Method of and apparatus for measuring the movement of a lens with four measurement points
AssigneeZBE, Incorporated
InventorsZac Bogart, Matthew Keennon, Rodney Martinez
Life of this patent
Estimating the term…
Abstract
A method and apparatus for measuring the linear movement between first and second substantially planar surfaces and is useful, for example, in an automatic focusing system of a photographic enlarging or printing machine. The linear movement between a first plane, e.g., a lens plane and a second plane, e.g., a film or print plane, at a single point, e.g., the lens optical center, is determined by measuring the linear movement of two diametrically opposed points proximate to the lens plane equidistant from the lens optical center. The two measured distances are then averaged to yield a distance measurement at the lens optical center corrected for any deflection of the lens plane.
Claims19
A method of measuring relative linear movement between a first planar surface and a second planar surface, comprising the steps of:
- selecting first and second measurement points proximate to said first planar surface essentially diametrically opposed and equidistant from a first reference point on said first planar surface;
- selecting third and fourth measurement points proximate to said second planar surface essentially diametrically opposed and equidistant from a second reference point on said second planar surface;
- measuring relative linear movement between said first and third measurement points to determine a first measurement value;
- measuring relative linear movement between said second and fourth measurement points to determine a second measurement value;
- and
- computing a third measurement value representative of relative linear movement between said first and second reference points by averaging said first and second measurement values.
An apparatus for measuring relative linear movement between first and second planar surfaces, comprising:
- first and second measurement points diametrically opposed and equidistant from a first reference point proximate to said first planar surface;
- third and fourth measurement points diametrically opposed and equidistant from a second reference point proximate to said second planar surface;
- first measurement means for generating a first measurement signal corresponding to linear movement from said second measurement point to said fourth measurement point;
- and
- means for averaging said first and second measurement signals to determine a value indicative of relative linear movement from said first to said second reference points.
An apparatus for measuring the relative linear movement between a first planar surface and a second planar surface, comprising:
- first and second measurement points diametrically opposed and equidistant from a first reference point proximate to said first planar surface;
- third and fourth measurement points diametrically opposed and equidistant from a second reference point proximate to said second planar surface;
- a measurement device coupled to said first planar surface proximate to said second measurement point to generate a relative movement signal;
- a flexible elongate member coupled at a first end proximate to said first measurement point and at a second end to said measurement device proximate to said second measurement point;
- flexible elongate member direction means for directing said flexible elongate member via third and fourth measurement points diametrically opposed and equidistant from said second reference point;
- and
- means for diverting said flexible elongate member to avoid an axis defined by said first and second reference points.
Dependencies are inferred from the claim text.