Multi-point refractive liquid level sensor

An apparatus for sensing liquid level in a vessel, comprising:

• a mounting apparatus being adapted for insertion into the vessel;
• an array of sensing elements electrically connected in parallel and positioned along said mounting apparatus, the sensing elements each being spaced from one another at preselected locations and each being adapted to deliver an electric signal responsive to absence of liquid at the level of the respective sensing element wherein each sensing elements includes;
• radiant energy emitting means for producing radiant energy;
• radiant energy detecting means for delivering the electric signal responsive to received radiant energy;
• said radiant energy refracts away from the detecting means in the presence of liquid, and transmits to the detecting means in the absence of liquid, the detecting means adapted to deliver the electrical signal in response to receiving the radiant energy in the absence of liquid;
• means for summing the plurality of received electric signals and delivering a resultant liquid level signal in response thereto.

An apparatus for sensing liquid level with variable resolution in an irregularly shaped vessel, comprising:

• a strip of flexible printed circuit board adapted for inserting substantially vertically into the vessel and having a plurality of holes along the two longitudinal edges of the board for mounting the board to the vessel wall;
• a tubular member having a first and a second open ends, the tubular member being adapted to encompass the circuit board;
• means for filtering the liquid entering the tubular member, the filtering means being secured to both the first and second openings of the tubular member;
• an array of sensing elements electrically connected in parallel and positioned along said printed circuit board, the sensing elements being in spaced relationship from one another to adapt to the irregular shape of the vessel, and capable of delivering a plurality of electric signals responsive to immersion of sensing elements in liquid, wherein each sensing element includes;
• radiant energy emitting means for producing radiant energy;
• radiant energy detecting means for delivering the electric signal responsive to received radiant energy;
• said radiant energy emitting means being directed generally toward the respective detecting means, and the emitting and detecting means are in optical alignment with one another;
• a first housing portion encasing and sealing the radiant energy emitting means and connected to the printed circuit board;
• a second housing portion encasing and sealing the radiant energy detecting means and connected to the printed circuit board;
• said first housing portion being spaced apart from the second housing portion and having one side at a positive angle to the plane of the circuit board, wherein the angled side is arranged to generally face the second housing;
• said radiant energy refracts away from the detecting means at the angled side of the first housing portion in the presence of liquid, and transmits through the angled side to the detecting means in the absence of liquid, the detecting means being adapted to deliver the electrical signal in response to receiving the radiant energy in the absence of liquid;
• and
• means for summing the plurality of electric signals and delivering the resultant liquid level signal in response thereto.