DIGITAL DIRECT READING COLORIMETER

• US 3,819,276 A
• Filed: 02/08/1972
• Issued: 06/25/1974
• Est. Priority Date: 02/09/1971
• Status: Expired due to Term

• Current Assignee: Peter H. Stewart, Raymond W. Kiess
• Original Assignee: Peter H. Stewart, Raymond W. Kiess
• Inventors: Kiess, Raymond W., Stewart, Peter H.
• Primary Examiner(s): Wibert, Ronald L.
• Assistant Examiner(s): Webster, R. J.
• Application Number:
  US05/224,457
• Time in Patent Office: 868 Days
• Field of Search: 356/39-42,180,224,226,227 250/226,218 324/115 23/230,292 73/64.1
• US Class Current: 356/414
• CPC Class Codes: G01N 21/27 using photo-electric detection G01N21/31 takes precedence; circuits for computing concentration logarithmic circuits G06G7/24; photometric circuits in general G01J

Abstract

A combined blood constituent and prothrombin time analyzer is provided in which a plurality of removable and replaceable circuit modules are utilized to program the analyzer for appropriate light wavelength, reagent blank offset, scale factors and calibration parameters and which is self referencing to predetermined standards such that the results derived are all normalized for readout on a common digital readout device. The entire analyzer is contained in a compact console which includes controlled incubated storage for blood test samples together with insertion cavities for both constituent concentration and prothrombin time analysis. The results of each analysis are so normalized by the blood analyzer that a common digital counter can be used to convert these results to a numerical readout presentable on a common readout device and said results are substantially instantaneously displayed subsequent to initiation of any given test in the analyzer.

Claims

1. In direct reading digital filter photometers for use in performing a plurality of chemical analyses of liquid samples, wherein the concentration of a specific constituent of a sample for each particular analysis is proportional to the intensity of radiant energy of a particular frequency range transmitted through a sample, the combination including:

a source of radiant energy;

filter means for following a particular frequency range of radiant energy emitted from said source;

transducer means positioned to be responsive to said filtered radiant energy from said source and for generating a signal proportional to the intensity of said filtered radiant energy;

receptacle means for supporting a cuvette containing sample liquid to be analyzed in said path of radiant energy;

electrical digital readout means for providing a readout as a function of the intensity of said received radiant energy;

analog-to-digital computing circuit means for deriving and generating a signal proportional to the concentration of said constituent to be analyzed in said liquid;

assembly means comprising a plurality of electrical normalizing means comprising calibrated reference parameters for each constituent test, and a plurality of associated individual filter means;

each of said normalizing means being selectively electronically connectable with said computing circuit means for providing electrical reference parameters for said computing circuit means for constraining said readout means to provide a direct digital readout of the concentration of a specific constituent related to a particular analysis in response to the intensity of radiant intensity received from said source through a particular one of said filter means, each of said normalizing means being selectively connected with a particular one of said filter means; and

correlating means for selectively correlating said normalizing means with said readout means and said filter means for performing each said particular analysis.

2. The invention defined in claim 1, wherein said receptacle means comPrises:

an elongated hollow sheath having optical apertures in opposite sides thereof defining an optical path therethrough transverse the longitudinal axis thereof;

guide means for receiving and constraining a cuvette containing a test sample in a substantially symmetrical intersection with said optical axis; and

switch means mounted on said sheath for engaging a cuvette inserted therein for detecting the presence and position of a cuvette and test sample in said sheath and exerting a constraint on said testing means as a function of such presence.

3. The invention defined in claim 2, wherein said switch means comprises:

a first micro-switch mounted on said sheath sensing the initial insertion of a cuvette therein before said cuvette intersects said optical path;

a second micro-switch mounted on said sheath sensing the intermediate insertion of said cuvette therein subsequent to the intersection of said cuvette and said optical path; and

a third micro-switch mounted on said sheath sensing the substantially complete insertion of said cuvette therein.

4. In a direct reading filter photometer for performing a plurality of chemical analyses of liquid samples irradiated by light of preselected wavelengths, including constituent concentration and prothrombin time analyses, the combination comprising:

circuit means including detector means responsive to the instantaneous intensity of light transmitted through a sample for providing outputs representative of a constituent concentration and also selectively responsive to a change in the intensity of light transmitted through a sample for providing outputs representative of prothrombin time values;

converter means for converting said outputs to digital signals representative thereof; and

display means for receiving said digital signals for converting same to direct numerical readouts of said constituent concentrations and prothrombin times.

5. The invention defined in claim 1, wherein said normalizing of means comprises a plurality of circuit modules, each including a given set of said reference parameters, peculiar to a given analysis to be performed and selectively interconnected with said correlating means to effect a particular analysis.

6. The invention defined in claim 5 wherein said modules are selectively removable and replaceable in said assembly means to selectively vary the number of analyses performed.

7. A test console for performing liquid sample analysis by absorption photometry comprising:

a housing, including test sample receiving means;

radiant energy means and optical means in said housing for irradiating a test sample in said sample receiving means;

digital electrical readout means and transducer means responsive to radiant energy received from an irradiated test sample;

a circuit board in said housing comprising analyzing circuit means common to a variety of sample analyses to be performed;

for controlling said readout means; and

circuit module means comprising circuit modules for selective connection with said circuit board and said analyzing circuit means for conditioning the parameters of said analyzing circuit means to a given analysis represented by a given module.

8. The invention defined in claim 7 wherein said console further includes an array of analyses selecting switches;

and said circuit module means comprises a plurality of individual modules, one adjacent each of said switches interconnected with said circuit board and selectively interconnected through said switches to said common analyzing circuit means to normalize said common analyzing circuit means to a particular analysis to be performed.

9. The invention defined in claim 7 wherein said console further includes incubating means for receiving and storing a plurality of test samples.

10. Absorption photometer testing means for determining a particular constituent concentration in a liquid test sample irradiated by light of preselected wave lEngth comprising;

a support provided with a cavity for receiving a liquid test sample having a light path therethrough;

detector means for receiving light transmitted along a single light path through said cavity with and without a liquid sample contained therein and for providing first and second current signals proportional to the intensity of said transmitted light through an open and sample containing cavity, respectively;

amplifier means for receiving and converting said first current signal to a first output voltage representative of the light transmittance of said open cavity at a first conversion gain and for receiving and converting said second current signal to a second output voltage representative of the light transmittance through said test sample at a second conversion gain, said gains having respective values such that said amplifier produces equal output voltages for said open cavity and for the presence of a standard sample reagent blank in said cavity in place of said test sample;

-converter means for receiving and converting said first and second output voltages to first and second time intervals, respectively, said time intervals being proportional to the respective logarithms of said first and second output voltages;

reference clock means;

counter means; and

control means interconnected with said converter means, said reference clock means and said counter means for enabling said converter means to initiate said time intervals and for gating said clock means into said counter means at the beginning of and throughout said time intervals;

said control means including selecting means for constraining said counter to count to opposite directions over said first and second time intervals, and for subtracting one count from the other, whereby the difference in the said counts is representative of the said particular constituent concentration in said test sample.

11. The invention defined in claim 10, wherein said reference clock means comprises a variable frequency oscillator;

and wherein said testing means further comprises correlating means for constraining said oscillator to a particular clock frequency for each particular constituent concentration test performed by said testing means.

12. The invention defined in claim 10, wherein said reference clock means comprises a variable frequency oscillator;

and wherein said testing means further includes correlating means interconnected with said amplifier means and said reference clock means;

said correlating means for constraining said reference clock means to a predetermined frequency and for constraining the first said amplifier means to predetermine values of said first and second conversion gains for each particular constituent concentration test performed to normalize said testing means such that said counter means provides a count directly representative of the parameters of any given test.

13. The invention defined in claim 10, wherein said testing means further includes decoding and display means driven by said counter means and enabled by said control means to provide a digital readout of the resulting count in said counter means for each test performed.

14. The invention defined in claim 11, wherein said testing means further includes decoding and display means driven by said counter means and enabled by said control means to provide a digital readout of the resulting count in said counter means for each test performed.

15. The invention defined in claim 12, wherein said testing means further includes decoding and display means driven by said counter means and enabled by said control means to provide a digital readout of the resulting count in said counter means for each test performed.

16. Absorption photometer testing means for determining a particular constituent concentration in a liquid test sample irradiated by light of a preselected wave length comprising:

a support provided with a cavity for receiving a liquid teSt sample having a light path therethrough;

detector means for receiving light transmitted through said cavity along a single light path with and without a liquid sample contained therein and for providing first and second current signals proportional to the intensity of said transmitted light through an open and sample containing cavity, respectively;

amplifier means for receiving and converting said first current signal to a first output voltage representative of the light transmittance of said open cavity at a first conversion gain and for receiving and converting said second current signal to a second output voltage representative of the light transmittance through said test sample at a second conversion gain, said gains having respective values such that said amplifier produces equal output voltages for said open cavity and for the presence of a standard sample reagent blank in said cavity in place of said test sample;

converter means for receiving and converting said first and second output voltages to first and second digital signals, respectively; and

computer means for receiving and determining the difference in magnitude of said digital signals;

said difference representing the particular constituent concentration in said test sample.

17. The testing means defined in claim 16, wherein said converter means comprises linear-to-logarithmic converter means for converting said first and second output voltages to first and second digital outputs defining first and second time intervals proportional, respectively, to the logarithms of said first and second output voltages and the said input currents corresponding to the latter.

18. The invention defined in claim 17 wherein said testing means further includes display means for receiving and reading out said difference as a direct indication of constituent concentration.

19. The invention defined in claim 16 wherein said testing means further includes display means for receiving and reading out said difference as a direct indication of constituent concentration.

20. The invention defined in claim 18, wherein said console further includes incubating means for receiving and storing a plurality of test samples.