US4975724A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Lens position control device
Assignee: Canon Inc
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Filing: 1989-04-18
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Granted: 1990-12-04
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Expires: 2009-04-18
Abstract
Abstract A lens position control device for an optical instrument, the instrument including a variator and a compensator, the latter of which also serves as a focusing lens, comprises a detecting circuit for detecting the positions of the variator and the focusing lens, a memory for storing information representing the location and size of an impossible-to-focus zone for the focusing lens as the function of the zooming position of the variator, and a control circuit responsive to detection of the fact that the focusing lens falls in the impossible-to-focus zone on the basis of the information stored in the memory for causing the focusing lens to retire from the impossible-to-focus zone or for prohibiting the focusing lens from further moving in a direction toward the impossible-to-focus zone.
Inventors
- 👤 Masahide Hirasawa
- 👤 Hiroyuki Wada
- 👤 Naoya Kaneda
- 👤 Hirofumi Suda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 00:51
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/282
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
167 words
A lens position control device for an optical instrument, comprising: (a) a first lens group for performing a function of varying an image magnification by moving along an optical axis; (b) a second lens group for performing both a function of compensation at the time of variation of the image magnification and a function of focusing by moving along the optical axis; (c) detecting means for detecting a position of said first lens group and a position of said second lens group; (d) an electronic memory in which position information of an impossible-to-focus zone of said second lens group based on the position of said first lens group has been stored, said impossible-to-focus zone changing with a change of position of said first lens group; and (e) control means for causing said second lens group to retire from said impossible-to-focus zone when said detecting means detects that said second lens group lies in said impossible-to-focus zone on the basis of said position information stored in said memory.
Claim 2
Dependent Claim
167 words
A lens position control device for an optical instrument, comprising: (a) a first lens group for performing a function of varying an image magnification by moving along an optical axis; (b) a second lens group for performing both a function of compensation at the time of variation of the image magnification and a function of focusing by moving along the optical axis; (c) detecting means for detecting a position of said first lens group and a position of said second lens group; (d) an electronic memory in which position information of an impossible-to-focus zone of said second lens group based on the position of said first lens group has been stored, said impossible-to-focus zone changing with a change of position of said first lens group; and (e) control means for causing said second lens group to retire from said impossible-to-focus zone when said detecting means detects that said second lens group lies in said impossible-to-focus zone on the basis of said position information stored in said memory.
Claim 3
Dependent Claim
31 words
A device according to claim 1, wherein said impossible-to-focus zone represents a zone where no in-focus state is obtained in the position of the infinity side of said second lens group.
Claim 4
Dependent Claim
36 words
A device according to claim 2, wherein said memory stores a boundary between a possible-to-focus zone of said second lens group and said impossible-to-focus zone on the basis of each position of said first lens group.
Claim 5
Dependent Claim
32 words
A device according to claim 2, wherein said detecting means includes a signal forming mechanism for outputting a movement signal in accordance with movement of said first or said second lens group.
Claim 6
Dependent Claim
28 words
A device according to claim 2, further comprising a motor for moving at least one of said first lens group and said second lens group in axial directions.
Claim 7
Dependent Claim
25 words
A device according to claim 5, wherein said detecting means includes a circuit for detecting the position by counting a driving signal of said motor.
Claim 8
Dependent Claim
33 words
A device according to claim 2, wherein said control means causes said second lens group to retire from said impossible-to-focus zone by moving said second lens group toward a minimum object distance side.
Claim 9
Dependent Claim
30 words
A device according to claim 2, wherein said control means causes said second lens group to substantially retire from said impossible-to-focus zone by causing said first lens group to move.
Claim 10
Dependent Claim
60 words
A device according to claim 2, wherein said control means selectively causes said second lens group to retire from said impossible-to-focus zone by moving said second lens group or causes said second lens group to retire from said impossible-to-focus zone by leaving said second lens group stopped, when said first lens group is being moved to vary the image magnification.
Claim 11
Dependent Claim
18 words
A device according to claim 2, wherein said lens position control device is arranged in a photographic lens.
Claim 12
Dependent Claim
171 words
A lens position control device for an optical instrument, comprising: (a) a first lens group for performing a function of varying an image magnification by moving along an optical axis; (b) a second lens group for performing a function of compensation at the time of variation of the image magnification and a function of focusing, by moving along the optical axis; (c) detecting means for detecting a position of said first lens group and a position of said second lens group; (d) an electronic memory in which position information of an impossible-to-focus zone of said second lens group based on the position of said first lens group has been stored, said impossible-to-focus zone changing with a change of position of said first lens group; and (e) control means for prohibiting said second lens group from further moving in a direction toward said impossible-to-focus zone when said detecting means detects that said second lens group lies in said impossible-to-focus zone on the basis of said position information stored in said electronic memory.
Claim 13
Dependent Claim
171 words
A lens position control device for an optical instrument, comprising: (a) a first lens group for performing a function of varying an image magnification by moving along an optical axis; (b) a second lens group for performing a function of compensation at the time of variation of the image magnification and a function of focusing, by moving along the optical axis; (c) detecting means for detecting a position of said first lens group and a position of said second lens group; (d) an electronic memory in which position information of an impossible-to-focus zone of said second lens group based on the position of said first lens group has been stored, said impossible-to-focus zone changing with a change of position of said first lens group; and (e) control means for prohibiting said second lens group from further moving in a direction toward said impossible-to-focus zone when said detecting means detects that said second lens group lies in said impossible-to-focus zone on the basis of said position information stored in said electronic memory.
Claim 14
Dependent Claim
31 words
A device according to claim 11, wherein said impossible-to-focus zone represents a zone where no in-focus state is obtained in the position of the infinity side of said second lens group.
Claim 15
Dependent Claim
36 words
A device according to claim 12, wherein said memory stores a boundary between a possible-to-focus zone of said second lens group and said impossible-to-focus zone on the basis of each position of said first lens group.
Claim 16
Dependent Claim
32 words
A device according to claim 12, wherein said detecting means includes a signal forming mechanism for outputting a movement signal in accordance with movement of said first or said second lens group.
Claim 17
Dependent Claim
28 words
A device according to claim 12, further comprising a motor for moving at least one of said first lens group and said second lens group in axial directions.
Claim 18
Dependent Claim
25 words
A device according to claim 15, wherein said detecting means includes a circuit for detecting the position by counting a driving signal of said motor.
Claim 19
Dependent Claim
33 words
A device according to claim 12, wherein said control means allows said second lens group to move only in a direction to cause said second lens group to retire from said impossible-to-focus zone.
Claim 20
Dependent Claim
18 words
A device according to claim 12, wherein said lens position control device is arranged in a photographic lens.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-03 | 1994-06-04 | 1994-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-03 | 1998-06-04 | 1998-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-03 | 2002-06-04 | 2002-12-04 | $7700.00 | Window Closed / Lapsed |