JP3033110B2 - Progressive focus lens for glasses - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plastic spectacle lens, and more particularly to a progressive power lens for spectacles whose vertex refractive power changes progressively.

(Prior Art) In the case of elderly people, such as elderly people, in which the lens adjusting muscular strength of the eyeballs has decreased, it is necessary to use eyeglasses (reading glasses) for correcting this.

In the case of presbyopia, since presbyopic vision deteriorates near-field imaging ability, use glasses for various tasks and reading, such as desk work, and remove the glasses when going out or when it is not necessary to clearly see, or for long-sightedness I am dealing with it by changing to glasses. Therefore, it is necessary to change and remove the glasses on a daily basis, which is extremely troublesome. For this reason, various types of spectacle lenses using one pair of spectacles have been provided.

In the initially used bifocal spectacle lens, since the curvature for distance use (upper half) and that for near use (lower half) are clearly distinguished, it is apparent that the eye is presbyopic in appearance, which significantly impairs the appearance. Was something.

Therefore, recently, the curvature of the lens is changed progressively,
A progressive lens (for example, Japanese Patent Publication No. Sho 49-3595 and Japanese Patent Laid-Open Publication No. Sho 57-10113) has been proposed in which the boundary between the perspective and the perspective is not visible.

Generally, as shown in FIG. 4, the above progressive lens has a meridian (a), which is a main line of sight, as a center, and an upper portion is a sphere or a distance band (b) close to a sphere, and a lower portion is a lower portion. Is a near zone (c), and a progressive zone (d) in an intermediate region that connects these zones is an aspheric surface.
The near band is formed so that it can be seen continuously. Since this progressive band (d) is an aspherical surface which gradually shifts from a distance power to a near power curvature with a small area, when the line of sight shifts to a distance vision due to distortion mainly occurring in this band. The horizontal line appears to be distorted convexly or concavely, and when the line of sight is shifted in the horizontal direction, the length of the object appears to be elongated or compressed, which causes the line of sight to sway when passing through the progressive band (d). Feeling, causing significant discomfort to the user. Further, astigmatism in the progressive band (d) causes blurring of an image, and increases the feeling of shaking due to the distortion.

In order to solve these problems, the aforementioned Japanese Patent Publication No. 49-35
In the technique disclosed in Japanese Patent Publication No. 95, the skew distortion caused by making the progressive band that connects the distance band and the near band an aspheric surface is reduced, and this is reduced to a normal distortion to reduce the sense of fluctuation in the progressive band. And Japanese Unexamined Patent Publication No.
In the technology disclosed in Japanese Patent Application Publication No. -10113, astigmatism (and distortion) is made symmetrical with respect to the meridian (main gazing line),
This is because the lines of sight of the left and right eyes pass through the same aberration part of the left and right lenses.

(Problems to be Solved by the Invention) In the former case, the horizontal distortion at the center of the progressive band is reduced, but the vertical distortion and the distortion at the left and right sides are insufficiently removed. The disadvantage that the ear side and the nose side have large fluctuations is not solved. In the latter case,
Distortion is not changed between the ear side and the nose side (symmetrical design), and the difference in aberration between the left and right eyes is eliminated so that the same vision can be obtained with the left and right eyes. Therefore, the feeling of shaking when actually used is not eliminated.

In view of the above, an object of the present invention is to provide a progressive power lens for spectacles that can reduce distortion in the vertical direction on the ear side as compared with that on the nose side and make the lens easy to see.

(Means for Solving the Problems) An object of the present invention is to solve the above-mentioned problems of the prior art, and has a far band for an upper part and a near band for a lower part. In a spectacle lens having a progressive zone that is a progressively changing aspheric surface, the progressive zone is left-right asymmetric with respect to the line of sight, the maximum astigmatism on the ear side and the nose side is equal, and the vertical direction on the ear side. The curvature is made to be an aspherical surface with the nose side larger than the ear side so that the distortion of the nose side is smaller than that on the nose side.

(Effect) The distortion of the progressive surface of the aspheric surface that continuously connects the distance band and the near band is smaller on the ear side than on the nose side. In addition to the fact that the nose side is distorted, even if it is distorted, it is cut off when the frame is mounted, and in addition, the field of view of the eye on the nose side is substantially narrow, and the imaging by the opposite eye has priority. Thus, the eyeglass lens does not strongly recognize distortion and has less discomfort due to the distortion as a whole.

Hereinafter, the present invention will be described with reference to examples shown in the drawings.

As shown in FIG. 1, the upper part of the lens 1 is a distance band 2 and the lower part is a near band 3. A region connecting these bands 2 and 3 is an aspheric progressive band 4. The gazing line 5 passes through the center in the distance band 2 and is deviated to the nose side from the middle portion to the near band 3, and the amount of change in aberration in the progressive band 4 is asymmetric with respect to the main gazing line 5. I have. The maximum astigmatism in the aberration area 6 is equal on the ear side and the nose side.

The following table shows specific examples of the progressive curvature change amounts on the ear side and the nose side with respect to the main gaze line 5.

Therefore, the distortion 7 in the vertical direction is smaller on the ear side than on the nose side, and is perceived through a band where the aberration is practically small because the ear side aberration is smaller than the nose side aberration when the side is viewed. The aberration area 6 on the side has a large area that is cut off when mounted on the spectacle frame, and is not noticeably distorted by being corrected by the brain. Become smaller.

Further, since the distortion 8 in the horizontal direction is reduced in the near zone 3, the distortion when the line of sight shifts in the horizontal direction is reduced. Thus, the shape of the entire lens, that is, the lens curve becomes shallower, and the lens can be made thinner at the same time.

〔The invention's effect〕

As described above, according to the present invention, in a bifocal spectacle lens, the progressive band connecting the distance band and the near band is symmetrical with respect to the line of sight, and the maximum astigmatism between the ear side and the nose side is obtained. And the curvature on the nose side is larger than that on the ear side so that distortion in the vertical direction on the ear side is smaller than that on the nose side. The shift of the line of sight from the near band to the near band or in the opposite direction can be performed without discomfort.

Also, by reducing the amount of change in distortion in the horizontal direction, the width and length of the object when the line of sight is shifted in the horizontal direction can be prevented from fluctuating, thereby obtaining a spectacle lens with less discomfort due to distortion. At the same time, the lens can be made thinner.

[Brief description of the drawings]

FIG. 1 is a front view showing a progressive power surface of a progressive power lens for spectacles according to the present invention, FIG. 2 is an explanatory view showing distortion of the target grid, FIG. 3 is a partially enlarged view of the same, and FIG. FIG. 5 is a front view showing a progressive power surface of a progressive-focus lens. 1 ... lens, 2 ... distance band, 3 ... near band, 4 ...
... Progressive band, 5... Gaze line, 6.

Claims (2)

(57) [Claims] 1. A spectacle lens having a progressive zone in which an upper portion has a distance zone and a lower zone has a near zone, and these zones are joined to form an aspheric surface whose curvature changes progressively. Is asymmetric with respect to the gaze line, equalizes the maximum astigmatism between the ear side and the nose side, and has an aspherical surface with the nose side larger than the ear side so that the vertical distortion of the ear side is smaller than that of the nose side. A progressive lens for eyeglasses, characterized in that: 2. A progressive power lens for eyeglasses according to claim 1, wherein a change in a curvature in a horizontal direction of said near zone is made as small as possible.