PLASTIC LENS, METHOD FOR MANUFACTURING THE SAME, AND IMAGING DEVICE USING THE SAME

• US 20130176633A1
• Filed: 03/04/2013
• Published: 07/11/2013
• Est. Priority Date: 03/22/2011
• Status: Active Grant

• Current Assignee: Panasonic Automotive Systems Company of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: SUN, Yihong
• Granted Patent: US 9,348,064 B2
• Time in Patent Office: Days
• US Class Current: 359/811
• CPC Class Codes: B29C 2045/0058 removing material
• CPC Class Codes: B29C 45/0053 combined with a final operation, e.g. shaping injection-compression moulding B29C45/561
• CPC Class Codes: B29D 11/00432 Auxiliary operations, e.g. machines for filling the moulds B29D11/00125 takes precedence
• CPC Class Codes: G02B 13/004 having four lenses
• CPC Class Codes: G02B 3/00 Simple or compound lenses
• CPC Class Codes: G02B 7/02 for lenses supports for magnifying lenses G02B25/002
• CPC Class Codes: G02B 7/022 lens and mount having complementary engagement means, e.g. screw/thread

Abstract

A plastic lens 1 has a lens 2 that effectively functions as a lens at a center and an annular flange 3 that does not act as a lens along a circumference of the lens. A gate 4 serving as a flow channel through which molten plastic is to be poured during molding is formed on a circumference of the flange. The gate is cut and taken away at an angle of inclination so as to include a point of intersection between the gate 4 and the circumferential flange 3, whereby a circumferential flange having a given thickness or more is formed.

Claims

1. A plastic lens, comprising:

a main body making up an effective optical region; and

an annular flange integrally formed on a circumference of the main body;

wherein the flange has a tubular first circumferential surface that is parallel to an optical axis of the main body, and a second circumferential surface including an inclined surface that obliquely cuts the flange from a first point on the first circumferential surface toward a back of the main body with respect to the direction of the optical axis and that partially has a tubular shape formed continuously from the first circumferential surface.

2. The plastic lens according to claim 1, wherein a thickness of the first circumferential surface is one half or more of a thickness of the flange.

3. The plastic lens according to claim 1, wherein an angle of inclination 0 of the inclined surface with respect to the optical axis satisfies the following expression:

θ

≧

arctan ((D−

d)/(H1/2))  

 

(1)

D;

outer diameter of a flange

d;

radius of main body

H1;

entire length of flange in its thicknesswise direction

4. The plastic lens according to claim 1, wherein the plastic lens is manufactured by injection molding.

6. An imaging device, comprising:

a first surface lens made up of the plastic lens according to claim 1,

a group of lenses disposed inside the first surface lens;

a lens holder supporting the first surface lens and the group of lenses; and

an imaging element forming an image from entrance light passing through the first surface lens and the group of lenses.

7. The imaging device according to claim 6, wherein the lens holder and the first surface lens are anchored by means of thermal caulking.

5. A method for manufacturing a plastic lens, including:

steps of injecting a resin by a gate of dies and injection-molding a plastic lens having a main body making up an effective optical region, an annular flange formed integrally on an outer circumference of the main body, and a gate made up of a projection formed on a circumference of the flange from the gate of the dies; and

a cutting step of cutting the gate from the injection-molded plastic lens along a cut plane including a point of intersection between the gate and the flange at an angle of inclination α

1≦

θ

≦

α

2,

wherein, provided that an outer diameter of the flange is taken as D;

that an entire length of the flange in its thicknesswise direction is taken as H1;

that a height and a width of the gate for representing a size of the gate are H2 and W, respectively, that an entire length of the flange achieved in a direction of an optical axis is taken as H3;

that a point of intersection between the cut plane of the gate and the flange is taken as Q1, a point of intersection between the gate and the circumferential flange is taken as Q2 (Q2′

); and

that a vertical distance from a straight line passing through the points Q2 and Q2′

to a line parallel to the optical axis passing through the point Q1 is taken as δ

, a minimum angle of inclination α

1 and a maximum angle of inclination α

2 for obtaining an circumferential flange having a given thickness or more are set so as to fulfill Expressions (2), (3), (4), and (5) provided below.