Lens controlling device and method for lens system with variable focal length

• US 5,887,202 A
• Filed: 08/29/1997
• Issued: 03/23/1999
• Est. Priority Date: 08/26/1994
• Status: Expired due to Term

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Ohtake, Motoyuki, Ohshita, Koichi
• Primary Examiner(s): Metjahic, Safet
• Assistant Examiner(s): Dalakis, Michael
• Application Number:
  US08/921,320
• Time in Patent Office: 571 Days
• Field of Search: 396/79, 396/82, 396/86
• US Class Current: 396/86
• CPC Class Codes: G02B 7/102 controlled by a microcomputer cameras with interchangeable lenses G03B17/14

Abstract

A position controlling device in a lens system with a variable focal length with high-precision focusing having a small amount of required recorded information, even when there are large number of divisions of the object distance and of the focal length includes a distance measuring device that detects the object position and transmits photographic distance information. A detecting device detects the movement amount from a standard position of the movable lens group of the lens system when the focal length of the lens system changes. A calculating device calculates the required movement of the focusing lens unit of the lens system, based on the photographic distance information and the movement amount of the movable lens unit. Finally, a controlling device drives the focusing lens unit and performs focusing, based on the required movement calculated by the calculating device. The movable lens unit moves monotonically to the object side or to an image side when the focal length of the lens system is changed. In this manner, the focusing movement required increases monotonically and gradually when the focal length of the lens system changes from the wide-angle end to the telephoto end for a given photographic distance.

Claims

1. A position controlling device of a lens system with a variable focal length;

comprising;

a distance measuring device that detects a position of an object and outputs photographic distance information;

at least one movable lens unit, said at least one movable lens unit including a first movable lens unit that is movable to change the focal length of the lens system;

a detecting device that detects an amount of movement from a standard position of said first movable lens unit when the focal length of the lens system is changed and outputs said movement amount;

a focusing lens unit that is movable for focusing;

a calculating device that directly calculates a required movement γ

of said focusing lens unit using said photographic distance information received from said distance measuring device and said movement amount received from said detecting device and outputs said required movement γ

; and

a controlling device that drives said focusing lens unit to perform focusing of said lens system, based on said required movement γ

received from said calculating device,

wherein said required movement γ

of said focusing lens unit increases monotonically and gradually throughout the change of the focal length of the lens system from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

2. A position controlling device according to claim 1, wherein said calculating device calculates said required movement γ

of said focusing lens unit, based on the following formula;

space="preserve" listing-type="equation">γ

=Σ

.sub.i Σ

.sub.j a.sub.ij (1/R).sup.i δ

.sup.j (i=1,2,3, . . . ,j=0,1,2, . . . )

where R is said photographic distance information, δ

is said movement amount of said first movable lens unit, and a_ij are fixed coefficients.

3. A position controlling device according to claim 2, wherein said first movable lens unit moves monotonically between a position toward an object side and a position toward an image side.

4. A position controlling device according to claim 2, wherein said required movement γ

of said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

5. A position controlling device according to claim 2, wherein said detecting device detects said movement amount from said standard position of said first movable lens unit when the focal length of the lens system is changed.

6. A position controlling device according to claim 2, wherein δ

is detected from an angle of rotation of a zoom lens barrel.

7. A position controlling device according to claim 2, wherein said photographic distance information is variable when said focal length of the lens system changes.

8. A position controlling device according to claim 7, wherein said first movable lens unit moves monotonically between a position toward an object side and a position toward an image side, and wherein said required movement γ

of said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

9. A position controlling device according to claim 1, wherein said first movable lens unit moves monotonically between a position toward an object side and a position toward an image side when the focal length of the lens system is changed.

10. A position controlling device according to claim 9, wherein said required movement γ

of said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

11. A position controlling device according to claim 9, wherein said detecting device detects said movement amount from said standard position of said first movable lens unit when the focal length of the lens system is changed.

12. A position controlling device according to claim 1, wherein said required movement γ

of said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

13. A position controlling device according to claim 1, wherein said detecting device detects said movement amount from said standard position of said first movable lens unit when the focal length of the lens system is changed.

14. A position controlling device of a lens system with a variable focal length, comprising:

distance measuring means for detecting a position of an object and for outputting photographic distance information;

at least one movable lens unit, said at least one movable lens unit including a first movable lens unit that is movable to change the focal length of the lens system;

detecting means for detecting an amount of movement from a standard position of said first movable lens unit when a focal length of the lens system is changed and for outputting said movement amount;

a focusing lens unit that is movable for focusing;

calculating means for directly calculating a required movement γ

of said focusing lens unit using said photographic distance information and said movement amount and then outputting said required movement γ

; and

controlling means for driving said focusing lens unit to perform focusing of said lens system, based on said required movement γ

,

wherein said photographic distance information is fixed when said focal length of the lens system changes, and wherein said required movement of said focusing lens unit increases monotonically and gradually throughout the change of the focal length of the lens system from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

15. A position controlling device according to claim 14, wherein said calculating means calculates said required movement γ

of said focusing lens unit, based on the following formula;

space="preserve" listing-type="equation">γ

=Σ

.sub.i Σ

.sub.j a.sub.ij (1/R).sup.i δ

.sup.j (i=1,2,3, . . . ,j=0,1,2, . . . )

where R is said photographic distance information, δ

is said movement amount of said one of said first movable lens unit, and a_ij are fixed coefficients.

16. A position controlling device according to claim 14, wherein said first movable lens unit moves monotonically between a position toward an object side and a position toward an image side.

17. A position controlling device according to claim 15, wherein δ

is detected from an angle of rotation of a zoom lens barrel, and wherein said photographic distance information is variable when said focal length of the lens system changes.

18. A position controlling device according to claim 17, wherein said required movement γ

of said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances.

19. A position controlling device according to claim 14, wherein said first movable lens unit moves monotonically between a position toward an object side and a position toward an image side when the focal length of the lens system is changed.

20. A position controlling device according to claim 14, wherein said required movement of γ

said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances, and wherein said detecting device detects said movement amount from said standard position of said first movable lens unit when the focal length of the lens system is changed.

21. A method of controlling a lens position of a lens system with a variable focal length having at least one movable lens unit and a focusing lens unit, the method comprising the steps of:

detecting a position of an object and outputting photographic distance information;

moving a first movable lens unit of said at least one movable lens unit to change the focal length of the lens system;

detecting an amount of movement from a standard position of said first movable lens unit when a focal length of the lens system is changed and outputting said movement amount;

directly calculating and outputting a required movement γ

of said focusing lens unit using said photographic distance information and said movement amount; and

driving said focusing lens unit to perform focusing of said lens system, based on said required movement γ

,

wherein said photographic distance information is fixed when said focal length of the lens system changes, and wherein said moving step comprises increasing moving monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances, and wherein said driving step comprises increasing driving monotonically and gradually throughout the chance of the focal length of the lens system from a wide-angle end to a telephoto end for each of the plurality of predetermined photographic distances.

22. The method of claim 21, wherein said calculating step comprises calculating said required movement γ

of said focusing lens unit, based on the following formula;

space="preserve" listing-type="equation">γ

=Σ

.sub.i Σ

.sub.j a.sub.ij (1/R).sup.i δ

.sup.j (i=1,2,3, . . . ,j=0,1,2, . . . )

where R is said photographic distance information, δ

is said movement amount of said first movable lens unit, and a_ij are fixed coefficients.

23. The method of claim 21, wherein said moving step comprises moving said first movable lens unit monotonically between a position toward an object side and a position toward an image side.

24. The method of claim 22, further comprising detecting δ

from an angle of rotation of a zoom lens barrel, wherein said photographic distance information is variable when said focal length of the lens system changes.

25. The method of claim 21, wherein said moving step comprises monotonical movement between a position toward an object side and a position toward an image side when the focal length of the lens system changes.

26. The method of claim 21, wherein said driving step comprises increasing driving monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances, and wherein said detecting step comprises detecting said movement amount from said standard position of said first movable lens unit when the focal length of the lens system is changed.

27. A position controlling device of a lens system with a variable focal length, comprising:

a distance measuring device that detects a position of an object and outputs photographic distance information;

at least one movable lens unit, said at least one movable lens unit including a first movable lens unit that is movable to change the focal length of the lens system;

a detecting device that detects an amount of movement from a standard position of said first movable lens unit when the focal length of the lens system is changed and outputs said movement amount;

a focusing lens unit that is movable for focusing;

a calculating device that directly calculates a required movement γ

of said focusing lens unit using said photographic distance information received from said distance measuring device and said movement amount received from said detecting device and outputs said required movement γ

; and

a controlling device that drives said focusing lens unit to perform focusing of said lens system, based on said required movement γ

received from said calculating device,

wherein said required movement γ

of said focusing lens unit increases monotonically and gradually when the focal length of the lens system from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances, the required movement γ

being smaller at the wide-angle end than at the telephoto end.

28. A position controlling device of a lens system with a variable focal length, comprising:

distance measuring means for detecting a position of an object and for outputting photographic distance information;

at least one movable lens unit, said at least one movable lens unit including a first movable lens unit that is movable to change the focal length of the lens system;

detecting means for detecting an amount of movement from a standard position of said first movable lens unit when a focal length of the lens system is changed and for outputting said movement amount;

a focusing lens unit that is movable for focusing;

calculating means for directly calculating a required movement γ

of said focusing lens unit using said photographic distance information and said movement amount and then outputting said required movement γ

; and

controlling means for driving said focusing lens unit to perform focusing of said lens system, based on said required movement γ

,

wherein said photographic distance information is fixed when said focal length of the lens system changes, and wherein said required movement of said focusing lens unit increases monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances, the required movement γ

being smaller at the wide-angle end than at the telephoto end.

29. A method of controlling a lens position of a lens system with a variable focal length having at least one movable lens unit and a focusing lens unit, the method comprising the steps of:

detecting a position of an object and outputting photographic distance information;

moving a first movable lens unit of said at least one movable lens unit to change the focal length of the lens system;

detecting an amount of movement from a standard position of said first movable lens unit when a focal length of the lens system is changed and outputting said movement amount;

directly calculating and outputting a required movement γ

of said focusing lens unit using said photographic distance information and said movement amount; and

driving said focusing lens unit to perform focusing of said lens system, based on said required movement γ

,

wherein said photographic distance information is fixed when said focal length of the lens system changes, and wherein said moving step comprises increasing moving monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of a plurality of predetermined photographic distances, and wherein said driving step comprises increasing driving monotonically and gradually when the focal length of the lens system changes from a wide-angle end to a telephoto end for each of the plurality of predetermined photographic distances, the required movement γ

being smaller at the wide-angle end than at the telephoto end.