US4389659A
Expired / Lapsed
US
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Electro-optic line printer
Assignee: Xerox Corp
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Filing: 1980-09-17
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Granted: 1983-06-21
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Expires: 2000-09-17
Abstract
Abstract In an electro-optic line printer having a light valve comprising an electro-optic element with a plurality of individually addressable electrodes, sample and hold circuits maintain the data samples for each line of an image on the electrodes for essentially a full line printing time to increase the exposure contrast. A multiplexer may be used to ripple the data samples of a serial data stream onto the electrodes, and the polarity of the data samples applied to the electrodes may be occassionally reversed to prevent optical damage to the electro-optic element. Moreover, a pair of longitudinally displaced and laterally staggered electrode arrays may be used in light valves which rely on fringe fields to avoid electrode aligned blind spots.
Inventors
- 👤 Robert A. Sprague
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 18:28
CPC Classifications
B; B41; B41J; B41J2/00; B41J2/435; B41J2/465; G; G02; G02F; G02F1/00; G02F1/01; G02F1/03; G02F1/0305; G02F1/0316; G06; G06K; G06K15/00; G06K15/02; G06K15/12; G06K15/1238; G06K15/1242; G06K15/1252
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
183 words
In an electro-optic line printer having a multi-gate light valve for p-modulating a sheet-like, collimated light beam in accordance with input data samples of finite duration representing individual picture elements of an image, and p-sensitive optics for imaging the modulated light beam onto a photosensitive recording medium which advances in a cross line direction relative to said light valve, whereby said recording medium is exposed in an image configuration; said light valve including an optically transmissive electro-optic element having a predetermined optical axis, and a plurality of individually addressable electrodes intimately coupled to said electro-optic element, said electrodes being spaced apart orthogonally relative to said optical axis; the improvement comprising respective sample and hold circuits coupled to said electrodes for maintaining the data samples for each line of said image on said electrodes for period of time longer than the duration of any of said data samples, thereby increasing the exposure of said recording medium; said sample and hold circuits including capacitive storage means; said capacitive storage means being defined in substantial part by distributed capacitance between said electrodes and said electro-optic element.
Claim 2
Dependent Claim
183 words
In an electro-optic line printer having a multi-gate light valve for p-modulating a sheet-like, collimated light beam in accordance with input data samples of finite duration representing individual picture elements of an image, and p-sensitive optics for imaging the modulated light beam onto a photosensitive recording medium which advances in a cross line direction relative to said light valve, whereby said recording medium is exposed in an image configuration; said light valve including an optically transmissive electro-optic element having a predetermined optical axis, and a plurality of individually addressable electrodes intimately coupled to said electro-optic element, said electrodes being spaced apart orthogonally relative to said optical axis; the improvement comprising respective sample and hold circuits coupled to said electrodes for maintaining the data samples for each line of said image on said electrodes for period of time longer than the duration of any of said data samples, thereby increasing the exposure of said recording medium; said sample and hold circuits including capacitive storage means; said capacitive storage means being defined in substantial part by distributed capacitance between said electrodes and said electro-optic element.
Claim 3
Dependent Claim
31 words
The improvement of claim 1 wherein said sample and hold circuits maintain the data samples for each line of said image on said electrodes for nearly a full line printing time.
Claim 4
Dependent Claim
22 words
The improvement of claim 1 wherein said electrodes are at a Bragg angle relative to the optical axis of said electro-optic element.
Claim 5
Dependent Claim
46 words
The improvement of claim 3 wherein said sample and hold circuits maintain the data samples for each line of said image on said electrodes for approximately a full line printing time, and said capacitance substantially solely defines the storage means of said sample and hold circuits.
Claim 6
Dependent Claim
88 words
The improvement of claim 1 wherein said electro-optic element has a reflecting surface, said light beam is applied to said electro-optic element at a grazing angle of incidence relative to said reflecting surface and is brought to a wedge shaped focus on said surface to be totally internally reflected therefrom, said individually addressable electrodes are intimately coupled to said electro-optic element adjacent said reflecting surface for creating electric fringe fields within said electro-optic element to phase front modulate said light beam, and said p-sensitive optics are Schleiren optics.
Claim 7
Dependent Claim
34 words
The improvement of claim 5 wherein said electro-optic element is a crystal having a polished input face, a polished output face, and a polished reflecting surface between said input face and said output face.
Claim 8
Dependent Claim
49 words
The improvement of claim 5 wherein said individually addressable electrodes are paired with respective ground plane electrodes, and said ground plane electrodes are intimately coupled to said electro-optic element adjacent said reflecting surface and are distributed across said electro-optic element in alternating paired relationship with said individually addressable electrodes.
Claim 9
Dependent Claim
29 words
The improvement of claim 7 wherein said individually addressable electrodes and said ground plane electrodes are at a Bragg angle relative to the optical axis of said electro-optic element.
Claim 10
Dependent Claim
23 words
The improvement of claim 7 further including means for repeatedly reversing the polarity of said data samples relative to said ground plane electrodes.
Claim 11
Dependent Claim
97 words
The improvement of claim 1 further including a serial data bus for supplying said input data samples in adjacent picture element sequence and at a predetermined data rate, respective sampling gates for said sample and hold circuits, said sampling gates being coupled between said data bus and respective ones of said individually addressable electrodes, and a controller coupled to said sampling gates for sequentially and cyclically enabling said sampling gates at a ripple rate selected to match said data rate, whereby data samples for adjacent picture elements are rippled onto adjacent ones of said individually addressable electrodes.
Claim 12
Dependent Claim
83 words
The improvement of claim 10 wherein said sample and hold circuits further include respective reset gates, said reset gates being coupled between respective ones of said individually addressed electrodes and a ground plane, and said controller is coupled to said reset gates for sequentially and cyclically enabling said reset gates at said ripple rate with a phase delay relative to the enabling of said sampling gates, thereby causing said data samples to be held on said electrodes for said extended period of time.
Claim 13
Dependent Claim
29 words
The improvement of claim 11 wherein said phase delay is selected to cause said data samples to be held on said electrodes for substantially a full line printing time.
Claim 14
Dependent Claim
22 words
The improvement of claim 10 wherein the storage elements of said sample and hold circuits are substantially solely defined by said capacitance.
Claim 15
Dependent Claim
118 words
The improvement of claim 10 wherein said electro-optic element has a reflecting surface, said light beam is applied to said electro-optic element at a grazing angle of incidence relative to said reflecting surface and is brought to a wedge shaped focus on said surface to be totally internally reflected therefrom, said individually addressable electrodes are intimately coupled to said electro-optic element adjacent said reflecting surface for creating electric fringe fields within an interaction region of said electro-optic element proximate said reflecting surface, whereby the phase front of said light beam is modulated in accordance with the data samples applied to said electrodes as said light beam passes through said interaction region, and said p-sensitive optics are Schleiren optics.
Claim 16
Dependent Claim
22 words
The improvement of claim 14 wherein said electrodes are at a Bragg angle relative to the optical axis of said electro-optic element.
Claim 17
Dependent Claim
84 words
The improvement of claim 14 further including a plurality of ground plane electrodes, said ground plane electrodes being intimately coupled to said electro-optic element adjacent said reflecting surface and being distributed across said electro-optic element in alternating paired relationship with said individually addressable electrodes; and a plurality of reset gates coupled between respective ones of said individually addressable electrodes and said ground plane electrodes to reset said sample and hold circuits once per line scanning time in response to control signals from said controller.
Claim 18
Dependent Claim
54 words
The improvement of claim 1 wherein said light valve has first and second sets of electrodes longitudinally displaced from one another along said optical axis, the electrodes of said first and second sets being intimately coupled to said electro-optic element and being distributed thereacross in laterally staggered relationship for spatially modulating said light beam.
Claim 19
Dependent Claim
92 words
The improvement of claim 17 wherein said first and second sets of electrodes create electric fringe fields in said electro-optic element in response to said data samples, thereby modulating the phase front of said light beam in response to said data samples, said data samples are simultaneously applied to corresponding electrodes of said first and second sets, whereby all parts of the phase front of said light beam are modulated in accordance with said data samples, despite any electrode aligned nulls in said fringe fields, and said p-sensitive optics are Schleiren optics.
Claim 20
Dependent Claim
133 words
The improvement of claim 18 wherein said electro-optic element has a reflecting surface, said first and second sets of electrodes are intimately coupled to said electro-optic element adjacent said reflecting surface to create said fringe fields in an interaction region proximate said reflecting surface, and said light beam is applied to said electro-optic element at a grazing angle of incidence relative to said reflecting surface and is brought to a wedge shaped focus on said reflecting surface along a line approximately midway between said first and second sets of said electrodes, whereby said light beam interacts with the fringe fields created by said first set of electrodes while approaching said reflecting surface and with the fringe fields created by said second set of electrodes after being totally internally reflected from said reflecting surface.
Claim 21
Dependent Claim
24 words
The improvement of claim 19 wherein the corresponding electrodes of said first and second sets are electrically interconnected to receive said data samples simultaneously.
References Cited (Backward Citations)
US3829608A
Cited
US4281904A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-06-20 | 1986-12-20 | 1987-06-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-06-20 | 1990-12-20 | 1991-06-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-06-20 | 1994-12-20 | 1995-06-21 | $7700.00 | Window Closed / Lapsed |