US2287298A - Dissector tube arrangement - Google Patents

Description

June 23, 1942. w, D ER 2,287,298

DISSECTOR TUBE ARRANGEMENT Filed Oct. 31, 1940 SYNCHRO NIZING I'N PUT SYNCHRO- mzme INPUT SCANN G GENERATOR INPUT TO DEFLECTING' PLATES Patented June 23 1942 DISSECTOR TUBE ARRANGEMENT Wolfgang Dillenbnrger, Klein-Macbnow, Germany, assign or to Fernseh Zehlendorf, Germany Application ottoma1, 1940, Serial No. In Germany November 28, 1939 G. m. b. IL, Berlin- 3 Claims. (Cl. 178-12) The invention relates to dissector tubes particularly for television purposes in which the image to be transmitted is projected upon a photoelectric cathode so that a cathode ray is produced corresponding in its intensity distribution to the brightness values of the image. The electrons emitted by-the photoelectric cathode are accelerated in the direction of an anode and deflected over a scanning aperture so that the electron image is scanned in regular succession. A secondary emission multiplier is preferably arranged behind the aperture for amplifying the television signals.

It is an object of the invention to provide a dissector tube including a secondary emission amplifier with electrodes adapted to introduce a high frequency carrier. It is a further object to provide an electrode system in this multiplier for introducing auxiliary signals, for example, synchronizing signals.

According to the invention the dissector tube is provided with an additional deflecting system arranged adjacent to the stationary aperture.

The deflecting system is preferably situated behind the aperture so that the electrons passing through the aperture can be deflected over the opening of a further diaphragm arranged in the path of the electrons. This arrangement makes it possible to introduce additional signals by means of very small control voltages. It is for example, possible to introduce inthis manner a carrier frequency for the image signals. The deflection control electrodes can also be used for interrupting the carrier or for introducing additional impulses. The control electrode system may be arranged in such a manner that not only deflecting electrodes for one direction of deflection are provided but that a number of deflecting systems are arranged together with a suitable aperture acting in different directions. vAlso a number of deflecting systems may be arranged one behind the other along the path of the cathode ray.

Other aspects of my invention will be apparent or will be specifically pointed out in the description forming a part of this specification, but

I do not limit myself to the embodiment of the invention herein described, as various forms may be adopted within the scope of the appended claims.

Referring to the drawing The figure represents a diagrammatic crosssection of a dissector tube including a secondary emission amplifier. v

The dissector tube i includes a photoelectric ray bundle is moved in regular succession over an aperture 5. This aperture is arranged in the wall of the envelope of an .anode finger 4 having a high positive potential. A scanning aperture 6 within the finger has a-potential negative with respect to anode l. A deflecting system consisting of two deflecting plates 1 is arranged behind the aperture 6 and in front of a diaphragm I having an aperture II. A number of secondary emission electrodes 9 are arranged behind the diaphragm. I in form of grids. The output electrode of this multiplier is connected to an output resistor i2 from which the amplified signals are taken oil. If a control voltage is applied to the deflecting plates I, the electrons passing through the aperture 6 are deflected in such a manner that only a smaller or larger part of the electrons can pass through the opening I. of diaphragm I. The electron stream is thereby modulated or it may even be completely shut off. If, for example, a carrier frequency is applied. to plates I,

the carrier modulated with the image signals will be multiplied in piifler.

The system shown in Fig. 1 can be modified by arranging a second deflecting system at right angles to. the deflecting system 1 and bycontrolling the electrons passing through the aperture 6 by both deflecting systems. In a further modification a number of deflecting systems are arranged one behind the other along the path of the electrons passing through opening i together with suitable diaphragms, so that a repeated deflection control of the electrons is produced. One of the deflecting systems might, for example, be

the secondary emission amused for introducing the carrier and a second deflecting system for introducing synchronizing impulses so that a carrier wave modulated with image signals and complete synchronizing signals is produced.

The arrangement for controlling the electron stream is situated approximately in the plane towards the cathode are closer together than their edges towards the diaphragm 8. They may be curved or may be replaced by magnetic deflecting coils. The arrangement can further be modified by using the opening ill in the diaphragm 3 as scanning aperture so that the aperture I may be dispensed with. The aperture 6 and the opening [may also have a larger diameter than the aperture it, but it is preferred to use aperture 6 as scanning aperture.

The invention is in no way limited to the embodiment of Fig. 1. The deflecting control can be used not only-ior introducing carrier irequencies or auxiliary signals but also for introducing modulating frequencies, for example, frequencies corresponding to another image or to a background which is artificially introduced into the transmission.

If a number of deflecting systems are used one of them may be employed for introducing irame synchronizing signals and the other for introducing line synchronizing signals. The signals may be derived directly from the retrace periods of the deflecting coils H and ii of the dissector tube.

The arrangement can also be modifiecLin such a manner that oscillations are produced, for example, by feeding back oscillations from the output circuit of the secondary emission multiplier to the deflecting system. The carrier frequency is then produced within the dissector tube so that no external oscillator and amplifier is required. The resonant circuit from which the oscillations are fed back to the deflecting system may be-connected to an intermediate grid of the secondary emission multiplier. Behind this grid a second deflecting control system may be provided for introducing the synchronizing signals.

to a single-picture element to pass therethrough, an electron multiplier for multiplying said signal current passing through said aperture, electrode means having solid portions for intercepting electrons and an opening for passage of said electron picture signal current therethrough, and means for producing a deflecting field between said scanning aperture andsaid electrode means for deflecting said electron current upon said solid portions oi! said electrode means in accordance with a deflecting wave thereby to prevent said current from entering said multiplier and generating a picture signal.

2. An image dissector tube having a photoelectric cathode, an anode shield having a scanning aperture therein of dimensions permitting the electron picture signal current emitted by an elemental area of said cathode corresponding to a single picture element to pass therethrough, an electron multiplier ior multiplying said signal current passing through said aperture, an apertured diaphragm disposed between said multiplier and said scanning aperture having an aperture for passage of said electron current therethrough, and a deflecting system disposed between said scanning aperture and said diaphragm for deflecting said electron current to prevent said current from entering into said multiplier and generating a picture signal.

3. An image dissector tube having a photoelectric cathode, an anode shield having a scanning aperture therein of dimensions permitting the electron picture signal current emitted by an elemental area of said cathode corresponding to a single'picture element to pass therethrough, an electron multiplier i'or multiplying said signal current passing through said aperture, an apertured diaphragm disposed between said multiplier and said scanning aperture having an aperture for passage of said electron current therethrough, and a plurality of deflecting plates disposed between said scanning aperture and said diaphragm adapted to have a deflecting wave applied thereto for deflecting said electron current to prevent said current from entering into said multiplier and generating a picture signal.

WOLFGANG DILLENBURGER.

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