Patent ID: 7456385

Claim:
A system for detecting an end of a stroke or a beginning of the stroke, the system comprising: a compartment having a body defining an interior wherein the body has an interior surface and a length defined between a first end and a second end of the compartment wherein the compartment has a movable element within the interior of the compartment wherein the movable element moves within the interior of the compartment between a first position and a second position wherein the second position is adjacent to the first end of the compartment; a tube connected to the interior surface wherein the tube is located at the first end of the compartment and further wherein the movable element has a capacitance value and the tube has a capacitance value wherein the capacitance value of the tube is different than the capacitance value of the movable element; an electrical circuit connected to the tube wherein the electrical circuit has a total capacitance value wherein the total capacitance value of the electrical circuit is based on the capacitance value of the tube if the movable element is not in contact with the tube and further wherein the total capacitance value of the electrical circuit is based on the capacitance value of the tube and the capacitance value of the movable element if the movable element is in contact with the tube wherein the movable element is moved to the second position within the interior of the compartment wherein contact of the movable element with the tube connects the movable element to the electrical circuit wherein contact of the movable element with the tube changes the total capacitance value of the electrical circuit; a first detector connected to the first end of the compartment wherein the first detector determines an intensity of light emitted within the interior of the compartment wherein the intensity of the light detected within the compartment corresponds to the first position of the movable element within the compartment; and a microprocessor connected to the electrical circuit and the first detector wherein the microprocessor detects that the movable element is located at the first position within the compartment via the intensity of the light detected within the interior of the compartment which is not attenuated by the interior surface of the compartment or the movable element wherein the microprocessor detects that the movable element is located at the second position within the interior of the compartment via the second total capacitance of the electrical circuit.