JP3241149B2 - Method for manufacturing ophthalmic lens having toric surface - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of cutting a convex or concave surface of a lens with a toric shape, and more particularly to a method of continuously cutting the entire surface of a lens material to be processed by a cutting blade rotated about one axis. The present invention relates to a method for manufacturing an ophthalmic lens.

[0002]

BACKGROUND ART As one type of ophthalmic lenses such as contact lenses and spectacle lenses, there is a toric lens used for correcting astigmatism and the like. In such a toric lens, at least one of the lens convex surface and the concave surface is formed in a toric shape, so that different degrees of refraction are set in radial directions orthogonal to each other.

Conventionally, such a toric lens is manufactured generally by a cutting blade 6 of a cutting tool 6 capable of rotating a processing surface 4 of a lens material 2 around one axis, as shown in FIG. At the time of cutting at 8, the lens material 2 and the cutting tool 6 are relatively rotated around a pivot center point: O, which is offset by a predetermined distance in the axial direction and the axis perpendicular direction from the rotational center of the cutting blade 8. Has been implemented. FIG. 4 shows a case where the lens material 2 is turned with respect to the cutting tool 6.

However, in such a cutting method, when the surface 4 to be processed of the lens material 2 is cut, the lens material 2 may come into contact with the cutting tool 6 as shown in the figure. To be processed 4
It was extremely difficult to continuously cut the entire surface of the substrate at once.

[0005] For this purpose, for example, a method of processing the processing surface 4 of the lens material 2 by half from both sides in the turning direction has been dealt with. In such a method, processing is performed up to the central portion of the processing surface 4. Once the processing is interrupted and the lens material 2 is rotated, the remaining part of the processing surface 4 has to be processed, which is not only troublesome and inefficient, but also makes the processing surface 4 difficult. Center part (non-continuous part of processing)
The problem that a step is likely to occur is inherent. In addition, it is extremely difficult to remove the generated step, and in addition to requiring extremely troublesome polishing work,
There was also a risk that the shape of the machined surface cut and formed by such a polishing operation would be lost, and the desired optical characteristics of the lens would not be obtained.

[0006]

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to continuously cut the entire surface of a lens material to be processed. It is an object of the present invention to provide a method for manufacturing an ophthalmic lens that can easily and accurately obtain a target toric lens surface.

[0007]

In order to solve the above-mentioned problem, a feature of the present invention is that when a processing surface of a lens material is cut into a toric shape by a cutting blade rotated around one axis, the cutting is performed. While always keeping a constant angle between the rotation axis of the blade and the lens axis of the lens material on the surface to be processed, the rotation axis of the cutting blade is adjusted to the rotation axis and the lens axis on the surface to be processed of the lens material. In a method for manufacturing an ophthalmic lens having a toric surface, the surface to be processed is cut by moving the surface relative to the lens material in a plane including

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, in order to clarify the present invention more specifically, the specific structure of the present invention and its operation will be described in detail with reference to the drawings.

First, FIG. 1 is a schematic diagram specifically illustrating a method for cutting an ophthalmic lens according to the present invention. In this figure, reference numeral 10 denotes a cutting tool, which can be rotated around a rotation axis: L by a driving means (not shown). A cutting blade 12 such as a diamond chip is fixed to the tip of the cutting tool 10 so as to protrude outward from the cutting tool 10 in the direction perpendicular to the axis and in the axial direction.

On the other hand, in the figure, reference numeral 14 denotes a lens material;
The lens is held by the lens holding member 16 and fixedly held. Then, the processing surface 1 of the lens material 14
By subjecting the cutting surface 8 to cutting by the cutting blade 12 of the cutting tool 10, the processed surface 18 is processed into a toric shape.

In carrying out such a cutting process, first, the lens material 14 is set so that the lens axis M on the target surface 18 to be processed is at a predetermined angle with respect to the rotation axis L of the cutting tool 10 by: −α) Position so as to intersect at °.

Note that this intersection angle is, as described later,
It is set according to the shape of the target surface 18 to be processed. Further, the lens axis M of the surface 18 to be processed does not necessarily have to coincide with the axis of the lens material 14. For example, when processing a lens whose optical axis is decentered, the surface 18 to be processed is not required. Is set such that M is separated from the axis of the lens material 14 by a predetermined distance.

Then, under such a condition, the cutting tool 10
Is rotated around the rotation axis L, and the cutting tool 10 is moved so that the cutting blade 12 draws a locus of a target lens surface as shown in the figure. At this time, the intersection angle between the rotation axis L of the cutting tool 10 and the lens axis M on the processing surface 18 of the lens material 14 is: (90−
α) so that the cutting tool 10 is always constant.
The parallel movement is performed in a plane including the rotation axis: L and the lens axis: M of the processing surface 18 of the lens material 14. In addition, as shown in FIGS . 1 and 2 , for example, the movement control of the cutting tool 10 is performed by circular interpolation using a numerically controlled lathe that can be controlled by rectangular coordinates, so that the cutting tool 10 has a constant curvature. Implemented by moving along an arc having a radius: R.

That is, as shown in FIG. 2, when the lens axis M of the surface 18 to be processed of the lens material 14 is the Y axis and the axis orthogonal to the Y axis is the X axis, The radius of curvature of the processing surface 18 on the XY plane is
It is R. However, the X-
The shape on the Y plane does not necessarily have to be an arc shape, but may be formed in an elliptical shape or the like by performing arc interpolation between a plurality of coordinate points calculated in advance. When setting a shape other than an arc shape,
It is desirable to perform the circular interpolation so that the circular arcs on both sides of the previously calculated coordinate point have a common tangent line, thereby preventing the occurrence of a discontinuous portion at each coordinate point.

On the other hand, when the lens material 14 is cut as described above, the shape of the surface 18 to be processed on the ZY plane is determined by the position of the cutting tool 10 with respect to the lens axis M of the surface 18 to be processed in the lens material 14. Rotation axis: L tilt angle:
If α is not 0 °, it is considered to be an aspheric surface, and is represented as the position of the cutting edge P of the cutting blade 12 when X = 0.

Here, the rotational radius of the cutting edge P of the cutting blade 12 is represented by r, and the X of the cutting edge P of the cutting blade 12 is defined as X.
If the positions on the −Y plane and the ZY plane are represented by β and θ as shown in FIGS. 2 and 3, respectively, such a cutting edge: P
Coordinates (x, y, z) are given by (1), (2),
It is expressed as in equation (3).

X = R sin β + r sin α−r sin α · cos θ (1) y = R cos β−r cos α + r cos α · cos θ (2) z = r sin θ (3)

Therefore, the shape of the obtained work surface 18 on the ZY plane can be obtained as x = 0 in the above equation, and is expressed by the following equation (4).

Z ² + [y cos α + r−√ (R ² −y ² · sin ² α)] ² = r ² (4)

That is, from the equation (4), the radius of curvature of the surface 18 to be obtained on the ZY plane is the radius of curvature of the surface 18 to be processed on the XY plane: R
This is clearly different, and from this, the lens surface (work surface) 18 formed by the cutting process as described above.
Is sufficiently understood to have a function as a toric surface.

The radius of curvature of the work surface 18 on the ZY plane can be easily adjusted by the values of R and α, as is apparent from the above equation (4). By changing α with respect to the radius of curvature R of the surface 18 to be processed on the XY plane, Z
It is also easy to relatively tune the radius of curvature on the −Y plane.

According to the manufacturing method as described above, the rotation axis L of the cutting tool 10 is fixed to the lens axis M on the surface 18 to be processed of the lens material 14 at a constant crossing angle:
(90-α) °, the lens material 14 of the cutting tool 10 at the time of the cutting process.
Can be very advantageously avoided. In particular, by setting α> 0 ° as in the above specific example, the contact of the lens material 14 with the cutting tool 10 can be more advantageously avoided.

Therefore, in such a method, the cutting tool 10 is continuously moved, and the cutting blade 12 is moved to the lens material 1.
By moving continuously from one end to the other end on the XY plane of the surface 18 to be processed, the entire surface 18 can be continuously cut at once. You can.

Therefore, according to such a method, a step of a cutting mark does not occur on the lens surface (working surface), and a polishing process or the like for removing the step is not required, and processing time is reduced. It is possible to greatly reduce the amount of light, thereby facilitating the work, shortening the processing time and improving the production efficiency, and improving the optical quality of the manufactured lens and stabilizing it. This can be advantageously achieved.

Although the configuration and operation of the present invention have been specifically described above, the present invention should not be construed as being limited to the description based on the above-described specific examples, but rather, based on the knowledge of those skilled in the art. Such changes, modifications, improvements, etc. can be carried out in embodiments with such additions, and any such embodiments are included in the scope of the present invention unless departing from the spirit of the present invention. Some things are, of course, obvious.

For example, the above description has been made based on a specific example in which a concave surface of a lens is cut. However, the present invention is similarly applied to a case in which a convex surface of a lens is cut into a toric shape. What you get.

Further, in the above-described specific example, the cutting tool 10 having the cutting blade 12 is moved with respect to the lens material 14 fixedly held. Axis: Cutting blade 1 rotated around L
The lens material 14 is moved with respect to the cutting tool 10 provided with
Can also be cut.

In addition, the specific structure of a cutting tool or the like used in practicing the present invention is appropriately selected, and is not to be construed as being limited by the description of the above specific examples. For example, a predetermined rotational balance may be provided at the rotational axis symmetrical position of the cutting blade at the distal end of the cutting tool, or the distal end of the cutting tool may be formed in a hollow inverted conical shape, and the cutting blade may be provided on the end surface of the inverted conical portion. You can also provide
By doing so, the rotational balance of the cutting tool can be advantageously stabilized.

[0029]

As is apparent from the above description, in the method of the present invention, the cutting surface which is rotated about one axis is continuously moved relative to the surface to be processed of the lens material to thereby obtain the surface to be cut. Since the entire surface of the lens can be continuously cut, it becomes possible to cut the target toric-shaped lens surface extremely easily, and at the same time, to improve the precision of the lens surface and its optical quality. Stabilization can also be advantageously achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for specifically explaining a method of the present invention.

FIG. 2 shows the X-axis of the lens in order to clarify the shape of the lens surface formed by the cutting method shown in FIG.
FIG. 3 is a model diagram showing a relationship between a processing surface on a Y plane and a cutting blade.

FIG. 3 shows the Z-axis of the lens to clarify the shape of the lens surface formed by the cutting method shown in FIG.
FIG. 3 is a model diagram showing a relationship between a processing surface on a Y plane and a cutting blade.

FIG. 4 is an explanatory diagram for explaining a conventional method for cutting a lens surface having a toric shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Cutting tool 12 Cutting blade 14 Lens material 16 Lens holding member 18 Work surface

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-49-119277 (JP, A) JP-A-61-260903 (JP, A) JP-A-63-162144 (JP, A) 56805 (JP, A) Jikken 46-16214 (JP, Y1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23B 5/36, 5/40 B24B 13/00

Claims (4)

(57) [Claims] 1. When a processing surface of a lens material fixedly held is cut into a toric shape by a cutting blade rotated about one axis, a rotation axis of the cutting blade and a processing of the lens material are performed. While always keeping the angle formed by the lens axis on the surface constant, the rotation axis of the cutting blade is set within the plane including the rotation axis and the lens axis on the processing surface of the lens material.
A method of manufacturing an ophthalmic lens having a toric surface, characterized in that the surface to be processed is cut by moving continuously from one end side to the other end side and relative to the lens material. 2. A rotating shaft of said cutting blade and said lens material.
The angle of intersection with the lens axis on the work surface of
α), the value of α is set so that α> 0 °
An eye having a toric surface according to claim 1, which is set.
Manufacturing method of lens for use. 3. The lens cutting device according to claim 1 , wherein the rotation axis of the cutting blade is set to the lens material.
When moving the cutting blade relative to
The axis of rotation is placed on the rotation axis and the surface to be processed of the lens material.
Arc with a constant radius of curvature in the plane containing the lens axis
The toric according to claim 1 or 2, wherein the toric is moved along.
A method for producing an ophthalmic lens having a surface. 4. The processing surface of the lens material is a concave surface.
A toric surface according to any one of claims 1 to 3,
Of manufacturing an ophthalmic lens.