JP2769931B2 - Bifocal eyeglass lens - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bifocal spectacle lens for hyperopic eyes who does not get tired even when using a near lens portion.

[0002]

In general, bifocal spectacle lens for far mimetics have a long distance lens 10 of focal length as a base, with its lower half position to short focal length near the convex lens portion 20, a distance When passing through the convex lens 10, a distant object forms an image on the retinal surface. Further, when the near convex lens unit 20 is passed, an object closer to the retinal surface is imaged than when the far convex lens 10 is passed. That is, when looking at an object several meters to several tens of meters ahead, straighten the line of sight and correct it through the distance convex lens 10, and when viewing an object at hand of about several tens of centimeters, make the line of sight slightly downward and make a near vision. Through the convex lens part 20, it is possible to perform corrected vision.

[0003]

However, in the conventional bifocal spectacle lens, the use of the near convex lens portion 20 causes "convergence" (light rays from an object move right and left due to the prism effect of the lens). There is a problem that eye fatigue is easily generated. This is the near lens part 20
However, since it has a structure that is located closer to the nose than the optical center of the distance lens, a prism effect due to a change in the thickness of the distance lens portion is added when viewed from the near side (see FIG. b)). That is, taking the optical center portion of the near lens portion 20 as an example, a light beam from an object is refracted outward (to the ear side of the spectacle user) by this prism action. As a result, in order to see an object (for example, a book or newspaper) that is originally close to the face, both eyes must be directed inward, but the eyes must be directed further inward (nose side) (FIG. 3A). In other words, in extreme cases, the eyes need to move as if looking at an object placed at the tip of the nose, which increases the feeling of fatigue.

On the other hand, a bifocal spectacle lens for a myopic eye has a configuration in which a concave lens is used as a base and a convex lens portion is provided thereon as shown in FIG. Works in a manner opposite to that for the hyperopic, and in near vision, the convergence is less than with the naked eye (without glasses), so the above-mentioned problem does not occur.

SUMMARY OF THE INVENTION In view of the foregoing, it is an object of the present invention to provide a bifocal spectacle lens for a hyperopic eye, which hardly causes excessive convergence when viewing an object at a short distance, and thus causes less eye fatigue. .

[0006]

To achieve the above object, according to an aspect of this invention, the lower half position of the distance convex lens surface, the multifocal spectacle lens having a near convex lens portion, said
The optical center of the near-use convex lens portion is placed in the optics of the far-use convex lens.
Slightly below the heart and close to the nose
Rutotomoni, wherein the region of the nose side nearer from the optical center of the near-convex lens portion, toward the nose side superimposed forming a prism component as a wall thickness, can offset the prism which effects the distance lens and a near lens portions It is like that.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the accompanying drawings. FIG. 1A is a front view (as viewed from the user side) of the left lens of the present application lens, and FIG. 1B is a front view of the right lens similarly. FIG. 2A is an explanatory view of the right lens of the present bifocal spectacle lens in which a prism component for canceling the prism action of the convex lens is superimposed, and FIG. (A) is an explanatory view showing the convergence of the bifocal spectacle lens for the hyperopic eye, and (b) is an explanatory view showing the convergence of the bifocal spectacle lens for the myopic eye.

In the drawing, reference numeral 1 denotes a convex lens for near vision, and the convex lens for near vision 1 is similar to a conventional bifocal spectacle lens.
The lower convex lens 10 is provided at an appropriate position on the lower half surface. That is, the near convex lens portion 1 is formed of a downwardly convex semi-circular convex lens, and the optical center c thereof is located slightly below the optical center C of the distance convex lens 10 by a few mm toward the nose. Have been.

In the near convex lens portion 1, a prism component 1a which is thicker from the optical center toward the nose side is formed so as to overlap in a region closer to the nose side from the optical center c. That is, as shown in FIG. 2A, the prism component 1a has a vertex angle corresponding to the prism action of the convex lens, and is composed of a convergence canceling prism whose gradient direction is opposite to that of the near convex lens portion 1.
Is arranged between the rear surface of the lens and the front surface of the distance convex lens 10. In this case, the near convex lens 1 is slightly inclined with respect to the far convex lens 10, but the inclination angle is extremely small, and the optical center c of the near convex lens 1 is slightly closer to the nose. Therefore, the adverse effect of the inclination is negligible.

In this embodiment, the near convex lens portion 1 and the far convex lens 10 are made of plastic. However, it is a matter of course that other transparent materials such as glass may be used. Further, the present invention can be applied to other types of multifocal lenses and progressive lenses.

In the above embodiment, when a distant object is viewed, the line of sight is directed substantially toward the front, so that the corrected object light enters the user's eye through the distance convex lens 10. Next, when an object at a short distance is viewed, the object light enters the eye through the near lens unit 1 by turning the line of sight slightly downward. At this time, the object light that normally bends toward the ear side is corrected to bend toward the nose side by the prism component 1a and enters the eye, so that the user of the spectacle lens can hardly be aware of the convergence effect of the lens.

[0012]

The present invention as described above according to the present invention is the lower half position of the distance convex lens surface, the multifocal spectacle lens having a near lens unit, before the optical center of the near lens portions
Slightly below the optical center of the telephoto convex lens and approached to the nose side
While configured to be positioned, in the region of the nose side nearer from the optical center of the near-convex lens portion, because it is characterized in that superimposed form a prism component as a thicker toward the nose side, the far convex lens The excessive convergence caused by the above can be canceled by the prism component. As a result, it is possible to realize a bifocal spectacle lens that does not tire the eyes even if the user looks at a close object for a long time.

[Brief description of the drawings]

FIG. 1A is a front view (as viewed from a user side) of a left lens of the present application lens, and FIG. 1B is a front view of the same left lens.

2A is a diagram illustrating the principle when a prism component for canceling the prism function of a convex lens is superimposed, and FIG. 2B is a diagram illustrating the principle of a prism function that causes convergence.

FIG. 3A is an explanatory view showing convergence of lenses of bifocal glasses for hyperopic eyes, and FIG. 3B is an explanatory view showing convergence of lenses of bifocal glasses for myopic eyes.

[Description of Signs] 1 Near lens portion of present lens 1a Prism component 10 Far lens 20 Conventional near lens portion C Optical center of far lens c Optical center of near lens

Claims (1)

(57) [Claims] To 1. A lower half position of the distance convex lens surface, the multifocal spectacle lens having a near convex lens portion, said proximal
The optical center of the convex lens unit is
Construct so that it is slightly lower and closer to the nose
Together, the the region of the nose side nearer from the optical center of the near lens portions, multifocal spectacle lens, characterized in that the prism component as a thicker toward the nose side superimposed form.