US3711719A - Storage amplifier screen - Google Patents

Storage amplifier screen Download PDF

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Publication number
US3711719A
US3711719A US00091254A US3711719DA US3711719A US 3711719 A US3711719 A US 3711719A US 00091254 A US00091254 A US 00091254A US 3711719D A US3711719D A US 3711719DA US 3711719 A US3711719 A US 3711719A
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United States
Prior art keywords
layer
storage panel
display storage
radiation
display
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Expired - Lifetime
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US00091254A
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English (en)
Inventor
Z Szepesi
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Westinghouse Electric Corp
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Westinghouse Electric Corp
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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F55/00—Radiation-sensitive semiconductor devices covered by groups H10F10/00, H10F19/00 or H10F30/00 being structurally associated with electric light sources and electrically or optically coupled thereto
    • H10F55/10—Radiation-sensitive semiconductor devices covered by groups H10F10/00, H10F19/00 or H10F30/00 being structurally associated with electric light sources and electrically or optically coupled thereto wherein the radiation-sensitive semiconductor devices control the electric light source, e.g. image converters, image amplifiers or image storage devices

Definitions

  • ABSTRACT A storage amplifier screen comprising a layer of photoconductive material responsive to an input radiation and a layer of electroluminescent material emissive of an output radiation are sandwiched between two electrical conductive electrodes.
  • the screen provides high sensitivity, resolution and gain.
  • the photoconductive material, doped zinc oxide provides the property of persistence of the input image under excitation for over 10 minutes after removal of input radiation.
  • the photoconductive layer also provides the property of storage of the image for days in the absence of an electrical field,
  • This invention is generally directed to a storage amplifier screen and more particularly to a storage screen exhibiting the property of converting radiation in the X-ray region into a visible radiation.
  • Photographic film is presently used in medical and industrial radiography where high contrast and high resolution is required.
  • the expense, the time delay and inconvenience resulting from the required processing of the film, are undesired features of photographic radiography.
  • a general discussion of this background is found in an article entitled Solid State Image Intensifiers, Radiography Amplifiers, and Infrared Converters by the inventor in the Dec. 1969 issue of Electro- Technology.
  • This invention is directed to a storage display panel incorporating an electroluminescent layer and a photoconductive layer sensitive to an input radiation image to provide a conductivity image corresponding to said input image.
  • the photoconductive layer also exhibits the property of retaining this conductivity image for a substantial time after removal of the incident radiation.
  • a suitably doped zinc oxide layer provides a good quality image for a period of time of from to 100 minutes and the conductivity image may be erased by heating the storage display panel.
  • the storage panel 10 may be rectangular in shape and may be 8 X 10 inches in size.
  • the storage panel 10 is comprised of a support plate 12 of the suitable material transmissive to radiations generated by an electroluminescent layer 14.
  • a suitable material for the plate 12 is glass or plastic.
  • a glass sheet 12 having a thickness of about 1.5 millimeters may be utilized.
  • An electrical conductive layer 16 is provided on one surface of the support plate 12 and is also transmissive to radiations from the electroluminescent layer 14.
  • suitable material for the layer 16 is tin oxide evaporated to a thickness of about nanometers and having a resistance of about 100 ohms per square.
  • Electrical conductive bus bars 18 are provided on opposite sides of the conductive coating 16 and these bus bars 18 are of a suitable material such as copper and are connected to a potential source 20 through a variable resistance 22.
  • the source 20 may be a AC potential source of about 50 volts to provide means of applying electrical current through the layer 16 in order to provide heat to the storage amplifier.
  • the electroluminescent layer 14 is deposited on the conductive layer 16 and is comprised of an electroluminescent powder embedded in a high dielectric plastic material with the phosphor to dielectric ratio being approximately 3 to l by weight.
  • the thickness of the layer 14 may be from about 25 to 50 micrometers.
  • the electroluminescent material in layer 16 may be of a suitable electroluminescent phosphor such as zinc sulfide activated with copper and bromine and embedded in a high dielectric constant type plastic such as a mixture of cyanoethyl starch and cyanoethyl sucrose.
  • a photoconductive layer 23 is provided on the electroluminescent layer 14.
  • the layer 23 may be prepared in the following manner: Mix with 100 grams of very pure, very fine (less than 1) micron zinc oxide powder, 25 milligrams to 1 gram with an optimum amount of I00 milligrams of reagent quality sodium sulfate (Na SO and from 0 to 1 gram optimum 100 milligrams of reagent quality lead chloride (PbCl powder. This mixture, which includes less than 2 percent by weight of sodium sulfate and lead chloride, is baked in an air atmosphere at about 1000C for about 2 hours. This temperature may range from 900 to [200C After the powder is cooled, it is placed in a blender with deionized water and blended for one minute at high speed.
  • This mixture is then poured into a flask and the powder is settled down and the water decanted off. This process may be repeated for washing the powder.
  • the powder is then rinsed with 2 -propanol, settled, decanted and ultrasonically agitated for three minutes.
  • the resulting powder propanol paste is then dried on a 0.8' micrometer pore size filter and then in a forced air oven at a C for about 30 minutes. The powder then may be passed through a 200 mesh sieve.
  • the above doped zinc oxide powder is then mixed with a plastic about 100 grams of the sensitized zinc oxide powder to 3 to 30 grams of a silicone resin DC 804 purchased from Dow Corning, 25 grams of amyl alcohol and 2.5 grams of diethyl carbitol. This is ball mill mixed and is then ready to be applied to the electroluminescent layer 14.
  • the zinc oxide silicone mixture is bladed onto the electroluminescent layer 14 to a thickness of about 200 to 400 micrometers.
  • This coating 23 may be applied by simply utilizing a blade or a thin layer coating machine. The bladed-on layer 23 is then allowed to dry in a horizontal position.
  • the layer 23 has a resistance of about 10 ohm cm.
  • An electrically conductive layer 24 is then evaporated onto the photoconductive layer 23.
  • the layer 24 is transmissive to the input radiations and a suitable layer for X-rays is gold.
  • the layer 24 also absorbs the disturbing or scattered radiation.
  • the layer 24 is evaporated to a thickness of about 0.1 to l micrometer and has a resistance of about 20 ohms per square.
  • An AC voltage source 26 is connected between the conductive. layer 16 and the layer 24 to provide a voltage of about 200 to 400 volts and of a frequency of about 60to 1000 Hz.
  • the X-ray image is directed onto the storage amplifier 10 through the layer 24 and modifies the conductivity of the photoconductive layer 23 in accordance with the X-ray image input.
  • neither the potential source 20 nor the potential source 26 need be connected to the amplifier.
  • the storage layer 23 exhibits the property of integration over a period of time. After the completion of the exposure by the X-rays, an increased conductivity image remains in the layer 23 corresponding to the input radiation.
  • the potential source 26 may be applied, and an image may be viewed through the layer of 20 due to the AC potential applied across the electroluminescent layer 14 and the photoconductive layer 23. The light image will correspond to the conductivity image within the photoconductive layer 23.
  • the image may be viewed in this manner for several minutes and for as long as a 100 minutes without a substantial degradation of the light image. It is also possible, if desired, to remove the excitation of the potential 26 and the conductivity image will be retained in the photoconductive layer 23 for a period of several days and then by application of potential by the voltage source 26 the image may be viewed again.
  • the image Prior to the reuse of the screen, the image may be erased by applying the potential source 20 which provides an electrical current through the layer 16 causing the heating of the photoconductive layer 23 and thereby removing the conductivity image from the layer 23. After this erasing, the storage amplifier is ready to be utilized in the manner above.
  • the image can also be erased by simply baking the entire panel in a furnace for to minutes at a temperature of about 100C.
  • the device can be made more sensitive to other radiations such as visible light by the addition of an organic sensitizing dye to the zinc oxide powder.
  • an organic sensitizing dye for example, by mixing rhodamine, an organic dye, to the zinc oxide powder in a proportion by weight of l to 2000, the amplifier may be made sensitive to the visible light input.
  • the required characteristics for the photoconductive layer 23 is a material that has a trap density above the Fermi level (shallow traps) higher than 10 traps cm in an energy slice kT for an energy band of several tenths of an electron volt.
  • the materials must have a very low capture cross section of deep traps (recombination centers) or extremely short hole life time. Materials must have a high bandgap (between the valence and conduction band). In such material, the available electrons will supply a slowly decaying photoconductive current for several minutes after their radiation to the storage member is ceased.
  • the photoconductive layer 23, after a long time in the dark or after eraser, has a very low dark current.
  • the storage amplifier described above exhibits along storage time or persistence and decays to about onethird of maximum brightness in 5 to 50 minutes.
  • the device also exhibits high resolution of about 6 to 10 line pairs per millimeter.
  • the device also has a high contrast sensitivity and the device also exhibits medium high sensitivity to X-rays and very low sensitivity to visible light.
  • the radiographic quality of the panel is 2-2T. (This means 2T holes of a 2 per cent penetrameter can be detected.) These characteristics are particularly desirable in that these storage amplifiers may be substituted for radiographic film for nondestructive X-ray testing with the advantage of immediate viewing without film processing.
  • the device also may be erased and utilized over and over.
  • a display storage panel for reproduction of an image of incident radiation comprising a radiation responsive layer comprising zinc oxide material containing predetermined amounts of oxygen and sodium, said radiation responsive layer exhibiting the property of producing a conductivity image corresponding to said incident radiation in response to said input radiation and persisting after removal of said input radiation, a display layer of material coupled to said radiation responsive layer and including material responsive to conductivity changes in said radiation responsive layer to display an image corresponding to said conductivity image.
  • said means for impressing heat is an electrically conductive electrode extending across said panel and supplied with electrical current to heat said electrode.

Landscapes

  • Conversion Of X-Rays Into Visible Images (AREA)
  • Apparatus For Radiation Diagnosis (AREA)
  • Photo Coupler, Interrupter, Optical-To-Optical Conversion Devices (AREA)
  • Measurement Of Radiation (AREA)
  • Luminescent Compositions (AREA)
US00091254A 1970-11-20 1970-11-20 Storage amplifier screen Expired - Lifetime US3711719A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US9125470A 1970-11-20 1970-11-20

Publications (1)

Publication Number Publication Date
US3711719A true US3711719A (en) 1973-01-16

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Application Number Title Priority Date Filing Date
US00091254A Expired - Lifetime US3711719A (en) 1970-11-20 1970-11-20 Storage amplifier screen

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US (1) US3711719A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
JP (1) JPS5121757B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
DE (1) DE2156427A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)
GB (1) GB1360406A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3790867A (en) * 1972-02-22 1974-02-05 Matsushita Electric Ind Co Ltd Light-intensifying device
US3800194A (en) * 1972-04-07 1974-03-26 Hitachi Ltd Photoconductive target of an image tube
US3932025A (en) * 1974-10-25 1976-01-13 Xerox Corporation Imaging system
US4024389A (en) * 1973-06-15 1977-05-17 Sharp Kabushiki Kaisha Photo-image memory panel and activating method therefor
US4808880A (en) * 1984-12-18 1989-02-28 Centre National D'etudes Des Telecommunications Display means with memory effect comprising thin electroluminescent and photoconductive films
US4857416A (en) * 1987-12-31 1989-08-15 Loctite Luminescent Systems, Inc. Infra-red emitting electroluminescent lamp structures

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5367742A (en) * 1976-11-30 1978-06-16 Nitto Electric Ind Co Ltd Pressure-sensitive adhesive compositions
JPS59109540A (ja) * 1982-12-16 1984-06-25 Asahi Glass Co Ltd Ｓｂｒラテツクス組成物
JPH0690318B2 (ja) * 1988-03-29 1994-11-14 日亜化学工業株式会社 固体ｘ線映像変換装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2909692A (en) * 1957-06-14 1959-10-20 Gen Electric Field enhanced luminescence system
US2939029A (en) * 1958-12-08 1960-05-31 Du Pont Method of image storage and release
US2972692A (en) * 1958-05-02 1961-02-21 Westinghouse Electric Corp Method for operating electroluminescent cell and electroluminescent apparatus
US3500101A (en) * 1955-02-02 1970-03-10 Sylvania Electric Prod Photocapacitive electroluminescent light amplifier

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3500101A (en) * 1955-02-02 1970-03-10 Sylvania Electric Prod Photocapacitive electroluminescent light amplifier
US2909692A (en) * 1957-06-14 1959-10-20 Gen Electric Field enhanced luminescence system
US2972692A (en) * 1958-05-02 1961-02-21 Westinghouse Electric Corp Method for operating electroluminescent cell and electroluminescent apparatus
US2939029A (en) * 1958-12-08 1960-05-31 Du Pont Method of image storage and release

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3790867A (en) * 1972-02-22 1974-02-05 Matsushita Electric Ind Co Ltd Light-intensifying device
US3800194A (en) * 1972-04-07 1974-03-26 Hitachi Ltd Photoconductive target of an image tube
US4024389A (en) * 1973-06-15 1977-05-17 Sharp Kabushiki Kaisha Photo-image memory panel and activating method therefor
US3932025A (en) * 1974-10-25 1976-01-13 Xerox Corporation Imaging system
US4808880A (en) * 1984-12-18 1989-02-28 Centre National D'etudes Des Telecommunications Display means with memory effect comprising thin electroluminescent and photoconductive films
US4857416A (en) * 1987-12-31 1989-08-15 Loctite Luminescent Systems, Inc. Infra-red emitting electroluminescent lamp structures

Also Published As

Publication number Publication date
JPS5121757B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1976-07-05
JPS4710526A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1972-05-26
DE2156427A1 (de) 1972-05-31
GB1360406A (en) 1974-07-17

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