US2109474A

US2109474A - Spectacle lens

Info

Publication number: US2109474A
Application number: US579451A
Authority: US
Inventors: Evans Charles Ernest
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-12-07
Filing date: 1931-12-07
Publication date: 1938-03-01
Anticipated expiration: 1955-03-01

Description

" dioptric power of which varies gradually from- Patented Mar. 1, 1938 I Application December 7. BBL-Serial No. 579,451 RenewedMay28,1937

1401mm. totes-54)" My invention relates to a lens, the

one edge to the opposite edge with certain allowable modifications as hereinafter-set forth.

ing diagrammatically the method ing the lens surface.

Figures 7, 8 and-9 are diagrammatic representations of other forms of lenses which may be of generat In the following statements, it is assumed that produced in accordance with the present inven- 5 i the lens varies in dioptric power from top to tion. a bottom with the near vision at the bottom. 1 This gmluated grinding may be imposed on However, it is obvious that such a lens could be the convex or concave or both sides of the'lens rotated any amount to suit special conditions, as best suitsvarious cases, an for purpose of 10 up to 180 degrees, as might be required by the illustration I have shown a graduated grinding 10 operator of an' overhead crane. formed on the concave surface of the lens.

The primary objects of my invention are: One way in which the graduated surface of To produce an improved lens which will give such a lens could be generated would be by a the .user selective focal lengths to suit various line of the same curvature as a vertical element 15. conditions; .of said surface, the location of such vertical ele- To provide a lens that practically entirely ment being indicated by the line V-V on Figeliminates all blurring, aberration and prismatic ures.2, 3, 7, 8 and 9. Each end of this curved effects such as are ordinarily present in lenses line may be constrained to move in an approxi-, having the usual multi-focal grindings; 'mately horizontal plane, so that the points of To produce a lens which will give' unintersaid line will describe horizontal lines across 20 rupted vision over its entire surface and which -the lens surface as seen in Figure 3; or the has no visible indication of the multi-focal efends of the generating line may be constrained feet and which also can be ground from one to move in concentrically curved paths so piece of glass of a uniform index of refraction that all points in the line will describe conwithout a multiplicity of operations; centric curves on the lens surface, as seen in 25 To provide a lens having focal lengths arranged Figure 2. In either case the opposite ends of in a sequence to bemost convenient to theusers this generating curved line will swing across natural use of same while working at a table, the lens surface on different radii centered in two desk or bench or on a machine, or playing varlfixed points respectively, the position of the ous'games, such as tennis, ball, cards, etc.; points and the length of the two radii being 30 And also to provide a lens of this character chosenso asto produce the desired surface. This which can be carried in stock sizes with one face lens could be ground by means of a lap or grindground and leaving the other face to be ground ing block whose surface had been formed to. the with any of the usual or special grindings which reverse shape of thesurface required for the lens; may be necessary to correct various defects of this lap or grinding block being given a double 3 the eye or to improve the vision. reciprocating motion with respect to the lens To acquaint those skilled in the art with the while in contact with the same. Such a lens manner of constructing and practicing the pres-' can also be ground on machines especially conent invention, I shall now describe certain emstructediorthe purpose. 4 0 bodiments of the same in connection with the It is not required that such a lens have an 40 accompanying drawing in which: axis of generation; therefore the loci of the sur- Figure 1 shows a lens with the usual bifocal face can be located without regard to such an grindings with a more or less clearly defined line axis, and as best suited tov other conditions. between the areas-of different dioptric power. Therefore also points of equal focal lengths can Figures 2 "and 3 indicate two forms in which abe on practically horizontal lines, or on lines of a 45 lens embodying my invention may be ground. desirable curvature, without reference to' such Figure 4 shows for purpose of illustration a-' an axis of generation. However, it is obvious face view of a rectangular blank whose over-all that a lens of limited characteristics could be dimensions are such as topermit forming of generated about one axis of generation, the dithe various conventional shapes of lenses. optric power of which lens would vary graduo 1 Figure 5 is a vertical section taken at line, 5-5, ally from one edge to the opposite edge.

. n Figure 4, showing diagrammatically the meth- If any transverse segment indicated at a, or 0d of generating the surface of a lens embodying b, of the lens, A, shown in Figures 2 and 3 re- I my invention. 1 spectively, were ground as a lens whose strength 3 Figure 6 is a plan viewof the lens also showwas midway between that of its two adjacent 55 segments, and these segments were made inflnitely narrow, we would have a lens that varied in dioptric power gradually from one edge to the other. For purpose of illustration we may assume that the original shape of the lens blank is rectangular in outline, as indicated at B, and

is of proper size for producing the conventional shapes.

. Referring now to Figures 4 and 5 of the drawing, it will be seen that the lens blank, B, has a convex exterior surface ground to a single radiusof curvature indicated at R, and a concave inner surface ground to varying radii, R R R R R It and R".

employed for forming this graduated concave surface of the lens so as toproduce an uninterrupted, smooth surface of gradually varying dioptric power. By-way of illustration I have shown in Figure 1 6 of the drawing the true lengths of radiiindicated as R R, R" and R, etc., as equal to the radii, R R, R and R in Figure 5 of the drawing. It will be apparent that when actually measured on the drawing, these radii, R R, R" and 'R', in Figure 6 are equal to the projected lengths of the radii, R R,'R" and R, in Figure 50f the drawing. However, it is manifest that the vertical curvature of the inner or concave surface of the lens formed by the radii, as seen in Figure 5,

i f approximately correct. For instance, it might be advisable not to'make the true lengths of radii R to R in Figure 6 exactly equal to radii R to R in Figure 5, but to modify them so as to obtain the best optical effect. As may .be seen in the drawing, the loci of the radii, R R, R, R, R

R, and R are shown located on a curved line;

40 and it will be manifest that if said radii are of:

such length as to produce a surface of the lens that would'be a true involute curve, then such loci of'said radii would be located on an arc of a circle. In any event, the inner surface of the lens may be conceived as generated by swinging this curved line transversely of the lens so that its upper end swings on a radius substantially the points X and Y toward the lens in Figure 5. a

This graduated focal grinding may be ground so that it will merge at either or both edges with spherical .grindings for distance and, or, read- 0 ing vision,.providing areas of constant dioptric powers, so that the eye may be shifted from re'gistration with one portion of the lens to another without producing any abrupt'ness' or unevenness of vision. For purpose of illustration the 5 lens, C, shown in Figure 7 of the drawing is formed with an upper portion, (1, of constant dioptric power ground for distant vision, and slower portion, e, formed with a graduated focal grinding to provide an area of gradually changing dioptric power which blends and merges at its edge .of said area merges and blends into the It will be manifest thatan in finite number of radii of desired lengths may be area, G, of constantly varying dioptric power. By virtue of the construction shown in Figures 7 and ,8, the eye may be shifted to selectively register for vision through any desired focal region of the areas, 2 or not gradually varying dioptric powers, so that objects in the near distance range may beseen clearly and distinctly,-and when the for registration with the areas of constant dioptric power indicated as d and Lthe change will be practicallyunnoticeable by the eye, since there will be no aberration or prismatic efiect because the portions of the graduated focal areas, e and 0 immediately adjacent these constant dioptric power areas gradually blend so that at the line at which these areas merge, the dioptric power is the same.' It will be manifest that such'alens will not have any interruption of its entire sur- 4 face and completely insures against double or distorted imagm which are characteristic of the usual bifocal lenses. If required, this graduated focal grinding can have a diiferent dioptric power horizontally than vertically at the same point.

When both eye is caused tobe shifted from the areas, e or a,

from that measured -on a vertical axis and still the dioptric power of the lens may be constant in all directions at one point.

As is well understood in the art, the vertical or horizontal meridians of the lens may be located several degrees one way or the other from the degree or degree bases of the lens. Therefore, wherever reference is made in the specification and claims to vertical or horizontal measurement of the lens power, or dioptric curvatures of the lens surface, it is to be understood that such measurements are taken along the principal meridians of the lens.

It will be manifest that for commercial purposesalens ofthischaractercanbecarriedin stock dzes with one surface provided with a graduated focal grinding and the other surface to be ground with any of the usual or special grindings necessary to obtain a lens of desired specifications to correct certain defects of the eye 'or to improve the vision.

While there'is shown and described herein certain specific embodiments of my invention, it will be manifest to those skilled in the art that the invention is capable'of further modification without departing from the spirit and scope thereof, and thatthe same is not to be limited to the particular forms herein shown and described, except in so far as indicated herein by the appended claims.

I claim: 1. An optical element made from one piece of glass of a uniform index of refraction having a ground uninterrupted surface, the dioptric curvature of which increases gradually from one edge to the opposite edge, the curvature of said surface in transverse direction being constant along concentrically curved lines, and the curvature at practically any point along any one of said concentric lines being substantially equal to the vertical curvature at said point.

2. An optical element having a. ground unin rupted surface, the dioptric curvature of which increases gradually from one edge to the opposite edge, said-sln'face being generated by a line of the same curvature as an element of said -surface, one end of which line is constrained to move 2,109,474 two fixed points, while the other end of said line moves similarly on a radius said fixed points.

3. An optical element having a ground, uninterabout the other of rupted, multi-focal surface including an area, the

dioptric curvature of which, when measured along the vertical meridian, gradually varies from one 'edge of said area towardthe opposite edge, and the curvature of said surface area, in the direction transverse to said vertical meridian, being generated on concentric lines, so that the dioptric curvature of said area, when measured transversely to the vertical meridian at practically any point along any of said concentric lines,'is substantially equal to the vertical curvatureat said P int.

4. An optical element having a ground uninterone edge to the opposite edge of the area, the surface of said area being generated by a line of the same graduated curvature as an element of W said surface, the opposite ends of which line are constrained to move about separate fixed points at respectively diiierent radial distances from said points and along curves concentric with each other.

5. An optical element having a ground, uninterrupted surface including an area the dioptric curvature of which gradually varies from one edge toward the other edge where it merges and blends with an area of constant dioptric curvature, said first mentioned area being generated by a line of the same curvature as an element of said surface, the ends of which line are constrained to move in curved paths tangent to horizontal planes through said element on radii about two fixed points, respectively.

6. An optical element made from one piece of vature of which increases gradually from one T increases gradually from one edge to the oppoedge to the opposite edge and in which, in a transverse direction, points of equal dioptric curvature lie on a horizontal line parallel to other lines passing through points of other equal dioptric curvature, the dioptric curvature of. said surface at practically any one point being sub stantially the same horizontally as vertically.

7. An optical element having a ground uninterrupte'd surface, the dioptric curvature of which site edge, said surface being generated by a line of the same curvature as an element of said surface, the ends of which line are constrained to move in substantially horizontal planes on radii about two fixed points, respectively.

8. An optical element made from one piece of glass of a uniform index of refraction having a ground, uninterrupted surface including an area, the dioptric curvature of which gradually varies from one edge to the opposite edge of said area, 1 and in which area, in a transverse direction,'points I of equal dioptric curvature lie on a-horizontal 9. An-optical element having a ground uninterrupted surface including an area, the dioptric curvature of which gradually varies from one edge toward the other edge where it merges and blends with an area of constant dioptric curvature, said first mentioned area being generated by a line of the same curvature as a vertical element of said surface, the ends of which line are constrained to move in substantially horizontal planes on radii about two fixed points, respectively.

.10. A lens including a portion having opposite ground surfaces, the dioptric curvature when measured horizontally at any point on one of said surfaces being diflferent from the vertical curvature at said point, and the dioptrlc power of said lens portion when measured horizontally at said point being the same as the dioptric power when measured vertically at said point.

11. A lens including a portion having opposite ground surfaces, one of said surfacesbeing an uninterrupted multifocal surface, the dioptric curvature of which, when measured along the vertical meridian, gradually varies from one edge of said portion toward the other edge, the dioptric curvature when measured horimntally at any point on one of the surfaces of said portion being diil'erent from the vertical curvature at said point,

and the dioptric power'of said lens portion when measured horizontally at said point being the same as the dioptric power when measured vertically at said point.

12. An optical element having a ground, uninterrupted multi-focal surface including an area, the dioptric power of which, when measured along the vertical meridian, gradually varies from one edge toward the opposite edge where it merges and blends with an area of constant dioptric power, and the curvature of said multi-focal surface area in the direction transverse to said vertical meridian being generated on concentrically curved lines, and the dioptric power of said area, when measured transversely to the vertical meridian, being the same at all points along any one of said concentric lines.

13. An optical element having a ground, uninterrupted surface including an area the dioptric curvature of which area increases gradually from one edge toward the opposite edge of the area,

the surface of said area being generated by a line of the same graduated curvature as an element of said surface, the opposite ends of which line are constrained to move about separate fixed points at respectively different radial distances from said points and along paths parallel to each other.

14. An optical element having a ground, uninterrupted surface including an area, the dioptrlccurvature of which, when measured along the vertical meridian, gradually varies from one edge of said area toward the opposite edge, and the