US2421520A - System for energizing the electrodes of cathode-ray devices from the deflecting circuit - Google Patents

Description

June 3, 1947. W J POCH 2,421,520

SYSTEM FOR ENERGIZING THE ELECTRODES 0F GATHODE RAY DEVICES FROM THE DEFLECTING CIRCUIT wg/wm.

T TOPNE )u/ 2,421,520 THODE W. J. POCH June 3, 1947.

SYSTEM FOR ENERGIZING THE ELECTRODES OF CA RAY DEVICES FROM THE DEFLECTING CIRCUIT Filed June 18, 1943 2 Sheets-Sheet 2 4BY v Patented June 3, 1947 imitan star ingr rr Fries Waldemar 3. Poeh, Moorestown, N. J., assigner to Radio Corporation of America, a corporation of Delaware Appiication June 1S, i943, Serial No. 491,332

This invention is directed to electronic apparatus and particularly to television apparatus of the electronic variety.

Most television apparatus incorporates a scanning or camera tube of which there are many and various types. For purposes of illustration, this invention will be related to a scanning or camera tube or" the so-.called storage type such, for example, as that type which is now commonly known in the art as the iconoscope In many television installations where particular emphasis is given to the lightness of weight the transportability of such equipment, it is frequently desirable to rely upon a common source oi energy for developing both the necessary high voltage ior operating the system, as well as for developing the heater current for the cathode electron emitters. Usually the heater current is an alternating current of low frequency serving to heat the electron emitters so that a stream or flow of electrons is released to form the electron scanning beam or cathode ray. It is usually desirable that there be some established frequency relationship between the sources used to produce the high voltage energy and to develop the heater currents, in order that greater eciency i operation shall be had, and such a relationship is had by this invention. The vestablished relationship prevents any possible cross-talk eiects from resulting in any noticeable picture ripple.

At the same time, this invention makes provision so that the usually considered separate heater current supply source becomes unnecessary, and the heater currents themselves are derived from one of the energy deections sources which, of themselves, serve to control, in known manner,

5 Claims. (Cl. 315-22) the motion or traverse of the scanning cathode ray beam across a target or mosaic element to produce a signal representative of an optical image which has been cast upon this target or mosaic.

In most embodiments of television systems where unilateral scanning is relied upon, the scanning electron beam developed within the tube is controlled in its deection under the influence of deiiection energy of substantially saw-tooth wave formation. Accordingly, in the present invention, the control energy from which .the operating voltages for producing the relatively high voltage, aswell as for producing the heater currents, are developed and controlled under the iniiuence of the produced delecting wave energy.

To this end, various means have been provided for producing a control wave from which the energy is adequate to provide the heater current.

At the same time, this invention makes vprovision for developing the higher voltages by .Way of a suitable high voltage rectier element which is energized by a control Wave representing, for instance, a back-kick voltage developed during the snap-back or return-trace portion of each scanningI The invention herein to be disclosed also makes provision for providing various ways and means by which the aforesaid results may be obtained, and, at the same time, provides ways and means by which the various relationships between the high voltage energy and the heater currents developed may be established.

It accordingly becomes one of the objects of this invention Yto provide a television system having included therein a scanning instrumentality in which a scanning beam is developed to scan an area, and in which the beam not only can be controlled in a suitable manner in its deflection, but also suitable provision may be made whereby certain portions of the energy of the controlling wave may be utilized todevelop the voltages by which the scanning beam is formed, and, at the same time, to provide the heater current energy source which causes the initial release of the electrons to make up the scanning beam.

Other objects of the invention are those of providing a power supply system for a television or cathode ray device wherein the operating voltages are developed from a self-contained. unit, and wherein separate sources for developing the high voltages and the heater currents are avoided.

Other objects and advantages of the invention are those of providing ways and means by which previously existing defects in prior art systems are overcome and, at the same time, a power supply system is developed in which there is a great simplification .of the existing parts and a greater eiliciency of operating `than heretofore obtained.

Other objects and advantages of the invention wlil become apparent to those skilled in the art to which the invention is directed when the following speciications are considered in connection with the accompanying drawings, wherein,

Fig. 1 represents schematically one form of system in which the features of the invention are incorporated;

Fig. 2 represents a modication of a portion of the circuit of Fig. l; and,

Fig. 3 represents still further modication of the arrangements of Figs. 1 and 2.

Now making reference to the drawings for a further understanding of the invention. it will be assumed, for the purpose of these considerations, that an electron tube of the cathode ray type (not shown) is provided with suitable deilecting electrode means to which currents or voltages of saw-tooth wave formation are applied, and the saw-tooth wave formation acting upon the deflecting electrode means causes the developed cathode ray or scanning beam to traverse a target area of the cathode ray tube according to a desired pattern of scanning.

The wave form of the voltage or current developed and applied to the defiecting electrode means (not shown) is of the general wave shape comprising a saw-tooth wave portion and an impulse wave portion, somewhat like the wave forms shown by (b) on Fig. l. Accordingly, during the impulse section of such a wave, the impulse effects may be transmitted in a wave formation, illustrated by way of example as the wave form (a) on Fig. l, to an input terminal point Il, from which it is fed across the resistor element i3 and through the coupling condenser l5 to the grid or control electrode l1 of an amplifier tube 25. This amplier tube 2] is illustrated, for example, Vas being of the form of a double triode, although it is obvious that two separate tubes may be utilized where desired. However, for purposes of illustration, a tube of the general type, known in the art as the 12SL7GT, has been found to be suitable and is referred to by way of example.

The input energy of pulse wave formation, as shown adjacent to terminal point Il, is, as above stated, applied to the control electrode or grid i1 of the first half of the tube 25, of which the cathode element i9 connects directly to ground 25, and a grid-leak to ground to provide bias is connected in the form of the resistor 2l between the grid or control electrode I7 and the cathode.

Also, for purposes later to be explained, blanking pulses (which do not directly affect the production of the heater current) for control are applied at the second input terminal 23 and fed through the resistor 2l and capacitor 29 to the grid or control electrode 3l of the second half of the tube 20. At the point 28, constituting the junction of one end of the resistor I3 and the resistor 21, the line impulses fed to the terminal Il are miXed with the Vertical blanking pulses applied to the terminal 23. These two .pulses then serve to control both deflection and (if desired) blanking in the scanning or camera tube (not shown) although the rst half of the tube serves as that section of the tube used mainly in connection with the power supply constituting primarily the invention herein to be claimed.

At this point, however, it should be noted that the Second half of the tube 2i) also has its cathode element 33 preferably connected to ground 25, and the resistor element 34 is connected in the same manner as the grid resistor 2! of the iirst half of the tube.

When impulses are applied to the first half of the tube 25, it can be seen that with the cathode I9 connected directly to ground, no degeneration takes place within the first half of the tube 20, and the impulses are amplified in suitable manner. The amplied impulses are fed from the plate or anode 36 of the tube 20 by way of conductor 31 to the control electrode 39 of the amplier 5G. These energy pulses are fed across the resistor il and the serially arranged condenser 43 so that, at the junction point 44, a voltage pulse comprising the saw-tooth section and the impulse section is developed where, it will be seen, a substantial portion of the voltage wave is below the 4 reference line, so that when the impulse section of the wave-form (b) is fed to the grid or control electrode 39 of the tube 40 by way of the coupling condenser M5, a substantial amount of energy is supplied in order that the current for operating the heater elements of the television or cathode ray tube, later to be described, will be available.

The ampliiier tube 40 has its cathode biased to ground 25 by way of the cathode resistor 4l, which is shunted by a condenser s to by-pass any high frequency components. The grid bias for the tube is provided by way of the resistor 5l connected between the grid or control electrode 39 and ground 25.

For purposes of these considerations, it may be assumed that the plate or anode 53 of the tube iii), as well as the plate or anode elements 55 of the first half of tube Eil, and 58 of the second half of tube 2b, are held positive relative to the cathode elements by means of a voltage applied at the terminal point 55 relative to the cathode elements of the tubes. In this connection it will be seen that the plate or anode 53 of tube 0 is held positive relative to its cathode 54 by the voltage from the source 55 (not shown in detail) being applied to the plate or anode 53 through the primary winding 51 of an Voutput transformer 5S having secondary windings 59 and El, respectively.

When the voltage wave shown adjacent to the point 44 is applied across the load resistor 55 for the rst half of tube 2) to the input of the tube dil, it produces, through the auto-transformer section 51-59 a relatively high voltage which is applied by way of a coupling condenser 63 to the plate element 65 of a rectifier element 5l', having its cathode 69 grounded at 25. Under these circumstances, the tube 61 functions in a manner somewhat similar to a grid-leak detector.

It will be seen that a rather large positive pulse is developed across the resistor 'il due to the large positive pulse applied by way of transformer section 5S with the Voltage wave form as appearing at point d applied to control the tube d5. This voltage also appears across`the tube 6l so that a negative D. C. potential appears at the plate element 55. The tube 51 has its plate or anode 65 connected to ground through condenser 13. The load resistor 'H and capacitor 'i3 together form a lter which will remove all effects of the line pulses.

Under these circumstances there is developed, at the point i5, a negative potential relative to ground when the tube 61 draws current, so that a relatively high voltage bleeder resistor, shown as comprising the resistor sections 75, 16 and 11, connects between the point 'I8 and ground 25, so that the high voltage bleeder is connected in parallel with capacitor 'i3 as the filter.

In this way it can be seen that the potential at point 18, which is transferred to a terminal point Bil by way of resistor 8|, is negative relative to ground, and it may be assumed, for purposes of these considerations, that the bias applied to the control electrode element of the cathode ray type camera tube (not shown) is established by a connection made at the point 85.

A connection to the cathode element of the same cathode ray or camera tube is made from point 82 and some intermediate point, such as 83, on the bleeder resistor combination, and the rst anode element (not shown) of the same cathode ray or camera tube (not shown) may be assumed to connect at point S4, which is tapped to the bleeder resistor at point 85, which is substantially more positivev than the cathode connecting at point 83 and yet negative relative to ground 25. The second anode (not shown) of the same cathode ra-y tube Will be assumed, for purposes of these considerations, to operate as the most positive element of the system and, consequently, it will be connected in any suitable manner (not shown )l directly to ground.

From what has been stated above, it will be apparent that rectifier 61 derives operating voltage in accordance with the output of the tube 40, which is controlled by a control voltage of saw-tooth and impulse wave formation', and that when this voltage wave is rectiiied by the halfwave rectier 61 and suitably smoothed by the lte'r combination, including resistor 1| andL con"- denser 13, of which the latter' is rather large'as a general rule, suitable high voltage operation of theV tube is made possible.

At theY same time, the output voltage from the tube 48, as it appears in the primary winding 51 of the auto-transformer 58, is applied to the secondary winding 6|, as above noted, and this transferred voltage is then of a frequencywhich is directly related to the frequency of the pulses applied at the input terminal l. In this way, at the. output terminals 86 and 88 which connect by conductors 89 and 9| to the outer terminals of the secondary winding 6|, Suitable heater current for the heater element of the cathode ray or camera tube (both not shown) is developed. Where desired, the inductance element 93 may be included in the heater element leads in order to obtain the eiTects of greater second anode voltage for the tube and less heater current.

1 At the same time, since it was pointed out above that blanking on both the horizontal return-trace and the vertical return-trace is essential, provision is made for feeding a part of the output of the second half of the tube by way of conductors 9d and 95 through the condenser 96 to the terminal point 8D, so that the blanking impulse may be applied at each Snap-back or pulse period of the deecting wave energy at the terminal point 89. In this connection, it should be noted that it is preferable to arrange the time constant of the resistor 8| and the capacitor 95 so that the hold period is approximately equalto the field frequency repetition rate, which, according to present R. M, A. practice, would beof the order of 1/60 second.

Y Now, referring to the modifications of Fig. 2, it will be seen that the output voltage from the tube 40 (only a portion of the circuits are completed for simplication reasons) is supplied to the auto-transformer sections 57 and 59 (of which the latter constitutes the secondary winding) in the same manner as described in connection with Fig. 1. However, in contrast to the arrangement of Fig. 1, there are two further secondary windings, namely, the winding 6| from which the output voltage is fed to the terminal points 86 and 88 to supply heater current for the cathode ray tube (not shown), and also the winding 98 which has its output terminals connected to the deecting coil elements 99 and |00, which are conventionally represented. These deecting coils may or may not have the condenser |0| connected in shunt.

In the circuit modification shown by Fig. 2, it is apparent that the tube 40 is controlled from the pulses, such as those applied at terminal input point and the saw-tooth voltage Wave formation which appeared at point 44 in Fig. 1 is then caused to be transferred directly to the deflecting coils to force a saw-tooth current wave therethrough, in contrast to the separate input energy pulses hereinabove'explained in connection with Fig. l. The output voltage from the secondary winding 69 from the auto-transformer 58 is supplied', as in the arrangement of Fig. 1, through the capacitor 63 to the high voltage rectifier 67 (not shown in Fig. 2).

In the modification of Fig. 3, provision has been made for utilizing a separater oscillator which is synchronized from the horizontal or line deflection frequency pulses which are shown and ap- Dlie'dto inputv terminal in Fig. 1. The heater and` anodeA operating voltages for the cathode rayy scanning or camera tube are then derived from this oscillator. The voltage pulses, which appear at the point 44 in Fig. 1, are` applied by way of the condenser t9' at the input or control electrode|03 of an oscillator tube I D5.

The oscillator tube has its cathode |07 grounded by a direct connection to ground at 25, and its grid condenser |89 is. provided With a grid leak resistor also connecting between the grid control electro'de |113 and ground. The anode H3 of this oscillator tube has connected in series with the terminal point 55, from which the tube operating voltage is supplied, a tunedV resonant circuit H5 comprising the primary winding ||1 of a transformer element IIS and a variable condenser element 2| connected in parallel with the transformer to tune the primary Winding to a predetermined frequency. Feed-back energy from the plate ||3 to the grid |03 is provided by way of the' secondary winding |23, which has one terminal connected to ground 25 and the other tei-- minal connectedv by |25 to feed back energy to plate l 3` to the control plate of grid 83 to sustain oscillations.

In the connection shown, heater current is now supplied to the terminal points 88 and 88 by way of the additional secondary winding 6| (as eX- plained for Figs. l and 2).

The high voltage for controlling the rectier 6l is supplied from the connection point |21 by way of conductor |29 and the condenser 63 to the high voltage rectifier (not shown) but similar to the recti'er |51 of Fig. 1.

From what has been described above, it becomes apparent that' many and various modifications4 of thesystem herein set forth and disclosed may be relied upon to produce the desiredheating currents and high operating voltages, and that these same currents and voltages may be developed and produced completely in accordance with the deflection voltages used for deflecting the cathode ray scanning beam developed in the apparatus which is to be controlled. Accordingly, it becomes apparent that many and various modications may be made and utilized in accordance With the teachings of the invention as set forth.

Having described the invention, what is claimed 1s:

1. In television apparatus wherein is included a camera tube having a target and means to develop an electron beam in combination With means to cause the developed beam to scan the target, electrical wave generating means for producing electrical waves for controlling the deection of the electron beam relative to the target area, transformer means adapted to be energized by the output deflection controlling electrical Waves from the generator, means for developing alternating current energy from the said transformer output to provide heating current for the electron beam developing means, and rectier means also adapted to be energized from the transformerA output for developing relatively high voltage direct current output for energizing other electrodes of the electron beam developing means.

2. In television apparatus wherein is included a camera tube having a target and means to develop an electron beam in combination with means to cause the developed beam to scan the target, electrical saw-tooth wave generating means for producing electrical waves having an impulse and a saw-tooth component for controlling the deiiection of the electron beam relative to the target area, transformer means adapted to respond to the impulse component of the said electrical saw-tooth waves of the output of said generator, and means for developing from the said transformer output alternating current energy of a frequency related to the frequency of the impulse components to provide heating current for the electron beam developing means.

3. In television apparatus wherein is included a camera tube having a target and means to develop an electron beam in combination with means to cause the developed beam to scan the target, electrical saw-tooth wave generating means for producing electrical waves having an impulse and a saw-tooth component for controlling the deflection of the electron beam relative to the target area, transformer means connected to receive said generating means output and adapted to respond to the impulse component of the said electrical saw-tooth waves, means for developing from the said transformer output alternating current energy of a frequency related to the frequency of the impulse components to provide heating current for the electron beam developing means, and rectifier means also adapted to be energized from the transformer output for developing relatively high voltage direct current output for energizing other electrodes of the electron beam developing means.

4. In television apparatus wherein a cathode ray tube is used forv scanning and wherein the said cathode ray tube has an indirectly heated cathode for emitting electrons and direct current energized accelerating electrodes for forming the electrons into a beam and for directing the said beam to a target electrode, means for developing electrical voltage waves ofpredeterrnined wave-form for controlling the deflection of the developed cathode ray beam across the target electrode according to a predetermined pattern of deflection,

transformer means adapted to have the primary winding thereof energized by said voltage waves, rectifier means adapted to be energized by the output energy of the transformer secondary winding for developing a relatively high unidirectional voltage output controlled from the beam deecting energy, and means 'for developing directly from the transformer secondary alternating current energy of a frequency coinciding substantially with the frequency of the developed deflecting voltage waves and adapted to be used for heating the cathode element, whereby cross talk and scanning ripple eiects are substantially eliminated.

5. In television apparatus wherein is included a cathode ray scanning tube having a target area adapted to be traversed by a scanning cathode ray beam and wherein the cathode ray beam is developed from an indirectly heated source releasing electrons which are accelerated and formed into a beam under the influence of relatively high uni-directional voltages, means to generate sawtooth beam deiiecting voltage waves for controlling the deflection of the developed cathode ray beam for each deflection cycle relatively slowly in one direction and rapidly returning it subsequently substantially to its initial position, transformer means connected to have the input thereof energized by the saw-tooth voltage waves, direct connections from the transformer output for deriving alternating current energy adapted to be supplied to the heater elements from which the cathode ray beam is developed, and means controlled by the current iiow in the transformer means for simultaneously developing uni-directional accelerating voltages from the said saw-tooth deflecting voltage waves, whereby cross talk and scanning ripple effects in the scanning pattern are eliminated.

WALDEMAR J. POCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,962,873 Parker June 12, 1934 2,051,372 Farnsworth Aug. 18, 1936 2,074,495 Vance Mar. 23, 1937 2,262,630 Bahring Nov. 11, 1941 2,265,620 Bahring Dec. 9, 1941

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