Abstract There is described an apparatus for producing an electrical signal related to the varying concentration of a solution, for example a sugar solution. Light is inclinedly directed upon a surface of a prism which is in contact with the solution, so that light falling on one side of a boundary line, the position of which is a function of the concentration of the solution, is transmitted into the solution while light falling on the other side of this boundary line is totally reflected. The reflected light is directed towards an assembly including two photocells which are spaced apart in the direction of movement of the boundary as the solution concentration varies. The outputs of the two photocells are combined in a difference amplifier to yield a signal denoting that the solution concentration has reached a predetermined value dependent upon the position in said direction of movement to which the assembly is adjusted.
Apparatus for measuring and comparing the concentration of a solution comprising a prism in contact with the solution, means for directing a beam of light on said prism for total refraction therein, a screen receiving an optical image of the boundary formed by the limit of the refracted light, a carriage movably mounted behind said screen, a graduated scale indicating the position of said carriage, means for guiding said carriage in movement in a direction parallel to the plane of displacement on said screen of the refracted beam, two spaced photoelectric cells mounted on said carriage receiving the refracted beam, one of said cells being electrically connected through an amplifier to an electric signal comparator and furnishing a first signal thereto, the other of said cells being electrically connected through An amplifier and a voltage divider to said comparator providing a second reduced signal thereto differing from said first signal by a constant coefficient, said comparator changing state when said first and second signals are equal and an alarm actuated by the change of state of said comparator.
Claim 2
Dependent Claim
178 words
Apparatus for measuring and comparing the concentration of a solution comprising a prism in contact with the solution, means for directing a beam of light on said prism for total refraction therein, a screen receiving an optical image of the boundary formed by the limit of the refracted light, a carriage movably mounted behind said screen, a graduated scale indicating the position of said carriage, means for guiding said carriage in movement in a direction parallel to the plane of displacement on said screen of the refracted beam, two spaced photoelectric cells mounted on said carriage receiving the refracted beam, one of said cells being electrically connected through an amplifier to an electric signal comparator and furnishing a first signal thereto, the other of said cells being electrically connected through An amplifier and a voltage divider to said comparator providing a second reduced signal thereto differing from said first signal by a constant coefficient, said comparator changing state when said first and second signals are equal and an alarm actuated by the change of state of said comparator.