EP0035081A2 — A refractometer

Claim 1

Independent Claim 86 words

A method for determining the concentration of dissolved solids in a liquid sample, characterised in that said method comprises the steps of: placing a liquid sample to be tested into a hollow prismatic container (13) which is enclosed in an opaque housing (11), directing a collimated beam of monochromatic light (31) through the filled prismatic container, measuring (40) the refraction of the beam through the sample filled prism, and displaying (51) the measured refraction as a function of the concentration of dissolved solids in the sample.

Claim 2

Independent Claim 86 words

A method for determining the concentration of dissolved solids in a liquid sample, characterised in that said method comprises the steps of: placing a liquid sample to be tested into a hollow prismatic container (13) which is enclosed in an opaque housing (11), directing a collimated beam of monochromatic light (31) through the filled prismatic container, measuring (40) the refraction of the beam through the sample filled prism, and displaying (51) the measured refraction as a function of the concentration of dissolved solids in the sample.

Claim 3

Dependent Claim 54 words

A method according to claim 1 characterised in that the measuring step is deferred until after a predetermined amount of said sample has been placed in the prismatic container, and until after the predetermined amount has been in the container for a period sufficient to free the liquid in the container from air bubbles.

Claim 4

Dependent Claim 49 words

A method according to claim 1 or claim 2 characterised in that there is a step of automatically draining the sample from the prismatic container once the refraction of the beam has been measured, and indicating when the container has been drained and is ready to receive another sample.

Claim 5

Independent Claim 224 words

A method of using a refractometer for determining the amount of dissolved solids in a series of sample solutions characterised in that said method comprises: directing a collimated monochromatic light beam (31) through an empty hollow prismatic container (13) and refracting it onto first light sensing means (36), indicating (53) when the refractometer is ready to receive a sample, introducing a sample solution into the prismatic container (13), thereby causing refraction of the collimated light beam passing therethrough to a second light-sensing means (40), instead of to the first light-sensing means (36), commencing the testing sequence only after all of the light beam has been refracted away from the first light-sensing means (36), and slmultaneously indicating (54) that testing is in progress, determining the amount of refraction of the light beam caused by passing through the sample solution, converting the amount of refraction of the light beam into an analog electrical signal, converting the analog signal to a digital signal, displaying digitally (51) an amount corresponding to the digital signal, stated as a function of the concentration of dissolved solids in the sample solution, automatically draining the prismatic container ( 13 ), and simultaneously causing the light beam to be refracted to the first light-sensing means (36), and automatically recommencing the sequence by indicating (53) that the refractometer is ready to receive another sample,

Claim 6

Independent Claim 224 words

A method of using a refractometer for determining the amount of dissolved solids in a series of sample solutions characterised in that said method comprises: directing a collimated monochromatic light beam (31) through an empty hollow prismatic container (13) and refracting it onto first light sensing means (36), indicating (53) when the refractometer is ready to receive a sample, introducing a sample solution into the prismatic container (13), thereby causing refraction of the collimated light beam passing therethrough to a second light-sensing means (40), instead of to the first light-sensing means (36), commencing the testing sequence only after all of the light beam has been refracted away from the first light-sensing means (36), and slmultaneously indicating (54) that testing is in progress, determining the amount of refraction of the light beam caused by passing through the sample solution, converting the amount of refraction of the light beam into an analog electrical signal, converting the analog signal to a digital signal, displaying digitally (51) an amount corresponding to the digital signal, stated as a function of the concentration of dissolved solids in the sample solution, automatically draining the prismatic container ( 13 ), and simultaneously causing the light beam to be refracted to the first light-sensing means (36), and automatically recommencing the sequence by indicating (53) that the refractometer is ready to receive another sample,

Claim 7

Dependent Claim 141 words

A refractometer for determining the concentration of dissolved solids in a sample solution, comprising an enclosing opaque housing, light source means in said housing for producing a beam of substantially collimated monochromatic light, and a container for a sample solution characterised in that said container is a hollow prismatic container (13) in said housing (11) having two transparent optical walls (14, 15) disposed in the path of said light beam (11), said refractometer further comprising light-sensing means (40) disposed in the refracted path (44) of said light beam after the said beam has passed through said prismatic container (13) when filled with a liquid sample and responsive to the exact refraction of said light heam, and display means (51) actuated by said light-sensing means foi displaying the refraction as a function of the concentration of dissolved solids in the liquid sample.

Claim 8

Dependent Claim 141 words

A refractometer for determining the concentration of dissolved solids in a sample solution, comprising an enclosing opaque housing, light source means in said housing for producing a beam of substantially collimated monochromatic light, and a container for a sample solution characterised in that said container is a hollow prismatic container (13) in said housing (11) having two transparent optical walls (14, 15) disposed in the path of said light beam (11), said refractometer further comprising light-sensing means (40) disposed in the refracted path (44) of said light beam after the said beam has passed through said prismatic container (13) when filled with a liquid sample and responsive to the exact refraction of said light heam, and display means (51) actuated by said light-sensing means foi displaying the refraction as a function of the concentration of dissolved solids in the liquid sample.

Claim 9

Dependent Claim 39 words

A refractometer according to claim 5 characterised in that diain means (24) are connected to said prismatic containet (13) and control means (82) open said drain means causing said prismatic container to be emptied after testing has been completed.

Claim 10

Dependent Claim 226 words

A refractometer for determining the concentration of dissolved solids in a sample solution, including in combination: an enclosing opaque housing, light source means in said housing for producing a beam of collimated monochromatic light, and a container for a sample solution characterised in that said container is a hollow prismatic container (13) in said housing (11) having two transparent optical vertical walls (14, 15) disposed in the path of said light beam (31) said refractometer further compris- esing first and second light-sensing means (36, 40) said first light-sensing means (36) being disposed in the path of said light beams after the said beam has passed through said prismatic container when empty, and said second light-sensing means (40) being disposed in the refracted path of said light beam after the said beam has passed through said prismatic container when filled with a liquid sample, said second light-sensing means including means responsive to the exact refraction of said light beam, control means (72) to actuate testing as soon as said first light-sensing means ceases being illuminated by said light beam, and differentiating means and display means (51) for comparing the exact refraction of said light beam through a sample to the exact refraction of said light beam through a reference sample and displaying that difference as a function of the concentration of dissolved solids in the test sample.

Claim 11

Dependent Claim 226 words

A refractometer for determining the concentration of dissolved solids in a sample solution, including in combination: an enclosing opaque housing, light source means in said housing for producing a beam of collimated monochromatic light, and a container for a sample solution characterised in that said container is a hollow prismatic container (13) in said housing (11) having two transparent optical vertical walls (14, 15) disposed in the path of said light beam (31) said refractometer further compris- esing first and second light-sensing means (36, 40) said first light-sensing means (36) being disposed in the path of said light beams after the said beam has passed through said prismatic container when empty, and said second light-sensing means (40) being disposed in the refracted path of said light beam after the said beam has passed through said prismatic container when filled with a liquid sample, said second light-sensing means including means responsive to the exact refraction of said light beam, control means (72) to actuate testing as soon as said first light-sensing means ceases being illuminated by said light beam, and differentiating means and display means (51) for comparing the exact refraction of said light beam through a sample to the exact refraction of said light beam through a reference sample and displaying that difference as a function of the concentration of dissolved solids in the test sample.

Claim 12

Dependent Claim 109 words

A refractometer according to claim 7 characterised in that said first light-sensing means is a phototransistor (36) which emits a signal upon being illuminated, and said control means to actuate testing is an electronic circuit comprising: an amplifier (70), connected to said phototransistor, a Schmitt trigger (72), connected to said amplifier (70), and a timer (78) connected to said Schmitt trigger via a switch (74) the signal of said phototransistor being amplified by said amplifier and received by said Schmitt trigger, so that when said phototransistor ceases being illuminated said Schmitt trigger is operated making a sharp cutoff in the electronic circuit which actuates said timer through said switch.

Claim 13

Dependent Claim 229 words

A'refractometer according to claim 8 charaterised in that said second light-sensing means (40) is a photo- potentiomeer emitting an output voltage which corresponds to the exact refraction of said light beam as caused by passing through a liquid sample, and said differentiating means is an electronic circuit comprising: a differential amplifier (61), said differential amplifier being connected to the output voltage of said photopotentiometer and amplifying an analog signal which corresponds to the difference between said output voltage and the output voltage of a liquid sample having a fixed predetermined concentration of dissolved solids, an analog-to-digital converter (64) connected to said differential amplifier, receiving said amplified analog signal, and converting it to a digital signal of pulses at a frequency which corresponds to said amplified analog signal, a testing duration timer (81), a gate (66) connected to and receiving the digital signal of pulses from said analog-to-digital converter, said gate also being connected to said testing duration timer to receive its output during its period, and a decade counter (67) is connected to the output of said gate,so that the digital signal of pulses passes through said gate to be counted by said decade counter only when the output of said timer is also received by the gate, the number of pulses counted by said decade counter being proportional to the concentration of dissolved solids in a test sample.

Claim 14

Dependent Claim 123 words

A refractometer according to claim 9 characterised in that calibrating means are provided for adjusting said differentiating means, said calibrating means comprising: first switch means (74), an astable timer (89) connected through said first switch means (88) to said control means (72) to actuate testing, said astable timer also being connected to said decade counter (67) to reset said decade counter at the beginning of each period of said astable timer, second switch means (80) connecting the output of said astable timer to actuate and re-actuate said testing duration timer at the beginning of each period of said astable timer, and adjustment means connected to said testing duration timer, said adjustment means controlling the period for which said testing duration timer is set.

A refractometer

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