US5325235A — Compact zoom lens system

Claim 1

Independent Claim 157 words

A compact zoom lens system comprising, in order from the object side, a first lens unit having a positive focal length, a second lens unit having a positive focal length and a third lens unit having a negative focal length, said first, second and third lens units being all movable toward the object side during zooming from the wide angle to telephoto side such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, characterized in that it satisfies the following conditional formula: 0.34<f.sub.3 (1-β.sub.3W)/f.sub.W <1.00, (1) and 0.30<f.sub.2 /f.sub.W <0.90, (2) where f W is the focal length of the total system at the wide angle end, β 3W is the image-formation magnification of the third lens unit at the wide angle end, and f 2 and f 3 are the focal lengths of the second and third lens units, respectively.

Claim 2

Dependent Claim 157 words

A compact zoom lens system comprising, in order from the object side, a first lens unit having a positive focal length, a second lens unit having a positive focal length and a third lens unit having a negative focal length, said first, second and third lens units being all movable toward the object side during zooming from the wide angle to telephoto side such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, characterized in that it satisfies the following conditional formula: 0.34<f.sub.3 (1-β.sub.3W)/f.sub.W <1.00, (1) and 0.30<f.sub.2 /f.sub.W <0.90, (2) where f W is the focal length of the total system at the wide angle end, β 3W is the image-formation magnification of the third lens unit at the wide angle end, and f 2 and f 3 are the focal lengths of the second and third lens units, respectively.

Claim 3

Dependent Claim 22 words

A compact zoom lens system as claimed in claim 1, characterized in that said first and third lens units are movable together.

Claim 4

Dependent Claim 66 words

A compact zoom lens system as claimed in claim 1, characterized by satisfying the following conditional formula: 0.40<L.sub.23W /IH<1.05, (3) where L 23W is the distance at the wide angle end from the surface of the second lens unit proximate to the object to the surface of the third lens unit proximate to the image plane and IH is the maximum value of an image height.

Claim 5

Dependent Claim 56 words

A compact zoom lens system as claimed in claim 1, characterized in that the first lens unit comprises a positive meniscus lens convex on the object side, the second lens unit comprises a stop, a negative meniscus lens concave on the object side and a positive lens, and the third lens unit comprises a negative lens.

Claim 6

Dependent Claim 53 words

A compact zoom lens system as claimed in claim 1, further characterized by satisfying the following conditional formula: 1.2<f.sub.1 /f.sub.W <8,0, (4) and ν.sub.d1 >62.8, (5) where f 1 is the focal length of the first lens unit and ν d1 is the Abbe's number of the lens of the first lens unit.

Claim 7

Dependent Claim 115 words

A zoom lens system including, in order from the object side, a first lens unit being a single positive lens element, a second lens unit comprising one negative lens element and one positive lens element air-spaced from one another, and having a positive refractive power as a whole, and a third lens unit comprising a single negative lens component, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephone side.

Claim 8

Dependent Claim 115 words

A zoom lens system including, in order from the object side, a first lens unit being a single positive lens element, a second lens unit comprising one negative lens element and one positive lens element air-spaced from one another, and having a positive refractive power as a whole, and a third lens unit comprising a single negative lens component, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephone side.

Claim 9

Dependent Claim 18 words

A zoom lens system as claimed in claim 6, wherein the second lens unit includes an aspherical surface.

Claim 10

Dependent Claim 18 words

A zoom lens system as claimed in claim 6, wherein the third lens unit includes an aspherical surface.

Claim 11

Dependent Claim 18 words

A zoom lens system as claimed in claim 7, wherein the third lens unit includes an aspherical surface.

Claim 12

Dependent Claim 109 words

A zoom lens system including, in order from the object side, a first lens unit including a single positive lens element, a second lens unit consisting of air-spaced negative and positive lens elements, and having a positive refractive power as a whole, and a third lens unit including a single negative lens element, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephoto side.

Claim 13

Dependent Claim 109 words

A zoom lens system including, in order from the object side, a first lens unit including a single positive lens element, a second lens unit consisting of air-spaced negative and positive lens elements, and having a positive refractive power as a whole, and a third lens unit including a single negative lens element, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephoto side.

Claim 14

Dependent Claim 18 words

A zoom lens system as claimed in claim 10, wherein the second lens unit includes an aspherical surface.

Claim 15

Dependent Claim 18 words

A zoom lens system as claimed in claim 10, wherein the third lens unit includes an aspherical surface.

Claim 16

Dependent Claim 18 words

A zoom lens system as claimed in claim 11, wherein the third lens unit includes an aspherical surface.

Claim 17

Dependent Claim 109 words

A zoom lens system including, in order from the object side, a first lens unit being a single positive lens element, a second lens unit consisting of air-spaced negative and positive lens elements, and having a positive refractive power as a whole, and a third lens unit including a single negative lens element, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephoto side.

Claim 18

Dependent Claim 109 words

A zoom lens system including, in order from the object side, a first lens unit being a single positive lens element, a second lens unit consisting of air-spaced negative and positive lens elements, and having a positive refractive power as a whole, and a third lens unit including a single negative lens element, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephoto side.

Claim 19

Dependent Claim 18 words

A zoom lens system as claimed in claim 14, wherein the second lens unit includes an aspherical surface.

Claim 20

Dependent Claim 18 words

A zoom lens system as claimed in claim 14, wherein the third lens unit includes an aspherical surface.

Claim 21

Dependent Claim 18 words

A zoom lens system as claimed in claim 15, wherein the third lens unit includes an aspherical surface.

Claim 22

Dependent Claim 128 words

A zoom lens system including no more than four lens elements in all, and including, in order from the object side, a first lens unit formed of a single positive lens element, a second lens unit consisting of one negative lens element and one positive lens element being air-spaced from one another, and having a positive refractive power as a whole, and a third lens unit including a single negative lens element, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephoto side.

Claim 23

Dependent Claim 128 words

A zoom lens system including no more than four lens elements in all, and including, in order from the object side, a first lens unit formed of a single positive lens element, a second lens unit consisting of one negative lens element and one positive lens element being air-spaced from one another, and having a positive refractive power as a whole, and a third lens unit including a single negative lens element, said lens units being all movable toward the object side along the optical axis during zooming such that the first and second lens units are spaced away from each other, while the second and third lens units are moved toward each other, whereby the focal length is varied from the wide angle to the telephoto side.

Claim 24

Dependent Claim 18 words

A zoom lens system as claimed in claim 18, wherein the second lens unit includes an aspherical surface.

Claim 25

Dependent Claim 18 words

A zoom lens system as claimed in claim 18, wherein the third lens unit includes an aspherical surface.

Claim 26

Dependent Claim 18 words

A zoom lens system as claimed in claim 19, wherein the third lens unit includes an aspherical surface.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-06-27	1997-12-27	1998-06-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-06-27	2001-12-27	2002-06-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-06-27	2005-12-27	2006-06-28	$7700.00	Window Closed / Lapsed

Compact zoom lens system

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