Compact lens with external aperture stop

• US 20020012176A1
• Filed: 08/03/2001
• Published: 01/31/2002
• Est. Priority Date: 09/27/1999
• Status: Active Grant

• Current Assignee: Alex Ning
• Original Assignee: Alex Ning
• Inventors: Ning, Alex
• Granted Patent: US 6,441,971 B2
• Time in Patent Office: Days
• US Class Current: 359/728
• CPC Class Codes: G02B 13/0035 having three lenses
• CPC Class Codes: G02B 9/16 all the components being simple

Abstract

A lens assembly particularly suited to use with high resolution digital cameras suitable for incorporation in compact portable electronic devices such as cellular telephones, portable digital assistants and the like. The lens assembly includes a distal meniscus lens element formed from glass, and first and second, aberration correcting, aspheric lens elements formed from plastic, such as an acrylic, and positioned proximal to said meniscus lens element. An aperture stop plane is provided just in front of the front group. A fixed aperture stop or a combined variable aperture and shutter device may be positioned at the aperture stop plane.

Claims

1. A compact lens assembly which comprises:

a glass meniscus lens element at a distal assembly end;

a first aspherical plastic lens element spaced proximally from said first lens element;

a second aspherical plastic lens element spaced proximally from said first aspherical plastic lens element; and

an aperture stop located at an aperture stop plane adjacent to said distal end of said glass lens element at a predetermined distance from said glass lens element.

2. The compact lens assembly according to claim 1 wherein said lens assembly has a focal length from about 4.1 to 4.3 mm and an overall length from said aperture stop to an image plane of from about 5.2 to 5.4 mm.

3. The compact lens assembly according to claim 1 wherein said meniscus lens element is formed from a glass selected from the group consisting of C-ZLAF2, BK-7 and SK-16 glasses and said aspherical lens elements are formed from an acrylic material.

4. The compact lens assembly according to claim 1 further including a cover glass position proximal to said second lens element.

5. The compact lens assembly according to claim 1 wherein lens assembly satisfies the following data:

6. The compact lens assembly according to claim 1 wherein lens assembly satisfies the following data:

7. The compact lens assembly according to claim 1 wherein said aperture stop is selected from a fixed aperture and a variable aperture means.

8. The compact lens assembly according to claim 7 further including a shutter means also located substantially at said aperture stop plane.

9. In a compact digital camera having a camera body, a sensor for forming a digital image corresponding to varying light image falling thereon, a lens assembly for forming said light image, and an aperture stop for controlling light image intensity passing through said lens assembly, the improvement comprising:

said lens assembly comprising a glass meniscus lens element at a distal end of said lens assembly, a first aspherical plastic lens element spaced proximally from said first lens element; and

a second aspherical plastic lens element spaced proximally from said first bi-aspheric plastic lens element;

said aperture stop located adjacent to said distal end of said lens assembly at a predetermined distance from said glass lens element; and

a shutter/variable aperture combined with said aperture stop for shielding the sensor during digital image read-out from said sensor.

10. The improvement according to claim 9 wherein said lens assembly has a focal length of from about 4.0 to 4.3 mm and an overall length from said aperture stop to an image plane of from about 5.2 to 5.4 mm.

11. The improvement according to claim 9 wherein said meniscus lens element is formed from a glass selected from the group consisting of C-ZLAF2, BK-7 and SK-16 glasses and said bi-aspheric lens elements are formed from an acrylic material.

12. The improvement according to claim 9 further including a cover glass position proximal to said second lens element.

13. The improvement according to claim 9 wherein the lens assembly satisfies the following data:

14. The improvement according to claim 9 wherein the lens assembly satisfies the following data, wherein the surfaces are as designated in FIG. 2: