Automatic lensmeter

• US 5,349,433 A
• Filed: 01/21/1992
• Issued: 09/20/1994
• Est. Priority Date: 02/01/1991
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Iwane, Toru
• Primary Examiner(s): Willis, Davis L.
• Assistant Examiner(s): Pham, Hoa Q.
• Application Number:
  US07/822,948
• Time in Patent Office: 973 Days
• Field of Search: 356/124-127
• US Class Current: 356/124
• CPC Class Codes: G01M 11/0235 by measuring multiple properties of lenses, automatic lens meters

Abstract

An automatic lensmeter for automatically measuring a lens characteristic of a lens to be tested, comprises: a measuring unit including an optical system for detecting a refraction characteristic of the lens; a calculation unit for calculating a lens characteristic value in accordance with information from the measurement unit; a display unit for displaying the lens characteristic value calculated by the calculation unit; an actual eccentricity calculation unit for calculating an actual eccentricity based on the lens characteristic value calculated by the calculation unit; and an optical axis position determination unit for determining whether the actual eccentricity calculated by the actual eccentricity calculation unit is within a predetermined range or not to determine whether the measurement and/or the marking are permitted. The display unit displays the determination of the optical axis position determination unit.

Claims

1. An automatic lensmeter for automatically measuring a lens characteristic of a lens to be tested comprising:

a measuring unit including an optical system for detecting a refraction characteristic of the lens;

a calculation unit for calculating a lens characteristic value in accordance with information from said measurement unit;

a display unit for displaying the lens characteristic value calculated by said calculation unit;

said display unit including a screen and a target movable on the screen;

an actual eccentricity calculation unit for calculating an actual eccentricity based on the lens characteristic value calculated by said calculation unit; and

an optical axis position determination unit for determining whether the actual eccentricity calculated by said actual eccentricity calculation unit is within a predetermined range or not to determine whether measurement and/or marking are permitted;

said display unit displaying the determination of said optical axis position determination unit,

said display unit having a display control unit for converting the actual eccentricity calculated by said actual eccentricity calculation unit to a corresponding quantity on the screen of said display unit to move the target to a position deviated from a reference position by the actual eccentricity,

wherein said display unit displays dot by dot on the screen, the size of one dot on the screen is 0.3 mm and the conversion is effected by the following formulas;

space="preserve" listing-type="equation">NX=0.3X

space="preserve" listing-type="equation">NY=0.3Y

where

NX;

an X coordinate on the display screen

NY;

a Y coordinate on the display screen.

2. A progressive focal length lens lensmeter comprising:

a collimator including a light source for projecting a plurality of collimated light beams to a lens to be tested;

an optical system for directing the light beams refracted by passing through the lens to a photosensing system;

photo-detection means for converting a light signal from said optical system to an electrical signal;

control means for determining refractive power data based on the output of said photo-detection means and determining a progressive addition and a position of a progressive area; and

display means for displaying the data of said control means,

wherein said control means determines the progressive addition of the lens by the following formulas;

space="preserve" listing-type="equation">Δ

P=κ

K×

D

where

Δ

P;

a vector

K;

an increment of diopter per unit distance

D;

a diameter of an aperture on a lens measurement table

κ

;

conversion coefficient.

3. An automatic lensmeter for automatically measuring a lens characteristic of a lens to be tested, comprising:

a measuring unit including an optical system for detecting a refraction characteristic of the lens;

a determining unit inputting information from said measuring unit for determining a lens characteristic value;

a display unit for displaying the lens characteristic value determined at said determining unit;

actual eccentricity determining means for determining an actual eccentricity on the basis of the lens characteristic value determined at said determining unit and a condition for determining the actual eccentricity; and

optical axis position judging means for judging whether or not the actual eccentricity determined at said actual eccentricity determining means is within a predetermined range and for determining whether or not a measurement and/or a marking are permitted, said display means displaying the result of the judgement;

wherein said actual eccentricity determining means determines the eccentricity in accordance with the following equations when S(S+C)<

ζ

₀ is not satisfied;

space="preserve" listing-type="equation">X=10(PX(S+C(1-cos (2AX))/2-PY sin (2AX))/(S(S+C))

space="preserve" listing-type="equation">Y=10(PY(S+C(1+cos (2AX))/2-PX sin (2AX))/(S(S+C))

where

S;

a degree of sphere of the lens to be tested;

C;

a degree of cylinder of the lens to be tested;

ζ

.sub. ;

a predetermined value;

PX;

a horizontal prism value of the lens;

PY;

a vertical prism value of the lens;

AX;

an angle.

4. An automatic lensmeter according to claim 3, wherein said optical axis position judging means judges that a marking can be made onto the lens to be tested in accordance with the following equation:

space="preserve" listing-type="equation">SQR(X.sup.2 +Y.sup.2)<

ζ

.sub.0

where

η

₀ ;

a predetermined value.

5. An automatic lensmeter for automatically measuring a lens characteristic of a lens to be tested, comprising:

a measuring unit including an optical system for detecting a refraction characteristic of the lens;

a determining unit inputting information from said measuring unit for determining a lens characteristic value;

a display unit for displaying the lens characteristic value determined at said determining unit;

actual eccentricity determining means for determining an actual eccentricity on the basis of the lens characteristic value determined at said determining unit and a condition for determining the actual eccentricity; and

optical axis position judging means for judging whether or not the actual eccentricity determined at said actual eccentricity determining means is within a predetermined range and for determining whether or not a measurement and/or a marking are permitted, said display means displaying the result of the judgement;

wherein said optical axis position judging means judges that a measurement can be made on the lens to be tested in accordance with the following equation when S(S+C)<

ζ

₀ is satisfied;

space="preserve" listing-type="equation">SQR(PX.sup.2 +PY.sup.2)>

ε

.sub.1

where

space="preserve" listing-type="equation">ε

.sub. =ζ

.sub. η

.sub. 0/10

η

₀ ;

a permissive deviation when the refractive power is ζ

₁.