Method for optimizing piston diameter in a non-contact tonometer, and non-contact tonometer having fluid pump designed by said method
AssigneeReichert, Inc.
InventorsBruce Siskowski, David A. Luce
Life of this patent
Estimating the term…
Abstract
A fluid pump system of a non-contact tonometer is numerically simulated through its compression stroke by a simulation software program. System dynamic behavior is modeled for a variety of piston diameters, whereby an optimal piston diameter or range of piston diameters is selected in view of stoke length limitations and target applanation pressure requirements.
Claims4
In a non-contact tonometer of the type having a piston of diameter Dp movable in a compression stroke relative to a cylinder to compress air within an air compression volume of said non-contact tonometer, and a discharge tube in flow communication with said air compression volume for directing an air pulse at an eye to be tested, said discharge tube having a length L and an exit orifice of diameter De, the improvement comprising:
- said piston diameter Dp being chosen such that a system ratio SR given by
- SR=(Dp*De*L)/Vnet
- is in the range of 0.1507 through 0.1621.
A method of selecting the diameter of a piston used in a non-contact tonometer, said piston being movable in a compression stroke to compress air within a compression volume to discharge an air pulse from a discharge tube in flow communication with said compression volume, said method comprising the steps of:
- A) establishing a maximum stroke length of said piston;
- B) setting a target plenum pressure;
- C) calculating a required stroke length of said piston that is the minimum stroke length necessary to achieve said target plenum pressure, said required stroke length being calculated for a plurality of piston diameters;
- and
- D) selecting the smallest piston diameter that corresponds to a stroke length less than said maximum stroke length.
Dependencies are inferred from the claim text.