Eastman-kodak Company

Other

Dennis G Howe

Joseph J Wrobel

Harold T Thomas

Hugh M Hilden

Alan B Marchant

Edward J Weldon, Jr

James K Lee

Frederick F Geyer

Jay S Schildkraut

Richard N Blazey

Mool Chand Gupta

Michael Scozzafava

James A Barnard

Evan A Edwards

James C Owens

Conrad G Houle

Kathy L Page

Bruce G Fike, Deceased

Bruce G Fike

A rapid installation and removal ladder slide prevention system is an easily installed and removed ladder slide prevention device that may be installed without the use of hand tools. The system may include an upper and a lower U-shaped bracket for each ladder leg that are slid onto the legs and secured by a bolt through the legs of the U-shaped bracket and are each locked into place with a wing nut. A cylindrical sleeve is attached to the back of each U-shaped bracket. A sharpened leg stake is able to be slid through the two sleeves on the two U-shaped brackets on each ladder leg and each adjusted in length in relation the ladder feet, and locked into place by an R-clip passed through holes in the lower bracket sleeves on each lower U-shaped bracket. The device increases ladder safety for users.

Rapid installation and removal ladder slide prevention system

In a shift correction decoder which processes d,k-constrained RLL data that is encoded in accordance with a shift correction code whose symbols in GF(p) comprise modulo p reductions of cumulative sums of successive run symbols of the RLL data (where p is an odd prime), additive errors (i.e., drop-out and drop-in errors) in the received RLL data are corrected by relying in part on information pertaining to the sequence of the polarities of successive 1-bits in the received RLL data. The polarity information is used to either insert missing 1-bits (due to drop-outs) or delete spurious 1-bits (due to drop-ins) and specify to the shift correction decoder the location of an additive error as an erasure. Synchronization slips are corrected by pre-multiplying the received codeword polynomial by a factor which reduces to two the number of errors created by a single synchronization slip. GF(p) is selected such that p.ltoreq.k-d+ 1 and the minimum distance of the shift correction code is selected to be sufficient to enable correction of a limited number of shift errors, additive errors and synchronization slips within one received codeword.

Shift correction code system for correcting additive errors and

In a shift-correcting code which represents (d,k)-constrained run-length-limited (RLL) channel data as symbols drawn from GF(p.sup.m), the encoding process produces a set of redundant parity ternary GF(p.sup.m) symbols representing three shift error conditions: forward shift, backward shift and no shift, for p=3 and m=1 for example. The encoder of the invention transforms the parity symbols into (d,k)-constrained RLL channel bits to produce a binary data sequence that can be inserted in the RLL channel data stream without a large number of linking bits to maintain compliance with the (d,k) RLL constraints. A shift error in the RLL channel data representing parity symbols affects no more than one decoded parity symbol. The encoder of the invention efficiently transforms ternary symbols into (d,k)-constrained binary data by coding successive ternary symbols into one of six binary channel words in accordance with (a) the contents of the input ternary symbol and (b) the current state of the encoder, and sets its state to one of two states in preparation for encoding the next ternary symbol. In the first state, the encoder generates one of three channel words each comprising two bits preceded by b zeroes and in the second state generates one of three channel words each comprising two bits preceded by a one and b-1 zeroes, where b is related to d and k so as to maintain the (d,k)-constraints of a number of practically useful RLL codes.

Shift-correcting code system with efficient symbol-to-channel bit

A method for coding/decoding ternary symbols to d,k-constrained binary runs in a way that (i) associates (codes) a number of ternary symbols with a lesser number of d,k-constrained binary runs and (ii) provides that an individual single-shift error in any of the received binary runs that constitute a binary data codeword will cause at most one ternary symbol to be in error in the associated (decoded) ternary symbol codeword. This method allows shift-correction codeword parity checks to be transmitted (i.e., transformed to a d,k-constrained channel data sequence) with increased efficiency, so that the required number of channel bits needed to represent the parity checks is decreased.

Shift-correction code rate-enhancing parity encoding/decoding

Channel encoded data (for example run length limited encoded data) is further encoded in accordance with a shift correction code prior to transmission. Upon reception, forward and backward shift errors present in the received channel encoded data are corrected by a shift correction decoder. The shift error correction is accomplished using a code, such as (for example) a BCH code over GF(p) or a negacyclic code, which treats each received symbol as a vector having p states. For a single shift error correction, p=3 and there are three states (forward shift, backward shift, no shift). In one embodiment, conventional error correction codewords which encode the user data may be interleaved within successive shift correction codewords prior to channel encoding, thereby enabling the error correction system to easily handle a high rate of randomly distributed shift errors (which otherwise would result in a high rate of short error bursts that exceed the capacity of the block error correction code).

Shift correcting code for channel encoded data

A photorefractive system is disclosed containing interposed between electrodes an electrophotographic photoreceptor layer unit and a layer having a second order polarization susceptibility of greater than 10.sup.-9 electrostatic units comprised of organic polar aligned noncentrosymmetric molecular dipoles having an electron donor moiety linked through a conjugated .pi. bonding system to an electron acceptor moiety. The device can be employed to transfer information from one source of electromagnetic radiation to another.

Photorefractive system and process for its use

A photographic contact printing process is disclosed having application in the mass production of replicate video discs from a master disc, and other applications wherein it is desired to replicate micro-detail over a relatively large area. A problem with conventional contact printing from a mask to a photographic medium is one of maintaining intimate contact over a relatively large area since dust, dirt, etc., are almost impossible to completely eliminate in any practical manner. In accordance with the present invention, a contact printing process is provided wherein intimate contact is not necessary for making high quality contact prints. The present invention recognizes that in contact printing information from a master disc to a replicate disc, the contact printing process is significantly less sensitive to imperfect contact between the master disc and the replicate disc if one employs a replicate disc comprising a photosensitive material having a certain optical properties. In particular, the photosensitive material initially has a high level of absorption to the actinic radiation used for exposure but, under the influence of such actinic radiation, the absorption decays to a lower level during exposure.

Producing a replicate video disc by a method of photographic contact

An improved method of optically writing and/or reading high density information involves: (1) predeterminedly positioning a flat, uniformly thick, flexible, optical disc with respect to an axis of rotation; (2) rotating the disc on such axis at a high speed and in a predeterminedly spaced relation to a predeterminedly shaped, smooth, featureless reference surface and (3) coupling a central region between the disc and reference surface to an ambient gas source. Related apparatus and disc configurations, including embodiments having flexible disc covers, also are disclosed.

Optical disc unit and method and apparatus for writing and/or reading

A method for writing and/or reading information on an optical recording element, such as an optical disk, utilizes a recording element comprising a recording layer having physical and optical properties which are optimized for phase-shift read-out. The optical properties of the recording layer give rise to a non-linear relative phase shift/layer thickness curve which, in combination with a predetermined nominal thickness of the recording layer, enhances the signal-to-noise ratio of the read-out signal.

Method for optically writing and/or reading information on optical

An optical disk unit, of the kind having a record element and a flexible cover sheet that are attached around an outer periphery in a manner providing an outer spacing and a generally enclosed inter-space therebetween, has an improved construction which significantly reduces the likelihood of contact between the record element and cover sheet. Central spacing means provide a central sheet-to-element spacing that is significantly larger than said outer spacing and vent means, into and out of the inter-space cause a reduction in the spacing between the record portion of the element and the cover sheet during write/read operation. The air flow through the vent means also reduces the formation of visible debris in the enclosed record element/cover sheet inter-space.

Protective construction for optical disk units

A recording element comprising a support having thereon a heat-deformable optical recording layer having a transparent ceramic overcoat characterized in that the overcoat has a thickness up to about 0.05 .mu.m is disclosed.

Ceramic overcoated optical recording element

The quality of spot-focus of optical writing and reading light upon the information surface of a flexible optical disc is passively enhanced by (1) rotating the disc with its neutral plane stabilized in space and (2) directing such light through the optical disc support into precise spot-focus on the information surface. With this technique spherical aberration induced by the disc support compensates for thickness variation of the support. Various structural embodiments are disclosed.

Optical disc write/read employing passive focus maintenance

High information density retrieval method and system which employ the scanning of an optical disk, having a thermally-deformable record layer overlying a reflective support, with a read light beam. The optical disk tracks contain information in the form of variable-width, approximately 0.5.pi. phase-depth, pit regions interleaved between nominal thickness land regions. The pits have varying track lengths within a pit-length range constituting a disk fractional band-width of greater than 4.0 and read light reflected from the tracks is split-detected. The split-detected, electrical analog signal is peak-detected to reconstruct recorded digital data on the disk.

Optical disk retrieval methods, media and systems employing digital data

An improved method of optically writing and/or reading high density involves: (1) predeterminedly positioning a flat, uniformly thick, flexible, optical disc with respect to an axis of rotation; (2) rotating the disc on such axis at a high speed and in a predeterminedly spaced relation to a predeterminedly shaped, smooth, featureless reference surface and (3) coupling a central region between the disc and reference surface to an ambient gas source. Related apparatus and disc configurations, including embodiments having flexible disc covers, also are disclosed.

Optical disc method, media and apparatus for writing and/or reading

In accordance with the present invention, methods and apparatus are provided for making optical disk recordings having marks in radial format, representing information signals, of total fractional bandwidths greater than about 3 wherein information is recorded along constant width tracks irrespective of the radial position of recording. Specifically, constant track width recording is achieved by controlling the various recording parameters (recording spot size, tangential velocity of the optical disk, and the modulation of the recording spot) such that the optical disk receives approximately the same maximum energy density during recording of all information marks.

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Pittsford, NY, United States of America

Dennis G Howe