DE2448244A1 - Trifocal spectacles - lenses have different dioptric number for each of three visual ranges - Google Patents

Abstract

The lenses for spectacles with various dioptric numbers for each of the three sight zones are so arranged that under the zone for near seeing, there is an additional zone for seeing at medium distances (1.5-3.0 m). Its focal length gives rise to a sharp definition of the object under observation. An additional zone for seeing at medium range covers one quarter of the lens surface. Zone with the highest focal length for near seeing is situated between the zones for half near and for distant seeing. The shapes of trifocal arrangements can take various forms. They can cover the entire width of a lens or only a section of it.

Description

Wolfgang Petzold on October 9, 197 4

7000 Stuttgart 70
In Asem Forest 54-9

Spectacle lenses with different diopters for three fields of vision

The invention relates to a spectacle lens with different dioptric numbers, as it is used especially for the correction of the widespread presbyopia. Such spectacle lenses are known in various designs, the zones being different Breaking power either ground in, melted down or cemented in are. Furthermore, designs are known in which by suitable Grinding processes the refractive power changes steadily or in narrow zones in such a way that image jumps between the individual visual areas be avoided. (DT-PS 871 076 and 1 422 127, FR-PS 478 320 and 959 573, US-PS 2 109 474)

These designs of spectacle lenses all show one of the above refractive power increasing towards the lower visual area, so you are in the upper Visual range for vision in the distance and in the lower visual range for the near vision set up. A possible third viewing area for viewing semi-close objects is always between the arranged upper and lower viewing area.

So useful this version for the change from seeing to the distance for close-up vision is so serious is the disadvantage that occurs when wearing such glasses when walking and especially when walking on not completely flat ground. The one for seeing Lets the lowest area of the spectacle lenses set up in close proximity namely a sufficiently sharp image of the foot and path area when walking in an upright position, so that the wearer does not Glasses through thresholds, curbs, steps, stairs, escalators and similar obstacles are seriously endangered. On the other hand, he usually cannot lower his head so low when walking, around these obstacles through the in the upper half of the lens arranged viewing area for the distance or the zone in the middle of the lens for viewing in the semi-close range to recognize.

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24A8244 - 1 -

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This is fatal for the wearer of such multi-zone lenses The disadvantage leads to a general insecurity of movement and not infrequently to falls with sometimes serious injuries.

The invention is based on the object, the advantages of the known Use multi-zone lenses in their various designs to be able to without having to accept the described and dangerous disadvantage.

This object is achieved according to the invention in that the zones different diopter numbers in contrast to the previously customary and exclusively used arrangement with increasing from top to bottom Refractive power can now be distributed as sensibly as it corresponds to the actual needs of the ametropolitan. After that is to divide the spectacle lens into at least three zones, of which the upper zone is the smallest, as was previously the case as a wide range zone Has refractive power. This zone takes up about the upper half of the lens. The zone closes at the bottom with the maximum refractive power, which is intended for close-up vision at a moderately inclined viewing angle. Finally is located under This close-range zone is a third zone with a refractive power that is suitable for objects in the semi-close range at a distance from about 1.5 to 3 mtr with a downward viewing angle in the To depict the eye with clear sharpness.

For the solution of the given problem it is irrelevant whether the zone of the spectacle lens intended for the close range is again is divided into two focus areas or has a smooth transition to the zone above for the far area.

The key advantages of inserting a The zone below for seeing in the semi-close range lies in the fact that the wearer of such spectacle lenses is more secure when walking and when climbing stairs and the like. Wins. He can without his glasses to have to take off or to use several pairs of glasses in alternation, the surrounding areas important for him in the respective surrounding area Clearly recognize the habitual and natural posture. He thus gains one that is particularly well adapted to the diverse needs Visual aid.

609817/0085

2U8244

The attached drawing shows various designs of the subject matter of the invention as well as a schematic representation of the viewing angles and the viewing areas.

Figure 1 shows a lens with three zones of different refractive power, these each run over the entire width of the lens. The zone with the lowest refractive power (1) For long-range vision, roughly the upper half of the lens, the highest zone, takes up Refractive power (2) for near vision joins it downwards, while the zone with medium or "Low refractive power (3) for vision in the half-close range occupies approximately the lower quarter of the lens.

FIG. 2 shows a spectacle lens, the glass body of which is first ground for the long range (1). In this vitreous are in the lower half in a central arrangement the two zones for the close range (2) and the semi-close range (3) inserted.

FIG. 3 shows a spectacle lens in a configuration similar to that shown in FIG. 2, but with the one for the semi-close range (3) the same refractive power is provided as for the far range (1), a design as in still weak farsightedness is required. Here is the zone with the highest refractive power (2) for close range below the center of the lens centrally inserted into the lens so that it is equally suitable for the Far range (1) as determined for the semi-close range (3) Zone of equal refractive power is enclosed both from above and from below.

Figure 4 shows the eye (4) with the lens (5) in front of it as well as the zones of the spectacle lens (9-11) assigned to the different viewing angles (6-8). With a horizontal and / or upward viewing angle (6), the beam path runs through the one in the upper one Zone of lowest refractive power (9) lying half of the spectacle lens and thus covers the far range.

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2U824A

With a slightly to moderately downward viewing angle (7) the beam path runs through the zone of greatest refractive power (10) and below the center of the spectacle lens thus captures the near range when reading and the like Viewing angle (8) the beam path, the zone lying approximately in the lower quarter of the spectacle lens, middle to lower Refractive power (11) and thus covers the semi-near area when walking and the like.

609817/0085

Claims (1)

.5. Patent claims: 'Π
.-. A / Spectacle lens, with zones of different dioptric numbers arranged one below the other for long-distance vision and close-up vision, characterized in that underneath the
a zone of highest refractive power intended for near vision, an additional zone for vision in the semi-near range is arranged, the refractive power of which produces a sharp image of objects that are at a distance of about 1.5 to 3 meters from the eye. Spectacle lens according to Claim 1, characterized in that the additional zone for vision is in the semi-close range
includes about the lower quarter of the lens. Spectacle lens according to claims 1 and 2, characterized in that the zone of highest refractive power for the
Close-range vision between the zones for vision in the
semi-close range and vision in the far range is arranged. 609817/0085 .6. Le e r e i t e