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US5337106A
Expired / Lapsed
US
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Liquid-crystal image director for single-lens-reflex camera
Assignee: Kowa Co Ltd
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Filing: 1993-06-09
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Granted: 1994-08-09
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Expires: 2013-06-09
Abstract
Abstract The mirror in a single-lens-reflex (SLR) camera is eliminated by employing a liquid crystal cell and a polarizing beam splitter. The light from an illuminating lamp (32) is linearly polarized in a horizontal direction by a polarizer (58). The polarized illuminating light is totally reflected by a polarizing beam splitter (PBS) (54) and passes through a quarterwave plate (QWP) (56) and an objective lens (36). After passing through QWP (56) for the second time, the light is vertically polarized and totally passes through PBS (54). A focusing lens (40) focuses the image onto a film (30). A voltage supply (46) is connected to a liquid-crystal (LC) cell (44) by an electric switch (52) that can turn LC cell (44) on or off. When LC cell (44) is off, the polarization of the light is rotated by 90 DEG to be horizontally polarized. Thus the light is reflected by another PBS (48) to a prism (24) for viewing by a user (26). When the LC cell (44) is on, the light polarization is not rotated, and the light is transmitted through the PBS (48) to a mechanical shutter (28). During the shutter's (28) open period, an intense light pulse from a strobe lamp (42) illuminates a patient's eye (38) and exposes film (30). Shutter (28) can be eliminated since the LC cell (44) and the PBS (48) may also function as shutter.
Inventors
- 👤 Suganda Jutamulia
- 👤 Hideaki Niwa
- 👤 Shinji Toyoda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:14
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
154 words
A light-directing mechanism for replacing a hinged mirror in a single-lens-reflex camera, comprising: polarizing means for polarizing incident light to provide a beam of polarized incident light, polarization-rotating means for rotating the polarization of said beam of polarized light to provide an output beam from said polarization-rotating means, activating means for activating said polarization-rotating means so that said output beam from said polarization-rotating means is not rotated, a polarizing beam splitter for receiving said output beam from said polarization-rotating means and causing said output beam from said polarization-rotating means to traveling in a first direction when said output beam from said polarization-rotating means is rotated and in a second direction when said output beam from said polarization-rotating means is not rotated, first utilization means for utilizing light traveling in said first direction from said polarizing beam splitter, and second utilization means for utilizing light traveling in said second direction from said polarizing beam splitter.
Claim 2
Dependent Claim
154 words
A light-directing mechanism for replacing a hinged mirror in a single-lens-reflex camera, comprising: polarizing means for polarizing incident light to provide a beam of polarized incident light, polarization-rotating means for rotating the polarization of said beam of polarized light to provide an output beam from said polarization-rotating means, activating means for activating said polarization-rotating means so that said output beam from said polarization-rotating means is not rotated, a polarizing beam splitter for receiving said output beam from said polarization-rotating means and causing said output beam from said polarization-rotating means to traveling in a first direction when said output beam from said polarization-rotating means is rotated and in a second direction when said output beam from said polarization-rotating means is not rotated, first utilization means for utilizing light traveling in said first direction from said polarizing beam splitter, and second utilization means for utilizing light traveling in said second direction from said polarizing beam splitter.
Claim 3
Dependent Claim
26 words
The mechanism of claim 1 wherein said first utilization means is a viewer and said second utilization means is a portion of film in said camera.
Claim 4
Dependent Claim
22 words
The mechanism of claim 1 wherein said polarization-rotating means is a liquid-crystal cell comprising a pair of transparent electrodes and liquid-crystal materials.
Claim 5
Dependent Claim
43 words
The mechanism of claim 1 wherein: said first utilization means is a viewer and said second utilization means is a portion of film in said camera, and said polarization-rotating means is a liquid-crystal cell comprising a pair of transparent electrodes and liquid-crystal materials.
Claim 6
Dependent Claim
317 words
A light-directing mechanism for replacing a hinged mirror in a single-lens-reflex camera, comprising: polarizing means for polarizing incident light to provide a first beam of polarized light, a first polarizing beam splitter for reflecting said first beam of polarized light to provide a reflected beam of polarized light, a quarter-wave plate for causing said reflected beam of polarized light to be circularly polarized to provide a beam of circularly polarized light, imaging means for imaging said beam of circularly polarized light onto an object so that said beam of circularly polarized light is reflected from said object to provide a reflected beam of reverse circularly polarized light so that said reflected beam of reverse circularly polarized light passes through said quarter-wave plate to cause said reflected beam of reverse circularly polarized light to be a second beam of polarized light with polarization perpendicular to the polarization of said first beam of polarized light from said polarizing means so that said second beam of polarized light passes through said first polarizing beam splitter to provide an output beam of polarized light from said first polarizing beam splitter, polarization-rotating means for rotating said output beam from said first polarizing beam splitter to provide an output beam from said polarization-rotation means, activating means for activating said polarization-rotating means so that said output beam from said polarization-rotating means is not rotated, a second polarizing beam splitter for receiving said output beam from said polarization-rotating means and causing said output beam from said polarization-rotating means to travel in a first direction when said output beam from said polarization-rotating means is rotated and in a second direction when said output beam from said polarization-rotating means is not rotated, first utilization means for utilizing light traveling in said first direction from said second polarizing beam splitter, and second utilization means for utilizing light traveling in said second direction from said second polarizing beam splitter.
Claim 7
Dependent Claim
317 words
A light-directing mechanism for replacing a hinged mirror in a single-lens-reflex camera, comprising: polarizing means for polarizing incident light to provide a first beam of polarized light, a first polarizing beam splitter for reflecting said first beam of polarized light to provide a reflected beam of polarized light, a quarter-wave plate for causing said reflected beam of polarized light to be circularly polarized to provide a beam of circularly polarized light, imaging means for imaging said beam of circularly polarized light onto an object so that said beam of circularly polarized light is reflected from said object to provide a reflected beam of reverse circularly polarized light so that said reflected beam of reverse circularly polarized light passes through said quarter-wave plate to cause said reflected beam of reverse circularly polarized light to be a second beam of polarized light with polarization perpendicular to the polarization of said first beam of polarized light from said polarizing means so that said second beam of polarized light passes through said first polarizing beam splitter to provide an output beam of polarized light from said first polarizing beam splitter, polarization-rotating means for rotating said output beam from said first polarizing beam splitter to provide an output beam from said polarization-rotation means, activating means for activating said polarization-rotating means so that said output beam from said polarization-rotating means is not rotated, a second polarizing beam splitter for receiving said output beam from said polarization-rotating means and causing said output beam from said polarization-rotating means to travel in a first direction when said output beam from said polarization-rotating means is rotated and in a second direction when said output beam from said polarization-rotating means is not rotated, first utilization means for utilizing light traveling in said first direction from said second polarizing beam splitter, and second utilization means for utilizing light traveling in said second direction from said second polarizing beam splitter.
Claim 8
Dependent Claim
26 words
The mechanism of claim 5 wherein said first utilization means is a viewer and said second utilization means is a portion of film in said camera.
Claim 9
Dependent Claim
22 words
The mechanism of claim 5 wherein said polarization-rotating means is a liquid-crystal cell comprising a pair of transparent electrodes and liquid-crystal materials.
Claim 10
Dependent Claim
43 words
The mechanism of claim 5 wherein: said first utilization means is a viewer and said second utilization means is a portion of film in said camera, and said polarization-rotating means is a liquid-crystal cell comprising a pair of transparent electrodes and liquid-crystal materials.
Claim 11
Dependent Claim
15 words
The mechanism of claim 5 wherein said object is the fundus of a human eye.
Claim 12
Dependent Claim
157 words
A light-directing mechanism for replacing a hinged mirror in a single-lens-reflex camera, comprising: polarizing means for polarizing incident light to provide a beam of polarized incident light, polarization-rotating means for rotating the polarization of said beam of polarized light to provide an output beam from said polarization-rotating means, activating means for activating said polarization-rotating means so that said output beam from said polarization-rotating means is not rotated, a polarizing beam splitter for receiving said output beam from said polarization-rotating means and causing said output beam from said polarization-rotating means to traveling in a first direction when said output beam from said polarization-rotating means is rotated and in a second direction when said output beam from said polarization-rotating means is not rotated, a viewer for receiving light traveling in said first direction from said polarizing beam splitter, and a portion of film in said camera for receiving light traveling in said second direction from said polarizing beam splitter.
Claim 13
Dependent Claim
157 words
A light-directing mechanism for replacing a hinged mirror in a single-lens-reflex camera, comprising: polarizing means for polarizing incident light to provide a beam of polarized incident light, polarization-rotating means for rotating the polarization of said beam of polarized light to provide an output beam from said polarization-rotating means, activating means for activating said polarization-rotating means so that said output beam from said polarization-rotating means is not rotated, a polarizing beam splitter for receiving said output beam from said polarization-rotating means and causing said output beam from said polarization-rotating means to traveling in a first direction when said output beam from said polarization-rotating means is rotated and in a second direction when said output beam from said polarization-rotating means is not rotated, a viewer for receiving light traveling in said first direction from said polarizing beam splitter, and a portion of film in said camera for receiving light traveling in said second direction from said polarizing beam splitter.
Claim 14
Dependent Claim
22 words
The mechanism of claim 10 wherein said polarization-rotating means is a liquid-crystal cell comprising a pair of transparent electrodes and liquid-crystal materials.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-08-08 | 1998-02-07 | 1998-08-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-08 | 2002-02-07 | 2002-08-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-08 | 2006-02-07 | 2006-08-09 | $7700.00 | Window Closed / Lapsed |