Method and apparatus for determining colorimetric concentrations

Claim 3

The method of claim 1 including employing only two different filter sectors, alternately passing light through each said filter sector, synchronizing the rotation of the filter disc with relay means for segregating the electrical signals corresponding to each filter sector, and evaluating the difference between said signals with a difference measuring bridge.

Claim 4

Apparatus for determining colorimetric concentrations in liquids comprising a single light source, a measuring bulb for liquid to be examined and a photo-electric cell positioned to register light flow from said source transmitted through liquid in said bulb, a filter disc having at least two absorption filter sectors mounted for rotation to place said filter sectors sequentially in the path of light passing from said bulb to said cell, one filter sector of said filter disc passing light in a wide wave-length range including the wave-lengths absorbed by the concentration to be determined, another filter sector of said filter disc passing light only in a narrow wave-length range within said wide range, said narrow wave-length range not including the wave-lengths absorbed by the concentration to be determined, a difference measuring bridge operatively connected with said photo-electric cell for measuring differences in electrical signals produced by said cell, means for rotating said filter disc and means for synchronizing the flow of signals from said photo-electric cell to different sides of said bridge with the rotation of said disc whereby the difference measured by said bridge represents the difference between light flows through said filter sectors.

Claim 5

Apparatus for determining colorimetric concentrations in liquids comprising a single light source, a measuring bulb for liquid to be examined and a photo-electric cell positioned to register light flow from said source transmitted through liquid in said bulb, a filter disc having at least two absorption filter sectors mounted for rotation to place said filter sectors sequentially in the path of light passing from said bulb to said cell, one filter sector of said filter disc passing light in a wide wave-length range including the wave-lengths absorbed by the concentration to be determined, another filter sector of said filter disc passing light only in a narrow wave-length range within said wide range, said narrow wave-length range not including the wave-lengths absorbed by the concentration to be determined, a difference measuring bridge operatively connected with said photo-electric cell for measuring differences in electrical signals produced by said cell, means for rotating said filter disc and means for synchronizing the flow of signals from said photo-electric cell to different sides of said bridge with the rotation of said disc whereby the difference measured by said bridge represents the difference between light flows through said filter sectors.

Claim 6

The apparatus of claim 3 wherein the filter sectors of said filter disc are of equal size.

Claim 7

The apparatus of claim 3 wherein the filter sectors are of different sizes and including a compensation filter for balancing light energy flowing to the photoelectric cell.

Claim 8

The apparatus of claim 3 and including a compensation filter positioned between the filter disc and the photo-electric cell.

Claim 9

The apparatus of claim 3 and including a grey filter added to one filter sector for adjusting the flow of light therethrough so that flow of light through the filter sectors is equal.

Claim 10

The apparatus of claim 3 wherein the synchronizing means comprises a sector disc mounted on the same axis with the filter disc for concurrent rotation therewith and a sensing device positioned near the sector disc for controlling the flow of signals to said different sides of the bridge by means of relays.