Progressive lens and method of manufacture thereof
Apparatus and methods are described including a progressive lens that is configured to provide a far-vision correction and a near-vision correction. The progressive lens includes a single-focus, far-vision corrective lens that is configured to provide only a portion of the far-vision correction, and a film coupled to the single-focus, far-vision corrective lens. The film defines a far-vision corrective portion that is configured to provide the remainder of the far-vision correction, a near-vision corrective portion that is configured to provide additive near-vision correction, and an intermediate portion in which the film transitions between the far-vision corrective portion and the near-vision corrective portion. Other applications are also described.
1. Apparatus comprising:
a progressive lens that is configured to provide a far-vision correction and a near-vision correction, the progressive lens comprising:
a single-focus, far-vision corrective lens that is configured to provide only a portion of the far-vision correction; and
a film coupled to the single-focus, far-vision corrective lens, the film comprising a thermoplastic material and being configured to define:
a far-vision corrective portion that is configured to provide the remainder of the far-vision correction;
a near-vision corrective portion that is configured to provide additive near-vision correction; and
an intermediate portion in which the film transitions between the far-vision corrective portion and the near-vision corrective portion,
wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that an edge thickness of the film is at least 0.1 mm, and wherein the edge thickness of the film being at least 0.1 mm facilitates manufacture of the film using injection molding of the thermoplastic material when the thermoplastic material is in melted form.
2. The apparatus according to claim 1 , wherein the single-focus, far-vision corrective lens is rigid.
3. The apparatus according to claim 1 , wherein the film comprises a flexible film.
4. The apparatus according to claim 1 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that a thickness of the film is substantially uniform.
5. The apparatus according to claim 1 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that a ratio of a center thickness of the film to an edge thickness of the film is between 1:2 and 2:1, when a diameter of the film is greater than or equal to 70 mm.
6. The apparatus according to claim 1 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that a ratio of a center thickness of the film to an edge thickness of the film is between 1:1.6 and 1.6:1, when a diameter of the film is greater than or equal to 40 mm.
7. The apparatus according to claim 1 , wherein the far-vision corrective portion of the film is configured to provide a far-vision correction such that a far-vision correction that is provided by the single-focus, far-vision corrective lens is an integer multiple of 0.25 Diopters.
8. The apparatus according to claim 1 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that an edge thickness of the film is at least 0.3 mm.
9. The apparatus according to claim 8 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that an edge thickness of the film is at least 0.3 mm, even when a center thickness of the film is less than or equal to 0.7 mm.
10. The apparatus according to claim 8 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that an edge thickness of the film is at least 0.3 mm, even when a diameter of the film is greater than or equal to 70 mm.
11. The apparatus according to claim 8 , wherein the far-vision corrective portion of the film is configured to provide a portion of the far-vision correction such that an edge thickness of the film is at least 0.3 mm, even when a center thickness of the film is less than or equal to 0.7 mm, and a diameter of the film is greater than or equal to 70 mm.
12. The apparatus according to claim 1 , wherein the edge thickness of the film being greater than 0.1 mm facilitates manufacture of the film using injection molding of the thermoplastic material when the thermoplastic material is in melted form without introducing stress marks in the material.