US3902812A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photometer using three kinds of light wavelengths
Assignee: Hitachi Ltd
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Filing: 1974-05-20
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Granted: 1975-09-02
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Expires: 1994-05-20
Abstract
Abstract In the quantitative measurement of one of plural components contained in a specimen, three kinds of light wavelengths are used to eliminate the influence of two components except one to be measured. The outputs with respect to the three kinds of wavelengths are converted to the corresponding electric signals, which are in turn subjected to the logarithmic conversion. One output with respect to one of the three kinds of wavelengths is inverted in polarity and the polarity-inverted output is then combined with the other outputs so that the relationship between the light absorption quantity and the wavelength, concerning the component to be measured, can be obtained with the result that the quantity of the component in the specimen can be determined.
Inventors
- 👤 Tadashi Honkawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 20:59
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/314
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
116 words
A photometer comprising a first means for producing light including at least three kinds of light components each having a single wavelength, a second means for taking out said three kinds of light components separately, a third means for converting said three kinds of light components into three electric signals respectively after said light components are respectively passed through a specimen, a fourth means having hold units for respectively holding said three electric signals from said third means, and a fifth means for inverting the polarity of one of said three electric signals held by said fourth means with respect to those of the other signals and for summing the polarity-inverted signal and the other signals.
Claim 2
Dependent Claim
116 words
A photometer comprising a first means for producing light including at least three kinds of light components each having a single wavelength, a second means for taking out said three kinds of light components separately, a third means for converting said three kinds of light components into three electric signals respectively after said light components are respectively passed through a specimen, a fourth means having hold units for respectively holding said three electric signals from said third means, and a fifth means for inverting the polarity of one of said three electric signals held by said fourth means with respect to those of the other signals and for summing the polarity-inverted signal and the other signals.
Claim 3
Dependent Claim
71 words
A photometer as claimed in claim 1, wherein said second means includes gate signal generating units for respectively generating gate signals with respect to the three taken-out wavelengths and said photometer further comprises gate units provided between said third means and said fourth means for respectively serving to pass the electric signals from said third means to said fifth means in response to the gate signals from said gate generating units.
Claim 4
Dependent Claim
59 words
A photometer as claimed in claim 2, wherein said second means includes three kinds of filters for respectively transmitting selectively said three kinds of light components, said filters being provided on a rotatable disc so that said filters traverse the light path between said first means and said third means in a predetermined order when said disc is rotated.
Claim 5
Dependent Claim
37 words
A photometer as claimed in claim 3, wherein each of said hold units of said fourth means includes an operational amplifier and at least one capacitor connected between the input and output terminals of said operational amplifier.
Claim 6
Dependent Claim
24 words
A photometer as claimed in claim 3, wherein said photometer futher comprises logarithmic converters respectively provided between said hold units and said fifth means.
Claim 7
Dependent Claim
37 words
A photometer as claimed in claim 5, wherein each of said logarithmic converters includes at least one operational amplifier and a transistor whose emitter and collector are connected with the input and output of said operational amplifier.
Claim 8
Dependent Claim
52 words
A photometer as claimed in claim 6, wherein said fifth means includes an amplifier for inverting the polarity of the output of one of said hold units of said fourth means and an operational amplifier for summing the outputs of the other hold units and the output of the polarity inverting amplifier.
References Cited (Backward Citations)
US3694092A
Cited
US3833304A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |