Slide projector with automatic slide warpage compensation

Claim 2

A projector comprising: means for supporting a transparency generally in a plane, said transparency typically exhibiting warpage such that the center of said transparency is displaced from said plane by a pop distance; means for measuring said pop distance; means for projecting light through said transparency; means including a lens having a preselected f-number for focusing the light projected through said transparency onto a viewing plane; and means responsive to said pop distance for varying the f-number of said lens so as to improve the focus of said transparency at said viewing plane.

Claim 3

The projector of claim 1 wherein said f-number varying means comprises a variable aperture disposed between said transparency and said lens.

Claim 4

The projector of claim 2 wherein said f-number varying means operates to increase said f-number when said transparency exhibits warpage.

Claim 5

The projector of claim 1 and further including autofocus means for measuring the distance to said viewing plane and automatically adjusting said focusing means such that the center of said transparency is in focus.

Claim 6

The projector of claim 1 wherein said projecting means comprises: a lamp for radiating light; and lens means for directing the light radiated by said lamp onto said transparency.

Claim 7

The projector of claim 1 wherein said measuring means comprises: means for impinging a beam of radiation at a predetermined angle onto the center of said transparency; and means for determining the angle at which said beam of radiation is reflected from said transparency.

Claim 8

The projector of claim 1 and further including a digital computer connected to said measuring means and said f-number varying means, said computer being responsive to said pop distance for appropriately adjusting said f-number varying means.

Claim 9

A projector comprising: means for supporting a transparency generally in a plane, said transparency typically exhibiting warpage such that the center of said transparency is displaced from said plane by a pop distance; means for impinging a beam of radiation at a predetermined angle onto the center of said transparency; and means for determining the angle at which said beam of radiation is reflected from said transparency so as to determine said pop distance; means including a lamp for projecting light through said transparency; means including a lens having a preselected f-number for focusing the light projected through said transparency onto a viewing plane; a variable aperture disposed between said transparency and said lens for varying the effective f-number of said lens; and a digital computer connected to said variable aperture, said digital computer responsive to said pop distance so as to adjust said variable aperture to increase the effective f-number of said lens when said transparency exhibits warpage.

Claim 10

A projector comprising: means for supporting a transparency generally in a plane, said transparency typically exhibiting warpage such that the center of said transparency is displaced from said plane by a pop distance; means for impinging a beam of radiation at a predetermined angle onto the center of said transparency; and means for determining the angle at which said beam of radiation is reflected from said transparency so as to determine said pop distance; means including a lamp for projecting light through said transparency; means including a lens having a preselected f-number for focusing the light projected through said transparency onto a viewing plane; a variable aperture disposed between said transparency and said lens for varying the effective f-number of said lens; and a digital computer connected to said variable aperture, said digital computer responsive to said pop distance so as to adjust said variable aperture to increase the effective f-number of said lens when said transparency exhibits warpage.

Claim 13

The method of claim 9 wherein said varying step comprises increasing said f-number in response to warpage of said transparency.

Claim 14

The method of claim 9 wherein said measuring step comprises the steps of: impinging a beam of radiation on the center of said transparency at a predetermined angle; and sensing the angle at which said beam of radiation is reflected from said transparency.

Claim 15

The method of claim 9 wherein said projector further comprises a variable aperture disposed between said projecting means and said lens, and wherein said varying step is performed by varying said aperture.