; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comPrising: means for attenuating the sample channel transmission signal by a factor which is variable as a function of the amplitude of a control signal applied thereto; means for generating an output signal which varies as a function of the logarithm of the ratio of the reference channel transmission signal to the attenuated sample channel transmission signal; a sample and hold circuit for selectively sampling said output signal and, during sampling, applying to said attenuating means a control signal having an amplitude which varies as a function of said output signal, thereby to form a feedback loop which adjusts said output signal to a predetermined level, said sample and hold circuit being selectively operative to store and continue to apply to said attenuating means a control signal at the existing control signal amplitude level, the system being operated in a sequence in which said sample and hold circuit, samples during measuring of a standard sample, stores the control signal amplitude level thereby produced in response to said standard sample, and holds said control signal amplitude level during the subsequent measurement of unknown samples whereby the output signal varies in relation to said predetermined level as a function of the relation of the absorptions of subsequent unknown samples to the absorption of the standard sample.
Claim 4
Dependent Claim
268 words
In an absorbance measuring system in which the transmission of a sample channel is compared with the transmission of a reference channel and signals representing the respective transmission characteristics are generated; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comPrising: means for attenuating the sample channel transmission signal by a factor which is variable as a function of the amplitude of a control signal applied thereto; means for generating an output signal which varies as a function of the logarithm of the ratio of the reference channel transmission signal to the attenuated sample channel transmission signal; a sample and hold circuit for selectively sampling said output signal and, during sampling, applying to said attenuating means a control signal having an amplitude which varies as a function of said output signal, thereby to form a feedback loop which adjusts said output signal to a predetermined level, said sample and hold circuit being selectively operative to store and continue to apply to said attenuating means a control signal at the existing control signal amplitude level, the system being operated in a sequence in which said sample and hold circuit, samples during measuring of a standard sample, stores the control signal amplitude level thereby produced in response to said standard sample, and holds said control signal amplitude level during the subsequent measurement of unknown samples whereby the output signal varies in relation to said predetermined level as a function of the relation of the absorptions of subsequent unknown samples to the absorption of the standard sample.
Claim 5
Dependent Claim
27 words
Apparatus as set forth in claim 2 wherein said predetermined level is coincident with one end of the range of said log ratio output signal generating circuit.
Claim 6
Dependent Claim
35 words
Apparatus as set forth in claim 2 including circuit means providing automatic gain control action maintaining the reference channel transmission signal applied to said log ratio output signal generating means at a substantially predetermined level.
Claim 7
Dependent Claim
361 words
In an absorbance measuring system in which the transmission of a sample channel is compared with the transmission of a reference channel and signals representing the respective transmission characteristics are generated; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comprising: means for attenuating both transmission signals by a factor which is variable as a function of a first control signal; means for generating and applying to said attenuating means as said first control signal, a signal which varies as a function of the amplitude of the attenuated reference channel transmission signal relative a predetermined voltage level thereby to maintain said attenuated reference channel transmission signal substantially at said predetermined voltage level; means for attenuating the sample channel transmission signals by a factor which is variable as a function of the amplitude of a second control signal; means for generating an output signal which varies as a function of the logarithm of the ratio of the attenuated sample transmission signal and the attenuated reference transmission signal; sample and hold means operative in a first state to generate and apply to said sample channel attenuating means as said second control signal a signal having an amplitude which varies as a function of the amplitude of said output signal relative a second predetermined voltage level thereby forming a feedback loop which adjusts said output signal to said second predetermined voltage level and operative in a second state to store and continue to apply to said sample channel attenuating means a signal at the existing level, the system being operated in a sequence in which said sample and hold means is in said first state during measuring of a standard sample, is switched to said second state to store the second control signal amplitude level produced in response to said standard sample, and is left in said second state during the subsequent measurement of unknown samples whereby the output signal varies in relation to said second predetermined voltage level as a function of the relation of the abSorptions of subsequent unknown samples to the absorption of the previous standard sample.
Claim 8
Dependent Claim
361 words
In an absorbance measuring system in which the transmission of a sample channel is compared with the transmission of a reference channel and signals representing the respective transmission characteristics are generated; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comprising: means for attenuating both transmission signals by a factor which is variable as a function of a first control signal; means for generating and applying to said attenuating means as said first control signal, a signal which varies as a function of the amplitude of the attenuated reference channel transmission signal relative a predetermined voltage level thereby to maintain said attenuated reference channel transmission signal substantially at said predetermined voltage level; means for attenuating the sample channel transmission signals by a factor which is variable as a function of the amplitude of a second control signal; means for generating an output signal which varies as a function of the logarithm of the ratio of the attenuated sample transmission signal and the attenuated reference transmission signal; sample and hold means operative in a first state to generate and apply to said sample channel attenuating means as said second control signal a signal having an amplitude which varies as a function of the amplitude of said output signal relative a second predetermined voltage level thereby forming a feedback loop which adjusts said output signal to said second predetermined voltage level and operative in a second state to store and continue to apply to said sample channel attenuating means a signal at the existing level, the system being operated in a sequence in which said sample and hold means is in said first state during measuring of a standard sample, is switched to said second state to store the second control signal amplitude level produced in response to said standard sample, and is left in said second state during the subsequent measurement of unknown samples whereby the output signal varies in relation to said second predetermined voltage level as a function of the relation of the abSorptions of subsequent unknown samples to the absorption of the previous standard sample.
Claim 9
Dependent Claim
390 words
In an absorbance measuring system in which the optical transmission of a sample channel is compared with the optical transmission of a reference channel said channels being chopped at different frequencies and being combined for detection by a common detector; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comprising: means for attenuating a signal obtained from the detector by a factor which is variable as a function of a first control signal; detector means for obtaining, from said attenuated detector signal, a sample channel transmission signal and a reference channel transmission signal; means for generating and applying to said attenuating means as said first control signal, a signal which varies as a function of the amplitude of said reference channel transmission signal relative a predetermined voltage level, thereby to maintain said reference channel transmission signal substantially at said predetermined voltage level; means for attenuating said sample channel transmission signal by a factor which is variable as a function of the amplitude of a second control signal; means for generating an output signal which varies as a function of the logarithm of the ratio of the attenuated sample transmission signal and said reference transmission signal; sample and hold means operative in a first state to generate and apply to said sample channel attenuating means as said second control signal a signal having an amplitude which varies as a function of the amplitude of said output signal relative a second predetermined voltage level thereby forming a feedback loop which adjusts said output signal to said second predetermined voltage level and operative in a second state to store and continue to apply to said sample channel attenuating means a signal at the existing level, the system being operated in a sequence in which said sample and hold means is in said first state during measuring of a standard sample, is switched to said second state to store the second control signal amplitude level produced in response to said standard sample, and is left in said second state during the subsequent measurement of unknown samples whereby the output signal varies in relation to said second predetermined voltage level as a function of the relation of the absorptions of subsequent unknown samples to the absorption of the previous standard sample.
Claim 10
Dependent Claim
390 words
In an absorbance measuring system in which the optical transmission of a sample channel is compared with the optical transmission of a reference channel said channels being chopped at different frequencies and being combined for detection by a common detector; apparatus for providing a signal representing the absorbance of an unknown sample as compared with the absorbance of a standard sample, said apparatus comprising: means for attenuating a signal obtained from the detector by a factor which is variable as a function of a first control signal; detector means for obtaining, from said attenuated detector signal, a sample channel transmission signal and a reference channel transmission signal; means for generating and applying to said attenuating means as said first control signal, a signal which varies as a function of the amplitude of said reference channel transmission signal relative a predetermined voltage level, thereby to maintain said reference channel transmission signal substantially at said predetermined voltage level; means for attenuating said sample channel transmission signal by a factor which is variable as a function of the amplitude of a second control signal; means for generating an output signal which varies as a function of the logarithm of the ratio of the attenuated sample transmission signal and said reference transmission signal; sample and hold means operative in a first state to generate and apply to said sample channel attenuating means as said second control signal a signal having an amplitude which varies as a function of the amplitude of said output signal relative a second predetermined voltage level thereby forming a feedback loop which adjusts said output signal to said second predetermined voltage level and operative in a second state to store and continue to apply to said sample channel attenuating means a signal at the existing level, the system being operated in a sequence in which said sample and hold means is in said first state during measuring of a standard sample, is switched to said second state to store the second control signal amplitude level produced in response to said standard sample, and is left in said second state during the subsequent measurement of unknown samples whereby the output signal varies in relation to said second predetermined voltage level as a function of the relation of the absorptions of subsequent unknown samples to the absorption of the previous standard sample.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-30 | 1976-10-30 | 1977-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-30 | 1980-10-30 | 1981-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-30 | 1984-10-30 | 1985-05-01 | $7700.00 | Window Closed / Lapsed |