Ferroelectric Patents (Class 365/117)
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Patent number: 5361224Abstract: A nonvolatile memory device for storing data in a flip flop circuit comprising field effect transistors having respective ferroelectric gate films. A pair of writing/reading transistors is connected to the flip flop circuit. Each of the field effect transistors constituting the flip flop circuit retains its channel formation state because of a residual polarization in the ferroelectric gate film. Thus, when power goes OFF, the flip flop circuit retains its state just before power goes OFF. In this way, data can be stored on a nonvolatile basis, and stored data can be read without destroying the data. Additionally, no refreshing is needed, and therefore, a power demand in standby is reduced.Type: GrantFiled: February 24, 1993Date of Patent: November 1, 1994Assignee: Rohm Co., Ltd.Inventor: Hidemi Takasu
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Patent number: 5359565Abstract: An optical memory which allows for the high-speed random access of two-dimensional information. Portions of a light receiver made from material with photovoltaic or photoconductive effect are connected to corresponding portions of a ferroelectric liquid crystal panel through an amplifier layer. To write, a light image is shown on the light receiver. When light striking each portion of the light receiver is sufficiently strong, the state of the corresponding part of the liquid crystal panel is changed. The state of the panel can be read with an image scanner for scanning the liquid crystal panel.Type: GrantFiled: April 8, 1992Date of Patent: October 25, 1994Assignee: Yozan Inc.Inventor: Sunao Takatori
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Patent number: 5309392Abstract: In a semiconductor memory array, each cell includes a semiconductor switching element and a capacitor with a ferroelectric material layer. The ferroelectric material layer is sandwiched between opposing electrodes and exhibits a polarization varied in response to a voltage applied across the electrodes in such a manner that the direction of polarization is reversed if the voltage reaches a polarization reversal voltage. First electrodes of the capacitor elements are constituted by portions of semiconductor regions of the associated switching elements, while the second electrodes of the capacitor elements of the cells are constituted by a single common conductor layer. A first conductor is connected in common with the second main semiconductor regions of the switching elements of those cells which are on one column. A second conductor is connected in common with control electrodes of the switching elements of those cells which are on one row.Type: GrantFiled: July 6, 1993Date of Patent: May 3, 1994Assignee: Hitachi, Ltd.Inventors: Fumio Ootsuka, Masakazu Sagawa, Jun Sugiura
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Patent number: 5309390Abstract: A ferroelectric space charge capacitor memory device includes a pair of spaced first and second electrodes; a ferroelectric dielectric disposed between the electrodes; a coercive voltage supply for applying a coercive voltage to the dielectric to write the dielectric into one of two polarization states and to establish in each polarization state in the dielectric a space charge region proximate each electrode having a charge opposite to that of the electrode with a neutral region between the space charge regions, the relative sizes of the neutral and space charge regions defining the capacitance of the dielectric, the neutral region having an internal polarization field opposite to that represented by the space charge regions; a bias voltage supply for applying to the dielectric a bias voltage less than the coercive voltage at a rate lower than the rate of space charge formation to define a capacitance level representative of one of the polarization states; a pulse generator for introducing to the dielectricType: GrantFiled: November 15, 1991Date of Patent: May 3, 1994Assignee: The Charles Stark Draper Laboratory, Inc.Inventor: Ciaran J. Brennan
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Patent number: 5297077Abstract: A semiconductor memory device comprises a ferroelectric capacitor, a voltage output circuit for outputting a first voltage for reversely polarizing the ferroelectric capacitor and a second voltage by which the polarization of the ferroelectric capacitor is not reversed, regardless of data stored in the ferroelectric capacitor, a first reference capacitor having a such a capacitance as to accumulate less charge than charge which the ferroelectric capacitor accumulates, when the second voltage is applied to the ferroelectric capacitor, a second reference capacitor having such a capacitance that as to accumulate greater charge than the charge which the ferroelectric capacitor accumulates while the ferroelectric capacitor is forwardly polarized, when the first voltage is applied to the ferroelectric capacitor, thus reversely polarizing the ferroelectric capacitor, a sense amplifier connected to the ferroelectric capacitor and the first or second reference capacitor, a reference-capacitor selecting circuit for conType: GrantFiled: March 28, 1991Date of Patent: March 22, 1994Assignee: Kabushiki Kaisha ToshibaInventors: Motomasa Imai, Hiroshi Toyoda, Kazuhide Abe, Koji Yamakawa, Hisakazu Iizuka, Mitsuo Harata, Koji Sakui
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Patent number: 5257224Abstract: A plurality of strip shaped first polysilicon layers 3 are formed on a monocrystalline silicon substrate 1, a plurality of strip shaped second polysilicon layers 5 are formed thereon crossing the first polysilicon layers 3, and a plurality of strip shaped third polysilicon layers 8 are further formed thereon crossing the second polysilicon layers 5. The first and second polysilicon layers 3 and 5 are laser-annealed and monocrystallined. Contact holes 4 and 7 are selectively formed at the crossing points of the first polysilicon layers 3 and the second polysilicon layers 5, and the crossing points of the second polysilicon layers 5 and the third polysilicon layers 8. A PN junction is formed on each surface layer of the first polysilicon layers 3 and the second polysilicon layers 5 in the portions corresponding to these contact holes 4 and 7. Two layers of memory cell arrays using diode elements as memory cells are piled upon each other.Type: GrantFiled: September 3, 1991Date of Patent: October 26, 1993Assignee: Mitsubishi Denki Kabushiki KaishaInventors: Isao Nojiri, Masahide Kaneko
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Patent number: 5206829Abstract: An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.Type: GrantFiled: October 24, 1990Date of Patent: April 27, 1993Inventors: Sarita Thakoor, Anilkumar P. Thakoor
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Patent number: 5193023Abstract: A method of controlling the domain of a nonlinear ferroelectric optics substrate to form an inverted-domain structure in one major surface of a single-domain nonlinear ferroelectric optics substrate. A first electrode is formed in a first major surface of a nonlinear ferroelectric optics substrate in a pattern corresponding to a desired pattern of an inverted-domain structure to be formed, a second electrode is formed on a second major surface opposite the first major surface in a pattern corresponding to that of the first electrode or in a solid film, a dc voltage or a pulse voltage is applied across the first and second electrodes to form local, inverted domains in the desired pattern in the first major surface of the nonlinear ferroelectric optics substrate.Type: GrantFiled: July 15, 1991Date of Patent: March 9, 1993Assignee: Sony CorporationInventors: Masahiro Yamada, Koichiro Kishima
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Patent number: 5179533Abstract: An improved read/write optical disk is disclosed which is capable of being rewritten more than 10.sup.6 times. The disk utilizes a storage medium in which data is stored by causing a localized region of the storage medium to assume one of two states. The two states can be converted from one to another by the application of electric fields to the localized region of the storage medium. The localized region in question is selected by illuminating an area on an addressing layer directly above the region in question with light. The preferred embodiment utilizes a lead lanthanum zirconate titanate material for the storage medium.Type: GrantFiled: July 31, 1989Date of Patent: January 12, 1993Assignee: Radiant TechnologiesInventors: Jeff A. Bullington, Sylvia D. Mancha, Christopher DeHainaut
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Patent number: 5121353Abstract: A memory circuit including a plurality of ferroelectric capacitors arranged in a matrix, setting MOS field effect transistors for setting both electrodes of each of the ferroelectric capacitor at the same electric potential, and transmission MOS field effect transistors for transmitting information to the ferroelectric capacitors, and having a construction in which two word lines are provided corresponding to each line of the ferroelectric capacitors, one bit line is provided corresponding to each row of the ferroelectric capacitors, each of the transmission MOS field effect transistors is connected to one of the word lines and the bit line, and each of the setting MOS field effect transistors is connected to the other word line.Type: GrantFiled: July 6, 1990Date of Patent: June 9, 1992Assignee: Kabushiki Kaisha ToshibaInventor: Kenji Natori
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Patent number: 5070385Abstract: An improved non-volatile variable resistance element is disclosed. The resistive element is based on a semiconductor having a resistivity which is determined by the state of polarization of a ferroelectric layer.Type: GrantFiled: October 20, 1989Date of Patent: December 3, 1991Assignee: Radiant TechnologiesInventors: Joseph T. Evans, Jr., Jeff A. Bullington
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Patent number: 5060191Abstract: A ferroelectric memory includes a ferroelectric thin film having first and second surfaces opposite to each other, a first electrode assembly having a plurality of stripe electrodes arranged in parallel on the first surface side of the ferroelectric thin film, a second electrode assembly having a plurality of stripe electrodes arranged in parallel on the second surface side of the ferroelectric thin film to intersect the stripe electrodes of said first electrode assembly, first and second common electrodes arranged separately from the end portions of the respective first and second electrode assemblies to extend in respective directions in which the stripe electrodes of the first and second electrode assemblies are arranged, and selecting sections for respectively connecting the first and second electrode assemblies to the first and second common electrodes and selectively activating at least one of the stripe electrodes of each of the first and second electrode assemblies.Type: GrantFiled: June 28, 1989Date of Patent: October 22, 1991Assignee: Olympus Optical Co., Ltd.Inventors: Tatsuo Nagasaki, Masayoshi Omura, Hitoshi Watanabe, Shinichi Imade, Eishi Ikuta, Hiroyuki Yoshimori, Kazuhisa Yanagisawa
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Patent number: 5051950Abstract: An improved read/write optical disk is disclosed which is capable of being rewritten more than 10.sup.6 times. The disk utilizes a storage medium in which data is stored as different polarization states in the same phase of the material. The preferred embodiment utilizes a lead lanthanum zirconate titanate material for the storage medium. The state of polarization of the material at the location of a specified data bit is changed by applying a voltage to the bit location in question. The location is specified by illuminating the surface of the disk with light in the infra-red.Type: GrantFiled: July 31, 1989Date of Patent: September 24, 1991Assignee: Radiant TechnologiesInventors: Joseph T. Evans, Jr., Jeff A. Bullington
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Patent number: 5016992Abstract: A magnetic storage medium is read by incident polarized light and reflected outgoing light defining a common plane. The polarized incident light preferably has a polarization vector at 40.degree. to 50.degree. to this plane and at the storage medium, the magnetization is in a direction perpendicular to the plane. The preamplified output signal V.sub.M from the photodiode transducing the outgoing light beam has a fixed value V.sub.O subtracted therefrom where V.sub.O is a function of the sensitivity and resolving power of the electronic circuitry. The signal V.sub.M -V.sub.O is then amplified and processed to represent the stored data.Type: GrantFiled: March 13, 1990Date of Patent: May 21, 1991Assignee: Forschungszentrum Julich GmbHInventors: Theo Woike, Detlef Kerkmann, Thomas Beier, Wolfgang Krasser, Danilo Pescia
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Patent number: 4996667Abstract: A novel electron beam addressible recording device is disclosed, in which a recording layer formed of ferroelectric material having secondary electron emissivity .delta. greater than 1 is provided in a vacuum chamber. One surface of the recording layer is applied with a predetermined potential and the other surface is caused to have different potentials from the predetermined potential by scanning it with an electron beam. The difference of the potentials between two surfaces of the recording layer, causes poling patterns corresponding to the data recorded to be formed. The recorded data in the form of poling direction can be detected by electron beam scanning.Type: GrantFiled: February 5, 1990Date of Patent: February 26, 1991Assignee: Sony CorporationInventors: Kanji Murano, Senri Miyaoka
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Patent number: 4984198Abstract: The disclosed liquid crystal electrooptic memory device uses a ferroelectric liquid crystal sandwiched by a pair of molecular oriented films attached to opposite surfaces thereof, and a pair of transparent conductive films are attached to the outside surfaces of the molecular oriented films, respectively. An impedance having a constant electrostatic capacitance and a variable resistance is connected to one of the transparent conductive films. Further, an electric pulse source is connected across the transparent conductive films through the impedance. When a pulse from the pulse source is applied to the transparent conductive films, light transmittance of the ferroelectric liquid crystal is set at different levels depending on the resistance of the impedance. Thus, the resistance of the impedance is memorized in the form of the light transmittance of the ferroelectric liquid crystal. The impedance can be in the form of a photoconductive film attached to the molecular oriented film.Type: GrantFiled: March 20, 1990Date of Patent: January 8, 1991Assignee: Tokyo University of Agriculture and TechnologyInventors: Shunsuke Kobayashi, Hidenori Ikeno, Hiroki Maeda, Bai Y. Zhang, Masaaki Yoshida
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Patent number: 4972370Abstract: A three-dimensional memory element comprises a multilayer tunnel switch portion formed by alternately stacking conductive films and insulating films, both the ends of the switch portion consisting of insulating films, a write electrode formed on the insulating film as one end of the multilayer tunnel switch portion, a read electrode formed on the insulating film as the other end of the multilayer tunnel switch portion, and charge accumulating capacitors respectively connected to the conductive films of the multilayer tunnel switch portion.Type: GrantFiled: August 24, 1989Date of Patent: November 20, 1990Assignee: Olympus Optical Co., Ltd.Inventors: Masamichi Morimoto, Yoshiyuki Mimura, Yasuo Isono
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Patent number: 4954985Abstract: A card with a display function and a data storage capability comprises a pair of substrates; a plurality of electrodes on the substrates; a liquid crystal orientation control film on the electrodes; and a liquid crystal material with a strong dielectric property filled between the pair of substrates; wherein the liquid crystal material with the strong dielectric property is utilized to provide for a liquid crystal display region and a data storage region to write in, erase, and rewrite external data by addition of external energy to the liquid crystal material.Type: GrantFiled: May 9, 1988Date of Patent: September 4, 1990Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Shunpei Yamazaki
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Patent number: 4945514Abstract: A method for bistable storage of binary optical information includes an antiferroelectric (AFE) lead lanthanum zirconate titanate (PLZT) layer having a stable antiferroelectric first phase and a ferroelectric (FE) second phase obtained by applying a switching electric field across the surface of the device. Optical information is stored by illuminating selected portions of the layer to photoactivate an FE to AFE transition in those portions. Erasure of the stored information is obtained by reapplying the switching field.Type: GrantFiled: May 31, 1988Date of Patent: July 31, 1990Inventor: Cecil E. Land
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Patent number: 4918654Abstract: A transpolarizer is employed as a programmable capacitance divider. Two ferroelectric capacitors are coupled in series to form a common node and two extreme poles. The polarization of the two capacitors is set by grounding the two poles and then bringing them both up to VCC while impressing a voltage at the common node corresponding to data to be stored. Therefore, while one pole is held at VSS, the other pole is pulsed from VSS to VCC with the common node floating. A voltage develops at the common node which is above or below the midpoint between VSS and VCC, and will be indicative of the stored data. The capacitance divider is programmed in accordance with data. One such divider is added to a DRAM memory cell to form a shadow DRAM cell. Two such dividers are added to a static RAM memory cell to form a shadow static RAM cell. The same divider arrangement is operable in both volatile and non-volatile modes. An improvement arises by using PZT as dielectric in 54:46 mole ratio.Type: GrantFiled: January 3, 1989Date of Patent: April 17, 1990Assignee: Ramtron CorporationInventors: S. Sheffield Eaton, Jr., Michael Parris
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Patent number: 4914627Abstract: A transpolarizer is employed as a programmable capacitance divider. Two ferroelectric capacitors are coupled in series to form a common node and two extreme poles. The polarization of the two capacitors is set by grounding the two poles and then bringing them both up to VCC while impressing a voltage at the common node corresponding to data to be stored. Therefore, while one pole is held at VSS, the other pole is pulsed from VSS to VCC with the common node floating. A voltage develops at the common node which is above or below the midpoint between VSS and VCC, and will be indicative of the stored data. The capacitance divider is programmed in accordance with data. One such divider is added to a DRAM memory cell to form a shadow DRAM cell. Two such dividers are added to a static RAM memory cell to form a shadow static RAM cell. The same divider arrangement is operable in both volatile and non-volatile modes. An improvement arises by using PZT as dielectric in 54:46 mole ratio.Type: GrantFiled: January 3, 1989Date of Patent: April 3, 1990Assignee: Ramtron CorporationInventors: S. Sheffield Eaton, Jr., Michael Parris
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Patent number: 4910708Abstract: A transpolarizer is employed as a programmable capacitance divider. Two ferroelectric capacitors are coupled in series to form a common node and two extreme poles. The polarization of the two capacitors is set by grounding the two poles and then bringing them both up to VCC while impressing a voltage at the common node corresponding to data to be stored. Therefore, while one pole is held at VSS, the other pole is pulsed from VSS to VCC with the common node floating. A voltage develops at the common node which is above or below the midpoint between VSS and VCC, and will be indicative of the stored data. The capacitance divider is programmed in accordance with data. One such divider is added to a DRAM memory cell to form a shadow DRAM cell. Two such dividers are added to a static RAM memory cell to form a shadow static RAM cell. The same divider arrangement is operable in both volatile and non-volatile modes. An improvement arises by using PZT as dielectric in 54:46 mole ratio.Type: GrantFiled: January 3, 1989Date of Patent: March 20, 1990Assignee: Ramtron CorporationInventors: S. Sheffield Eaton, Jr., Michael Parris
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Patent number: 4888630Abstract: A non-volatile memory cell having a floating-gate transistor is disclosed, which has a ferroelectric material for the dielectric between the floating gate electrode and the control gate electrode. The ferroelectric material provides for non-linear capacitance characteristics with voltage, and is polarizable into two states by the application of voltage across the capacitor plates of sufficient magnitude. The memory cell is read by applying a voltage to the control gate electrode which will sufficiently be capacitively coupled to the floating gate electrode to turn on the transistor when the ferroelectric material is in the programmed state, but which will not be sufficiently coupled in the erased state to turn the transistor on. The ferroelectric material may be incorporated directly above the floating gate transistor electrode, or may be formed remotely from the transistor between two metal layers, the lower of which is connected to the floating gate electrode.Type: GrantFiled: March 21, 1988Date of Patent: December 19, 1989Assignee: Texas Instruments IncorporatedInventor: James L. Paterson
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Patent number: 4873455Abstract: The network comprises several memory elements made of ferroelectric polymer, arranged in a matrix organization at the intersections of row and column electrodes. Each memory element (Mij) memorizes a synaptic coefficient a.sub.ij of the network which may be restored by pyroelectric effect on the corresponding column of the network. Amplifier circuits, respectively connected to the columns, give a voltage which is equal to the sum, to which a sign is assigned, of the products of the synaptic coefficients by the voltage components applied to each of the lines of the network.Type: GrantFiled: October 17, 1988Date of Patent: October 10, 1989Assignee: Thomson-CSFInventors: Emmanuel de Chambost, Francois Micheron, Francois Vallet, Jean-Michel Vignolle
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Patent number: 4855976Abstract: An improved magneto-optical disc memory writing and reading method with a ferroelectric liquid crystal (FLC) is shown. As FLC a chiral smectic liquid crystal is employed to exhibit a hysteresis between a pair of substrates which have easy polarization axes normal to each other. Informations to be recorded are written on the disc in terms of a binary system by use of the hysteresis.Type: GrantFiled: March 3, 1988Date of Patent: August 8, 1989Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Shunpei Yamazaki
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Patent number: 4853911Abstract: An improved magneto-optical disc memory recording and reading system with a ferroelectric liquid crystal (FLC) is shown. As FLC a chiral smectic liquid crystal is employed to exhibit a bistability between a pair of substrates which have easy polarization axes normal to each other. Informations to be recorded are written on the disc in terms of a binary system by use of the bistability.Type: GrantFiled: June 13, 1986Date of Patent: August 1, 1989Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Shunpei Yamazaki
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Patent number: 4845695Abstract: An improved magneto-optical disc memory with a ferroelectric liquid crystal (FLC) is shown. As FLC a chiral smectic liquid crystal is employed to exhibit a hysteresis between a pair of substrates which have easy polarization axes normal to each other Informations to be recorded are written on the disc in terms of a binary system by use of the hysteresis.Type: GrantFiled: October 8, 1987Date of Patent: July 4, 1989Assignee: Semiconductor Energy Laboratory Co., Ltd.Inventor: Shunpei Yamazaki
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Patent number: 4731754Abstract: An electro-optic memory effect providing for storing, erasing and rewriting igital information relies upon a ferroelectric polymer, polyvinylidene fluoride. Recent development of tri-fluoroethylene copolymers of this material with Curie temperatures below the melting point provides a means of selective writing, storage and erasure. The advantage of the polyvinylidene fluoride material for optical recording is its high chemical and physical stability. This material provides a mechanism for bit-by-bit erasure and long time storage of information.Type: GrantFiled: September 12, 1985Date of Patent: March 15, 1988Assignee: The United States of America as represented by the Secretary of the NavyInventors: T. Roger Ogden, Debra M. Gookin
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Patent number: 4420772Abstract: Methods and apparatus for reading information from a record with the aid of a plurality of electrically controlled light gates illuminate the light gates with light of a first intensity above zero light intensity and precondition the light gates to subsequent opening in response to electric control signals by electrically biasing the light gates to an initially open condition wherein the gates pass light from the illumination at an intensity above zero light intensity and below a second intensity lower than the first intensity.Type: GrantFiled: July 20, 1981Date of Patent: December 13, 1983Assignee: Bell & Howell CompanyInventor: John H. Jacobs
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Patent number: 4391901Abstract: The photosensitivity of lead lanthanum zirconate titanate (PLZT) ceramic material used in high resolution, high contrast, and non-volatile photoferroelectric image storage and display devices is enhanced significantly by positive ion implantation of the PLZT near its surface. Implanted ions include H.sup.+, He.sup.+, Ne.sup.+, Ar.sup.+, as well as chemically reactive ions from Fe, Cr, and Al. The positive ion implantation advantageously serves to shift the absorption characteristics of the PLZT material from near-UV light to visible light. As a result, photosensitivity enhancement is such that the positive ion implanted PLZT plate is sensitive even to sunlight and conventional room lighting, such as fluorescent and incandescent light sources. The method disclosed includes exposing the PLZT plate to the positive ions at sufficient density, from 1.times.10.sup.12 to 1.times.10.sup.17, and with sufficient energy, from 100 to 500 KeV, to provide photosensitivity enhancement.Type: GrantFiled: January 28, 1982Date of Patent: July 5, 1983Assignee: The United States of America as represented by the United States Department of EnergyInventors: Cecil E. Land, Paul S. Peercy
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Patent number: 4360894Abstract: Domain wall motion in a slab of ferroelectric material gives rise to an electrical signal which may correspond, e.g., to electrode width fluctuations or to a radiation pattern incident on a sensitive layer. A device may have numerous ferroelectric readout tracks, in which case the number of electrical leads can be minimized by a layout in which unidirectional movement of a planar ferroelectric domain wall not only serves to scan a track but also select a track from a large number of tracks. Such device operation is a feature of a device in which a ferroelectric slab is cut, e.g., in the manner of a comb or ladder. Resulting devices may be operated by judicious cycling of voltages at as few as two control electrodes, one defining an access track, and the other being common to the readout tracks.Type: GrantFiled: November 20, 1980Date of Patent: November 23, 1982Assignee: Bell Telephone Laboratories, IncorporatedInventor: John M. Geary
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Patent number: 4348611Abstract: A pyroelectric or ferroelectric sensing element consists of a substrate with a thin layer of sodium nitrite. Electrodes may be applied to both sides of the sodium nitrite layer, or, alternatively, only one electrode may be used. In one embodiment, an array of electrodes is applied to one side of a continuous sodium nitrite layer, while the other side has a continuous electrode. In another embodiment, the sodium nitrite layer consists of separate portions, each interposed between one electrode of an electrode array and either the substrate or a second, continuous electrode.Type: GrantFiled: December 5, 1980Date of Patent: September 7, 1982Inventors: Wolfgang Ruppel, Ullrich Hetzler, Horst Vogt, Peter Wurfel
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Patent number: 4285576Abstract: Light is selectively gated with an array of electrically switchable illuminated light gates in an electrooptically active solid-state material displaying field-induced and photoinduced birefringence between a light polarizer and a complementary light analyzer. The illuminated light gates are selectively switched through field-induced birefringence by selective application of externally provided electric potentials, until photoinduced birefringence occurs in the light gate array. Such photoinduced birefringence is neutralized by illuminating the light gates in circumvention in either the polarizer or the analyzer while maintaining externally provided electric potentials away from the light gates.Type: GrantFiled: May 7, 1979Date of Patent: August 25, 1981Assignee: Bell & Howell CompanyInventors: Thomas H. Garland, Michael T. Zimmerman
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Patent number: 4250567Abstract: A three dimensional memory which is comprised of a plurality of stacked memory planes, each of which includes at least a continuous transparent photovoltaic-ferroelectric layer sandwiched between two continuous plane transparent electrodes. In one embodiment, the memory planes are comprised of only the photovoltaic-ferroelectric layer sandwiched between the two electrodes, and in another embodiment the ferroelectric layer and a continuous transparent photoconductive layer are sandwiched between the two electrodes.Type: GrantFiled: June 20, 1979Date of Patent: February 10, 1981Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Philip S. Brody
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Patent number: 4247914Abstract: A three dimensional memory having an increased storage capacity. The memory block has a matrix of cylindrical cavities, each of which has a fiber optic light guide means disposed therein. Each light guide means is comprised of a cylindrical core having a first index of refraction and a cladding surrounding the core having a second, smaller index of refraction; a plurality of spaced deformations are formed at the core-cladding interface for allowing light to leak out of the guide laterally.Type: GrantFiled: June 12, 1979Date of Patent: January 27, 1981Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Philip S. Brody
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Patent number: 4158201Abstract: A flat PLZT plate is utilized to form erasable images thereon which images may be projected or viewed directly. One embodiment includes electrically conductive islands on one side of the PLZT plate which are surrounded by and electrically isolated from an electrically conductive grid pattern. The portion of the PLZT plate located between an island and the surrounding portion of the grid pattern constitutes a pixel or image forming element. By grounding the grid pattern and applying an electrical charge to selected ones of the islands, an image can be formed on the PLZT plate which can be viewed directly or projected by means of polarized light. In order to form the erasable images on the PLZT plate by optical means, the grid pattern and islands are coated with a layer of photoconductive material upon which a layer of a transparent conductor is coated.Type: GrantFiled: October 18, 1977Date of Patent: June 12, 1979Assignee: The Singer CompanyInventors: Michael R. Smith, Richard H. Burns
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Patent number: 4139908Abstract: A data recording and read-out apparatus and method in which a ferroelectric eramic substrate is remanently polarized to store information. Upon being illuminated, the substrate produces a photovoltaic voltage, which is detected to effect read-out. A disk of ferroelectric ceramic material to which information is entered by spiral tracking, either in a single track or in multiple tracks. A self-scanning data record comprised of a plurality of ferroelectric ceramic cells which are remanently polarized, and which are read out by a register.Type: GrantFiled: August 15, 1977Date of Patent: February 13, 1979Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Philip S. Brody
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Patent number: 4103341Abstract: A method of transferring remanent polarization information from a photovoic ferroelectric unit to a polarizable unit which may either be another portion of the photovoltaic ferroelectric material or a separate piece of material. The photovoltaic ferroelectric unit is illuminated to produce a photovoltage and the voltage is applied to the unit to be polarized to induce the polarization. An optically addressable read-write photovoltaic ferroelectric memory plane having means for allowing writing and erasing of information by the transfer of remanent polarization from one portion of the memory plane to another.Type: GrantFiled: August 15, 1977Date of Patent: July 25, 1978Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Philip S. Brody
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Patent number: 4101975Abstract: A high storage capacity, fast access time, photovoltaic ferroelectric mem apparatus including a plurality of memory planes which are stacked in a three dimensional configuration. Each plane is comprised of a photovoltaic ferroelectric layer and a photoconductive layer sandwiched between two electrodes. Writing of information is effected by illuminating a selected xy location on the planes while simultaneously applying a voltage pulse to a selected z plane, and reading is effected by illuminating a selected xy location while connecting a selected z plane to a read amplifier.Type: GrantFiled: August 15, 1977Date of Patent: July 18, 1978Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Philip S. Brody
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Patent number: 4085576Abstract: Disclosed is an electronic timepiece display arrangement in which certain rroelectric monocrystals having two stable optical states may be switched from one state to another by voltage pulses applied through electrodes. A polarizing filter is located past one face of the crystal and a reflecting surface is located past the opposite face. A second crystal and a second polarizer are employed in certain embodiments.Type: GrantFiled: September 11, 1974Date of Patent: April 25, 1978Assignee: Societe Suisse pour l'Industrie Horlogere Management Services, S.A.Inventor: Jacques Alain Deverin
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Patent number: 4086124Abstract: In a method of polarization of a ferroelectric material having a Curie point at a temperature T.sub.c, the material is brought to a temperature above T.sub.c, subjected to a temperature gradient and then returned to a temperature below the Curie point. No electric field is applied, because the temperature gradient itself has been found to produce ferroelectric polarization under the described circumstances.Type: GrantFiled: May 19, 1975Date of Patent: April 25, 1978Assignee: Commissariat a l'Energie AtomiqueInventors: Jean Claude Peuzin, Michel Tasson
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Patent number: 4071841Abstract: For dielectric matrix devices, plural stripe-shaped vertical and horizontal electrodes are crossed with each other respectively and disposed on the front surface of a predetermined dielectric plate, while on the back surface of said dielectric substrate independent electrodes are disposed on both the corresponding portions to the crossed areas of horizontal and vertical electrodes and the neighboring portions to these areas.The present dielectric matrix element is characterized in that the lead wire to the horizontal and vertical electrodes disposed on the dielectric substrate is connected to only one side of this dielectric substrate.Type: GrantFiled: October 21, 1975Date of Patent: January 31, 1978Assignee: Hitachi, Ltd.Inventor: Akio Kumada