JPH0786444B2 - Simultaneous measurement of base curve and center wall thickness of contact lens and its measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention measures the radius of curvature (base curve) on the concave surface side (the side in contact with the eyeball) of a contact lens, and at the same time,
It is intended to provide a method capable of measuring the central wall thickness and a measuring device using the method.

[Conventional technology]

The manufacturing of contact lenses is essentially a lens manufacturing technology that uses plastic as a material, and a plastic material of an appropriate size is subjected to processing such as cutting and polishing to obtain a desired diameter, radius of curvature, center wall thickness, etc. Manufactures contact lenses that have.

Since the contact lens is directly attached to the human eye, it is designated as a medical device and has a standard for its quality.Therefore, the contact lens manufactured as a finished product is based on the quality standard. Curves, refractive power, lens center thickness, diameter, etc. are inspected.

Among these, the method of measuring the base curve includes (a) a method of projecting a certain size or the like from a certain distance using the base curve surface as a spherical reflecting surface, and measuring the size or interval, (b)
The position of the center of curvature of the spherical surface is found, and the distance from this position to the surface of the spherical surface, that is, the radius of curvature is directly found. There are a calculation method, a method using (d) Moire fringes, and the like.
A radiusscope is used as the measuring means in the method of (b), an Atsube sphere meter is used in the method of (c), and a toposcope is used in the method of (d).

The thickness of the center of the contact lens, that is, the center thickness, is usually obtained by directly measuring the distance between the upper and lower surfaces of the center of the lens using a dial cage with a handheld or a stand (minimum scale 0.01 mm). .

[Problems to be Solved by the Invention]

In the conventional inspection of the contact lens, the base curve and the center wall thickness of the contact lens are separately measured by different measuring devices as described above, so that the inspection is inefficient.

Also, the dial cage, which measures the center wall thickness of the contact lens, needs to be applied gently because the measurement pressure ranges from several tens of grams to more than 100g, and if the dial gauge push-up lever is released midway, an unexpected load is applied. As a result, cracks (crevices) may occur in the important center part of the lens, although not so much as being visible.

On the other hand, in the manufacturing process of a contact lens, usually, the concave side of the lens is first cut into a spherical surface with a required curvature, and the cutting,
Measurement of the radius of curvature of the semi-finished lens and the thickness of the center of the semi-finished lens in a semi-finished state after polishing is performed for quality control.

This is because the radius of curvature on the convex side of this semi-finished lens is uniquely determined by the radius of curvature on the concave side (base curve), the refractive power of the lens, the thickness of the lens, and the refractive index of the material.

Incidentally, a device for automatically measuring the concave curvature of a contact lens is described in JP-A-1-119705, but the device described in this publication is the curvature of the concave processed product during the lens manufacturing process. Since it is a dedicated device used for inspection, the central thickness of the lens cannot be measured at the same time.

Therefore, if the radius of curvature of the lens and the center wall thickness in the semi-finished state of the contact lens can be measured at the same time as well as the finished product of the contact lens, it will not only improve the inspection efficiency of the finished product but also be significant in terms of quality control in the lens manufacturing process. However, a simultaneous measuring method for measuring the lens curvature with the wall thickness and a measuring device have not been proposed yet.

In view of the problems in the conventional inspection of contact lenses, the present invention improves the measurement method of the base curve by the radius scope, and can measure the center wall thickness at the same time as the measurement of the base curve, and only the finished product. It is an object of the present invention to provide a simultaneous measuring method of lens curvature and wall thickness, which can be applied to a semi-finished lens.

[Means for Solving the Problems]

The configuration of the measuring method of the present invention made for the purpose of solving the above-mentioned problems is to project a target pattern on a contact lens placed with the concave side facing the objective lens of a radial scope, and to form the contact lens and the objective lens. Are moved relative to each other to form focus images of the pattern on the concave center and the concave surface of the contact lens respectively, and when these focus images are detected by the optical sensor through the eyepiece of the radial scope,
The radius of curvature of the contact lens is obtained from the difference in the position on the optical axis of the contact lens or the objective lens where two focus images are formed, and the focus image of the pattern is formed at the center of the convex side or the back side of the lens. Center of the contact lens by comparing the position on the optical axis of the contact lens or the objective lens where the focus image on the convex surface side or the back surface side and the focus image on the concave surface side are formed by the sensor. It is characterized by determining the wall thickness, the configuration of the measuring apparatus for carrying out this method, a microscope formed by an eyepiece lens and an objective lens arranged on the same optical axis, and the microscope An optical sensor provided on the optical axis close to the eyepiece lens, a semitransparent mirror arranged on the optical axis between the lenses, and the pair from the side of the optical axis through the semitransparent mirror. A mirror unit including a target unit for projecting a target pattern on the lens side, a lens mount for movably holding a contact lens on the optical axis, the mount holding the contact lens, or the mirror unit. When the lens is moved on the optical axis, the measuring means reads the amount of movement, and by moving the lens holder or the mirror body part, a focused image of the projected pattern that can be detected by the sensor is obtained. The base of the contact lens by measuring the position on the optical axis of the mounting table or the mirror body portion corresponding to the center of the concave surface and the surface of the concave surface and the center of the convex surface or the back surface of the contact lens to be formed, respectively. It is characterized in that the curve and the center wall thickness are calculated.

[Work]

INDUSTRIAL APPLICABILITY The present invention can be applied not only to a finished contact lens but also to a semi-finished contact lens in the manufacturing process. That is, when the contact lens side is moved, focus images formed by two reflections of the concave surface of the lens on the concave surface side of the lens as a mirror and the reflection as a curved surface are respectively detected by the optical sensor and the lens is moved. The position on the optical axis of the lens is detected by detecting the focal image formed by the reflection on the back side (or the surface of the lens holder) that has passed through this lens while obtaining the position on the optical axis. Seeking
The central wall thickness is calculated from the difference between the focus image formed on the front surface side and the lens position.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic side view illustrating an example of the measuring method of the present invention applied to a contact lens in a completed state, and FIG. 2 is a schematic side view illustrating another example of the measuring method of the present invention applied to a contact lens in a semi-finished state. FIG. 3 is a structural block diagram of an example of the measuring device of the present invention for a contact lens in a completed state, and FIG. 4 is a structural block diagram showing another example of the device of the present invention for a contact lens in a semi-finished state.

In FIG. 1, 1 is a radial scope lens barrel, 1a is an objective lens arranged at the lower end side of the lens barrel 1, 2 is a radial scope optical axis, 3 is a completed contact lens, and 3a is this The concave side center of the lens 3, 3b is also the convex side center, 3s is also the concave side surface, 4 is the optical path of the target pattern projected onto the contact lens 3 through the objective lens 1a of the lens barrel 1, and 4a is the focus of the objective lens 1a. Is.

Thus, in order to measure the radius of curvature (base curve) R and the center wall thickness T of the concave surface 3s of the contact lens 3, first the concave surface 3s of the contact lens 3 is directed toward the objective lens 1a of the lens barrel 1. Then, the centers 3a and 3b on the concave and convex sides are aligned with the optical axis 2.

Next, the contact lens 3 is positioned at the position shown in FIG. 1, and the lens 3 is moved up and down on the optical axis 2 to form a focus image of the target pattern on the concave surface 3s. The position on the optical axis 2 is the origin.

Then, the contact lens 3 is moved from the position of the origin to the position shown in FIG. 1 to form a focus image of the target pattern at the concave side center 3a, and on the optical axis 2 of the contact lens 3 at this time. Measure the position of. The measured value at this position indicates the radius of curvature R of the lens 3 as it is.

Generally, the difference between the measured value at the above position and the measured value at this position is calculated as the radius of curvature R of the contact lens 3.

Then, the contact lens 3 is moved on the optical axis 2 from the position shown in FIG. 1 to the position shown in FIG. 1 to form a focus image of the target pattern at the center 3b of the convex surface,
The position of the contact lens 3 on the optical axis 2 at this time is measured, and the difference t between the measured value at this position and the measured value at the position shown in FIG. 1 is obtained. The difference t between the measured values does not directly indicate the central thickness T of the contact lens 3.

The center thickness T can be easily calculated from the difference t, the refractive index of the lens material and the calculated radius of curvature R.

As described above, the radius of curvature (base curve) can be extremely easily obtained by measuring the position of the contact lens 3 by focusing in the order of FIG.
R and the center wall thickness T can be calculated.

In the present invention, the contact lens 3 is fixed at a fixed position on the optical axis 2, the lens barrel side of the radius scope is moved on the optical axis 2, and the radius of curvature R and the central wall thickness T are calculated based on the amount of movement. May be.

Next, another example of the measuring method of the present invention used for a semi-finished contact lens will be described with reference to FIG.

Incidentally, the same reference numerals as those shown in FIG. 1 in FIG. 2 denote the same members,
The same structure is shown.

5 is a lens mount having a surface 5m formed into a mirror surface, 5a is the center of the surface 5m of the lens mount, 6 is a semi-finished state, that is, the contact lens with the concave side processed, 6a is the concave side center of this lens 6, 6b is the center of the back surface side, and 6s is the surface of the concave surface side.

In order to obtain the base curve R'and the center wall thickness T'of the contact lens 6 in a semi-finished state, first, as shown in FIG. 2, the surface 5m of the lens holder 5 is directed to the lens barrel 1 side, and its center 5a. Is placed on the optical axis 2 and the center 5a is used as an objective lens.
The position on the optical axis 2 of the lens mount 5 at which the focus image of the target pattern is formed when it coincides with the focus 4a of 1a is measured.

Next, the contact lens 6 is attached to the concave surface 6s of the lens barrel 1.
The lens holder 5 is placed and held on the surface 5m of the lens holder 5. At that time, the center 6b of the back side of the contact lens 6 is attached to the lens mount 5.
Match the center 5a of the surface 5m.

From this state, the lens mount 5 is moved on the optical axis 2 to the position shown in FIG.
In Fig. 2, a focus image of the target pattern is formed, the position on the optical axis 2 of the lens holder 5 when this image is formed is measured, and the contact lens is obtained by the difference T'from the value measured at the position shown in Fig. 2. The center wall thickness of 6 is calculated. In this case, the difference T'of the actual measurement value becomes the center thickness as it is, and it is not necessary to perform the correction calculation like the lens 3 of the finished product shown in FIG.

Thereafter, the lens mount 5 is moved on the optical axis 2 from the position shown in FIG. 2 to the position shown in FIG. 2 to form a focus image of the target pattern on the concave surface 6s of the contact lens 6, and this image is Lens stand 5 when formed
Is measured on the optical axis 2 and the difference from the value measured at the position shown in FIG. 2 is calculated to obtain the base curve R ′ of the contact lens 6.

Although the case where the lens mount 5 is moved on the optical axis 2 has been described above, the lens mount 5 is fixed and the lens barrel side of the radius scope is moved, and the base curve R ′ and the center wall thickness T ′ are determined based on the amount of movement. May be asked.

FIG. 3 is a block diagram of an example of the measuring apparatus of the present invention corresponding to an example of the measuring method of the present invention described with reference to FIG. 1, and FIG. 4 corresponds to another example of the measuring method of the present invention described with reference to FIG. It is a block diagram of another example of the measuring apparatus of the present invention.

In FIGS. 3 and 4, reference numeral 7 is an eyepiece lens arranged on the optical axis 2, and a microscope is formed by the lens 7 and the objective lens 1a which is also arranged on the optical axis 2.

8 is a semitransparent mirror placed on the optical axis 2 between the eyepiece 7 and the objective lens 1a with a 45 ° inclination with respect to the optical axis 2, and 9 is the intersection of the semitransparent mirror 8 and the optical axis 2. A target is arranged on a line orthogonal to the passing optical axis 2, and 10 is a lamp arranged behind the target 9 on the same line. The lamp 10 and the target 9 form a target portion.
Thus, the pattern of the target 9 is projected onto the objective lens 1a side via the semitransparent mirror 8.

As described above, 1a and 7 to 10 form the mirror body portion A of the present invention as a radial scope.
The apparatus of the present invention shown in the figure has a structure in which an optical sensor 11 is provided on the optical axis 2 close to the eyepiece lens 7 and works in conjunction with the body A.

Reference numeral 12 denotes a lens mounting table for the contact lens 3 in a completed state, which mounts and holds the contact lens 3 with the concave surface side facing the objective lens 1a as shown in FIG.

Reference numeral 13 is a height adjusting device for the lens stand 12, and 14 is a length measuring sensor for measuring the height position of the lens stand 12.

Thus, the measuring device shown in FIGS. 3 and 4 has the base curves R and R'and the center wall thicknesses T and T'of the contact lenses 3 and 6.
The optical sensor 11 arranged close to the eyepiece lens 7 serves as a substitute for the observing eye, and the center 3a, 6a of the concave side of the contact lens 3, 6 and the surface 3s, 6s of the concave side, And the center 3b of the contact lens 3 on the convex side
(Fig. 3), center 5a of the surface 5m of the lens stand 5 (Fig. 4)
The height adjusting device 13 is controlled stepwise by the focusing control circuit 15 until the focused pattern images of the target 9 formed in each are detected.

When the optical sensor 11 detects the focused pattern image, it is transmitted to the arithmetic circuit 16 as a signal. At this time, the height positions of the lens mounts 5 and 12 are detected by the length measuring sensor 14 at the height position and input to the arithmetic circuit 16, so that the pattern image is formed on the concave side centers 3a and 6a of the contact lenses 3 and 6. It is possible to detect which of the concave side surfaces 3s and 6s, the convex side center 3b, or the center 5a of the surface 5m of the lens mount 5 is formed.

Reference numeral 17 is a data output display unit for the base curves R, R'and central wall thicknesses T, T ', and 18 is a digital numerical value input switch for inputting the correction data of the difference t between the actual measured values of the contact lens in FIG. Is.

Although the focus image is automatically detected in the one shown in FIGS. 3 and 4, it may be observed with the naked eye, and the lens mount may be raised and lowered manually. Furthermore,
The structure may be such that the side of the mirror body portion A is moved.

〔The invention's effect〕

The present invention is as described above, and since the base curve and the center wall thickness of the contact lens can be simultaneously measured and calculated by one measuring device, the quality inspection of the contact lens can be performed extremely efficiently as compared with the conventional method.

Further, not only inspection of the finished contact lens but also measurement and calculation of the base curve and center thickness of the semi-finished contact lens in the manufacturing process can be performed at the same time, which is significant in quality control during contact lens manufacturing. .

Furthermore, the measuring device of the present invention is economical because it can be manufactured by adding some improvements to the conventional radioscope.

[Brief description of drawings]

FIG. 1 is a schematic side view illustrating an example of the measuring method of the present invention applied to a contact lens in a completed state, and FIG. 2 is a schematic side view illustrating another example of the measuring method of the present invention applied to a contact lens in a semi-finished state. FIG. 3 is a structural block diagram showing an example of the measuring device of the present invention for a contact lens in a completed state, and FIG. 4 is a structural block diagram showing another example of the device of the present invention for a contact lens in a completed state. 1 ... Lens barrel, 1a ... Objective lens, 2 ... Optical axis, 3,6 ...
Contact lens, 3a, 6a …… Concave side center, 3b …… Convex side center, 3s, 6s …… Concave side surface, 4 …… Optical path, 5,12 ……
Lens stand, 7 ... Eyepiece, 8 ... Semi-transparent mirror, 9 ...
… Target, 10… Lamp, 11… Optical sensor, 13… Height adjustment device, 14… Height measurement sensor, 15… Focusing control circuit, 16… Arithmetic circuit,
17: Data output display unit, 18: Digital numerical input switch, A: Mirror, R, R '... Base curve (curvature radius), T, T' ... Center thickness

Claims (2)

[Claims] 1. A target pattern is projected onto a contact lens, which is placed with the concave side facing the objective lens of a radial scope, and the contact lens and the objective lens are moved relative to each other, and the center and concave surface of the contact lens on the concave side. On the optical axis of the contact lens or the objective lens on which the two focus images are formed, when forming the focus images of the patterns on the side surfaces and detecting these focus images by the optical sensor through the eyepiece lens of the radial scope The radius of curvature of the contact lens is obtained from the difference in the position of the contact lens, and the focus image of the pattern is formed on the center of the convex surface or the back surface of the lens and detected by the sensor, and the focus image of the center of the convex surface or the back surface is obtained. Of the contact lens or the objective lens on which a focus image of the concave side center is formed Simultaneous measurement of the base curve and center thickness of the contact lens by comparing the position of the on-axis and obtaining the central thickness of the contact lens. 2. A microscope formed by an eyepiece lens and an objective lens arranged on the same optical axis, an optical sensor provided on the optical axis close to the eyepiece lens of the microscope, and light between the two lenses. On the optical axis, there is provided a mirror section including a semitransparent mirror disposed on the axis and a target section projecting a target pattern from the side of the optical axis to the objective lens side through the semitransparent mirror. A lens holder for movably holding the contact lens, the holder for holding the contact lens, or a length measuring means for reading the amount of movement of the mirror body when moved on the optical axis, By moving the lens holder or the mirror body, the focus side image of the projected pattern that can be detected by the sensor is formed. The concave side center and the concave side surface of the contact lens and the convex side or The contact lens characterized in that the base curve and the center wall thickness of the contact lens are calculated by respectively measuring the position on the optical axis of the mounting table or the mirror portion corresponding to the surface side center. Simultaneous measurement system for base curve and center wall thickness.