Browse Prior Art Database

Constant Focus Image Protection

IP.com Disclosure Number: IPCOM000073521D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Landsiedel, FW: AUTHOR [+2]

Abstract

In standard viewers, the optical path imposes severe constraints on the relationship between the objective lens and the film plane. The object 11 to be viewed can move in the horizontal X or Y plane. A lens 15 is contained in the lens housing 14 and is brought to focus by operation of the focus shaft 18. The lens 15 has a very shallow depth of focus usually in the order of not more than 4 mils. If the slightest amount of misalignment is introduced between the lens 15 and the film plane 11, it will not be possible to obtain uniformly sharp focus across the entire projected image on the screen. Accordingly, a gimbal support 12 is provided which allows the lens to essentially "float" on the film plane 11. The gimbal mechanism 12 consists of a yoke 13, a gimbal support 16 and a lens barrel 14.

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Constant Focus Image Protection

In standard viewers, the optical path imposes severe constraints on the relationship between the objective lens and the film plane. The object 11 to be viewed can move in the horizontal X or Y plane. A lens 15 is contained in the lens housing 14 and is brought to focus by operation of the focus shaft 18. The lens 15 has a very shallow depth of focus usually in the order of not more than 4 mils. If the slightest amount of misalignment is introduced between the lens 15 and the film plane 11, it will not be possible to obtain uniformly sharp focus across the entire projected image on the screen. Accordingly, a gimbal support 12 is provided which allows the lens to essentially "float" on the film plane 11. The gimbal mechanism 12 consists of a yoke 13, a gimbal support 16 and a lens barrel 14. The lens 15 is free to move in the vertical plane normal to the film surface 11 thereby permitting it to self align with the surface of the film. This insures absolute focus on the screen at all times and takes into account any imperfections in the thickness of the film itself, the glass plate 19 that the film rests on or any other mechanical variations in the card carrier mechanism. The gimballing 12 provides an axis 20 through the yoke 13 and lens housing 14 giving the lens 15 one degree of freedom. The lens 15 is free to move about an additional axis 22 at right angles to the housing axis 20 as defined by the turning of yoke 13 giving the lens...