US2758235A - Means and techniques for preventing keystone effects - Google Patents

Means and techniques for preventing keystone effects Download PDF

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Publication number
US2758235A
US2758235A US363181A US36318153A US2758235A US 2758235 A US2758235 A US 2758235A US 363181 A US363181 A US 363181A US 36318153 A US36318153 A US 36318153A US 2758235 A US2758235 A US 2758235A
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United States
Prior art keywords
plates
target
pair
tube
techniques
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Expired - Lifetime
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US363181A
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English (en)
Inventor
Jr William E Evans
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.)
Technicolor Motion Picture Corp
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Technicolor Motion Picture Corp
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Publication date
Application filed by Technicolor Motion Picture Corp filed Critical Technicolor Motion Picture Corp
Priority to US363181A priority Critical patent/US2758235A/en
Priority to FR1145877D priority patent/FR1145877A/fr
Application granted granted Critical
Publication of US2758235A publication Critical patent/US2758235A/en
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Expired - Lifetime legal-status Critical Current

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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
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/74—Deflecting by electric fields only

Definitions

  • the present invention relates to improved means and techniques for preventing so-called keystone effects when a beam of charged particles, as in a cathode ray tube, iconoscope and the like is directed onto a target for scanning a selected portion thereof, with such target having its plane inclined a substantial amount with respect to the beam.
  • a trapezoidal or keystone shape pattern is scanned, instead of a desired rectangular or square pattern, unless precautions are taken.
  • Such scanning may be accomplishcd where the target is a photo-sensitive plate such as a mosaic in an image recreating type of tube such as an iconoscope or where such target is a light emissive plate which emits light in response to electrons impinging thereon.
  • the keystone or trapezoidal pattern is obtained in devices of this character when the target is inclined a substantial amount with respect to the axis of scanning beam since the beam is deflected or flared out different amounts depending upon the particular point where the beam is intercepted by the target.
  • the target When inclined, the target has what may be considered to be a portion relatively close to the beam source as well as a portion relatively far from the beam source.
  • the beam when intercepted by such relatively close portion is deflected a smaller amount than when the same beam is later intercepted by the relatively far portion thereby to obtain a trapezoidal or keystone shaped pattern, field or raster instead of a desired square or rectangular pattern, as the case may be.
  • Another object of the present invention is to provide an improved tube construction having keystone correction means incorporated therein.
  • Another object of the present invention is to provide keystone correction without special external circuitry, other than that required to sweep or scan a rectangular raster.
  • Another object of the present invention is to provide improved means and techniques useful in producing scanning rasters for cathode ray tubes which have their electron gun structures directed at some angle to the target plate, i. e., fluorescent screen, or mosaic, other than normal to it.
  • Another object of the present invention is to achieve these indicated results by shaping the deflecting plates for the beam in a characteristic manner.
  • Another object of the present invention is to achieve these indicated results by the use of nonparallel beam deflecting plates.
  • Figure 1 shows a view in elevation of a cathode ray tube embodying features of the present invention, a portion of such tube beingv shown also in the perspective view which constitutes Figure 2.
  • Figure 3 shows a perspective view of a portion of another tube showing a modified structure also embodying features of the present invention.
  • Figure 4 shows a perspective view of a portion of still another tube show-ing a modified structure also embodying features of the present invention.
  • Figures 5 and 6 show respectively a trapezoidal or keystone raster 40 which is customarily obtained, and a rectangular raster 42 which is obtained in accordance with features of the present invent-ion.
  • Each of the tubes disclosed in Figures 1-4 is considered to incorporate the following conventional elements, namely, a heated cathode for producing a source of electrons, means for accelerating said electrons to provide a beam of charged particles, i. e., electrons, and means for focusing said beam onto the target of the corresponding tube.
  • the cathode beam in all of the figures is represented by the line 10 and the target plate is represented by the reference numeral 12 which are incorporated in the tube 14 illustrated in Figures 1 and 2 and in the tubes 15 and 16 illustrated respectively in Figures 3 and 4.
  • the electron gun structure is represented by the reference numeral 20 and this incorporates conventional structure for producing the directed cathode beam 10.
  • Each of the cathode ray tubes incorporates beam deflecting means, i. e., two pairs of electro-static plates between which the cathode beam passes for deflection thereby in accordance with voltages applied to such plates.
  • a first pair of such plates includes conventional parallel spaced vertical deflection plates 22 and 23, while the second pair of such plates (plates 24, 25 in Figures 1 and 2; plates 26, 27 in Figure 3; plates 28, 29 in Figure 4) are arranged in a special manner with respect to thetarget plate 12.
  • the horizontal deflection plates- 24 and 25 are flat plates which have their planes inclined, one with respect to the other i. e., the planes of plates 24, 25 are divergent with the planes of each plate 24, 25 making an acute angle with respect to the:
  • the horizontal deflection plates (assuming a voltage of constant intensity on such horizontal plates) produce a decreased effect on the beam when directed by the-vertical plates to such lower or relatively far portion of the target than is the case when the beam is directed to the upper portion or relatively close portion of the target.
  • the electro-static field intensity between the plates 24, 25 is not uniform but is gradated in accordance with the divergence of the plates 24, 25, the field intensity being relatively small where the separation is greatest and being relatively large where the separation is smallest.
  • the cathode beam is deflected in an amount depending upon the intensity of the field through which the beam is directed by the vertical plates 22, 23.
  • the horizontal deflection plates 26, 27 both extend vertically, i. e., the planes of plates 26, 27 extend perpendicular to the planes of plates .22, 23.
  • the plates 26, 27, however, are wedge-shaped or taperedwith the smaller end of the plates 26, 27 extending downwardly.
  • the electrons which constitute the beam 10 are acted upon for a greater length of time when such beam is directed to the upper portion of the target 12 than isthe case when such beam is directed to the. lower portion of the target.
  • thev beam in the first instance is acted upon for a greater period or duration, the deflection imparted to the beam is greater than in the second instance where the beam passeszbetween a smaller portion of the tapered plates 26, 27.
  • each arrangement there is a desired substantial linear distribution of deflection sensitivity so that, instead of obtaining a scanned pattern or raster 40 having a trapezoidal or keystone shape as illustrated in Figure 5, the scanned pattern or raster 42 is rectangular as illustrated in Figure 6.
  • a tube of the character described comprising a source of charged particles, a target, means for forming a beam of said charged particles and for directing said beam on said target, said target having a portion relatively' close to said source, and having a portion relatively far from said source, beam deflecting news comprising a pair of plates arranged to produce less deflecting force on said beam when said beam is directed on said far portion than when said beam is directed on said relatively close portion said beam deflecting means comprising a second pair of plates spaced from the aforementioned pair of plates and comprising substantially rectangular plates with their planes extending generally parallel.
  • Apparatus of the character described comprising means including a tube for producing a beam of charged particles and for projecting the same on a target, said target having its plane inclined with respect to the axis of the beam and. having a relatively close portion and having a relatively far portion, beam deflecting means associated with the beam comprising a pair of spaced plates arranged to produce less deflecting force on said beam when it is projected on said far portion than when said beam is projected on said close portion said beam deflecting means comprising a second pair of plates spaced from the aforementioned pair of plates and comprising substantially rectangular plates with their planes extending generally parallel.

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  • Electron Sources, Ion Sources (AREA)
US363181A 1953-06-22 1953-06-22 Means and techniques for preventing keystone effects Expired - Lifetime US2758235A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US363181A US2758235A (en) 1953-06-22 1953-06-22 Means and techniques for preventing keystone effects
FR1145877D FR1145877A (fr) 1953-06-22 1956-03-19 Perfectionnements aux dispositifs et aux procédés pour empêcher les effets de distorsion en clef de voûte ou en trapèze

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US363181A US2758235A (en) 1953-06-22 1953-06-22 Means and techniques for preventing keystone effects

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US2758235A true US2758235A (en) 1956-08-07

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US363181A Expired - Lifetime US2758235A (en) 1953-06-22 1953-06-22 Means and techniques for preventing keystone effects

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US (1) US2758235A (fr)
FR (1) FR1145877A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3151270A (en) * 1961-03-31 1964-09-29 Bell Telephone Labor Inc Electron ribbon beam encoder tube with beam tilt control
USD720463S1 (en) * 2011-04-27 2014-12-30 Fenf, Llc Hand therapy and aligning device
US10365546B1 (en) 2018-04-16 2019-07-30 The Boeing Company Vehicle projection system and method of using

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2069460A (en) * 1933-09-30 1937-02-02 Vladimir K Zworykin Cathode ray tube
US2076086A (en) * 1933-01-26 1937-04-06 Rca Corp Cathode ray tube
US2103312A (en) * 1933-08-29 1937-12-28 Rca Corp Cathode ray device
US2182382A (en) * 1936-10-29 1939-12-05 Radio Patents Corp Cathode ray device
US2574975A (en) * 1950-01-17 1951-11-13 Heinz E Kallmann Electron beam deflecting system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2076086A (en) * 1933-01-26 1937-04-06 Rca Corp Cathode ray tube
US2103312A (en) * 1933-08-29 1937-12-28 Rca Corp Cathode ray device
US2069460A (en) * 1933-09-30 1937-02-02 Vladimir K Zworykin Cathode ray tube
US2182382A (en) * 1936-10-29 1939-12-05 Radio Patents Corp Cathode ray device
US2574975A (en) * 1950-01-17 1951-11-13 Heinz E Kallmann Electron beam deflecting system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3151270A (en) * 1961-03-31 1964-09-29 Bell Telephone Labor Inc Electron ribbon beam encoder tube with beam tilt control
USD720463S1 (en) * 2011-04-27 2014-12-30 Fenf, Llc Hand therapy and aligning device
US10365546B1 (en) 2018-04-16 2019-07-30 The Boeing Company Vehicle projection system and method of using

Also Published As

Publication number Publication date
FR1145877A (fr) 1957-10-30

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