US2743430A - Information storage devices - Google Patents
Information storage devices Download PDFInfo
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- US2743430A US2743430A US274485A US27448552A US2743430A US 2743430 A US2743430 A US 2743430A US 274485 A US274485 A US 274485A US 27448552 A US27448552 A US 27448552A US 2743430 A US2743430 A US 2743430A
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- current
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- cell
- film
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- 210000004027 cell Anatomy 0.000 description 31
- 239000000463 material Substances 0.000 description 23
- 229910052981 lead sulfide Inorganic materials 0.000 description 12
- 229940056932 lead sulfide Drugs 0.000 description 12
- 239000004020 conductor Substances 0.000 description 11
- 238000000576 coating method Methods 0.000 description 5
- 238000000151 deposition Methods 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- WUPHOULIZUERAE-UHFFFAOYSA-N 3-(oxolan-2-yl)propanoic acid Chemical compound OC(=O)CCC1CCCO1 WUPHOULIZUERAE-UHFFFAOYSA-N 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 3
- 230000004913 activation Effects 0.000 description 3
- 229910052980 cadmium sulfide Inorganic materials 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- XSOKHXFFCGXDJZ-UHFFFAOYSA-N telluride(2-) Chemical compound [Te-2] XSOKHXFFCGXDJZ-UHFFFAOYSA-N 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000001413 cellular effect Effects 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 150000003346 selenoethers Chemical class 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- 101150004141 Vcan gene Proteins 0.000 description 1
- AQCDIIAORKRFCD-UHFFFAOYSA-N cadmium selenide Chemical compound [Cd]=[Se] AQCDIIAORKRFCD-UHFFFAOYSA-N 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000009791 electrochemical migration reaction Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 230000000873 masking effect Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 239000011669 selenium Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- 210000000352 storage cell Anatomy 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C13/00—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00
- G11C13/04—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using optical elements ; using other beam accessed elements, e.g. electron or ion beam
- G11C13/048—Digital stores characterised by the use of storage elements not covered by groups G11C11/00, G11C23/00, or G11C25/00 using optical elements ; using other beam accessed elements, e.g. electron or ion beam using other optical storage elements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
- H01J9/233—Manufacture of photoelectric screens or charge-storage screens
Definitions
- This invention relates to devices for storage of information. f More particularly, the invention relates to improvements in devices which store information in response Fto alight stimulus and release the stored information, also, in response to stimulation of light energy.
- the invention is based upon the discovery that a certain light-sensitive material can be made photo-voltaic .witli a'polarity in one sense if current is first passed through in a lcertain direction, while itv can be made photo-voltaic with a polarity in the opposite sense if cur- 'rent is lirst passed through it in the opp'osite direction.
- a photo-voltaic element of this nature is placed in electrically conductive contact with another element composed of photo-conductive material, which acts as a light switch,'apparatus may be constructed for storing information which may exist in either of two different forms and for making this information available at a later time.
- the storage effect decreases with time, however, the lim'it'of storage length being about l hour after activation has occurred.
- An activated lm of lead sulfide is preferred as the directionally sensitive photo-voltaic 'material, although" the selenide or telluride of lead may also be used.
- the photo-conductive material may be cadmium sulfide, selenide, or telluride, selenium, antimonyitrioxide or trisultide, mercuric sulde, or any one of many' other materials well known yto vhave this property.
- Lead sulfide has previously been known as a photo- 'conductive material sensitive to ordinary light energy and, when specially activated, has also been known to be sensitive to energy in the infra-red portion of theenergy spectrum.
- the present invention ho'wever, is based upon the discovery of another particular novel property of an activated film of lead sulfide.
- the lead sulfide may be deposited'from the vapor phase in vacuo and then activated by heating in the presence of oxygen for about to minutes at v1100"-475 C.
- the activated film is modified by electrolytic migration so that ifordinary light energy is directed upon it, it will exhibit a photo-voltaic effect with a polarity in one sense. If the current'is passed through in the opposite direction -and light is again directed upon the lm, it will then exhibit a photo-voltaic effect with polarity in a sense opposite to that exhibited previously.
- One object of the present invention is to provide a novel light-sensitive information storage cell.
- Another object of the invention is to provide ran improved apparatus for. storing information of a binary nature.
- Another objectpof the invention is to provide an improved photo-sensitive memory device.
- a further object of the invention is to provide an irnproved apparatus for recording and, later, delivering information.
- a still further object of the invention is to provide an improved.lightserisitive memory cell which is simple to construct and operate.
- FIG. l is a plan view of a novel unit cell constructed in accordance with the present invention.
- Figure 2 is a diagrammatic view of apparatus, including the cell of Figure l in cross section, for recording information and for later reading the stored information,
- Figure 3 is a screen containing a plurality of unit cells such as illustrated in' Figure l, and
- Figure 4 is an apparatus utilizing the screen of Figure 3.
- the cell may comprise an insulating base plate 2, which may be of glass, mica, or other material having electrical insulating and heat resistant properties.
- insulating base plate 2 which may be of glass, mica, or other material having electrical insulating and heat resistant properties.
- One of the major surfaces of the base plate is provided with two oppositely positioned electrodes 4 and 6. These may be prepared by painting a stripe of colloidal graphite suspension along two opposing edges of the surface and then drying. These electrodes may also be of gold or platinum or some other conductive material which does not react with the surface coatings later to be applied.
- a coating of lead sulfide 8 This may be deposited by masking the portion of the surface not to be covered, placing the base plate in a vacuum chamber and then evaporating and depositing the lead sulfide.
- the lead sulde may be evaporated from a tantaluni boat heated with a tungsten filament and the pressure in -the vacuum chamber may be of the order of 10-5 mm. of mercury. The thickness of the deposited film is' not critical.
- the deposited film is then activated by heating it in the presence of oxygen for about 5 to 20 minutes at a temperature of about 400-475 C.
- the next step of preparing a unit cell is the deposition of the photo-conductive portion 10. This may be done by ⁇ masking the coating S already deposited, placing the partially coated base plate once more in the'vacuum chamber and depositing a coating of a photo-conductive material on the unmasked portion of the plate such that the photo-conductive material is in contact with the activated'lead'sullide.
- the deposition may be carried out in a manner similar to the deposition of the lead sulfide previously described.
- the material is then given such activation treatment as may be required by the particular photo-conductor used.
- the photo-conductive portion may comprise a coating of cadmium sulfide or any one of many other materials.
- the cell describedabove may be utilized in information storage apparatus, one simple example of which is illustrated in Figure 2.
- the electrodes 4 and 6 of the cell of Figure l are connected through leads 12 and 14, respectively, to the poles of a' conventional reversing switch 16, which may be either solenoid operated or -manually operated.
- a source of direct current such as a battery 18, is connected to one side of the switch.
- An optical system 24 may also be provided for focusing the light from the source onto the coated surface ofthe cell.
- the light source is turned on and the cell illuminated, causing the photoconductive portion 10 to assume a conductive condition.
- the information may be Asuch as to indicate either one of two dilerent conditions (for example, to indicate l or 0),
- the information 1 may lcorrespond to the .condition existing when a is and b is The information 0 will then correspond to the condition existing when a is and b is L+.
- the switch 16 Ais 'controlled such that current -is made to flow from a to Jb.
- the switch is reversed such that current is caused to flow from b to a.
- the yreversing switch 16 may either Abe controlled manually by yan operator or Vautomatically from a source such as a punched tape.
- the current may be passed through the cell for a ile'ngthof .time from the order of a few :hundredths .of a
- thecurrent from .'th'esource 18 is cut off and the coated surface ofthe cell, including the pho'to-voltaic portion y8 is again illuminated bythe light source 20.
- This activates both the photoconductive and the photo-voltaic portion and a small -current will be generated inthe electrode .leads, the electrodes having a polarity depending upon the vmanner in which current was originally passed through the cell when the information was stored.
- any polarity-sensing ydevice 24, such ,as a galvanometer or ahigh impedance vamplifier is lconnectedvto ⁇ the electrode leads of the cell.
- lamps 26 'and';28 deflection -of the armature in one direction can be utilized to close con- :tacts to one of the lamps, while opposite deflection of the :armature can be used to close another pair loft contacts closing a circuit through the other lamp.
- the information y may Aalso be recorded on a photographic, magnetic, or lpunched tape.
- a plurality of storage elements such as described 'in connection with Figure l, may be incorporated on a screen 30 such as illustrated in Figure 3.
- This screen comprises .a relatively large base plate 32, which maybe of fglass, '.with a large number of cells 34 on one Vof its surfaces.
- Each cell has electrodes similar 'tovthose described in connection with the single cell. All corresponding electrodes on the side of each cell containing the photo-voltaic material 'are connected in parallel to one of themain leads 36,
- a multi-element screen 30 is'placed, preferably with its coated'face adjacent lthe phosphor coated screen 40 of a cathode ray-tube 42 hav- 'ing'horizontal deflection yoke transformer coils 44 and lvertical-yoke transformer coils v46.
- rIfhe phosphor'ernf ployed in this type of tube is of the short-decay lperiod type.
- Each of the deflection ⁇ yokes l is lprovided with a Vsource f A.C. potentialfor sweep voltage purposes.
- the spotof light illuminates each unit cell in turn and as eachvcell is illuminated, the reversing switch (as shown in Figure 2) is ⁇ operated and D.C. potential is applied to the leads 48 and 50 such'that current flows throughy the illuminatedcell in either one direction lor the other.
- This operation .conditions each cell so -that when itis later 4 illuminated to read the information it contains, it will vexhibit a polarityeither in ,one sense or theother.
- a conventional light beam scanning device may be used to illuminate each of the unit cells.
- the stored information is read from each cell by again scanning with the moving spot of light and applying the output voltage to a polarity sensing device such as that previously described.
- the -reversing switch is held at a .neutral position so that Ano current from the D.C. source is being applied to the cell.
- the apparatus ymaybe used by directing ⁇ a beam of energy at any particularelement of the screen desired without scanning 'the entire screen.
- a focused light beam may be directed to one particular ⁇ element, or, a beam of electrons maybe 4directed to -a corresponding part of .a phosphor screen.
- the apparatus illustrated-in Figure-4 includesc'ontrols for applying -any desired relative Vpotentials to .each 'of the horizontal deflection .plates V52 and to each of the -vertical deflection .plates 54.
- These control means- may comprise .potentiometers 56 and 58 connected to a common source of D.C. potential.
- the sliding contact 60 of potentiometer 56 may be connected to one of the horizontal ⁇ deflection plates, the .other plate of the pair being grounded.
- the sliding contact v62 of -potentiometer 58 is connected to one of the vertical deflection plates, kthe other being connected to ground.
- the potentials applied to the horizontal and vertical deflection plates may be varied so 'as ,to direct the beam of electrons to any desired part ofi the Iviewing screen40.
- Electrical apparatus comprising a cell having abase plate, one portion of said plate being coated with a photoconductive material and another adjacent portion of 'which is coated with directionally sensitive photovoltaic lead sulfide in electrical contact with said photoconduc- 'tivematerial land in the form ofa film that can be given a first polarity when current is passed therethrough fin Eone ,direction and can be given the opposite polarity whencurrent Vis passed therethrough-in theopposite direction, and an electrode in contact with each of said portions.
- Apparatus according to claim 3 including means for applying a potential of desired polarity to said electrodes.
- Apparatus according to claim 4 including, in addition, means for applying a beam of light to both of said coated portions of said plate.
- Apparatus according to claim V5 including, also, means connected to said electrodes for detecting the polarity of said electrodes.
- Apparatus comprising a plate having a surface comprising a plurality of cellular elements, each of said elements comprising one surface portion film of a photoconductive material and an adjacent surface portion film of a directionally sensitive photo-voltaic material consisting essentially of lead sulfide in electrical contact with said photo-conductive material and that can be given a first polarity when current is passed therethrough in one direction and can be given the voppositelpolarity when current is passed therethrough in the opposite direction, an electrode connected to each of said portions of each of said elements, means for passing a weak current across said photovoltaic film in either of two opposite directions, means for directing a beam of light to any of said elements, and means for detecting the polarity of any of said electrodes when light is directed to the element connected thereto.
- An information storage and indicating apparatus comprising an element including a film of material that can be made photo-voltaic with a first polarity when current is passed through said film in one direction and which can be made photo-voltaic with a second polarity opposite to that of said first polarity when current is passed through said film in another direction opposite to said one direction, a film of photo-conductive material adjacent and in contact with said film of photovoltaic material, and an electrode in contact with each of said films.
- Apparatus according to claim 8 including means for applying a potential of desired polarity to said electrodes.
- Apparatus according to claim 9 including means for applying a beam of light to said film.
- Apparatus according to claim 10 including means for detecting the polarity of said electrodes when light is directed onto both of said lms.
- a method of storing information of a binary nature comprising rendering directionally photo-voltaic in a desired sense a film of photo-voltaic material having the property of assuming a polarity in one sense when current is passed through in a first direction and of assuming a polarity in an opposite sense when current is passed through in a second direction opposite to said first direction, and, later, reading said information by directing a beam of light onto said film while detecting the polarity of said film.
- a method according to claim 12 including placing a film of photo-conductive material adjacent and in contact with said film of photo-voltaic material and directing light onto said photo-conductive film whenever it is desired to pass a current through said photo-voltaic film.
- Apparatus comprising a plate having a surface comprising a plurality of cellular elements, each of said elements comprising one surface portion film of a photoconductive material and an adjacent surface portion film of a directionally sensitive photovoltaic material in electrical contact with said photo-conductive material that can be given a first polarity when current is passed through said film in one direction and the opposite polarity when current is passed through in the opposite direction, an electrode connected to each of said portions of each of said elements, means for passing a weak current across said photovoltaic film in either of said two directions, means for directing a beam of light to any of said elements, and means for detecting the polarity of any of said electrodes when light is directed to the element connected thereto.
- An electrical cell comprising a layer of photovoltaic material having the property of assuming a polarity in one sense when current is passed therethrough in a first direction and of assuming polarity in an opposite sense when current is passed therethrough in the opposite direction, means for selectively passing current through said layer in either of said directions and means for directing light upon said layer.
Description
April 24, 1956 M. L. scHuL-rz ETAL 2,743,430
INFORMATION STORAGE DEVICES Filed March 1, 1952 Paz/iwf 5MM/6 bfi Dir/cf- AVC,
:inventors 'MELVIN I.. B :HuL-rz EEEJREE H MDRTDN Gttomeg INFORMATION sroRAGE DEVICES Melvin L. Schultz and George A. Morton, Princeton, N. J.,
assignors to Radio Corporation of America, a corporation of Delaware Application March 1, 1952, Serial No. 274,485
16 Claims.` (Cl. 340-473) This invention relates to devices for storage of information. f More particularly, the invention relates to improvements in devices which store information in response Fto alight stimulus and release the stored information, also, in response to stimulation of light energy.
The invention is based upon the discovery that a certain light-sensitive material can be made photo-voltaic .witli a'polarity in one sense if current is first passed through in a lcertain direction, while itv can be made photo-voltaic with a polarity in the opposite sense if cur- 'rent is lirst passed through it in the opp'osite direction. When a photo-voltaic element of this nature is placed in electrically conductive contact with another element composed of photo-conductive material, which acts as a light switch,'apparatus may be constructed for storing information which may exist in either of two different forms and for making this information available at a later time. The storage effect decreases with time, however, the lim'it'of storage length being about l hour after activation has occurred. An activated lm of lead sulfide is preferred as the directionally sensitive photo-voltaic 'material, although" the selenide or telluride of lead may also be used. The photo-conductive material may be cadmium sulfide, selenide, or telluride, selenium, antimonyitrioxide or trisultide, mercuric sulde, or any one of many' other materials well known yto vhave this property.
Lead sulfide has previously been known as a photo- 'conductive material sensitive to ordinary light energy and, when specially activated, has also been known to be sensitive to energy in the infra-red portion of theenergy spectrum. The present invention, ho'wever, is based upon the discovery of another particular novel property of an activated film of lead sulfide. The lead sulfide may be deposited'from the vapor phase in vacuo and then activated by heating in the presence of oxygen for about to minutes at v1100"-475 C. lf a current is'then passed through it in one direction, it has now been found that the activated film is modified by electrolytic migration so that ifordinary light energy is directed upon it, it will exhibit a photo-voltaic effect with a polarity in one sense. If the current'is passed through in the opposite direction -and light is again directed upon the lm, it will then exhibit a photo-voltaic effect with polarity in a sense opposite to that exhibited previously.
. One object of the present invention is to provide a novel light-sensitive information storage cell.
,Another object of the invention is to provide ran improved apparatus for. storing information of a binary nature.
Another objectpof the invention is to provide an improved photo-sensitive memory device.
A further object of the invention is to provide an irnproved apparatus for recording and, later, delivering information.
A still further object of the invention is to provide an improved.lightserisitive memory cell which is simple to construct and operate.
These and other objects will be more apparent and the invention will be morereadily understood from the following'description, including the drawings, of which:
- Figure l is a plan view of a novel unit cell constructed in accordance with the present invention,
Figure 2 is a diagrammatic view of apparatus, including the cell of Figure l in cross section, for recording information and for later reading the stored information,
Figure 3 is a screen containing a plurality of unit cells such as illustrated in'Figure l, and
Figure 4 is an apparatus utilizing the screen of Figure 3.
Referring now to Figure l, there is shown one embodiment of a unit cell constructed in accordance with the invention. The cell may comprise an insulating base plate 2, which may be of glass, mica, or other material having electrical insulating and heat resistant properties. One of the major surfaces of the base plate is provided with two oppositely positioned electrodes 4 and 6. These may be prepared by painting a stripe of colloidal graphite suspension along two opposing edges of the surface and then drying. These electrodes may also be of gold or platinum or some other conductive material which does not react with the surface coatings later to be applied.
Upon one-half the surface of the plate, including that part covered by one of the electrodes 4, there is then deposited a coating of lead sulfide 8. This may be deposited by masking the portion of the surface not to be covered, placing the base plate in a vacuum chamber and then evaporating and depositing the lead sulfide. The lead sulde may be evaporated from a tantaluni boat heated with a tungsten filament and the pressure in -the vacuum chamber may be of the order of 10-5 mm. of mercury. The thickness of the deposited film is' not critical. The deposited film is then activated by heating it in the presence of oxygen for about 5 to 20 minutes at a temperature of about 400-475 C.
The next step of preparing a unit cell is the deposition of the photo-conductive portion 10. This may be done by`masking the coating S already deposited, placing the partially coated base plate once more in the'vacuum chamber and depositing a coating of a photo-conductive material on the unmasked portion of the plate such that the photo-conductive material is in contact with the activated'lead'sullide. The deposition may be carried out in a manner similar to the deposition of the lead sulfide previously described. The material is then given such activation treatment as may be required by the particular photo-conductor used. As also indicated previously, the photo-conductive portion may comprise a coating of cadmium sulfide or any one of many other materials.
The cell describedabove may be utilized in information storage apparatus, one simple example of which is illustrated in Figure 2. The electrodes 4 and 6 of the cell of Figure l are connected through leads 12 and 14, respectively, to the poles of a' conventional reversing switch 16, which may be either solenoid operated or -manually operated. A source of direct current, such as a battery 18, is connected to one side of the switch. There mayalso be provided alight source 20'having a switch 22 for turning the source oi and on as desired. An optical system 24 may also be provided for focusing the light from the source onto the coated surface ofthe cell.
To store information on the cell, the light source is turned on and the cell illuminated, causing the photoconductive portion 10 to assume a conductive condition. When used as a' binary memory ydevice in which the information may be Asuch as to indicate either one of two dilerent conditions (for example, to indicate l or 0),
current may be passed through the cell either from a to b Vmainlead 38. :upon or read from each element, -using any'well `known -system such .as that illustrated in Figure 4.
3 or from b --to atto establish the reading polarity. The information 1 .may lcorrespond to the .condition existing when a is and b is The information 0 will then correspond to the condition existing when a is and b is L+. 'If it iis then desired to store @the information 1, the switch =16 Ais 'controlled such that current -is made to flow from a to Jb. `If it is desired to store the infomation 0, the switch is reversed such that current is caused to flow from b to a. In order to control the .direction of current flow, the yreversing switch 16 may either Abe controlled manually by yan operator or Vautomatically from a source such as a punched tape.
The current may be passed through the cell for a ile'ngthof .time from the order of a few :hundredths .of a
second to several seconds; i. e.,.4.o'r V5. 'lhevoltagexof the current source Vmay be from la-.few volts, say, about -10, -to yseveral '-hundred. Although v.neither -time or .passage Vof. the current nor magnitude .of voltage is critical, the
subsequentoutputof fphoto current will depend upon the magnitude of these two factors. The'longer the time of passage of current and the higher the voltage the higher i -thezoutput current up to saturation.
To read back the stored information, thecurrent from .'th'esource 18 is cut off and the coated surface ofthe cell, including the pho'to-voltaic portion y8 is again illuminated bythe light source 20. This activates both the photoconductive and the photo-voltaic portion and a small -current will be generated inthe electrode .leads, the electrodes having a polarity depending upon the vmanner in which current was originally passed through the cell when the information was stored. To detect the polarity, any polarity-sensing ydevice 24, such ,as a galvanometer or ahigh impedance vamplifier is lconnectedvto `the electrode leads of the cell. This mayihave visible indicating means, such as lamps 26 'and';28, one .of which lights when the-voltage is of one polarity and the other of which lights Awhen the voltage is of. opposite polarity. For example, ifa galvanometer'is used, deflection -of the armature in one direction can be utilized to close con- :tacts to one of the lamps, while opposite deflection of the :armature can be used to close another pair loft contacts closing a circuit through the other lamp. The information ymay Aalso be recorded on a photographic, magnetic, or lpunched tape.
,In order to store a large number of items of information,
a plurality of storage elements, such as described 'in connection with Figure l, may be incorporated on a screen 30 such as illustrated in Figure 3. This screen comprises .a relatively large base plate 32, which maybe of fglass, '.with a large number of cells 34 on one Vof its surfaces. Each cell has electrodes similar 'tovthose described in connection with the single cell. All corresponding electrodes on the side of each cell containing the photo-voltaic material 'are connected in parallel to one of themain leads 36,
while all the electrodes in contact with the photo-conductiveinaterial portion of each cell are connected-,to -another Information can thenbe stored rapidly Referring now to Figure 4, a multi-element screen 30 is'placed, preferably with its coated'face adjacent lthe phosphor coated screen 40 of a cathode ray-tube 42 hav- 'ing'horizontal deflection yoke transformer coils 44 and lvertical-yoke transformer coils v46. rIfhe phosphor'ernf ployed in this type of tube is of the short-decay lperiod type. Each of the deflection `yokes lis lprovided with a Vsource f A.C. potentialfor sweep voltage purposes. As the electron beam is swept across the face of the tube, ,the spotof light illuminates each unit cell in turn and as eachvcell is illuminated, the reversing switch (as shown in Figure 2) is `operated and D.C. potential is applied to the leads 48 and 50 such'that current flows throughy the illuminatedcell in either one direction lor the other. This operation .conditions each cell so -that when itis later 4 illuminated to read the information it contains, it will vexhibit a polarityeither in ,one sense or theother.
Instead of a cathode rayV tube, a conventional light beam scanning device may be used to illuminate each of the unit cells.
The stored information is read from each cell by again scanning with the moving spot of light and applying the output voltage to a polarity sensing device such as that previously described. The -reversing switch is held at a .neutral position so that Ano current from the D.C. source is being applied to the cell.
Instead of applying and reading information from a multi-element screen by means of a flying spot scanning device, the apparatus ymaybe used by directing `a beam of energy at any particularelement of the screen desired without scanning 'the entire screen. Using a two-dimensional coordinate system, a focused light beam may be directed to one particular` element, or, a beam of electrons maybe 4directed to -a corresponding part of .a phosphor screen. vThis maybe kdone with suitable x, y 'coordinate controls for directing either the light bearnfor the electron .beam tothe desired pointon the screen. Conventional oscillographs khave controls for 'thus-directing the electron beam. The apparatus illustrated-in Figure-4 includesc'ontrols for applying -any desired relative Vpotentials to .each 'of the horizontal deflection .plates V52 and to each of the -vertical deflection .plates 54. These control means-may comprise .potentiometers 56 and 58 connected to a common source of D.C. potential. The sliding contact 60 of potentiometer 56 may be connected to one of the horizontal `deflection plates, the .other plate of the pair being grounded. '.In a similar manner, the sliding contact v62 of -potentiometer 58 is connected to one of the vertical deflection plates, kthe other being connected to ground.` By varying the settings of the sliding contacts in conventional manner, the potentials applied to the horizontal and vertical deflection plates may be varied so 'as ,to direct the beam of electrons to any desired part ofi the Iviewing screen40. There has thus been described a 'novel method ,and yapparatus for storing information of a binary nature and, later, reading the stored information. The invention is based on the discovery. that certain materials, such as :lead sulfide, telluride, or selenide, when specially activated,
exhibit a photo-voltaic effect with one polarity if current iszrst passed through in one directionduring light ,activation and the opposite polarity if current is first `passed lthrough in the :opposite direction while light is `directed onalm of the material.
:We claim as our invention:
l. Electrical :apparatus .comprising a cell having .fa
surface, a first portion of vwhich is .composedofaphotovconductive material and ,a second portion of 4which is composed 'of a photo-voltaic material capable ofvchang- .ing the direction of its 'photo-current output and Lconsisting essentially of directionally sensitive photovoltaic -lead sulfide in the form of a film -that can begiven '.a
first polarity-when current is passed therethroughin lone direction and Vcan be given the opposite polarity when current is passed therethrough in the opposite direction, said second portion being in -electrical contactvwith said first portion, and 'an electrode in contact with each of said portions.
2. A device accordingto claim l in which saidphotoconductive material is cadmium sulfide.
3. Electrical apparatus comprising a cell having abase plate, one portion of said plate being coated with a photoconductive material and another adjacent portion of 'which is coated with directionally sensitive photovoltaic lead sulfide in electrical contact with said photoconduc- 'tivematerial land in the form ofa film that can be given a first polarity when current is passed therethrough fin Eone ,direction and can be given the opposite polarity whencurrent Vis passed therethrough-in theopposite direction, and an electrode in contact with each of said portions.
4. Apparatus according to claim 3 including means for applying a potential of desired polarity to said electrodes.
5. Apparatus according to claim 4 including, in addition, means for applying a beam of light to both of said coated portions of said plate.
6. Apparatus according to claim V5 including, also, means connected to said electrodes for detecting the polarity of said electrodes.
7. Apparatus comprising a plate having a surface comprising a plurality of cellular elements, each of said elements comprising one surface portion film of a photoconductive material and an adjacent surface portion film of a directionally sensitive photo-voltaic material consisting essentially of lead sulfide in electrical contact with said photo-conductive material and that can be given a first polarity when current is passed therethrough in one direction and can be given the voppositelpolarity when current is passed therethrough in the opposite direction, an electrode connected to each of said portions of each of said elements, means for passing a weak current across said photovoltaic film in either of two opposite directions, means for directing a beam of light to any of said elements, and means for detecting the polarity of any of said electrodes when light is directed to the element connected thereto.
8. An information storage and indicating apparatus comprising an element including a film of material that can be made photo-voltaic with a first polarity when current is passed through said film in one direction and which can be made photo-voltaic with a second polarity opposite to that of said first polarity when current is passed through said film in another direction opposite to said one direction, a film of photo-conductive material adjacent and in contact with said film of photovoltaic material, and an electrode in contact with each of said films.
9. Apparatus according to claim 8 including means for applying a potential of desired polarity to said electrodes.
10. Apparatus according to claim 9 including means for applying a beam of light to said film.
11. Apparatus according to claim 10 including means for detecting the polarity of said electrodes when light is directed onto both of said lms.
12. A method of storing information of a binary nature comprising rendering directionally photo-voltaic in a desired sense a film of photo-voltaic material having the property of assuming a polarity in one sense when current is passed through in a first direction and of assuming a polarity in an opposite sense when current is passed through in a second direction opposite to said first direction, and, later, reading said information by directing a beam of light onto said film while detecting the polarity of said film.
13. A method according to claim 12 including placing a film of photo-conductive material adjacent and in contact with said film of photo-voltaic material and directing light onto said photo-conductive film whenever it is desired to pass a current through said photo-voltaic film.
14. Apparatus comprising a plate having a surface comprising a plurality of cellular elements, each of said elements comprising one surface portion film of a photoconductive material and an adjacent surface portion film of a directionally sensitive photovoltaic material in electrical contact with said photo-conductive material that can be given a first polarity when current is passed through said film in one direction and the opposite polarity when current is passed through in the opposite direction, an electrode connected to each of said portions of each of said elements, means for passing a weak current across said photovoltaic film in either of said two directions, means for directing a beam of light to any of said elements, and means for detecting the polarity of any of said electrodes when light is directed to the element connected thereto.
15. An electrical cell comprising a layer of photovoltaic material having the property of assuming a polarity in one sense when current is passed therethrough in a first direction and of assuming polarity in an opposite sense when current is passed therethrough in the opposite direction, means for selectively passing current through said layer in either of said directions and means for directing light upon said layer.
16. A cell according to claim 15 in which said photovoltaic material is lead sulfide.
References Cited in the le of this patent UNITED STATES PATENTS 2,160,383 Kannenberg May 30, 1939 2,258,294 Lubszynski et al. Oct. 7, 1941 2,406,139 Fink et al. Aug. 20, 1946 2,416,215 Rath Feb. 18, 1947 2,540,490 Bittner Feb. 6, 1951 2,698,928 Pulvari Ian. 4, 1955
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US274485A US2743430A (en) | 1952-03-01 | 1952-03-01 | Information storage devices |
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US274485A US2743430A (en) | 1952-03-01 | 1952-03-01 | Information storage devices |
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Cited By (38)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2816850A (en) * | 1953-12-30 | 1957-12-17 | Bell Telephone Labor Inc | Semiconductive translator |
US2891169A (en) * | 1955-09-02 | 1959-06-16 | Rca Corp | Electroluminescent device to give negative pictures |
US2905830A (en) * | 1955-12-07 | 1959-09-22 | Rca Corp | Light amplifying device |
US2912592A (en) * | 1954-10-07 | 1959-11-10 | Horizons Inc | Memory device |
US2926336A (en) * | 1955-04-14 | 1960-02-23 | Bell Telephone Labor Inc | Ferroelectric device |
US2939029A (en) * | 1958-12-08 | 1960-05-31 | Du Pont | Method of image storage and release |
US2953690A (en) * | 1957-09-03 | 1960-09-20 | Nat Res Dev | Photosensitive cells, radiation filters and semiconductor materials for use in such cells and filters |
US2957991A (en) * | 1957-09-30 | 1960-10-25 | Rca Corp | Photoconductive control circuit for light amplifiers and like device |
US2961546A (en) * | 1956-07-19 | 1960-11-22 | Brunsviga Maschinenwerke Ag | Apparatus for electrically transmitting decade counter tube results |
US2968799A (en) * | 1957-10-24 | 1961-01-17 | Ibm | Magnetic transducer |
US2968724A (en) * | 1957-06-28 | 1961-01-17 | California Research Corp | Pulse height analyzer |
US2981777A (en) * | 1956-05-11 | 1961-04-25 | Donald C Reynolds | Cadmium sulfide barrier layer cell |
US3007139A (en) * | 1956-05-22 | 1961-10-31 | Ibm | Circuit element for use in logical and memory circuits |
US3011157A (en) * | 1958-04-16 | 1961-11-28 | Ncr Co | Storage devices |
US3017612A (en) * | 1956-11-23 | 1962-01-16 | Nat Scient Lab Inc | Method and apparatus for storing information |
US3028499A (en) * | 1959-11-02 | 1962-04-03 | Gen Electric | Expanded scale photoelectric device |
US3037189A (en) * | 1958-04-23 | 1962-05-29 | Sylvania Electric Prod | Visual display system |
US3043961A (en) * | 1955-08-26 | 1962-07-10 | Rca Corp | Electroluminescent device and circuits therefor |
US3050580A (en) * | 1957-02-04 | 1962-08-21 | Xerox Corp | Electrostatic techniques |
US3054961A (en) * | 1958-07-11 | 1962-09-18 | Ibm | Information storage device employing atomic particle bombardment to effect semi-permanent change in target lattice |
US3059115A (en) * | 1958-04-10 | 1962-10-16 | Sylvania Electric Prod | Energy storage device |
US3060317A (en) * | 1959-12-30 | 1962-10-23 | Ibm | Memory device |
US3069551A (en) * | 1957-05-16 | 1962-12-18 | Ass Elect Ind Woolwich Ltd | Electrical apparatus for intensifying images |
US3072832A (en) * | 1959-05-06 | 1963-01-08 | Texas Instruments Inc | Semiconductor structure fabrication |
US3082392A (en) * | 1959-02-17 | 1963-03-19 | Santa Barbara Res Ct | Composite infrared radiation detector |
US3121861A (en) * | 1960-06-27 | 1964-02-18 | Gen Dynamics Corp | Storage apparatus |
US3146138A (en) * | 1961-07-10 | 1964-08-25 | Fred A Shirland | Vacuum evaporated barrier for a cds crystal |
US3148354A (en) * | 1961-12-20 | 1964-09-08 | Ibm | Photoelectric recording apparatus |
US3188594A (en) * | 1962-01-25 | 1965-06-08 | Gen Electric | Thermally sensitive resistances |
US3198980A (en) * | 1957-09-27 | 1965-08-03 | Ibm | Light-sensitive glow discharge apparatus |
US3220260A (en) * | 1961-06-15 | 1965-11-30 | Case Inst Of Technology | Aircraft altimeter system |
US3238843A (en) * | 1961-11-15 | 1966-03-08 | Ibm | Electro-optical devices utilizing the stark shift phenomenon |
US3259887A (en) * | 1956-10-15 | 1966-07-05 | Ibm | Superconductive persistent current apparatus |
US3297878A (en) * | 1956-11-28 | 1967-01-10 | Sylvania Electric Prod | Photosensitive bistable element for use in information storage |
US3475610A (en) * | 1964-04-02 | 1969-10-28 | Stanford Research Inst | Electronic control device composed of photoconducting insulators |
US3502891A (en) * | 1967-03-22 | 1970-03-24 | Bell Telephone Labor Inc | Variable reflectance memory device |
US3675134A (en) * | 1971-05-27 | 1972-07-04 | Rca Corp | Method of operating an information storage tube |
FR2195033A1 (en) * | 1972-08-01 | 1974-03-01 | Thomson Csf |
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US2258294A (en) * | 1938-03-29 | 1941-10-07 | Emi Ltd | Photoelectric device |
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Publication number | Priority date | Publication date | Assignee | Title |
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US2816850A (en) * | 1953-12-30 | 1957-12-17 | Bell Telephone Labor Inc | Semiconductive translator |
US2912592A (en) * | 1954-10-07 | 1959-11-10 | Horizons Inc | Memory device |
US2926336A (en) * | 1955-04-14 | 1960-02-23 | Bell Telephone Labor Inc | Ferroelectric device |
US3043961A (en) * | 1955-08-26 | 1962-07-10 | Rca Corp | Electroluminescent device and circuits therefor |
US2891169A (en) * | 1955-09-02 | 1959-06-16 | Rca Corp | Electroluminescent device to give negative pictures |
US2905830A (en) * | 1955-12-07 | 1959-09-22 | Rca Corp | Light amplifying device |
US2981777A (en) * | 1956-05-11 | 1961-04-25 | Donald C Reynolds | Cadmium sulfide barrier layer cell |
US3007139A (en) * | 1956-05-22 | 1961-10-31 | Ibm | Circuit element for use in logical and memory circuits |
US2961546A (en) * | 1956-07-19 | 1960-11-22 | Brunsviga Maschinenwerke Ag | Apparatus for electrically transmitting decade counter tube results |
US3259887A (en) * | 1956-10-15 | 1966-07-05 | Ibm | Superconductive persistent current apparatus |
US3017612A (en) * | 1956-11-23 | 1962-01-16 | Nat Scient Lab Inc | Method and apparatus for storing information |
US3297878A (en) * | 1956-11-28 | 1967-01-10 | Sylvania Electric Prod | Photosensitive bistable element for use in information storage |
US3050580A (en) * | 1957-02-04 | 1962-08-21 | Xerox Corp | Electrostatic techniques |
US3069551A (en) * | 1957-05-16 | 1962-12-18 | Ass Elect Ind Woolwich Ltd | Electrical apparatus for intensifying images |
US2968724A (en) * | 1957-06-28 | 1961-01-17 | California Research Corp | Pulse height analyzer |
US2953690A (en) * | 1957-09-03 | 1960-09-20 | Nat Res Dev | Photosensitive cells, radiation filters and semiconductor materials for use in such cells and filters |
US3198980A (en) * | 1957-09-27 | 1965-08-03 | Ibm | Light-sensitive glow discharge apparatus |
US2957991A (en) * | 1957-09-30 | 1960-10-25 | Rca Corp | Photoconductive control circuit for light amplifiers and like device |
US2968799A (en) * | 1957-10-24 | 1961-01-17 | Ibm | Magnetic transducer |
US3059115A (en) * | 1958-04-10 | 1962-10-16 | Sylvania Electric Prod | Energy storage device |
US3011157A (en) * | 1958-04-16 | 1961-11-28 | Ncr Co | Storage devices |
US3037189A (en) * | 1958-04-23 | 1962-05-29 | Sylvania Electric Prod | Visual display system |
US3054961A (en) * | 1958-07-11 | 1962-09-18 | Ibm | Information storage device employing atomic particle bombardment to effect semi-permanent change in target lattice |
US2939029A (en) * | 1958-12-08 | 1960-05-31 | Du Pont | Method of image storage and release |
US3082392A (en) * | 1959-02-17 | 1963-03-19 | Santa Barbara Res Ct | Composite infrared radiation detector |
US3072832A (en) * | 1959-05-06 | 1963-01-08 | Texas Instruments Inc | Semiconductor structure fabrication |
US3028499A (en) * | 1959-11-02 | 1962-04-03 | Gen Electric | Expanded scale photoelectric device |
US3060317A (en) * | 1959-12-30 | 1962-10-23 | Ibm | Memory device |
US3121861A (en) * | 1960-06-27 | 1964-02-18 | Gen Dynamics Corp | Storage apparatus |
US3220260A (en) * | 1961-06-15 | 1965-11-30 | Case Inst Of Technology | Aircraft altimeter system |
US3146138A (en) * | 1961-07-10 | 1964-08-25 | Fred A Shirland | Vacuum evaporated barrier for a cds crystal |
US3238843A (en) * | 1961-11-15 | 1966-03-08 | Ibm | Electro-optical devices utilizing the stark shift phenomenon |
US3148354A (en) * | 1961-12-20 | 1964-09-08 | Ibm | Photoelectric recording apparatus |
US3188594A (en) * | 1962-01-25 | 1965-06-08 | Gen Electric | Thermally sensitive resistances |
US3475610A (en) * | 1964-04-02 | 1969-10-28 | Stanford Research Inst | Electronic control device composed of photoconducting insulators |
US3502891A (en) * | 1967-03-22 | 1970-03-24 | Bell Telephone Labor Inc | Variable reflectance memory device |
US3675134A (en) * | 1971-05-27 | 1972-07-04 | Rca Corp | Method of operating an information storage tube |
FR2195033A1 (en) * | 1972-08-01 | 1974-03-01 | Thomson Csf |
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