US2558120A

US2558120A - Push-pull electron tube for instruments or television

Info

Publication number: US2558120A
Application number: US139069A
Authority: US
Inventors: Jose W Acosta
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-01-17
Filing date: 1950-01-17
Publication date: 1951-06-26
Anticipated expiration: 1968-06-26

Description

June 26, 1951 Filed Jan. 17, 1950 J. W. ACOSTA PUSH-PULL ELECTRON TUBE FOR INSTRUMENTS OR TELEVISION 2 Sheet s-Sheet 1 Hoe. Sue-5P GENEKITQK V1050 SIGNAL l l I INVENTOR J. W. ACOSTA PUSH-PULL; ELECTRON TUBE FOR INSTRUMENTS 0R TELEVISION June 26, 1951 2 Sheets-Sheet 2 Filed Jan. 17, 1950 INVENTOR 7'4,

JOJ'E' 072mm W ATTORNEY6.

Patented June 26, 1951 PUSH-PULL ELECTRON TUBE .FOR INSTRU- MENTS OR TELEVISION Jos W. Acosta, Chicago, Ill.

Application January 17, 1950, Serial No. 139,069

8 Claims. 1

This invention relates to cathode ray tubes, tan]? more particularly to a cathode ray picture A main object of the invention is to provide a novel and improved cathode ray tube wherein there is improved control of the scanning beams, and wherein distortion is minimized, said tube being relatively simple in construction, providing a relatively flat viewing screen, and being relatively short in length from the front to the rear of the tube.

A further object of the invention is to provide an improved multiple-gun cathode ray tube which involves relatively simple components, has a relatively flat screen of substantial size, and which provides substantially constant brightness for a given degree of modulation of the cathode ray beams over all areas of the viewing screen.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

Figure 1 is a front elevational view of an improved dual-gun cathode ray tube constructed in accordance with the present invention;

Figure 2 is a longitudinal, vertical, cross-sectional view taken through the tube of Figure l, and showing a projection lens system which may be employed with said tube;

Figure 3 is a fragmentary, longitudinal, vertical, cross-sectional view taken through a tube according to the present invention, showing schematically the wiring connections to the elements of the tube;

Figure 4 is a view similar to Figure 3, but showing a tube according to the present invention employing electromagnetic deflection rather than electrostatic deflection;

Figure 5 is a vertical, longitudinal, crosssectional view taken through a tube according to the present invention, wherein electrostatic deflection of the scanning beam is employed at one of the electron guns of the tube, and electromagnetic deflection of the scanning beam is employed at the other electron gun of the tube;

Figure 6 is an elevational view of an improved cathode ray tube according to the present invention, showing the use of accelerating coils for attracting the electron beams toward the fluorescent viewing screen, said tube also being provided with projection lens elements for projecting images.

Referring to the drawings, and more particularly to Figureslto 3, illustrating one form of.

the invention, I I designates the transparent glass envelope of the tube, said envelope comprising a central, enlarged portion l2 and symmetrical, inclined neck portions l3 and I4 communicating with the central portion l2 and directed toward the inner surface of the substantially flat, front wall [5 of said central portion. Said inner surface is provided with the conventional coating ll of fluorescent material employed as the screen material of television picture tubes. Designated at l 6 is an inner, conductive coating surrounding the fluorescent screen I! and having an outwardly extending terminal l8 which is connected to the positive terminal of a high voltage D. C. power supply, not shown. The coating l6 constitutes the second anode of the tube.

Each of the neck portions l3 and I4 contains a conventional electron gun. Thus, as shown in Figures 2 and 3, the electron gun in neck portion 13 comprises the heater filament N3, the cathode 2B, the electron modulating grid 21, the screen grid 22, the focusing ring 23, the

horizontal deflection plates

24 and 25, and the vertical deflection plates 25 and Bl. As shown in Figure 2, the electron gun in neck portion It comprises the

corresponding elements

19, 20, 2!, 22', 23', 24', 25, 26 and 21'.

Secured to the inside surface of the rear wall 28 opposite screen ll and substantially equal in diameter thereto is a flat, annular conductive ring 28 having an outwardly extending terminal 30 connected to the negative terminal of a voltage source 32 which is substantially greater than the grid-biasing voltage employed with either elec-' tron gun, i. 'e., substantially greater than the voltage of the biasing source shown at 31 in Figure 3. The positive terminal of the biasing source 32 is grounded.

Secured to the rear wall 28 of central portion I2 is a lens 33 which is cooperatively arranged with respect to another lens 34, or a suitable lens system, not shown, to project the picture traced on the fluorescent screen I! by the electron beams of the respective electron guns onto a. suitable external screen. Since the picture is generated on the screen ll, light rays may pass through the transparent wall 28 to the projection lens system. The picture may be also directly viewed through the tranparent front wall l5 of the tube.

Referring to Figure 3, it will be seen that the various elements of the respective electron guns are connected in parallel to suitable electrical circuits of the type customarily employed in television receivers of the electrostatic deflection type, except that the top, left, horizontal deflection plate 24, as viewed in Figure 3, is connected to the lower, right, horizontal deflection plate 25, the plates 24 and 25' being connected to one output terminal of the horizontal sweep generator 35, and the lower, left, horizontal deflection plate 25 is connected to the upper, right, horizontal deflection plate 24, the plates 25 and 2 3 being connected to the remaining output terminal of the horizontal sweep generator.

Assuming that the electron beams of both electron guns are focused to strike a common point on the screen ii, the two beams will be swept in tandem synchronously over the screen, and since the modulating grids 2! and El are connected together, both electron beams will be modulated simultaneously by the video input signal. of the horizontal deflection plates, when the electron beam in neck portion is is swept clock wise, as viewed in Figure 3, the electron beam in neck portion It will also be swept clockwise, and vice versa. When the beam from the electron gun in neck portion 24 moves from the right side of the screen to the left side, its intensity becomes attenuated due to the increased length of travel thereof. However, the length of travel of the electron beam from the electron gun in neck portion i3 is simultaneously being shortened, so that its intensity increases. The result of this arrangement is to maintain the net excitation of the fluorescent screen I! substantially constant over its entire width, all other factors being equal.

Due to the use of two electron beams to excite the screen rather than a single beam as in conventional television tubes, the required value of second anode voltage to obtain a given, highlight brightness is materially reduced. Also, due to the symmetrical, angled relationship of the neck portions to the central light-generating portion of the tube, the over-all, front-to-rear dimension of the tube is substantially smaller than the length of a tube giving comparable performance and utilizing a single, axially arranged electron gun, and, therefore, the problem of designing a suitable cabinet for the television receiver is greatly simplified.

Where the tube is to be employed for projection television, the lens 33 may be either detachable from or may be molded integrally with the rear wall of the central portion of the tube.

The negative ring 29 acts to repel electrons toward the portion of the tube adjacent the fluorescent screen H. The electrostatic field provided by ring 29 thereby assists the field provided by second anode HS in urging the electrons toward the screen ll, thereby improving the clarity of the reproduced image.

By connecting the respective modulating grids 2!, 2i to different signal sources, it is possible to obtain a composite image consisting of a first picture with a second picture superimposed thereon. By employing the tube in this manner, it is possible to accurately compare two difierent signal frequencies by applyin one of the frequengi'es to grid 21 and the other frequency to grid Referring now to Figure 4, another form of the present invention is disclosed wherein the tube is of the electromagnetic deflection type. The various elements of the tube are substantially the same as in the embodiment of Figures 1 to 3, except that horizontal

deflecting coils

36, 37 and 36, 37' are employed with the left and right" tube neck portions l3 and i l in place of the horizontal deflection plates of Figures 1 to 3,

Because of the above-describedconnections: I

all)

4.- and vertical deflecting coils, shown at 38 and 38 are employed in place of the vertical deflection plates of Figures 1 to 3. As shown in Figure 4, the outer terminal of the lower, left, horizontal deflection coil 36 and the outer terminal of the upper, right, horizontal deflection coil 3? are both connected to one output terminal of the horizontal sweep generator 39, and the outer terminal of the upper, left coil 31 and the outer terminal of the lower, right coil 36 are connected together to the other output terminal of said horizontal sweep generator. Coils 3E, 37 are woundin the same direction as coils 36', 3'5, as viewed in Figure 4, but the magnetomotive forces developed in the respective

sets oi coils

36, 3i and 36, 3'! will be opposite in polarity due to the above-described manner of connecting the coils to the horizontal sweep generator. The vertical deflecting coils 38 and 33' are connected in parallel to the output terminals of the vertical sweep generator lfi, .as shown in Figure 4. The'operation of the tube 10f Figure 4 will be substantially similar to the operation of the tube of Figures 1 to 3.

In the embodiment of the invention shown in Figure 5, the left neck portion I3 is provided with

electrostatic deflection plates

24, 25, 26,121 and the right neck portion it is provided with electromagnetic deflection coils 36, 3?, 38'. The left horizontal deflection plates 2d, 25 are connected to the output of a suitable horizontal sweep generator, not shown, and the right, horizontal deflection 00115.36, 31" are connected. to the output of another'suitable horizontal sweep generator, the respective sweep voltages applied to the

plates

24, 25 and the coils 36, 37' being out of phase, so that respective electron beams produced by the leftand right electron guns may trace synchronously over the fluorescent screen in the same manner as in the tubes of Figures 1 to 3 and Figure 4. The

vertical plates

26, 27 and the vertical deflection coil 38 are connected to respectivevertical sweep generators whose output voltages are in phase, so that vertical deflections of the respective electron beams are synchronized.

The tube disclosed in Figure 5 is particularly suitable for comparing two different signals by applying the respective signals to the respective grid 2i and 2 I In the embodiment of the invention illustrated in Figure 6, annular, accelerating coils 4| and 42 are mounted externally adjacent the margins of the respective front and rear faces of the central portion i2 of the tube, the coils being arranged to provide a magnetornotive force directed axially of said central portion and acting to urge the electron beams toward the fluorescent screen. The coils H and 42 may be connected to a constant D.'C. source so as to merely reinforce the effect of the second anode in attracting electrons toward the screen, or' alternatively may be coupled to the output of the last video output stage, so as to modulate the elecron beams with the video signal. By the use of the accelerating coils, the required second anode voltage is materially reduced. When the coils d! and 42 are coupled to the video signal, not only is the picture intensity increased, but the defocusing of the beams at the side marginal portions of the screen is reduced. When the coils M and d2 are employed in the latter manner, they are preferably energized with a steady D. (3. current and the video signal is superimposed thereon.

- of the electromagnetic deflection type of Figure 4. In the illustrated tube of Figure 6, the neck portions I3 and I4 have electromagnetic deflection yokes 44 and 44' mounted thereon which contain the electromagnetic sweep coils of Figure 4.

A tube similar to that described above and illustrated in any one of Figures 1 to 6 may be employed in a system such as is described in the MYE Technical Manual, page 280, published by the P. R. Mallory Co., Inc. In this system, a crystal plate is employed in place of the fluorescent screen and a transparent collector screen is disposed adjacent the crystal plate. The electron beams are scanned over the collector screen and develop potentials thereon. A projection lamp, a condenser lens and a polarizing element are arranged behind the tube, oriented to project polarized light through the crystal plate. Disposed adjacent the front face of the tube is another polarizing element crossed with respect to the polarizing system in the tube. Disposed forwardly of the second polarizing element is a projection lens arranged to project light from the second polarizing element onto a suitable viewing screen. The potentials on the collector screen locally rotate the plane of polarization of the crystal plate to degrees corresponding to the magnitudes of the local potentials. The intensity of the light emerging from the second polarizing element at any point therefore depends upon the intensity of the electron beams at their corresponding point of impingement on the collector screen.

While certain specific embodiments of an im: proved multiple-gun cathode ray tube have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.

What is claimed is.

1. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a pair of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of phase, a first conductive element mounted adjacent to and surrounding said face, and a second conductive element mounted in the envelope opposite and spaced from said face.

2. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a

pair of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of phase, a conductive element mounted adjacent to and surrounding said face, and a fiat, annular conductive ring mounted in the envelope opposite and spaced from said face between the axes of the electron gun assemblies.

3. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a

pair of electron gun assemblies carried in said envelope, each electron gun assembl being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of phase, a conductive element mounted adjacent to and surrounding said face, the envelope wall opposite said face being transparent, and a flat angular conductive ring mounted on said opposite envelope wall.

4. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a pair of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of phase, a conductive element mounted adjacent to and surrounding said face, and a transparent lens carried by the envelope opposite said face.

5. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a pair .of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of '7 phase, and a transparent lens carried by the envelope wall opposite said face. V

6. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a pair of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of phase, a conductive element mounted adjacent to and surrounding said face, a transparent lens carried by the envelope wall opposite said face, and a, flat annular conductive ring mounted on said opposite envelope wall around the periphery of said lens.

7. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a pair of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis, respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected 180 out of phase, and an accelerating coil mounted concentrically with said face, the axis of said coil being 8 included between the axes .of the electron gun assemblies.

8. An electronic picture tube comprising an evacuated envelope having a transparent face internally coated with fluorescent material, a pair of electron gun assemblies carried in said envelope, each electron gun assembly being directed toward said transparent face, said electron gun assemblies being disposed on opposite sides of the longitudinal central axis of said envelope and having their axes positioned at equal angles with respect to said longitudinal central axis; respective vertical and horizontal beam deflection means associated with the electron gun assemblies, the vertical beam deflection means of the respective electron gun assemblies being connected in phase and the horizontal beam deflection means being connected out of phase, a first conductive element mounted adjacent to and surrounding said face, a second conductive element mounted in the envelope opposite and spaced from said face, and an accelerating coil mounted concentricall with said face, the axis of said coil being included between the axes of the electron gun assemblies.

JOSE W. ACOSTA.

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

UNITED STATES PATENTS Number Name Date 2,147,760 Vance et al Feb. 21, 1939 2,179,205 Toulon Nov. 7, 1939 2,227,484 Bouwers Jan. 7, 1941 2,260,911 Knick et al. Oct. 28, 1941 2,402,758 Leverenz June 25, 1946 2,412,520 Langmuir et a1 Dec. 10, 1946 2,457,175 Parker Dec. 28, 1948 2,464,420 Snyder Mar. 15, 1949 2,481,458 Wertz Sept. 6, 1949 2,481,839 Goldsmith Sept. 13, 1949