Prism, forming mold, and method of producing prism

Patent metadata

Field	Value
Publication number	US-10974475-B2
Application number	US-201816127467-A
Country	US
Kind code	B2
Filing date	Sep 11, 2018
Priority date	Sep 22, 2017
Publication date	Apr 13, 2021
Grant date	Apr 13, 2021

Abstract

A forming mold for forming a prism by press molding includes a first mold, a second mold, and a third mold. The second mold includes a surface configured to form a base surface of a non-optical surface and is configured to define, together with the first mold, a space in which a material is disposed. The third mold is slidable with respect to the second mold so as to project toward the space with respect to the second mold and is configured to form a recess portion recessed with respect to the base surface.

First claim

What is claimed is:

1. A method of producing a prism comprising an optical surface and a non-optical surface, the method comprising:
a first step of sandwiching a material by a first mold and a second mold, the second mold comprising a surface configured to form a base surface of the non-optical surface;
a second step of pressing the material by causing a third mold to project toward the material with respect to the surface of the second mold configured to form the base surface, the third mold being configured to form a recess portion recessed with respect to the base surface; and
a third step of cooling the material.

2. The method according to claim 1 , wherein, in the third step, a temperature difference is imparted such that a temperature of the third mold is higher than a temperature of the first mold and a temperature of the second mold in a cooling process of the material.

3. The method according to claim 1 , wherein, in the second step, the material is pressed by sliding the third mold with respect to the second mold in a direction inclined with respect to a direction of a normal to the surface of the second mold configured to form the base surface.

4. The method according to claim 3 , wherein the third mold comprises a slide contact surface and an inclined surface, the slide contact surface being configured to come into slide contact with the second mold, the inclined surface being inclined with respect to the slide contact surface, and
wherein, in the second step, the material is pressed by causing a part of the slide contact surface and whole of the inclined surface to project toward the material with respect to the surface of the second mold configured to form the base surface in a state in which the inclined surface is parallel to the surface configured to form the base surface.

5. The method according to claim 4 , wherein at least one of the first mold and the second mold comprises a surface configured to form the optical surface, and
wherein, in the second step, the material is pressed in a state in which the inclined surface is perpendicular to the surface configured to form the optical surface.

6. The method according to claim 1 , further comprising a fourth step of opening the first mold, the second mold, and the third mold,
wherein, in the fourth step, the second mold is separated from the material after the third mold is separated from the material.

7. The method according to claim 1 , wherein the material is a thermoplastic resin.

8. A forming mold for forming a prism by press molding, the prism comprising an optical surface and a non-optical surface, the forming mold comprising:
a first mold;
a second mold that comprises a surface configured to form a base surface of the non-optical surface of the prism and is configured to define, together with the first mold, a space in which a material is disposed; and
a third mold that is slidable with respect to the second mold so as to project toward the space with respect to the second mold and is configured to form a recess portion recessed with respect to the base surface.

Assignees

• Canon Kk

Inventors

• Takata Atsushi

Classifications

• B29D11/00432 Primary

  Auxiliary operations, e.g. machines for filling the moulds (B29D11/00125 takes precedence) · CPC title

• B29C2043/522

  selectively heating a part of the mould to achieve partial heating, differential heating · CPC title

• B29C43/52

  Heating or cooling · CPC title

• G02B1/045

  Light guides · CPC title

• B29L2011/00

  Optical elements, e.g. lenses, prisms · CPC title