US3930261A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic focus apparatus
Assignee: Honeywell Inc
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Filing: 1974-08-27
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Granted: 1975-12-30
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Expires: 1994-08-27
Abstract
Abstract A focus control system for a still camera includes a photoelectric amplifier and a high frequency spatial filter. The filter is arranged to scan the image region of a fixed focus lens as the taking lens of the camera is moved from an extended position toward the infinity position thereof. During a first portion of the scanning movement the filter provides an initial signal representative of the brightness of the imaging light bundles for automatic gain control. The gain of a photosensitive detector is initially set during this period. During a second portion of the scanning movement, the filter moves through the image space and continues to provide a signal for adjusting the gain of the detector. This signal has a maximum amplitude as the filter passes through the actual image. A change of slope detector senses this position and actuates a mechanical stop to freeze the position of the taking lens at that position. It is contemplated that the shutter of the camera would then be released to initiate the exposure.
Inventors
- 👤 Norman L Stauffer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:29
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/30; G02B7/305
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
263 words
Optical focusing structure for a camera including a taking lens, said taking lens being adjustable through a range of positions from substantially an extended position to substantially an infinity position, a spatial frequency filter, a fixed focus lens, said fixed focus lens providing imaging light ray components in the region of said filter from a subject to be photographed, means coupled to said taking lens and to said filter and operable on command to move said taking lens progressively between the last-mentioned two positions and simultaneously to move saId filter in a first direction through said components to chop the latter, and in a second direction along said components to scan for the position of the subject image produced by said components, light sensitive detector means positioned to receive said components and to produce a detector signal of a frequency dependent upon the rate at which said filter chops said components, and of a value which reaches a maximum when said motion of said filter in said second direction causes said filter to intercept said image, peak detecting means connected to said detector means and responsive to the value of said detector signal to produce a stop signal when said value reaches said maximum, and means connected to said peak detecting means and responsive to said stop signal to stop the adjustment of said taking lens at its then position of adjustment upon the receipt of said stop signal, the last-mentioned position of said taking lens causing the latter to focus an image of said subject on a film plane of the camera.
Claim 2
Dependent Claim
263 words
Optical focusing structure for a camera including a taking lens, said taking lens being adjustable through a range of positions from substantially an extended position to substantially an infinity position, a spatial frequency filter, a fixed focus lens, said fixed focus lens providing imaging light ray components in the region of said filter from a subject to be photographed, means coupled to said taking lens and to said filter and operable on command to move said taking lens progressively between the last-mentioned two positions and simultaneously to move saId filter in a first direction through said components to chop the latter, and in a second direction along said components to scan for the position of the subject image produced by said components, light sensitive detector means positioned to receive said components and to produce a detector signal of a frequency dependent upon the rate at which said filter chops said components, and of a value which reaches a maximum when said motion of said filter in said second direction causes said filter to intercept said image, peak detecting means connected to said detector means and responsive to the value of said detector signal to produce a stop signal when said value reaches said maximum, and means connected to said peak detecting means and responsive to said stop signal to stop the adjustment of said taking lens at its then position of adjustment upon the receipt of said stop signal, the last-mentioned position of said taking lens causing the latter to focus an image of said subject on a film plane of the camera.
Claim 3
Dependent Claim
89 words
Optical focusing structure as set forth in claim 1, wherein said light sensitive detector means includes gain controlling means which determines the gain of said detector means under the control of said detector signal, and wherein said filter includes a portion which is operative during the initial movement of said filter in said first direction to make said detector signal so vary that said gain controlling means sets the gain of said detector means in accordance with the brightness level of said components emerging from said fixed focus lens.
Claim 4
Dependent Claim
85 words
Optical focusing structure as set forth in claim 2, wherein said portion of said filter causes said detector signal to vary at a relatively low frequency during said initial movement of said filter, and wherein the remainder of said filter, during the remainder of said movement of said filter in said first direction, causes said detector signal to vary at a relatively high frequency and said gain controlling means to vary the gain of said detector means in accordance with changes in said brightness level.
Claim 5
Dependent Claim
61 words
Optical focusing structure as set forth in claim 3, wherein said remainder of said filter comprises alternate transparent and opaque bars arranged in pairs, with the bars of any pair being of equal width and the widths of adjacent pairs being selected to be randomly different from each other, and wherein said bars extend transversely of said first and second directions.
Claim 6
Dependent Claim
58 words
Optical focusing structure as set forth in claim 1, wherein said filter comprises alternate transparent and opaque bars arranged in pairs, with the bars of any pair being of equal width and the widths of adjacent pairs being selected to be randomly different from each other, and wherein said bars extend transversely of said first and second directions.
Claim 7
Dependent Claim
89 words
Optical focusing structure as set forth in claim 5, wherein said light sensitive detector means includes gain controlling means which determines the gain of said detector means under the control of said detector signal, and wherein said filter includes a portion which is operative during the initial movement of said filter in said first direction to make said detector signal so vary that said gain controlling means sets the gain of said detector means in accordance with the brightness level of said components emerging from said fixed focus lens.
Claim 8
Dependent Claim
30 words
Optical focusing structure as set forth in claim 6, wherein said movement of said filter in said second direction is delayed until after said initial movement in said first direction.
Claim 9
Dependent Claim
28 words
Optical focusing structure as set forth in claim 6, wherein said filter moves in said second direction at all times that is is moving in said first direction.
References Cited (Backward Citations)
US3450018A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |