US 4,199,261 AGranted

Optical intensity meter

AssigneeSmith-Kettlewell Eye Research Foundation

InventorsLeon E. Tidd, Alan B. Scott, Julius M. J. Madey, Carter C. Collins

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Abstract

A meter and method for measuring the intensity of reflected or other light. The meter is particularly suitable for use by blind or visually impared diabetics to determine sugar level in their urine and in one embodiment is a handheld, battery-powered, audio-output device. A chemical impregnated sample under test is illuminated with a light source and reflected light is detected to form an electrical measurement signal. In order to minimize variations in light source output, the measurement signal is typically formed as a ratio of logrithmically scaled signals derived from the sample under test and from the light source. The measurement signal is compared with reference levels and the comparison results are encoded to provide signals to an audio or other indicator. A time sequencer is provided for causing the measurement signal to be examined at a predetermined time.

Claims23

Dependent claims

Apparatus for use by visually impared people for detecting an optical measurement level of a test sample comprising:

light source means for illuminating the test sample to cause light to emanate from the test sample to form the optical measurement level as a function of an optical property of the test sample and of the illuminating light,
an optical-to-analog converter for converting the light emanating from the test sample to an electrical analog measurement signal having an amplitude proportional to said optical measurement level,
measurement circuit means for measuring said measurement signal in relation to a plurality of different reference levels to provide a plurality of digital signals representing whether or not the measurement signal exceeds the reference levels, respectively,
said measurement circuit means including a plurality of comparators for comparing said measurement signal with said plurality of different reference levels thereby detecting the amplitude of said measurement signal between one or more pairs of said reference levels;
said plurality of comparators including first and second comparators simultaneously receiving said measurement signal for comparing said measurement signal with first and second reference levels, respectively, and including means for generating said first and second reference levels to establish a pretest optical measurement level for said test sample;
said plurality of comparators including a third comparator receiving said measurement signal for comparing said measurement signal with a third reference level and including means for generating said third reference level to establish a beginning-of-test optical measurement level for said test sample;
indicator means responsive to said digital signals for providing an indication, detectable by visually impared people, of said optical measurement level.

4 more elements

A battery-operable apparatus for the portable use of visually impared people in detecting an optical measurement level of a test sample comprising in one hand-held enclosure:

a test station for holding the test sample,
light source means for illuminating the test sample to cause light to reflect from the test sample to form the optical measurement level as a function of the reflectance of the test sample and of the intensity of the illuminating light,
an optical-to-analog converter for converting the reflected light from the test sample to an electrical analog measuring signal having an amplitude proportional to the intensity of said reflected light,
measurement circuit means including a plurality of comparators for comparing said measurement signal with a plurality of established reference levels to provide a digital signal representing the magnitude of the optical measurement level,
said plurality of comparators including first and second comparators simultaneously receiving said measurement signal for comparing said measurement signal with first and second reference levels, respectively, and including means for generating said first and second reference levels to establish a pretest optical measurement level for said test sample, said plurality of comparators including a third comparator receiving said measurement signal for comparing said measurement signal with a third reference level and including means for generating said third reference level to establish a beginning-of-test optical measurement level for said test sample,
indicator means responsive to said digital signal for providing an audible indication, detectable by visually impared people, of said optical measurement level.

3 more elements

Apparatus for detecting an optical measurement level of a test sample comprising:

light source means for illuminating the test sample to cause light to emanate from the test sample to form the optical measurement level as a function of an optical property of the test sample and of the illuminating light,
an optical-to-analog converter for converting the light emanating from the test sample to an electrical analog measuring signal having an amplitude proportional to said optical measurement level,
measurement circuit means including test reference generation means for generating a plurality of test reference levels, including comparator means for sequencially comparing said measurement signal with said plurality of test reference levels to provide a digital signal representing the magnitude of the optical measurement level, and including sequencer means for sequentially selecting said test reference levels one at a time whereby said comparator means sequentially compares the amplitude of said measurement signal with said plurality of test reference levels to detect the optical measurement level of the test sample,
indicator means responsive to said digital signal for providing an indication of said optical measurement level.

1 more element

Dependencies are inferred from the claim text.