US3701923A - Inherent storage for charged particle beam scanner - Google Patents

Inherent storage for charged particle beam scanner Download PDF

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Publication number
US3701923A
US3701923A US179092A US3701923DA US3701923A US 3701923 A US3701923 A US 3701923A US 179092 A US179092 A US 179092A US 3701923D A US3701923D A US 3701923DA US 3701923 A US3701923 A US 3701923A
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Prior art keywords
plate means
storage
target
plate
control
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Expired - Lifetime
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US179092A
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English (en)
Inventor
Walter F Goede
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Northrop Grumman Corp
Northrop Grumman Systems Corp
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Northrop Grumman Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/39—Charge-storage screens
    • H01J29/395—Charge-storage screens charge-storage grids exhibiting triode effect
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/52—Arrangements for controlling intensity of ray or beam, e.g. for modulation
    • H01J29/525—Digitally controlled systems, e.g. Digisplay

Definitions

  • ABSTRACT The output of an area of a charged particle source such as an electron source passes from this source through a plurality of control plates to a target which may comprise a phosphor target plate.
  • the control plates have a plurality of apertures formed therein which are aligned with each other from plate to plate to define channels between the electron source and the target.
  • the target is scanned by means of digital control signals which are applied to the control plates.
  • a collector plate and a storage plate are interposed between the control plates and the phosphor target in that order.
  • Control signals are successively applied to the various plates to first write signals onto the storage plate in accordance with the digital excitation of the control plates, to then apply the signals stored in the storage plate to the phosphor during a flood mode, and finally to erase the signals stored in the storage plate.
  • WALTER F. GOEDE SCKOLSKI 8
  • This invention relates to charged particle beam scanners such as electron beam scanners, and more particularly to a digitally controlled scanner which utilizes storage in its implementation.
  • the device of this invention affords a significant improvement in the operation of digital electron beam scanners as described in the aforementioned patent and patent applications in providing an increased brightness in the display without the need for any multiplier plates. Further, it is possible to use lower switching rates in view of the fact that the dwell time per display element can be substantially increased by virtue of storage. In addition, there is reduced power dissipation, and an overall increase in the efficiency of operation as a result of the storage implementation. In addition, the storage feature reduces or eliminates the requirement for frequent refreshing or rewriting of information by the original source, usually a computer, digital memory, or direct sensor.
  • the storage device of this invention as implemented with an electron beam scanner, has none of the above mentioned shortcomings. No additional electron source, complex collimating system, or significantly larger envelope are required. As a matter of fact, the device of this invention can be added to an existing electron beam scanner of the type described in the aforementioned patent at a rather nominal increase in size or cost. Thus, significant advantages are achieved with the storage device of the present invention in an electron beam scanner of the type described in the aforementioned patent and patent applications, without any of the problems and shortcomings normally associated with this type of device as implemented in the prior art in cathode ray tube structures.
  • FIG. 1 is a schematic drawing illustrating the basic features of the device of the invention
  • FIG. 2 is a graph illustrating the operation of the storage plate of the invention
  • FIG. 3 is a timing diagram illustrating the operation of the device of the invention in its various operation modes
  • FIG. 4 is an elevational view in cross section illustrating one embodiment of the device of the invention.
  • FIG. 5 is a cross sectional view in partial cutaway section taken along the plane indicated by 5-5 in FIG. 4;
  • FIG. 6 is a perspective view illustrating an alternative storage plate which may be utilized in the device of the invention.
  • FIG. 7 is a perspective view illustrating another alternative storage plate which may be utilized.
  • the device of the invention comprises an area charged particle source such as an electron source and a flat plate target between which is sandwiched a plurality of control plates which have apertures therein defining electron beam channels.
  • the control plates may be digitally excited to control the flow of electrons through the channels formed therethrough.
  • a storage plate having a secondary emissive layer, which may be a dielectric, deposited thereon.
  • a collector plate which is similar to the scanning plate except that it has overall electrodes on both sides rather than finger pattern electrodes, is located between the storage electrode and the control electrode to provide a return path for secondary electrons from the storage electrode.
  • a contrast enhancing plate may be placed between the storage electrode and the target to increase the contrast of the display by acting as a blanking grid during the erase mode to prevent electrons from reaching the target during this mode of operation.
  • An erase, write, and flood mode In the operation of the device, three sequential operational modes are utilized: An erase, write, and flood mode.
  • the erase mode potentials are applied to the various plates to place a uniform charge over the entire area of the dielectric surface of the storage plate such as to effectively erase any signals stored thereon.
  • the control plates receive digital signals to control the electron beam therethrough and simultaneously potentials are placed on the remaining plates to cause the scanning pattern to be stored on the storage plate by appropriately charging the dielectric surface of this plate.
  • the electrical charge information stored on the storage plate is used to appropriately energize the target.
  • Area cathode 11 which includes electron emitting filaments 11a, provides a source of electrons over a scanning area defined by scanning control plates 12.
  • Area cathode 11 may be of the type described in the aforementioned patent application Ser. No. 83,909, while the scanning control plates 12 may operate in response to digital signals as described in US. Pat. No. 3,539,719, and my application Ser. No. 853,l72 now US. Pat. No. 3,600,627.
  • the control plates 12 be electron multiplying dynodes, or that any type of electron multiplication whatsoever be used.
  • Storage plate 13 may comprise a backing plate portion 13a of a conductive metal such as nickel, having a thin layer 13b of dielectric secondary emitting material such as magnesium fluoride or a base layer of calcium fluoride having magnesium oxide deposited thereover.
  • backing electrode 13a may be a metal mesh having ll,000 lines/inch, may be a thin metal plate having apertures formed therein to match the channel apertures of scanning control plates 12, or may be a dielectric substrate having a metallic coating.
  • Plates l4 and 16 may both be metal plates having apertures formed therein which match and are aligned with the channels defined by the control plate apertures. These plates may also be formed on a dielectric substrate, this substrate being metal clad on both of the broad surfaces thereof with interconnecting through holes which also are metal coated to interconnect the electrodes on the opposite surfaces thereof such as described in application Ser. No. 89,879 filed Nov. 16, 1970 and assigned to Northrop Corporation.
  • the dielectric coating 13b may be deposited by means of vacuum deposition techniques to a thickness of the order of lmicrons. This coating is on the surface facing the control plates and on the surfaces of the apertured portions.
  • the thickness of deposition is dictated by the particular application requirements at hand, a thicker layer providing a lower capacitance with a faster write time capability. It is to be noted,
  • FIGS. 4 and 5 one embodiment of the device of the invention is illustrated. The details of structure will be but briefly described in view of the fact that they are thoroughly set forth in the aforementioned application Ser. No. 83,909 which is incorporated herein by reference.
  • Thermionic area cathode 11 is supported within evacuated casing 20. Supported in stacked relationship on insulating rods 35 are control plates 12, which as already noted may be controlled in response to digital signals. Mounted on insulating rods 35 between the control plates 12 and phosphorescent target 15 are collector plate 14, storage plate 13 and contrast enhancement plate 16. If intensity modulation of the signal is desired, a modulation electrode providing the functions of a control grid may be included, as described in US. Pat. No. 3,539,719.
  • Storage plate 13 for this embodiment as can be seen in FIG. 5 is a wire mesh 13a with dielectric coating 13b deposited thereon.
  • This alternative storage plate is fabricated of a metal plate 13a having apertures 13c formed over substantially the entire surface area thereof, these apertures corresponding to and being aligned with the apertures formed in control plate 12.
  • the plate has a dielectric secondary emissive coating 13b deposited thereon.
  • This plate comprises a dielectric substrate with an overall conductive electrode 13d on one side thereof and secondary emissive metallic coatings 13b forming collars in and around apertures 13c on the side thereof towards the cathode.
  • FIG. 3 illustrates typical operating potentials that have been successfully used in an operating embodiment of the device of the invention, but of course these can be varied somewhat in other embodiments to achieve the desired results.
  • FIG. 2 illustrates a typical secondary emission curve which will be used to demonstrate the operation of the storage plate.
  • FIG. 2 is a plot of secondary emission ratio against primary electron beam energy
  • the initial sequence in the operation of the device is to erase or prime the storage surface. This entails charging the storage dielectric material negatively with respect to the backing electrode. Referring to FIG. 3, this is achieved in the following manner. To simplify the representation, the times for the various modes of operation are shown to be the same but in actual practice their lengths would differ from each other considerably. It is to be noted that in FIG. 3 the potentials shown in the successive lines are those applied to the various plates with respect to the potential of the area cathode as follows:
  • the line designated V represents the modes of operation of scanning control plates 12 and does not represent potentials applied.
  • the contrast enhancement plate is placed at a voltage (V which is below the cathode potential Volts). This prevents electrons which will be used to erase the storage plate from reaching the target during the erasing operation. While the use of this contrast enhancement plate is not absolutely necessary to make for an operative device, it significantly increases the contrast of the displayed image by preventing the target from brightening in response to the electrons used for erasing, which could otherwise pass through during the erase cycle. This of course would give an overall average brightness background which would result in reduced contrast.
  • the backing electrode 13a of the storage plate is simultaneously placed at a potential (V which is below the cross-over potential (V shown and described in connection with FIG. 2. For the illustrative example, this was approximately 25 Volts above cathode potential.
  • the scanning control plates 12 are all placed in an on" state or flood mode such that all the channels are forward biased by the application of the appropriate potentials (approximately 100 volts).
  • the appropriate potentials approximately 100 volts.
  • the net result of this is that flood electrons from the area cathode collide with the storage dielectric. Since the electrons striking the dielectric have an energy below V the dielectric material is charged negative with respect to the backing electrode. Thus, for storage elements which had previously been written, the voltage on the dielectric element goes to zero (cathode potential) as indicated by V which is about 30 volts negative charge with respect to the backing electrode.
  • the voltage on the dielectric element remains at approximately zero (cathode potential) throughout the erase mode, this being a 30 volt negative charge with respect to the backing electrode. It is to be noted that in the operative embodiment of the invention referred to, less than 100 microseconds is required for total screen erasure.
  • the write mode occurs, during which information is written on the storage dielectric of the storage plate.
  • the scanning control plates are operated in their scan mode during which they are appropriately activated in response to digital control signals in the manner described in the aforementioned US. Pat. No. 3,539,719.
  • the backing electrode of the storage plate is elevated to a potential (V greater than V (of the order of several hundred volts), such that the secondary emission ratio is greater than one.
  • the collector electrode is placed at a potential (V somewhat higher than that on the backing electrode, to collect secondary electrons generated at the dielectric surface.
  • the contrast enhancement plate is also elevated to a potential (V above the backing electrode. This allows some of the writing electrons to pass through to the phosphor target.
  • V illustrates the charging of a storage element opposite the channel in which information is being written
  • V indicates the charge on a storage element opposite a channel which is cut off. It is to be noted that in the operative embodiment of the subject invention, less than 0.5 microseconds is required to write a single element.
  • the next and final mode of operation is the flood mode.
  • the electrical charge information that was written onto the storage plate is used to present a visual output on the phosphor target.
  • a potential V is first applied to the electron beam scanning plates to place them in the flood mode as previously described in connection with the erase mode.
  • the collector plate is brought to a potential V (approximately 50 volts)
  • the backing electrode of the storage plate is brought to a potential V near cathode potential (approximately 20 volts), such that areas V of the dielectric layer which were charged positively during the write mode will transmit flood electrons, and areas V which were charged negative during the erase mode and left undisturbed in the write mode, will repel the incoming flood electrons.
  • the repelled electrons are collected at the collector plate.
  • the contrast enhancement plate is placed at a voltage V above that of the backing electrode, such that the flood electrons coming through the storage plate will be refocused and directed onto the target. The three modes of the cycle are thus completed and a new similar cycle commenced.
  • the device of this invention thus provides simple and economical means for significantly increasing the brightness of the display of a digitally controlled electron beam scanner. This end result is achieved without addition of appreciable structures to an existing device and without greatly increasing the cost thereof. Inherent memory is also added to the device, eliminating, in some cases, the need for a refresh memory in the electronics.
  • a charged particle beam scanner having an area cathode, a target for receiving electrons from the cathode and control plate means having apertures therein defining beam channels running from the cathode to the target for controlling the flow of charged particles in said channels, the improvement comprising:
  • control plate means interposed between the control plate means for storing charge in accordance with the charged particle flow through said channels during a first mode of operation and releasing charged particles to the target during a second mode of operation, and
  • collector plate means interposed between the control plate means and said storage plate means and having apertures aligned with said channels for providing a return path for charged particles from said storage plate means
  • a first set of potentials being applied to said storage and said control plate means during said first mode to bring the secondary charged particle yield of said storage plate means to less than unity
  • a second set of potentials being applied to said storage and said control means during said second mode to bring the secondary charged particle yield of said storage plate means to above unity
  • a third set of potentials being applied to said storage and said control plate means during a subsequent mode of operation to erase the charge stored on said storage plate means.
  • said storage plate means comprises a conductive wire mesh having a dielectric secondary emissive material deposited on the surface thereof facing said control plate means.
  • said storage plate means comprises a flat conductive plate having apertures aligned with said channels formed therein, a dielectric secondary emissive material being deposited in the apertured portions of said plate and on the surface thereof facing said control plate means.
  • said storage plate means comprises a flat dielectric plate having apertures aligned with said channels formed therein, a secondary emissive material being deposited in the apertured portions of said plate on at least a portion of the surface thereof surrounding said apertured portions and facing said control plate means, the opposite surface of said plate having a conductive material thereon.
  • An electron beam scanner comprising:
  • control plates sandwiched between the cathode and target for controlling the electron flow therebetween, said control plates having apertures formed therein, the apertures on successive control plates being aligned with each other to define electron beam channels running between the cathode and target;
  • flat storage plate means sandwiched between the control plates and the target for storing charge thereon in accordance with the electron flow in said channels during a write mode of operation, the stored charge being used to energize said target during a subsequent flood mode of operation and being erased from said storage plate during a still subsequent erase mode of operation;
  • collector plate means sandwiched between said storage plate means and said control plates for providing a return path for electrons from said storage plate means.
  • control plates have finger pattern electrodes thereon for digitally controlligg the electron flow.
  • said storage plate means comprises a wire mesh having secondary emissive dielectric material deposited thereon.
  • said storage plate means comprises a flat conductive backing plate having apertures formed therein aligned with said channels, secondary emissive dielectric material being deposited on the surface of said plate facing said control plates and in the apertured portions thereof.
  • said storage plate means comprises a flat dielectric backing plate having apertures formed therein aligned with said channels, secondary emissive material being deposited on the portions of the plate surface surrounding said apertures and facing said control plates and in the apertured portions thereof, the opposite surface of said plate having a conductive material thereon.
  • conductive plate means for enhancing the contrast of the target signal by preventing electrons from reaching the target during the erase mode, said conductive plate means having apertures aligned with said channels formed therein.

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Particle Accelerators (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)
US179092A 1971-09-09 1971-09-09 Inherent storage for charged particle beam scanner Expired - Lifetime US3701923A (en)

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US17909271A 1971-09-09 1971-09-09

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US (1) US3701923A (enExample)
JP (1) JPS4838067A (enExample)
CA (1) CA973971A (enExample)
DE (1) DE2234998A1 (enExample)
FR (1) FR2152801A1 (enExample)
GB (1) GB1391102A (enExample)
NL (1) NL7210100A (enExample)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4070578A (en) * 1976-07-30 1978-01-24 Timothy John G Detector array and method

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS50122449A (enExample) * 1974-03-14 1975-09-26
DE3911343A1 (de) * 1989-04-07 1990-10-11 Nokia Unterhaltungselektronik Flache anzeigeeinrichtung
US5256937A (en) * 1989-04-07 1993-10-26 Nokia (Deutschland) Gmbh Flat panel fluorescent screen display tube

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3408532A (en) * 1965-12-06 1968-10-29 Northrop Corp Electron beam scanning device
US3483422A (en) * 1968-07-26 1969-12-09 Northrop Corp Electron beam scanner with transverse digital control
US3505559A (en) * 1968-09-25 1970-04-07 Northrop Corp Electron beam line scanner device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3408532A (en) * 1965-12-06 1968-10-29 Northrop Corp Electron beam scanning device
US3483422A (en) * 1968-07-26 1969-12-09 Northrop Corp Electron beam scanner with transverse digital control
US3505559A (en) * 1968-09-25 1970-04-07 Northrop Corp Electron beam line scanner device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4070578A (en) * 1976-07-30 1978-01-24 Timothy John G Detector array and method

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CA973971A (en) 1975-09-02
GB1391102A (en) 1975-04-16
DE2234998A1 (de) 1973-03-15
NL7210100A (enExample) 1973-03-13
JPS4838067A (enExample) 1973-06-05
FR2152801A1 (enExample) 1973-04-27

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