US3754158A - Character generating device - Google Patents

Character generating device Download PDF

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Publication number
US3754158A
US3754158A US00213126A US3754158DA US3754158A US 3754158 A US3754158 A US 3754158A US 00213126 A US00213126 A US 00213126A US 3754158D A US3754158D A US 3754158DA US 3754158 A US3754158 A US 3754158A
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US
United States
Prior art keywords
character
electrode
signal
collector electrode
plate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00213126A
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English (en)
Inventor
Y Nakagawa
O Konosu
Y Kaji
H Suzuki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Panasonic Holdings Corp
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Matsushita Electronics Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electronics Corp filed Critical Matsushita Electronics Corp
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Publication of US3754158A publication Critical patent/US3754158A/en
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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
    • H01J29/41—Charge-storage screens using secondary emission, e.g. for supericonoscope
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • H01J31/16—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen with mask carrying a number of selectively displayable signs, e.g. charactron, numeroscope

Definitions

  • ABSTRACT In a character generating device in which character signals are generated by scanning a character plate having character slits therein, with an electron beam, a signal developed across a load connected with an electrode provided in front of the character plate with respect to the travel of the beam by collecting with said electrode the secondary electrons emitted from a portion of the surface of said character plate other than said character slits when said beam hits against that portion and a signal developed across a load connected with a collector electrode provided in rear of the character plate with respect to the travel of the electron beam by collecting with the character plate the secondary electrons emitted from the collector electrode when the beam passes through the character slits of the character plate and impinges on the collector electrode, have the same polarity and both the signals are added through respective coupling capacitors to produce a composite signal.
  • the composite signal is opposite in polarity to the signal developed across the load connected with the character plate. Accordingly, if the composite signal and the signal across the load connected with the character plate are differentially combined and thereafter applied to an external circuit, then an output representing any character signal can be increased in magnitude. Consequently, since a high level output signal is obtained without increasing the electron beam current according to the proposed device, the resolution or character generating capacity is improved. 1f the resolution need notbe so high, the accelerating voltage can be accordingly reduced.
  • the present invention relates to a character generating device which generates character signals by scanning a target as a source of character information with an electron beam.
  • a character generating device which generates character signals by scanning a target as a source of character information with an electron beam.
  • a plate having cut-through slots corresponding to desired characters therein is placed in the path of a scanning electron beam, and if the beam scans a given slot corresponding to a certain character, then a signal representative of the character is derived.
  • the signal By applying the signal to the intensity modulating circuit of a picture tube which is synchronously connected with the scanning system, the character is visualized on the picture tube.
  • FIG. 1 is a schematic diagram of a conventional character generating device and its associated circuit
  • FIG. 2 shows the wave form of the output signal from the device shown in FIG. 1;
  • FIG. 3 shows graphically the voltage-current characteristic of the device shown in FIG. 1;
  • FIG. 4 is a schematic diagram of another conventional character generating device and its associated circuit
  • FIG. 5 is a schematic diagram of a character generating tube embodying the present invention and its associated circuit
  • FIG. 6 shows the wave forms of output signals of the tube as shown in FIG. 5, appearing several places at points A, B, C and D of the circuit in FIG. 5;
  • FIG 7 is a circuit diagram of another embodiment of the present invention.
  • FIG. 1 which shows a conventional character generating device
  • a cathode 1 an anode 2, deflecting electrodes 3, accelerating electrodes 4, a character plate 5 and a collector electrode 6 are hermetically contained in an envelope 7, and a coupling capacitor 8 and an amplifier 9 are connected in series with the collector electrode 6 to which a resistor R and a dc source V, are connected in series as a load circuit.
  • a signal current i flows through the resistor R only when the electron beam passes through a perforated slit corresponding to each character formed in the character plate 5 and impinges upon the collector electrode 6 Therefore, the wave form of the signal current i is that which is graphically shown in FIG. 2.
  • a signal voltage v, i,R, will appear at the point A in FIG. I when the electron-beam scans any character slit of the character plate 5.
  • the signal current i is equal to a current i, due to the electron beam so that the output signal voltage v, becomes equivalent to the product of i and R i.e.
  • FIG. 3 shows the condition of such a change in the signal current i with the voltage V varying from a high positive level to a level equal to the potential V,, at the cathode 1. It is noted from FIG. 3 that if the voltage V applied to the collector electrode 6 is slightly more positive than the potential V,, at the cathode 1 then the electron beam passes through the character slits of the character plate 5 and impinges on the collector electrode 6.
  • the number of secondary electrons emitted from the collector electrode 6 is small so that the signal current i, assumes a positive value.
  • the energy of the electron beam also increases with the result that secondary emission accordingly increases.
  • the potential at the collector electrode 6 is lower than that at the accelerating electrode 4 and the character plate 5 which are maintained at the same potential, all or part of emitted secondary electrons will be absorbed by the accelerating electrode 4 and/or the character plate 5. As a result, the signal current i, flowing into the collector electrode 6 will increase.
  • curves a, b and c represent the characteristics for the collector electrode made of stainless steel, Nesa film which is highly emissive of secondary electrons and carbon which has a low rate of secondary electron emission, respectively. From the curves a and b in FIG. 3, it is noted that the signal current i, and therefore the corresponding signal voltage v, which may be made negative as well as positive by controlling the voltage V applied to the collector electrode, can be derived. Therefore, it is possible to invert the contrast of a character image to be displayed on the picture tube.
  • the curve d is the ideal characteristic for the collector electrode made of an ideal material which produces no secondary electron under condition in question. Actually, the characteristic can not be attained.
  • the present invention not only the primary electrons from the electron gun but also the secondary electrons due to the impingement of the beam on the collector electrode are utilized to obtain a larger output than those obtained by the above described prior art devic s. With increased output the current carried by the beam could be decreased. Therefore the image resolution is improved. Moreover, if the resolution need not be so high, the accelerating voltage can be accordingly lowered.
  • FIG. 5 shows a character generating device embodying the present invention, in which in addition to the character plate 5 and the collector electrode 6, a secondary electron collector electrode 11 having a shape of a short hollow cylinder is provided in front of the character plate 5 as viewed from the electron gun, the collector electrode 6, the character plate 5 and the secondary electron collector electrode 11 having respectively dc voltages V V, and V, applied thereto through corresponding load resistors R R and R,, and the voltages being set such that V V, V, 0.
  • the character plate 5 and the collector electrode 6 are made of the same material and that all the secondary electrons emitted from the character plate 5 and the collector electrode 6 are absorbed by the secondary electron collector electrode 11 and the character plate 5 respectively, then the amounts of the corresponding changes in the potentials at A, C and B will be at values v,, v, and 2v,, respectively. Also the amount of change in the potential at A and that at C are added up to produce an amount 2v, of potential change at the point D.
  • the potential at B is opposite in polarity to that at D so that if both are amplified together through the differential amplifier 10 an output signal corresponding to an input level 4v, will be delivered. Therefore, it is noted that according to the present invention, an FIG.
  • the signal can be obtained which is four times as large in magnitude as the output signal obtained by the prior art device as shown in FIG. 1 and twice as large as the output signal obtainable with the well known device as shown in FIG. 3.
  • the value v, of the amount of the change in the potential at A or C depends on the current due to the secondary electrons emitted from the character plate 5 and the collector electrode 6. Consequently, by using a material having a high secondary-emission ratio for the character plate 5 and the collector electrode 6, the value of v can be made larger.
  • FIG. 7 shows a modification of the embodiment of the present invention shown in FIG. 5, in which the accelerating electrode 4 especially provided in the vicinity of the character electrode serves as the secondary electron collector electrode.
  • the dc voltages V and V should preferably be set such that V, V, 0.
  • the present invention provides a character generating device for generating a desired character signal by means of scanning with an electron beam, comprising an electron gun including a cathode, deflecting electrodes for the electron beam, a character plate having slits in the form of characters and a collector electrode, wherein a signal output due to the secondary electrons emitted from a portion of the character plate surface other than the character slits when the beam hits against that portion and a signal output due to the secondary electrons emitted from the collector electrode when the beam passes through the character slits of the plate and impinges on the collector electrode are respectively derived from an electrode means provided in the vicinity of the character plate and the collector electrode.
  • an output signal having a high level can be produced but also the character generating capacity is very much improved.
  • a character signal generating device comprising a cylindrical envelope having an electron gun including a thermionic emission cathode positioned at one side of said envelope, means for deflecting electron beam from said cathode in response to external signal, character electrode positioned on the other side of said envelope and having its surface of a secondary emissive ratio higher than unity opposite to said gun and having perforations shaped in desired character, means positioned,between said gun and said character electrode for capturing secondary electrons, and collector electrode positioned at the back of said character electrode distant therefrom for collecting primary electrons passed through the perforations and having its surface of a secondary emission ratio higher than unity for emitting secondary electrons toward said character electrode by the incidence of said primary electrons; wherein said device further comprising first, second and third voltage supplies connected to said secondary electron capturing means, said character electrode and said collector electrode respectively through respective load resistors such that said first voltage is set more positive than said second voltage set more positive than said third voltage; and a differential amplifier having its first input terminal connected through a capacitor to said character electrode and its second

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Electron Tubes For Measurement (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
US00213126A 1970-12-29 1971-12-28 Character generating device Expired - Lifetime US3754158A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP45124856A JPS526073B1 (de) 1970-12-29 1970-12-29

Publications (1)

Publication Number Publication Date
US3754158A true US3754158A (en) 1973-08-21

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00213126A Expired - Lifetime US3754158A (en) 1970-12-29 1971-12-28 Character generating device

Country Status (5)

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US (1) US3754158A (de)
JP (1) JPS526073B1 (de)
DE (1) DE2164294C3 (de)
FR (1) FR2121027A5 (de)
GB (1) GB1317079A (de)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054927A (en) * 1960-12-30 1962-09-18 Clem H Phillips Means for extending coverage in an area moving target radar
US3239766A (en) * 1961-09-07 1966-03-08 Philips Corp Circuit arrangements employing charge storage tubes
US3336498A (en) * 1964-03-20 1967-08-15 Scm Corp Cathode ray tube character generating and display system
US3439216A (en) * 1967-05-01 1969-04-15 Sylvania Electric Prod Monoscope cathode ray tube
US3439215A (en) * 1967-05-01 1969-04-15 Sylvania Electric Prod Monoscope cathode ray tube
US3551731A (en) * 1967-12-08 1970-12-29 Univ Ohio Image conversion by a semiconductor junction array
US3577171A (en) * 1968-09-03 1971-05-04 Vitro Corp Of America System using a modified ultrasonic imaging tube

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054927A (en) * 1960-12-30 1962-09-18 Clem H Phillips Means for extending coverage in an area moving target radar
US3239766A (en) * 1961-09-07 1966-03-08 Philips Corp Circuit arrangements employing charge storage tubes
US3336498A (en) * 1964-03-20 1967-08-15 Scm Corp Cathode ray tube character generating and display system
US3439216A (en) * 1967-05-01 1969-04-15 Sylvania Electric Prod Monoscope cathode ray tube
US3439215A (en) * 1967-05-01 1969-04-15 Sylvania Electric Prod Monoscope cathode ray tube
US3551731A (en) * 1967-12-08 1970-12-29 Univ Ohio Image conversion by a semiconductor junction array
US3577171A (en) * 1968-09-03 1971-05-04 Vitro Corp Of America System using a modified ultrasonic imaging tube

Also Published As

Publication number Publication date
GB1317079A (en) 1973-05-16
FR2121027A5 (de) 1972-08-18
DE2164294C3 (de) 1978-11-23
DE2164294A1 (de) 1972-07-13
JPS526073B1 (de) 1977-02-18
DE2164294B2 (de) 1978-03-23

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