US3402315A - Circuit for regulating the potential between the cathode and the high voltage anode of a cathode ray tube using a tube having two groups of electrodes - Google Patents

Description

Sept. 17, 1968 A. w. FRIEND 3,402,315

CIRCUIT FOR REGULATING THE POTENTIAL BETWEEN THE CATHODE AND THE HIGH VOLTAGE ANODE OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Original Filed July 15, 1963 6 Sheets-Sheet 1 INVENTOR A. W. Friend M2 4 Fm ATTORNEYS Sept. 17, 1968 A. w. FRIEND 3,402,315

CIRCUIT FOR REGULATING THE POTENTIAL: BETWEEN THE CATHODE AND THE HIGH VOLTAGE ANODE OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Original Filed July 15, 1963 6 Sheets-Sheet 2 H2 5 HI 1; 6Kv IIO 94) 82 I 7? I81 as 75''\ MM?8O ny l'-#4 r- 107 I08 I06 'f-u 927 L 93 i To Deflection e7 Yoke (Not 8+ Shown)? 95 390 V. DC. Power Source,

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INVENTOR A. W. Friend ATTORNEYS p 17, 1968 A. w. FRIEND 3,40 ,3 5

CIRCUIT FOR REGULATING THE POTENTIAL BETWEEN THE CATHODE AND THE HIGH VOLTAGE ANODEJ OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Original Filed July15, 1963 6 Sheets-Sheet 5 FIG. 3. I76

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CIRCUIT FOR REGULATING THE POTENTIAL BETWEEN THE CATHODE AND THE HIGH VOLTAGE ANODE OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Criginal Filed July 15, 1963- 6 Sheets-Sheet 4 INVENTOR A. W. Friend ATTORNEYS 3,402,315 THODE AND A. W. FRIEND Sept. 17, 1968 CIRCUIT FOR REEGULATING THE POTENTIAL BETWEEN THE CA THE HIGH VOLTAGE ANODE OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Original Filed July 15, 1963 6 Sheets-Sheet 5 is e INVENTOR A. W. Friend BYW y flak ATTORNEYS Sept. 17, 1968 A. w. FRIEND 3,402,315

CIRCUIT FOR REGULATING THE POTENTIAL BETWEEN THE CATHODE AND THE HIGH VOLTAGE ANODE OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Original Filed July 15 1963 6 Sheets-Sheet 6 |2| 2 m 1;; i |32 1 v 1 59, l59,l78 Or I98 5 a i If? H: M

INVENIOR A. W. Friend ATTORNEYS United States Patent Ofice 3,402,315 Patented Sept. 17, 1968 3,402,315 CIRCUIT FOR REGULATING THE POTENTIAL BETWEEN THE CATHODE AND THE HIGH VOLTAGE ANODE OF A CATHODE RAY TUBE USING A TUBE HAVING TWO GROUPS OF ELECTRODES Albert W. Friend, 5903 City Line Ave., Philadelphia, Pa. 19131 Original application July 15, 1963, Ser. No. 294,927. Divided and this application Dec. 9, 1966, Ser. No. 610,706

3 Claims. (Cl. 315-4) This invention relates to an electron discharge device and to a circuit for its application.

More particularly, the invention relates to a control system for the anode-cathode circuit of a cathode ray tube on a color television set.

Heretofore, the aforesaid anode-cathode circuit has employed two separate vacuum tubes, one for rectifying the current and the other for regulating the potential across said anode-cathode. The aforesaid prior art circuits have given considerable difi'iculty, especially with respect to insulation.

It is a main object of this invention to provide a new and improved circuit arrangement for the anode-cathode circuit of a cathode ray tube used in color television.

Another object of the invention is to provide circuitry in connection with the anode-cathode circuit of a cathode ray tube which is lower in cost than in the case of the prior art.

Yet another object of the invention is to provide circuitry for the anode-cathode of a cathode ray tube for color television, which is more efiicient and efiective than in the prior art.

Still another object of the invention is to provide circuitry which avoids the insulation problems of the prior art.

Another object of the invention is to reduce the number of components in the anode-cathode circuit.

A further object of the invention is to provide an improved tube which will pass current simultaneously and/or alternately in opposite directions therethrough.

A further object of the invention is to provide an improved tube for use in the anode-cathode circuit of a cathode ray tube.

A still further object of the invention is to provide an improved tube for sue in the anode-cathode circuit of a cathode ray tube used in color television.

In carrying out the invention, I employ a special tube having the low voltage terminals grouped at one end and the high voltage terminals grouped at the other end, with the envelope acting as the high voltage insulation. This tube has two groups of electrodes. One group acts as the high voltage electrodes and the other group acts as the low voltage electrodes, each group having adjacent anodes and cathodes, the cathode(s) of one group feeding the anode(s) of the other group. Each group has separate anodes and cathodes.

The high voltage group of electrodes is connected to a source of alternating current and has a cathode which cooperates with the anode of the low voltage group to provide a rectifier for supplying rectified potential and current to the anode-cathode circuit of the cathode ray tube, and to the associated energy storage capacitance (condenser) built into that tube, or connected to it. The cathode, and a control grid, of said low voltage group of electrodes cooperates with the anode of said high voltage group of electrodes to provide a regulator for the potential which represents the energy stored in the eifective condenser in parallel with the anode-cathode circuit of the cathode ray tube.

In the drawings:

FIGURE 1 is a cross-sectional view of one form of the new tube embodied in the invention;

FIGURE 2 is a schematic diagram of a portion of a color television receiver, showing the improved circuit constituting a part of my invention;

FIGURE 3 is a cross-sectional view of another form of tube embodying my invention;

FIGURE 4 is a cross-sectional view of still another tube embodying my invention;

FIGURE 5 is a cross-sectional view of yet another tube embodying my invention; and

FIGURE 6 illustrates one suitable mounting arrangement for the new tube, cathode ray tube, and other elements.

An electron discharge device, tube, or valve, is normally possessed of a cathode, emitter, or source, from which a current of electons fiows to an anode, or plate, electrode, or in some instances to more than one anode or plate. Such devices may also include means for control of the current flow, such as grids, deflection plates, or magnetic fields. The main flow of electric current is essentially in a single direction through all such devices, whether controlled or uncontrolled. It is determined by the direction of electron flow.

There are applications in which it is desirable to exert separate control of the flow of current in opposite directions in a single circuit. This can be done most advantageously by producing this effect within a single device, for both directions of current flow. For instance, when such a device is required to function at high-voltage with respect to surrounding and supporting objects it is desirable to minimize the number of necessary mechanical support and insulating members, to reduce the size, weight and cost, and to improve the reliability of the system. This can best be done by a single unit which minimizes the complexities of the system. A vacuum tube which provides current flow in both directions, each separately controlled, is described here.

FIGURE 1 shows a section along the axis through a bidirectional conduction vacuum tube suitable for application in the circuit of FIGURE 2, to be explained later. In FIGURE 1, an insulating (glass or ceramic) envelope 59 is closed at one end by a terminal pin header 60 which supports heater 61 and cathode 62. Surrounding this cathode 62 is an electrostatic shield 63 with an aperture 64 through which an electron stream 65 issues toward anode 66. Anode 66 is supported from a terminal pin header 67 at the opposite end of the tubular envelope 59.

Terminal pin header 67 supports a heater element 68 in a cathode 69, surrounded by a control grid structure 70. Around this is anode and electrostatic shield 66, with aperture 71 through'which issues electron stream 72 to anode and electrostatic shield 63. These elements are connected in a circuit as shown in FIGURE 2, taking note that inside this special tube the combined anode and shield 63 is electrically connected to cathode 62, and anode and shield 66 is electrically connected to cathode 69. If a tube is made with shields and anodes 63 and 66 not connected internally to cathodes 62 and 69, respectively, then they may be connected to essentially the same potential points externally, in the same or a similar circuit.

This controlled bidirectional conductive tube is specifically applicable to a combined horizontal deflection and regulated high voltage power supply for television, and especially for color television applications, essentially as shown in FIGURE 2. This is a schematic diagram of that portion of a modified color television receiver, all of which is the well known prior art of color television cathode ray tube circuits, except for tube 59 and its immediate circuitry. The horizontal output tube 73, a beam pentode,

is excited by an input saw-tooth voltage wave 74, via coupling capacitor 75, across grid shunting resistor 76 and through series grid resistor 77. Resistor 77 tends to prevent parasitic oscillations of tube 73. Pentode vacuum tube 73 has a heater element 78, a cathode 79, a control grid 80, a screen grid 81, a suppressor grid 82 (connected internally to the cathode 79) and an anode (plate) 83, all inside a vacuum envelope 73. The screen grid 81 is by-passed to cathode 79 and ground 84 via capacitor 85. Its screen grid 81 voltage is decreased by the voltage drop through series resistor 86 from terminal 87 of B+ power source 126.

The anode 83 is connected to the primary winding 88 of the horizontal deflection output transformer 89 which has a ferromagnetic core 90. The saw-tooth current wave of electrons from the anode 83 flows through primary winding 88 (with taps 91, 92 and 93), via the terminal 94 and out via terminal 95. The conventional current flow to is from 95 to 94. When this current reaches a maximum value the saw-tooth input signal 74 causes the tube 73 to cease conduction. This starts a reasonant ringing or oscillation in the circuit of the transformer windings and their associated capacitances. This oscillation is arrested after one half-cycle (about 7 to microseconds) when the anode 96 of damper diode 97 swings positive with respect to its associated cathode 98, heated by element 99. The resultant current through damper diode 97 conveys the stored energy of oscillation from the transformer magnetic field to the electric field of the B-boost storage capacitor 100, during the first portion of the electron beam deflection period. Inductive elements 101, 102 and 103 modify the wave shape of the discharge current. Capacitors 104, 105, 106 and 107 provide some additional wave shaping action, as do also inductor 108 and resistor 109. The latter three components are chiefly to control the focus voltage supplied to the cathode ray picture tube 119, by modification of the flyback pulse applied to rectifier 111.

Insulated lead 56-58 is made of only sulficient length to reach across the very short path between terminal connection 133, FIGURE 6, upon tube 59, 159, 178 or 198, and terminal 132 (or 131) upon transformer 89, plus a slight amount of slack to permit ease in replacing the tube. A length of no more than about 2 to 4 inches is estimated to be sufficient.

Insulated lead 129 carries the high-voltage from transformer 89, terminal 122, to cathode ray picture tube 119 final anode terminal 127. A length of just a few inches is sufficient.

It is apparent from FIGURE 6 that there are no components or sockets, at high voltage, which require separate mounting terminals beyond the top connector of the tube 59, 159, 178 or 198, the transformer 89 high voltage winding 120, terminals 121 and 122, or the terminal 127 of the cathode ray picture tube 119. The voltage pulse developed between primary terminals 95 and 91 is modified by capacitors 106 and 107, inductor 108 and resistor 109, and is applied to anode 110 of diode 111. This tube rectifies the pulse to furnish about 4.9 kv. output across storage capacitor 112, to the focussing electrode of the cathode ray picture tube 119. Diode rectifier 111 derives heating energy for its filament 113 from winding 114 via resistor 115. Resistors 116, 117 and 118 are connected in series and shunted across capacitor 112, as a bleeder load. The focus voltage for the cathode ray picture tube 119 is applied from capacitor 112 via lead 57.

The same system is used to excite a very high voltage across high voltage secondary winding 120. The pulse is positive at terminal 122 with respect to terminal 121. Terminal 122 is connected to the final anode of cathode ray picture tube 119, at final anode terminal 127. Within tube 119 is a storage capacitance 123 built into the tube between the final anode (terminal 127) through its connection to an internal conductive coating upon the glass envelope, and a similar external conductive coating 140,

externally connected to ground (chassis) 128. Terminal 121 is connected to the heater 61, cathode 62, and electrostatic shield 63 of high voltage rectifier and voltage regulator tube 59, with anode and electrostatic shield 66. It rectifies the pulse from high voltage secondary winding 120, to charge the storage capacitance 123 of the cathode ray picture tube 119. Its heater power is supplied from transformer winding 129 via dropping resistor 130.

Tube 59 is controlled as a triode in its reverse direction conduction. It has a heater element 68, a cathode 69, a control grid 70, and an electrostatic shield 66, which is also the anode 66 for the opposite direction conduction. The shield 63 of cathode 62 serves as the anode 63 of the voltage regulator function of tube 59.

Capacitor 134 with associated resistors 135, 136, 137 and 138 control the time constant (frequency response) of the grid circuit of voltage regulator tube 59. Resistors 135, 136, 137 and 138 are also utilized to adjust and control the grid bias and regulator control voltage applied betwen cathode 69 and grid 70 of this regulator tube section.

The horizontal deflection and high-voltage portion of a television receiver circuit schematic of FIGURE 2 is to replace a prior art circuit in which the high-voltage rectifier and voltage regulator tubes have been entirely separate and have required the use of special high-voltage insulating supports and corona shields with wide spacing of components.

The circuit of FIGURE 2 operates broadly as follows. The horizontal output tube 73 causes a sawtooth wave of current to flow in transformer primary winding 88. When this current suddenly ceases to flow, because the sawtooth excitation falls to zero, during its flyback interval, the collapsing of the stored energy of the magnetic field in core of transformer 89 induces a high voltage pulse across the windings of coils 88 and 120.

Terminal 121 of winding becomes negative with respect to terminal 122 during this first induction period. The generate-d negative pulse is applied to cathode 62 of vacuum tube 59. The complete circuit continues through tube 59, from anode 66 through small metering resistor (which may be omitted), through DC power supply 126 to ground (chassis) 84, via terminals 84 and 142, and thence through ground (chassis) terminal 128 to capacitor 123 and terminal 127, or through video and bias network 141, to the cathodes of cathode ray tube 119, and via the electron beams to the final anode, and then via terminal 127, high-voltage lead 129, terminal 122, and transformer winding 120, back to terminal 121.

The negative pulse applied to tube 59, operating as a diode rectifier causes capacitance 123 of tube 119 to become charged to a high voltage, of the order of 24 kv. This voltage accelerates the electron beam in cathode ray picture tube 119.

Tube 59 also conducts in a controlled manner in the reverse direction through the action of its triode portion. This consists of a cathode 69, a control grid 70 and an anode 63. It serves as a triode high-voltage shunting regulator tube. The DC bias voltage for this triode is obtained from the resistor network 135, 136, 137 and 138, which also introduces the control voltage for its regulating action. This regulation is to reduce the variation of the high voltage across capacitor 123 in tube 119, as the electron beam current of tube 119 varies with picture brightness.

The circuit of this invention works broadly as follows. The cathode ray tube 119 has internal capacitor 123 between its outside conductive coating 140 and its similar inside coating, connected to the final anode. This condenser 123 is charged to a high voltage during the flyback of the sawtooth Wave 24 by reason of the transformer 88-120. After the condenser 123 has been thus charged, it is desirable to regulate the voltage of the condenser during the period of the next rise in voltage of saw tooth 74 (the next horizontal movement of the cathode ray beam) and this regulation is performed by the circuit starting at the left-hand side of condenser 123, the secondary 120, the anode 63, grid 70 and cathode 69, the latter being connected to ground and thus to the righthand side of condenser 123.

The secondary 120 feeds the conventional cathode ra tube yoke of cathode 119.

One of the important advantages of the present invention over the prior art is the reduction of high voltage (of the order of 24 thousand volts or more) terminals. Heretofore, it has been necessary to have two tubes, in place of the single tube 59. Each of these two tubes operated at high voltage, and indeed all of the terminals of one of these two tubes was at high voltage. This has given rise to many problems relating to the insulation of the high voltage parts with respect to the chassis, and also other components. In contrast, the presentinvention embodies the tube 59 in which all of the lower elements 66, 68, 69 and 70 terminating at one end of the tube 59 operate at potentials less than 1000 volts while the elements 61, "62 and 63 terminating at the other end of the tube 59 may operate at potentials of the order of 24 thousand volts, Therefore, the tube may be placed in a conventional socket in which the prongs extending out of header 67 (FIGURE 1) may fit into an ordinary low voltage socket. The envelope 59 of the tube acts as a high voltage insulator post, and the only terminals extending out of tube terminal pin header 60 operate at high voltage. The wire pair 56 and 58 extends through the air only a short distance to high voltage winding 120 of the horizontal output transformer. In addition to, or in place of, relying on the air to insulate wires 56 and 58, these wires may have a coating of any suitable type of wellknown high voltage insulating material.

The bidirectional conduction vacuum tube may be made essentially as shown in FIGURE 1, but the spirit of this invention is not at all confined to that precise mechanical arrangement. FIGURE 3 illustrates another form of the vacuum tube portion of this invention. Here, a vacuum envelope 159 has a terminal pin base 160. Mounted within the envelope 159 and upon the terminal pins of base 160 is an electrically conductive (metal) combination anode and cathode-shield structure 162. Within 162 is a heater 163 inside an electron emissive cathode 164, and around that is a control grid structure 165, the whole of which is situated just below an aperture 166 in the shield structure 162. Electrons emitted from cathode 164 pass through grid structure 1 65, through aperture 166, and are accelerated by the high voltage applied to anode structure 167. Their energy is dissipated there by the long anode structure.

Anode 167 is arranged with an annular skirt 168 into which fits an electron missive cathode 169 of an essentially toroidal shape. This cathode may be all in one piece, with one or more apertures for entry of heater connections, or it may be made of two or more segments. The shorter segments may be straight cylinders of cathode arranged about the skirt 168, and the skirt 168 may be shaped as a multisided figure, such as a hexagon or octagon, to fit a segmented cathode 169.

Cathode 169 is connected to anode 167 and this cathode contains a heater element 170 (or the heater may be the cathode) one terminal of which is connected to anode 167. The other heater (or filament) connection 171 may be insulated from anode and shield 167 by insulating bodies or any other arrangement of insulating material 172, and passed through an aperture 173 in tubular anode support 174, and there connected to a terminal pin 175 which passes through a vacuum seal insulating support 176, to make a coaxial external terminal. The tubular support member 174 is mounted by seal 177 to insulating glass or ceramic envelope 159.

A third possible embodiment of the combined, bidirectional conduction vacuum tube is shown in FIGURE 4. The envelope 178 and the terminal pin base 179 and top terminals 180 and 181 are essentially as in FIGURE 3. In FIGURE 4, the heater 182, cathode 183, control grid 184, and aperture 185, are shifted somewhat off the center of the shield and anode structure 186, to admit a thimble-type of anode part 187, indented into the main deck surface 188 of the anode and shield structure 186. This permits the use of an existing type of high-voltage cathode or filament structure 189 mounted upon a mechanically stiff wire 190, with a second wire 191 to provide the return path for the heater current.

The first stiff wire 190 is rigidly afiixed to the anode 192. The heater return lead 191 is returned to the top of anode 192 inside a length of small size conductive tubing 193, via insulators 194. A small metal tab 196 is mounted essentially as shown in FIGURE 4 to block the possible bombardment by the electron stream of the heater terminal seal insulation 197.

A fourth embodiment is shown in FIGURE 5. The envelope 198, the terminal pin base 199, and the top terminals 200 and 201 are again basically similar to the arrangement of FIGURE 3. In FIGURE 5, however, the thimble part 202 of the anode structure 203 is mounted coaxially down into the shield structure 203 and is an integral part of this general structure. This may also be directly connected to the cathode, or cathodes, 204. One or more cathodes 204 with heaters 205 and associated grids 206 are mounted adjacent to apertures 207 in shield and anode structure 203, as shown in FIGURE 5. The anode 208 is a common cup-type of high-voltage vacuum tube anode, except that it has a central tubular portion 209 upon which the cathode (or filament) 210 and heater 211 is mounted by stiff support wire 212. A coaxial central conductor 213 carries the return electrical path for the heater or filament. Conductor 213 extends through an insulating coaxial seal 214 inside the tubular terminal 200 of the anode 208 and the cathode (or filament) 210, to form an external connection pin 201.

It should be recognized that the heater, cathode, and grid assemblies of FIGURES 3, 4 and 5 could each be of a different form without departing from the spirit of the invention. For instance, they could utilize button-type cathodes within aperture-type grid structures, as in the cathode ray or traveling wave tube electron guns.

The tube structures of FIGURES l, 3, 4 and 5 are all equally effective in minimizing the required amount of external high voltage wiring and components. That is, each one mounts with its lower terminal pins in a relatively low voltage socket and all high voltage terminals are grouped together at the upper end. In each one, the envelope serves as the high voltage terminal insulator. The only necessary high voltage wiring consists of the short leads to the high voltage secondary winding of transformer 89, of FIGURE 2.

FIGURE 6 illustrates a possible mounting arrangement in socket 139 of any one of the tubes 59, 159, 178 or 198, of FIGURES 1, 3, 4 or 5, upon a chassis 130 adjacent to a horizontal deflection output transformer 89 and a cathode ray picture tube 119. High voltage connecting lead-pair 56-58, connects from the upper, high voltage terminal connector 133 of tube 59, 159, 178 or 198 to terminals 121 and 132 on transformer 89. Resistor 130 is mounted upon the terminal board of transformer 89 between terminals 131 and 132. Alternately, the very small resistor 130 may be mounted inside or upon terminal connector 133, of FIGURE 6, at the top of tube 59, 159, 178 or 198.

The word ground as used in this application shall be understood to include the chassis or any other part customarily regarded as a ground in electronic circuits.

I claim to have invented:

1. A cathode ray tube circuit comprising a cathode ray tube having a cathode and an anode with electrostatic capacity between the anode and the ground which is connected via video and bias networks to the cathode, a cire cuit including said anode and said cathode, a source of alternating potential in series with said circuit, a tube with two groups of electrodes with each group having at least an anode and a cathode, the cathode of the first of said groups and the anode of the second of said groups being in series with said circuit, and means including the cathode of the second group and the anode of the first group for regulating the potential between the cathode and anode of the cathode ray tube.

2. A cathode ray tube circuit as defined in claim 1 in which the tube has an envelope, the second group of electrodes operates at low voltage and have terminals extending out of one end of the envelope and the first group of electrodes operates at high voltage and extends out of the other end of the envelope.

3. A cathode ray tube circuit as defined in claim 1 in which the last-named means includes a control grid constituting part of the second group of electrodes and also includes means for varying the potential on said control grid to regulate the potential between the anode and cathode of the cathode ray tube.

References Cited UNITED STATES PATENTS 1,872,274 8/1932 Goldsborough 3133 1,925,558 9/1933 Foster 3133 2,431,740 12/1947 Eitel et a1 3133 X 2,432,260 12/ 1947 Thomas 3133 3,077,550 2/1963 Macovski 31522 3,202,865 8/1965 Stark 31522 3,350,599 10/1967 Rickling 31522 JAMES W. LAWRENCE, Primary Examiner.

V. LaFRANCHI, Assistant Examiner.

Claims (1)

1. A CATHODE RAY TUBE CIRCUIT COMPRISING A CATHODE RAY TUBE HAVING A CATHODE AND AN ANODE WITH ELECTROSTATIC CAPACITY BETWEEN THE ANODE AND THE GROUND WHICH IS CONNECTED VIA VIDEO AND BIAS NETWORKS TO THE CATHODE, A CIRCUIT INCLUDING SAID ANODE AND SAID CATHODE, A SOURCE OF ALTERNATING POTENTIAL IN SERIES WITH SAID CIRCUIT, A TUBE WITH TWO GROUPS OF ELECTRODES WITH EACH GROUP HAVING AT LEAST AN ANODE AND A CATHODE, THE CATHODE OF THE FIRST OF SAID GROUPS AND THE ANODE OF THE SECOND OF SAID GROUPS BEING IN SERIES WITH SAID CIRCUIT, AND MEANS INCLUDING THE CATH-

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