US2375968A - Black spot correcting means - Google Patents

Black spot correcting means Download PDF

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Publication number
US2375968A
US2375968A US430569A US43056942A US2375968A US 2375968 A US2375968 A US 2375968A US 430569 A US430569 A US 430569A US 43056942 A US43056942 A US 43056942A US 2375968 A US2375968 A US 2375968A
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United States
Prior art keywords
picture
black spot
signals
television
correcting means
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Expired - Lifetime
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US430569A
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English (en)
Inventor
Felgel-Farnholz Richard Ri Von
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Individual
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Individual
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
    • H04N23/80—Camera processing pipelines; Components thereof
    • H04N23/81—Camera processing pipelines; Components thereof for suppressing or minimising disturbance in the image signal generation

Definitions

  • My invention relates to television systems and particularly to television systems of the type in which a cathode-ray transmitter tube using the storage effect is employed.
  • an object of my invention to provide a method of and means for correcting, or otherwise controlling, the shading of a television picture.
  • the intensity of the electron beam scanning the storage electrode is so controlled that the picture modulation eiiected by the intensity control will be directly opposite to the picture modulationproducing the black spot, so that, at the output of the cathoderay transmitter tube, a picture signal practically free from disturbing signals is obtained.
  • a modulating potential is admitted to the beam modulating electrode, said potential being advantageously generated by means of signal generators whose output currents are mixed with one another across control elements.
  • Figure 1 is a circuit and block diagram of a television transmitter embodying my invention.
  • Fig. 2 shows the undesired black spot at the television receiver.
  • an optical image of object i to be teletransmitted is produced, by means of optical system 2, on storageelectrode 3 of a cathode-ray transmitter tube ll of the type described in an article by V. K. Zworykin published in the January, 1934, issue of the Proceedings of the Institute of Radio Engineers.
  • a cathode-ray transmitter tube ll of the type described in an article by V. K. Zworykin published in the January, 1934, issue of the Proceedings of the Institute of Radio Engineers.
  • an image of electrical charges is generated, said charges corresponding, in their respective distribution, to the brightness distribution of the scanned object,
  • the charge stored on the storage electrode is taken off by means of an electron beam generated in a gun comprising a cathode 5.
  • the intensity of the scanning beam can be varied by means of electric control signals, which are applied 'to Wehnelt-cylinder t.
  • the electric control signals of suitable form and frequency are fed to the Wehnelt cylinder across line H], the of said signals with respect to the saw-toothed cathode-beam deflecting waves being so chosen and their amplitude so dimensioned that the disturbing spurious signals otherwise resulting at the output of the cathode-ray transmitter tube will be substantially balanced out and disappear for this reason.
  • a mixing device H which may serve also for coupling purposes the electric control signal is composed of auxiliary signals.
  • the auxiliary signals are generated by means of signal generators l2, l3, l4, and I5 which generate, e.
  • a variable modulating device l6 has been provided, in order to modulate the amplitude of the saw-tooth oscillations produced by generator I3, in the rhythm of the line frequency (1. e., in proportion to the amplitude of the signals represented in curve l2a).
  • the gain of at least one stage of the picture modulation amplifier may be varied.
  • the amplification should be controlled independently of the amountof the compensating voltage required at any particular instant.
  • the gradation curve of the picture received will be practically the same 'at all spots of the scanned area of the camera tubes of the storage type.
  • a saw-tooth waveof line scanning frequency introduced into the transmitted television signal in phase with, or in opposite phase to, the saw-tooth wave used to deflect the cathode beam of a, cathode ray receiving tube across the screen will shade the image uniformly from one side to the other, and that the same is true with respect to a saw-tooth wave of field scanning frequency except that the resultant shading will extend from top to bottom of the field. If both shading waves are present the shading will extend diagonally of the field, as shown for example in Fig. 2.
  • acathode ray picture transmitter tube comprising means for forming a beam of electrons, a photosensitive target for said beam adapted to have radiations from an object or field of view applied thereto, said target having means associated therewith to produce, when scanned by an electron beam of substantially constant intensity, picture signals and undesired spurious variations which unevenly shade the picture, and means for controlling the intensity of said beam, and means for producing and applying to said controlling means signals of such form and intensity that the formation of said spurious variations is substantially prevented.
  • a cathode ray picture transmitter tube comprising means for forming a beam of electrons, a photosensitive target for said beam adapted to have radiations from an object or field of view applied thereto, said target having means associated therewith to produce, when scanned by an electron beam of substantially constant intensity, picture signals and undesired spurious variations which unevenly shade the picture, and means for controlling the intensity of the beam, and means for applying to said controlling means signals of such form and intensity that the formation of said spurious variations is substantially prevented, said controlling means comprising a Wehnelt cylinder which serves also to concentrate said beam.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
US430569A 1940-08-30 1942-02-12 Black spot correcting means Expired - Lifetime US2375968A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE220371X 1940-08-30

Publications (1)

Publication Number Publication Date
US2375968A true US2375968A (en) 1945-05-15

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ID=5834135

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US430569A Expired - Lifetime US2375968A (en) 1940-08-30 1942-02-12 Black spot correcting means

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US (1) US2375968A (enrdf_load_stackoverflow)
BE (1) BE442484A (enrdf_load_stackoverflow)
CH (1) CH220371A (enrdf_load_stackoverflow)
FR (1) FR874843A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2445040A (en) * 1943-05-13 1948-07-13 Rca Corp Dark spot corrector
US2654048A (en) * 1949-06-03 1953-09-29 Emi Ltd Circuits embodying cathode potential stabilized electron discharge devices
US2775644A (en) * 1950-10-14 1956-12-25 Soc Nouvelle Outil Rbv Radio Picture analysis and recording devices
US20070253632A1 (en) * 2006-04-28 2007-11-01 Hou-Chun Ting Method and Related Compensation Circuit for Compensating Black Cores of An Image Sensor

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2445040A (en) * 1943-05-13 1948-07-13 Rca Corp Dark spot corrector
US2654048A (en) * 1949-06-03 1953-09-29 Emi Ltd Circuits embodying cathode potential stabilized electron discharge devices
US2775644A (en) * 1950-10-14 1956-12-25 Soc Nouvelle Outil Rbv Radio Picture analysis and recording devices
US20070253632A1 (en) * 2006-04-28 2007-11-01 Hou-Chun Ting Method and Related Compensation Circuit for Compensating Black Cores of An Image Sensor
US7702179B2 (en) * 2006-04-28 2010-04-20 Novatek Microelectronics Corp. Method and related compensation circuit for compensating black cores of an image sensor

Also Published As

Publication number Publication date
FR874843A (fr) 1942-08-27
BE442484A (enrdf_load_stackoverflow)
CH220371A (de) 1942-03-31

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