Focus control system for interchangeable adjustable focus lenses

• US 4,182,563 A
• Filed: 04/20/1978
• Issued: 01/08/1980
• Est. Priority Date: 04/20/1978
• Status: Expired due to Term

• Current Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Original Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Inventors: Shenk, Edwin K., Biber, Conrad H., Tam, Shirley Y.
• Primary Examiner(s): Hix, L. T.
• Assistant Examiner(s): Perkey, William B.
• Application Number:
  US05/898,107
• Time in Patent Office: 628 Days
• Field of Search: 354/25, 354/163, 354/167, 354/195, 354/197, 352/140, 352/142, 250/201, 250/204, 355/55, 355/56
• US Class Current: 396/93
• CPC Class Codes: G02B 7/40 using time delay of the reflected waves, e.g. of ultrasonic waves
• CPC Class Codes: G03B 17/14 interchangeably

Abstract

A camera having an automatic focus control system for an adjustable focus lens is provided with a demountable adjustable or fixed focus lens that incorporates a device having an adjustable or fixed focus lens characteristic that causes said automatic focus control system to vary in accordance with said lens characteristic. The device is removable with the lens and means are provided for interconnecting said device with said control system when the lens is mounted on said camera.

Claims

1. In an auto-focus camera of the type alternatively employing interchangeable lens assemblies, said camera having means when energized for deriving an electrical range signal having a given functional relation to subject distance,

means for alternatively mounting a multi-element adjustable lens assembly, each having at least one lens portion thereof movable for focusing an image of the subject on a recording medium, the movable lens portions of at least some of said lens assemblies having differing lens-subject functions relating lens focal position to subject distance;

drive means for adjusting the movable lens portion of a mounted lens assembly; and

an electrical focus control circuit for controlling the operation of said drive means in accordance with said range signal and the lens-subject function of a mounted lens assembly to position the movable lens portion thereof at a focal position wherein the image of the subject is focused on said recording medium, said electrical focus control circuit including means for converting said range signal to a lens position parameter in accordance with said lens-subject function and for controlling said drive means to displace the movable lens portion of said mounted lens assembly to a position in accordance with said lens position parameter, the improvement wherein each said lens assembly carries an electrical circuit portion of said converting means to alter said resulting lens position parameter in accordance with the lens-subject function of said mounted lens assembly, and means for coupling said lens carried electrical circuit portion to said camera when each such interchangeable lens assembly is mounted thereon.

2. In a photographic camera of the type having:

means for selectively coupling said camera to a source of energy;

a camera housing;

a film plane located within said camera housing;

a lens housing demountably attached to said camera housing;

an adjustable focus lens having at least one movable lens element, said lens being mounted on said lens housing and having a particular nonlinear relationship between the subject-in-focus position of said lens element and the distance to subjects within the focusing range of said lens, for forming images of subjects positioned within said focusing range at said film plane;

means for deriving an electrical signal representative of the actual distance between said camera and a subject remote therefrom;

means including an electrical circuit for positioning said adjustable focus lens element to the proper subject-in-focus position in accordance with said electrical subject distance signal, said positioning means including an electrical circuit portion that makes the position to which said lens element is positioned dependent upon the lens position/subject distance function of said adjustable focus lens,

the improvement comprising;

that said electrical circuit portion of said lens element positioning means that makes the position to which said lens element is positioned dependent upon the lens position/subject distance function of said adjustable focus lens, is mounted on and is removable with said lens housing when said lens housing together with its said adjustable focus lens are demounted from said camera housing; and

means for interconnecting said electrical circuit portion with said lens element positioning means when said lens housing is mounted on said camera housing.

3. In a photographic camera of the type having:

means for selectively coupling said camera to a source of energy;

a camera housing;

a film plane located within said camera housing;

a lens housing demountably attached to said camera housing;

an adjustble focus lens having at least one movable lens element, said lens being mounted on said lens housing and having a particular nonlinear relationship between the subject-in-focus position of said lens element and the distance to subjects within the focusing range of said lens, for forming images of subjects positioned within said focusing range at said film plane;

means for positioning said adjustable focus lens to the proper subject-in-focus position, said lens positioning means including;

means for deriving an electrical signal representative of the actual distance between said camera and a subject remote therefrom;

means for generating an electrical signal representative of the focus position of said movable lens element of said adjustable focus lens;

an electrical circuit responsive to said subject distance signal for generating a signal representative of said nonlinear lens element position/subject distance relationship;

means responsive to said lens element focus position signal and to said nonlinear lens element position/subject distance relationship signal for generating a signal representative of the position to which said lens element must be moved to focus an image of a particular subject at said film plane; and

drive means, responsive to said signal representative of the position to which said lens element must be moved to focus said subject at said film plane, for focusing said lens element at the appropriate subject-in-focus position;

the improvement comprising;

that a portion of said electrical circuit for generating said signal representative of said nonlinear lens element position/subject distance relationship is mounted on and is demountable with said lens housing when said lens housing together with said adjustable focus lens are demounted from said camera housing; and

means for interconnecting said electrical circuit portion with said lens element positioning means when said lens housing is mounted on said camera housing.

4. In a photographic camera of the type having:

means for selectively coupling said camera to a source of energy;

a camera housing;

a film plane located within said camera housing;

a lens housing demountably attached to said camera housing;

an adjustable focus lens having at least one movable lens element, said lens being mounted on said lens housing and having a particular nonlinear relationship between the subject-in-focus position of said lens element and the distance to subjects within the focusing range of said lens, for forming images of subjects positioned within said focusing range at said film plane;

means for positioning said adjustable focus lens to the proper subject-in-focus position, said lens positioning means including;

means for deriving an electrical signal representative of the actual distance between said camera and a subject remote therefrom;

means for generating an electrical signal representative of the focus position of said movable lens element of said adjustable focus lens;

an electrical circuit responsive to said lens element position signal and said subject distance signal for generating a signal representative of said nonlinear lens element position/subject distance relationship;

means responsive to said subject distance signal and to said nonlinear lens element position/subject distance relationship signal for generating a signal representative of the position to which said lens element must be moved to focus an image of a particular subject at said film plane; and

drive means, responsive to said signal representative of the position to which said lens element must be moved to focus said subject at said film plane, for focusing said lens element at the appropriate subject-in-focus position;

the improvement comprising;

that a portion of said electrical circuit for generating said signal representative of said nonlinear lens element position/subject distance relationship is mounted on and is demountable with said lens housing when said lens housing together with said adjustable focus lens are demounted from said camera housing; and

means for interconnecting said electrical circuit portion with said lens element positioning means when said lens housing is mounted on said camera housing.

5. In an auto-focus camera having energizeable means for deriving an electrical range signal having a given functional relation to subject distance;

energizeable means for driving a moveable portion of a mounted camera lens assembly having a first lens-subject function relating the focal position of the moveable lens portion to subject distance, and an electrical focus control circuit for controlling the operation of said drive means in accordance with said electrical range signal and said lens-subject function, to position said moveable lens portion to a focal position wherein the image of a subject is focused on a recording medium within said camera, said electrical focus control circuit including a first converting means for converting said electrical range signal to a lens parameter in accordance with said lens-subject function and means for controlling said energizeable drive means to displace the moveable lens portion of said mounted lens assembly to a focus position in accordance with said lens parameter; and

means for releasably mounting at least a lens element resulting in a second lens-subject function different from said first lens-subject function, the improvement wherein said electrical focus control circuit includes a second converting means for converting said electrical range signal to a second lens parameter in accordance with said second lens-subject function, and switching means for interchanging said second converting means in said focus control circuit with said first converting means such that said focus control circuit controls the displacement of said moveable lens element in accordance with said second lens-subject function and not in accordance with said first lens-subject function, said switching means being responsive to the mounting of said lens element.

6. A photographic camera comprising:

means for selectively coupling said camera to a source of energy;

a camera housing;

a film plane located within said camera housing;

an adjustable focus lens housing demountably attached to said camera housing;

an adjustable focus lens having at least one movable lens element, said lens being mounted on said lens housing and having a particular nonlinear relationship between the subject-in-focus position of said lens element and the distance to subjects within the focusing range of said lens, for forming images of subjects positioned within said focusing range at said film plane;

a fixed focus lens having a fixed focus lens housing, said fixed focus lens housing being demountably attached to said camera, said fixed focus lens having its optical axis coincidently aligned with the optical axis of said adjustable focus lens;

means for deriving an electrical signal representative of the actual distance between said camera and a subject remote therefrom;

drive means for positioning said adjustable focus lens element to the proper subject-in-focus position in accordance with said electrical subject distance signal; and

means for changing the position to which said adjustable focus lens element is focused by said drive means, by a fixed ratio, said fixed ratio changing means being interconnected with said drive means when said fixed focus lens housing is attached to said camera.

7. A photographic camera as defined in claim 6, wherein said means for varying the position to which said adjustable focus lens is focused by said focusing means by a fixed ratio is mounted on said fixed focus lens housing and is removable with said fixed focus lens

8. The camera of claim 7 wherein said fixed ratio is greater than one.

9. The camera of claim 7 wherein said fixed ratio is less than one.

10. The camera of claim 7 wherein said ratio is equal to the square of the magnifying power of said fixed focus lens.

11. A photographic camera comprising:

means for selectively coupling said camera to a source of energy;

a camera housing;

a film plane located within said camera housing;

a lens housing demountably attached to said camera housing;

an adjustable focus lens having at least one movable lens element, said lens being mounted on said lens housing and having a particular nonlinear relationship between the subject-in-focus position of said lens element and the distance to subjects within the focusing range of said lens, for forming images of subjects positioned within said focusing range at said film plane;

a fixed focus lens having a fixed focus lens housing, said fixed focus lens housing being demountably attached to said camera, said fixed focus lens having its optical axis coincidently aligned with the optical axis of said adjustable focus lens; and

means for positioning said adjustable focus lens to the proper subject-in-focus position, said lens positioning means including;

means for deriving an electrical signal representative of the actual distance between said camera and a subject remote therefrom;

means for generating an electrical signal representative of the focus position of said movable lens element of said variable focus lens;

an electrical circuit for generating a signal that varies from said lens element focus position signal by a fixed ratio;

an electrical circuit responsive to said subject distance signal for generating a signal representative of said nonlinear lens element position/subject distance relationship; and

drive means responsive to said nonlinear lens element position/subject distance signal and to said varied lens element focus position signal when said fixed focus lens is attached to said camera and responsive to said nonlinear lens element position/subject distance signal and to said lens element focus position signal but not responsive to said varied lens element focus position signal when said fixed focus lens is detached from said camera, for positioning said movable lens element to the proper subject-in-focus position.

12. A photographic camera as defined in claim 11 wherein a portion of said electrical circuit for varying the position to which said adjustable focus lens is focused by said lens positioning means by a fixed ratio, is mounted on said fixed focus lens housing, is removable with said fixed focus lens, and is interconnected with said lens positioning means when said fixed focus lens is attached to said camera.

13. The camera of claim 12 wherein said fixed ratio is greater than one.

14. The camera of claim 12 wherein said fixed ratio is less than one.

15. The camera of claim 12 wherein said ratio is equal to the square of the magnifying power of said fixed focus lens.

16. A photographic camera comprising:

means for selectively coupling said camera to a source of energy;

a camera housing;

a film plane located within said camera housing;

a lens housing demountably attached to said camera housing;

an adjustable focus lens having at least one movable lens element, said lens being mounted on said lens housing and having a particular nonlinear relationship between the subject-in-focus position of said lens element and the distance to subjects within the focusing range of said lens, for forming images of subjects positioned within said focusing range at said film plane;

a fixed focus lens having a fixed focus lens housing, said fixed focus lens housing being demountably attached to said camera, said fixed focus lens having its optical axis coincidently aligned with the optical axis of said adjustable focus lens; and

means for positioning said adjustable focus lens to the proper subject-in-focus position, said lens positioning means including;

means for deriving an electrical signal representative of the actual distance between said camera and a subject remote therefrom;

means for generating an electrical signal representative of the focus position of said movable lens element of said adjustable focus lens;

an electrical circuit for generating a signal that varies from said lens element focus position signal by a fixed ratio;

an electrical circuit responsive to said lens element position signal and said subject distance signal for generating a signal representative of said nonlinear lens element position/subject distance relationship; and

drive means responsive to said nonlinear lens element position/subject distance signal and to said varied lens element focus position signal when said fixed focus lens is attached to said camera and responsive to said nonlinear lens element position/subject distance signal and to said lens element focus position signal when said fixed focus lens is detached from said camera, for positioning said movable lens element to the proper subject-in-focus position.

17. A photographic camera as defined in claim 16 wherein a portion of said electrical circuit for varying the position to which said adjustable focus lens is focused by said lens positioning means by a fixed ratio, is mounted on said fixed focus lens housing, is removable with said fixed focus lens, and is interconnected with said lens positioning means when said fixed focus lens is attached to said camera.

18. The camera of claim 17 wherein said fixed ratio is greater than one.

19. The camera of claim 17 wherein said fixed ratio is less than one.

20. The camera of claim 17 wherein said ratio is equal to the square of the magnifying power of said fixed focus lens.