Method of manufacturing eyeglass lens

Abstract

An aspect of the present invention relates to a method of manufacturing an eyeglass lens, comprising determining a manufacturing condition by a method of determining a manufacturing condition of an eyeglass lens comprising a vapor-deposited film formed by vapor deposition using a vapor deposition source the main component of which is ZrO.sub.2, and forming a vapor-deposited film by vapor deposition using a vapor deposition source the main component of which is ZrO.sub.2 under the manufacturing condition that has been determined.

Claims

1. A method of manufacturing an eyeglass lens, which comprises: determining a manufacturing condition by a method of determining a manufacturing condition of an eyeglass lens comprising a vapor-deposited film formed by vapor deposition using a vapor deposition source the main component of which is ZrO.sub.2; and forming a vapor-deposited film by vapor deposition using a vapor deposition source the main component of which is ZrO.sub.2 under the manufacturing condition that has been determined, wherein the method of determining a manufacturing condition comprises: pre-determining a threshold of grain size permitting formation of a ZrO.sub.2 vapor-deposited film with a desired heat resistance; determining a candidate vapor deposition condition to be employed in vapor deposition of the vapor-deposited film in actual manufacturing; forming a test vapor-deposited film by conducting vapor deposition under the candidate vapor deposition condition that has been determined; taking a transmission electron microscope (TEM) image of the test vapor deposited-film; comparing the grain size in the TEM image with the predetermined threshold of grain size, and determining the candidate vapor deposition condition as a vapor deposition condition to be employed in a vapor deposition for actual manufacturing of an eyeglass lens when the grain size of the test vapor-deposited film is greater than the predetermined threshold of grain size, or determining a vapor deposition condition, which is determined by adding change(s) so as to increase heat resistance of a ZrO.sub.2 vapor-deposited film or change(s) not affecting heat resistance of a ZrO.sub.2 vapor-deposited film to the candidate vapor deposition condition, as a vapor deposition condition to be employed in a vapor deposition for actual manufacturing of an eyeglass lens when the grain size of the test vapor-deposited film is greater than the predetermined threshold of grain size.

2. The method of manufacturing an eyeglass lens according to claim 1, wherein the TEM image is a planar TEM image.

3. The method of manufacturing an eyeglass lens according to claim 1, wherein the grain size to be employed for the determination is an average value of the grain size.

4. The method of manufacturing an eyeglass lens according to claim 1, wherein the vapor-deposited film is formed as a layer constituting a multi-layered antireflective film.

5. The method of manufacturing an eyeglass lens according to claim 1, wherein the major or minor diameter of the granular region is adopted as the grain size.

6. The method of manufacturing an eyeglass lens according to claim 1, wherein the equivalent circle diameter obtained by a circle projection method is adopted as the grain size.

7. The method of manufacturing an eyeglass lens according to claim 1, wherein the grain size serving as an indicator in determining the manufacturing condition is the maximum size, minimum size, or average value of the grains in a prescribed region of the TEM image.

8. The method of manufacturing an eyeglass lens according to claim 1, wherein among two or more sets of candidate conditions, the actual manufacturing condition is determined by a relative determination of adopting the condition of the largest grain size in the TEM image as the vapor deposition condition for the ZrO.sub.2 vapor-deposited film in actual manufacturing.

9. The method of manufacturing an eyeglass lens according to claim 1, wherein preliminary tests are conducted and a database is created of the correlation between the vapor deposition conditions of ZrO.sub.2 vapor-deposited films and their tendency to crack at high temperatures; based on the database, the threshold is pre-determined, and those grain sizes at or above the threshold is determined to be vapor deposition conditions for ZrO.sub.2vapor-deposited films in actual manufacturing.

10. The method of manufacturing an eyeglass lens according to claim 1, wherein the change(s) added to the candidate vapor deposition condition include at least one selected from the group consisting of change of current of an ion gun and change of voltage of an ion gun employed in a vapor deposition.

Description

EXAMPLES

(1) The present invention will be described below based on Examples. However, the present invention is not limited to the embodiments disclosed in Examples. A vapor deposition source comprised of the stated oxides except for impurities that might be inevitably mixed in was employed below. The film thicknesses given below are optical film thicknesses calculated from the film formation conditions.

(2) 1. Determining Candidate Vapor Deposition Conditions

(3) A ZrO.sub.2 vapor-deposited film was formed to a film thickness of about 70 nm by the ion assisted method under the conditions given in Table 1 on a glass plate using ZrO.sub.2 as the vapor deposition source.

(4) TABLE-US-00001 TABLE 1 Ion gun conditions Quantity of assist Degree Current Voltage gas introduced of (mA) (V) O.sub.2 or O.sub.2/Ar [sccm] vacuum Condition 1 150 300 20 4.3E3 Pa Condition 2 250 500 20 4.3E3 Pa

(5) 2. Measurement of Average Grain Size in Planar TEM Image

(6) The ZrO.sub.2 vapor-deposited film prepared by vapor deposition under Condition 1 and the ZrO.sub.2 vapor-deposited film prepared by vapor deposition under Condition 2 in 1. above were shaved away by etching by ion milling a portion of the glass plate from the opposite surface from that on which had been formed the ZrO.sub.2 vapor-deposited film. The etching was halted when the ZrO.sub.2 vapor-deposited film had been shaved to a thickness of about 20 nm. The sample thus prepared was introduced into a transmission electron microscope and a planar TEM image (dark-field image) was taken at a magnification of 100,000-fold. Within each planar TEM image, the number of grains was tallied and the major diameter of each grain was manually measured within a surface area region of 50 m50 m. The average grain size was calculated. The results are given in Table 2.

(7) TABLE-US-00002 TABLE 2 Average grain size Condition 1 5.8 nm Condition 2 11.5 nm

(8) 3. Evaluation of Heat Resistance

(9) A ZrO.sub.2 vapor-deposited film formed on a plastic lens substrate (product name EYAS, made by HOYA (Ltd.), refractive index 1.6, colorless lens) by the same method as in 1. above was placed for 2 hours in a heating furnace at the internal temperature shown in Table 3. Subsequently, the presence of cracks several centimeters or more in length in the ZrO.sub.2 vapor-deposited film was evaluated under a fluorescent lamp. The presence of cracks was evaluated as X, and the absence of cracks as o. The results are given in Table 3.

(10) TABLE-US-00003 TABLE 3 Heating Evaluation of Evaluation of temperature cracks in ZrO.sub.2 cracks in ZrO.sub.2 within the vapor-deposited vapor-deposited hearing film formed film formed furnace under Condition 1 under Condition 1 80 C. x 85 C. x 90 C. x 95 C. x 100 C. x

(11) Based on the above results, it was determined that as the grain sizes observed in the planar TEM image increased, the heat resistance of the ZrO.sub.2 vapor-deposited film improved.

(12) 4. Preparation of Eyeglass Lenses

(13) The total of 8 layers of vapor-deposited films shown in Table 4 were sequentially formed by the ion assisted method employing oxygen, or a mixed gas of oxygen and argon, as the assist gas on the surface of a hard coat on the convex surface side of a plastic lens substrate (product name EYAS, made by HOYA (Ltd.), refractive index 1.6, colorless lens) with a convex surface on the object side and a concave surface on the eyeball side, both surfaces of which had been optically finished and coated with hard coats in advance. Once the eighth layer of vapor-deposited film had been formed, a water-repellent layer was formed as a ninth layer over the other layers. An organic silicon compound containing a fluorine-substituted alkyl group, KY130, made by Shen-Etsu Chemical Co., Ltd., was employed as the vapor deposition source. Vapor deposition was conducted by halogen heating to form the film. Two types of eyeglass lens (eyeglass lenses 1 and 2) were prepared. During the preparation of eyeglass lens 1, the above Condition 1 was employed as the vapor deposition condition for the ZrO.sub.2 vapor-deposited film, and during the preparation of eyeglass lens 2, the above Condition 2 was employed as the vapor deposition condition for the ZrO.sub.2 vapor deposition film. The remaining manufacturing conditions were identical.

(14) TABLE-US-00004 TABLE 4 Vapor Film deposition thickness source (nm) Layer 1 SiO.sub.2 30 Layer 2 ZrO.sub.2 10 Layer 3 SiO.sub.2 200 Layer 4 ITO 10 Layer 5 ZrO.sub.2 30 Layer 6 SiO.sub.2 20 Layer 7 ZrO.sub.2 60 Layer 8 SiO.sub.2 90

(15) 5. Heat Resistance Test of Eyeglass Lens Sample

(16) The eyeglass lenses prepared in 4. above were placed for one hour in an oven at 100 C. A fluorescent lamp was then applied and the lenses were visually evaluated for cracks. Eyeglass lenses 1, with ZrO.sub.2 vapor-deposited films prepared under Condition 1, presented numerous cracks with a length of several centimeters in the ZrO.sub.2 vapor-deposited film. By contrast, eyeglass lenses 2, with ZrO.sub.2 vapor-deposited films prepared under Condition 2, did not have cracks generated and were highly transparent.

(17) Based on the results in 5. above, the preparation of the ZrO.sub.2 vapor-deposited film under the vapor deposition condition determined to yield good heat resistance based on the grain size observed in a planar TEM image was determined to yield an eyeglass lens having good durability. Conventionally, discovering vapor deposition conditions permitting the formation of ZrO.sub.2 vapor-deposited films with good heat resistance in this manner would require the repeated selection of candidate conditions and implementation of accelerated durability tests, such as by the oven heating implemented in 5. above. By contrast, the present invention makes it possible to determine manufacturing conditions making it possible to manufacture eyeglass lenses having good durability by means of the convenient method of preparing a test vapor-deposited film, taking a planar TEM image, and measuring the grain size.

(18) In the present Examples, a TEM was employed as the electron microscope. It is also possible to employ an AFM that permits morphological differentiation of grain size.

(19) The present invention is useful in the field of manufacturing eyeglass lenses.