JPS5942285B2 - eyeglass lenses - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface configuration of a progressive focus lens for presbyopia.

An object of the present invention is to provide a continuous and comfortable visual field from continuous use to near vision to people who have decreased accommodation ability of the crystalline lens.

Known documents regarding conventional progressive lenses include Japanese Patent Publication No. 49-3595 and Japanese Patent Application Laid-open No. 50-46348. It has regions corresponding to a correction part (hereinafter referred to as the intermediate part) and a near vision correction part (hereinafter referred to as the near vision part), and has a curvature value that gradually changes in order to provide a predetermined addition power. Based on the well-known technology of having a principal meridian curve, each has its own characteristics.

The former type of lens is based on the design concept of distributing the aberrations that inevitably occur in progressive lenses evenly over the entire lens surface to reduce image distortion and minimize the shaking that you feel when you move your face. In other words, the line of intersection between the plane perpendicular to the principal meridian and the refractive surface is circular only at approximately the midpoint of the intermediate vision correction portion, and the line of intersection above it becomes circular as it moves away from the principal meridian. Both are non-circular curves, with the radius of curvature on the line decreasing and increasing at the bottom.

Since all but one spot is a non-circular curve, it goes without saying that the clear vision range (defined as the range where the astigmatism is 0.5 diopters or less) is narrow in the near vision area. However, it is very narrow even in the distance part. This often feels inconvenient because when looking into the distance, you often have to look over a wide area. The design concept of the latter lens is to have large clear vision areas in the distance and near areas, concentrate aberrations in a band around these areas, and furthermore provide relatively good visibility outside of these areas. have.

For example, the middle part is divided into five parts in the horizontal direction, the central part is a region with small aberrations and includes the clear vision area, and the two outermost regions are corrected for skew distortion and set to 0. The sandwiched area is the boundary area between these areas.As a result, aberrations concentrate in this boundary area, and astigmatism becomes very large, causing the image to be greatly distorted here. (If you look at the horizontal line, it looks like an inverted U-shape in the center, but the outermost part is corrected so that it looks horizontal, so it curves sharply in the boundary area.) It has a spherical surface, and the distance portion is entirely spherical. Therefore, the clear vision range in the far vision area and the clear vision range in the near vision area are significantly larger than the former lens.
Since the skew distortion at the outermost part is corrected, the concentration of aberrations in the boundary area is large. When using this lens, when you move your face, you feel a large amount of shaking, which is uncomfortable. Therefore, even though these lenses have the advantage of having a wide clear vision range in the distance and near areas, when you actually wear them, you may feel that they are difficult to use. , may be suitable for specific applications depending on their characteristics. For example, certain types of sports, reading, writing, etc. However, for broader, general use that includes these tasks, the drawbacks mentioned above become a major complaint about these lenses. . Therefore,
The present invention comprehensively improves these drawbacks to create the ultimate progressive focus lens for general use. This ensures a conveniently wide clear viewing area, and reduces the concentration of aberrations in the peripheral areas. The following features will be explained according to embodiments. As shown in FIG. 1, this lens has a principal meridian M-M' in the vertical direction approximately at the center, and along the principal meridian M-M'' from the top, a distance portion F, an intermediate portion P, a near portion There is a boundary N, and these boundaries are continuously connected.

The curvature of the principal meridian M-M'' changes progressively in the middle in order to give a predetermined addition power.The mode of change is linear;
It can take a cubic curve shape or any other form.〇In order to minimize astigmatism along the principal meridian M-M', the entire line from the far vision part F to the near vision part N should be shaped like a wide point. .

The soaring point is a point where the radius of curvature in the direction of the radius of principal curvature is equal, and when viewed microscopically, it is a spherical surface. Below it, the distance portion F is a plane perpendicular to the principal meridian M-M'' and the lens. The line of intersection formed by the refractive surfaces is a non-circular curve whose radius of curvature decreases as it moves away from the point of intersection with the principal meridian M-M''.
This is because the radius of curvature on the principal meridian M-M' is larger in the distance part F than in the near part N, so the lines of intersection in the distance part F and near part N are both circular. If there is, the difference in power will gradually increase as the distance from the intersection point increases, so a non-circular curve like the one described above is used to reduce this difference and move from the distance part F through the intermediate part P to the near part. The connection to N is made smoothly and the astigmatism and distortion of the connection part are reduced. 〇The above-mentioned intersection line in the distance part F becomes more and more Decrease circularity.

In other words, it gradually approaches a circular shape, becomes circular at a certain position, and remains constant from then on. In this way, the shape of the intersection line is circular in the upper part of the distance portion F, so the astigmatism becomes very small. , you can obtain a wide clear vision range for distance vision.0 This is because when seeing far vision, people often use their upper eyes, and a wide clear vision range is required in the upper part of the distance vision area F. It's summery. In the near vision area N, the line of intersection between the lens refractive surface and the plane perpendicular to the principal meridian M-M' is the principal meridian M
It is a non-circular curve in which the radius of curvature initially increases and then decreases as it moves away from the intersection with 1M''.

The reason why the value of the radius of curvature is initially increased is to make the connection smooth as described above, but in order to widen the clear vision area of the near part N for ease of use, the increase rate is initially small. , then you need to make it slightly larger. Therefore, if you continue to increase the aberration, the aberration will become too large as you go to the side, so you should reduce it from the middle.If you set it to 0, you can ensure a wide clear vision area in the near area, and the distortion in the lateral near area will be reduced. Aberrations can be reduced to make shaking less perceivable, and astigmatism can also be reduced. In the intermediate portion P, the line of intersection between the plane perpendicular to the principal meridian M-M' and the refractive surface of the lens becomes closer to the connection point with the distance portion F as it moves away from the intersection with the principal meridian M-M'. The radius of curvature decreases in a part of the area, and the radius of curvature increases on the side of the connecting portion with the near portion N below this point.

(After that, it decreases in the same way as the near portion N.) During this period, it changes continuously from decrease to increase, but it is not a monotonous change, and the intersection line with the maximum rate of increase is the one in the intermediate portion P. 0 located almost in the center When doing this, the connection from the distance part F to the near part N becomes smoother, and astigmatism near the principal meridian M-M'' is reduced, so that when intermediate vision As an example, a CR-39 lens having a distance power of 0 diopters and an add power of 2.0 diopters will be described.

In Figures 2 and 3, the refractive power of each point is, and the point A
1 and point A3 are the optical centers of the distance part F and the near part N, respectively.The value of curvature on the principal meridian M-M'' is the optical center of the distance part F and the near part N, as shown in Figure 3a. It is constant within the area N, and changes from point A1 to point A3 according to a sine curve.

The value is 0. In this way, in the distance portion F and the near portion N, there is no change in power on the principal meridian M-M', so good visibility can be obtained.

In the distance portion F, the line of intersection between the plane perpendicular to the principal meridian M-M and the refractive surface of the lens is, for example, a quadratic curve y=Cx2/
It is expressed as (1+V"=[?=).

Here, K is the non-circular coefficient and c is the curvature (1/R), and the shape is as shown in Figure 4, and the radius of curvature decreases as it moves away from the principal meridian. In the figure, the dashed line indicates What is shown is a circle.0 In this intersection line shape, the value of K is larger at the lower end of the distance portion F, and the difference from the circle is large, but the value of K decreases toward the upper end (from the circle) ), and around the middle of distance part F, K = 1 (circular),
Everything above it is K = 1 (circular). This change in K is shown in Figure 3b. In Figure 2, the curvature change on the intersection line passing through point AF is as shown in Figure 5, a-a''. So, on all intersection lines above the intersection line passing through point AO, a-a/
' (Only half of the lines of intersection are shown in each case.) The above lines of intersection in the near part N1 and intermediate part P are not as simple as in the far part F, and also contain higher-order terms. However, in the vicinity of the principal meridian M-M'' (approximately 10 degrees on one side), it can be approximately approximated by the quadratic curve described above.

The change in K at this time is shown in Fig. 3b following the value in the distance part F. The above-mentioned intersection line in the near part N is shown in the middle part Except for the connection with P, there is no change in curvature or K, and the shape is almost constant.
The width of the clear vision area for near vision is also almost constant.The curvature change on the intersection line passing through the o point AN is as shown in bb" in Figure 5. In the middle part P, K is as shown in Figure 3. As shown in b, it changes so that it becomes K-1 (circular) near the connection with the lower part for distance vision, and has a minimum value almost at the middle of the middle part P (slightly close to the near part N). The distance vision section F is connected to the near vision section N, but both distortion and astigmatism are improved compared to when they are changed monotonically.

Figure 6 shows the distortion diagram when the square grid is viewed through this lens. Since the upper half of the distance portion F is substantially spherical, there is no distortion, and the grid viewed through the lens is the original. In the lower part of the 0 distance part F, which remains square and has the same size, the shape of the intersection line is a non-circular curve as described above, and the radius of curvature decreases as it moves away from the principal meridian M-M5. This can be seen in the progressively increasing spacing between the vertical lines of the grid in FIG.

In the near vision area N, there is a part near the principal meridian M-M'' that is larger than the original grid and looks almost square, and this almost coincides with the clear vision area for near vision.

As in the distance zone F, the change in the radius of curvature of the line perpendicular to the principal meridian M-M'' is reflected in the change in the interval between the vertical lines of the grating. Outside about halfway between , the vertical lines of the grid appear almost as straight lines.

However, it is slightly tilted from the vertical. This is because the value of the above-mentioned K (non-circular coefficient) changes in the far vision area. o Even in the intermediate area P1 and the near vision area N, the skew distortion is not corrected and the slope remains almost the same. However, even though this is not vertical, it is very slight, and it is better to see the eyes straight away than to have the eyes bend in the middle, because there is less shaking when you move your eyes or face. There is also less concentration of astigmatism, so there is less blur and it is easier to see. The same applies to the horizontal line. 0 In the outer part of the near area N and intermediate area P, the horizontal line of the grating is horizontal. It's close to 0, but it looks like it's going down little by little as you go outward.If it goes like this, the amount of curvature is smaller and the changes are gentler, so it's harder to feel the shaking.

Overall, the grid seen through this lens does not have any sudden changes, and there is little noticeable shaking.

The skew distortion value of this lens is as follows.

The value of the skew distortion is expressed as θ2f×θXay, where Z=f(X, y), where X and y respectively point to the geometric center of the lens (in this example, the optical center of the distance portion) as the origin. Z is the distance in the horizontal and vertical directions when Degree 2.
For a 0 diopter lens, in the lateral regions of the intermediate portion P it is 0.0007 to 0.0016. Note that this value becomes even larger when the addition power is large. Therefore, in the progressive focal lens of the present invention with an addition power of 1 to 3 diopters, it is approximately in the range of 0.0003 to 0.0020. The lens of the present invention has such a skew distortion due to the adoption of a special non-circular curve at the intermediate portion P, but considering the balance of the overall aberration of the lens, as already explained, No correction has been made to obtain the desired effect. The clear vision range of this lens for distance, near, and intermediate vision is as shown in Figure 7, and is wide enough for daily use. have.

In particular, the distance part is wide towards the top and almost the entire surface can be used, which is very convenient. In the figure, the hatched part is the part where astigmatism increases, and the amount of aberration increases as it goes outward. , rather than increasing rapidly, it is relatively gradual.

As described above, the lens according to the present invention has a very wide range of clear vision in the far distance area where it is necessary to see a wide range, and also has a clear vision range in the intermediate area of near vision that is wide enough to not cause any inconvenience in daily life. In addition to ensuring a clear vision range of 0 or more, the lens is dispersed to prevent emergency aberrations from concentrating on specific areas, and distortion is kept to a minimum, making it the most suitable for everyday use. It is a progressive focus lens. In actual use, the progressive focus lens of the present invention has a center point A1 and a point A1.
2. Rotate the lens so that it is slightly inward and wear it.0 This is because the pupil distance becomes smaller when viewing objects at a close distance.

Although one embodiment of the present invention has been described above in detail, the present invention is not limited to this one example.

For example, a quadratic curve was used as an example of the intersection between a plane perpendicular to the principal meridian M-M'' and the refractive surface of the lens.
Other curves may be used as long as they satisfy the configuration of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a front view of a progressive lens according to the invention, FIG. 2 is a perspective view of a progressive lens according to the invention, and FIG. Figure 3b shows the change in curvature along the axis of the progressive focusing lens of the present invention when the intersection line between the plane perpendicular to the principal meridian and the refractive surface is expressed as a quadratic curve. FIG. 4 shows the shape of the intersection line in the distance vision correction part of the progressive focus lens of the present invention. FIG. 5 shows the shape of the intersection line passing through points AO, AF, and AN. FIG. 6 is a distortion diagram of a square lattice viewed through the progressive focus lens of the present invention, showing changes in curvature.0 FIG. 7 is a diagram showing the clear vision area of the progressive focus lens of the present invention. : Distance vision correction part, P:
Intermediate vision correction part, N: Near vision correction part, M-M'': Principal meridian, Point A1: Point of contact of F(!:.P on the principal meridian, Point A2: Midpoint of point A1 and point A3, point A3: Point of contact between P and N on the principal meridian, Point AO: F on the principal meridian
Point AF, approximately the midpoint of Point AO: Point A, approximately the midpoint of Point AO and Point A1
N: Approximately the midpoint of N on the principal meridian.

Claims (1)

[Claims] 1. The lens has a distance vision correction portion F in the upper region, a near vision correction portion N in the lower region, and the surface refractive power is progressive from the upper region to the lower region in the intermediate region. In a spectacle lens that has an intermediate vision correction portion P that changes in a vertical direction, and has a principal meridian M-M′ in the longitudinal direction approximately at the center, a lens that is perpendicular to the principal meridian M-M′ in the lower part of the distance vision correction portion F; The line of intersection formed by the plane and the refractive surface is a non-circular curve whose radius of curvature decreases as it moves away from the intersection, and the rate of decrease in the radius of curvature goes above the distance vision correction portion F. Accordingly, the decreasing rate is 0 (
In other words, the line of intersection between the plane perpendicular to the principal meridian M-M' and the refractive surface in the near vision correction portion N decreases as it moves away from the point of intersection. It is a non-circular curve in which the radius of curvature increases and then decreases, and the rate of increase and decrease of the radius of curvature is
It is almost constant except for the vicinity of the connection with the intermediate vision correction part P, and in the intermediate vision correction part P, the main meridian M-
The line of intersection formed by the plane perpendicular to M' and the refractive surface is a non-circular curve whose radius of curvature increases as it moves away from the point of intersection, except for a part near the connection with the distance vision correction part F, The rate of increase in the radius of curvature takes a maximum value approximately at the center of the intermediate vision correction portion P, and the principal meridian M-M' has an umbilical point shape along the entire line, and in the intermediate vision correction portion P, the A spectacle lens characterized by having a change in curvature from the distance vision correcting portion F toward the near vision correcting portion N to provide a predetermined addition power. 2. Within the range of addition power of 1 to 3 diopters,
Skew distortion ∂^2f in the lateral region of the intermediate vision correction part
2. The lens according to claim 1, wherein /∂x∂y is within the range of 0.0003 to 0.0020.