US3822091A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic focusing apparatus
Assignee: Eastman Kodak Co
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Filing: 1973-04-13
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Granted: 1974-07-02
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Expires: 1993-04-13
Abstract
Abstract In image projection apparatus having an optical axis, automatic focusing apparatus maintaining the focus of an image projected along said axis from an image bearing medium irrespective of changes in location of the image layer of such medium. The apparatus includes an image bearing medium support including a pair of transparent members which hold the image bearing medium substantially flat. The opposing surfaces of the transparent members are provided with transparent conductive coatings adapted to contact the image bearing medium held between the members. Light from an illuminating source is transmitted through the image bearing medium and heats up the image layer of a supported medium. The conductive coatings in contact with the image layer will also heat up effecting a change in the electrical resistance thereof. The conductive coatings are part of an electrical circuit which develops a signal representative of the location of the heated image layer. This signal may be used in a variety of ways to adjust the focal distance to maintain the projected image in focus. In a preferred embodiment the signal is applied to a rotary solenoid to alternately position an optical compensating member into and out of the optical axis of the image projector.
Inventors
- 👤 C Altmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:54
CPC Classifications
G; G03; G03B; G03B21/00; G03B21/14; G03B21/53; G02; G02B; G02B7/00; G02B7/28; G02B7/36; G03B19/00; G03B19/18
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
136 words
In image projection apparatus having an optical axis, the combination comprising: support means positioned along said optical axis for supporting an image bearing medium having an image layer; focusable projection means positioned along said optical axis for projecting a focused image from said image bearing medium along said axis; illuminating means for illuminating a supported medium with light whereby the image layer thereof is heated up through absorption of light by said layer; heat sensing means responsive to the heat from the heated image layer of the supported medium for developing a signal representative of the location of the image layer; and control means responsive to said signal for controlling said projection means to thereby change the focus of said projection means as a function of the location of the image layer of the supported medium.
Claim 2
Dependent Claim
136 words
In image projection apparatus having an optical axis, the combination comprising: support means positioned along said optical axis for supporting an image bearing medium having an image layer; focusable projection means positioned along said optical axis for projecting a focused image from said image bearing medium along said axis; illuminating means for illuminating a supported medium with light whereby the image layer thereof is heated up through absorption of light by said layer; heat sensing means responsive to the heat from the heated image layer of the supported medium for developing a signal representative of the location of the image layer; and control means responsive to said signal for controlling said projection means to thereby change the focus of said projection means as a function of the location of the image layer of the supported medium.
Claim 3
Dependent Claim
72 words
The combination of claim 1 wherein said projection means includes a co-plano transparent member movable between a first position wherein said transparent member is out of the optical axis and a second position wherein said transparent member is in the optical axis and wherein said control means includes means for moving said co-plano member between said first and said second positions in response to said signal developed by said heat sensing means.
Claim 4
Dependent Claim
61 words
The combination of claim 1 wherein said support means includes a pair of transparent members which support an image bearing medium substantially flat and wherein said heat sensing means includes transparent electrically conductive layers on opposing inner surfaces of said transparent members, said electrically conductive layers being in contact with said image bearing medium when the medium is supported substantially flat.
Claim 5
Dependent Claim
53 words
The combination of claim 1 wherein said focusing means includes a projection lens movably mounted for movement along said optical axis and wherein said control means includes means for moving said projection lens as a function of the location of the image layer of an image bearing medium supported by said support means.
Claim 6
Independent Claim
92 words
A method of automatically maintaining the focus of an image projected by focusable projection means along an optical axis of projection apparatus comprising: supporting an image bearing medium having an image layer along said optical axis; illuminating said image bearing medium with light whereby said image layer is heated up through absorption of light; sensing the location of the heated image layer and producing an electrical signal representative of the location of said layer; and focusing the focusable projection means positioned along said optical axis as a function of said electrical signal.
Claim 7
Independent Claim
92 words
A method of automatically maintaining the focus of an image projected by focusable projection means along an optical axis of projection apparatus comprising: supporting an image bearing medium having an image layer along said optical axis; illuminating said image bearing medium with light whereby said image layer is heated up through absorption of light; sensing the location of the heated image layer and producing an electrical signal representative of the location of said layer; and focusing the focusable projection means positioned along said optical axis as a function of said electrical signal.
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) | 1977-07-01 | 1977-12-31 | 1978-07-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-01 | 1981-12-31 | 1982-07-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-01 | 1985-12-31 | 1986-07-02 | $7700.00 | Window Closed / Lapsed |