US2168892A

US2168892A - Cathode ray device

Info

Publication number: US2168892A
Application number: US722863A
Authority: US
Inventors: Vladimir K Zworykin
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1934-04-28
Filing date: 1934-04-28
Publication date: 1939-08-08
Anticipated expiration: 1956-08-08
Also published as: BE409165A; DE679329C; GB455927A; BE410128A

Description

ug- 8 1939 v K. zwoRYKlN 2,168,892

cATHoDE RAY DEVICE Filed April 28. 1954 mumlwawnmm mamy Patented Aug. 8, 1939 UNITED STATES cATnonE Vladimir K. zvwrykin,

RAY DEVICE Philadelphia, Pa., assignor to Radio Corporation of America, a corporation of Delaware Application April 28,

6 Claims.

My invention relates to improvements in cathode ray devices and themethod of construction thereof.

In the operation of cathode ray tubes, particularly those for use in a television system, it is' desirable to deilect the ray in one direction by electromagnetic coils, and in the other direction, at right angles to the rst direction, by an electrostatic eld between a pair of plates. The reason for this is due to the fact that when the ray is deflected in both directions by electromagnetic coils, the two magnetic fields interact or interfere with each other to cause distortion at the edges of the scanning pattern, and defocusing 15.- of the ray on the scanned surface of the screen.

While this disadvantage can be avoided by deflecting the ray in both directions by electrostatic fields, this would necessitate a substantially greater distance between the electron gun and the screen in order to make room ,for the two pairs of deecting plates. Use of two pairs of deflecting plates, also', would substantially increase the cost of manufacture.

For the purpose of dellecting the ray in one.

26 direction by an electrostatic eld, the plates for this purpose have either been sealed in place through the sides of the tube, or have been asy sembled with the electron gun. The rst method requires very careful workmanship in the glass 30 blowing operation which increases the cost of production and, in the construction of the socalled projection tubes, cannot be followed in any event because there is no available space in which to work. The second method of mounting the I6 plates is undesirable because, in operation, the leads from the plates may be at a potential of as much as 10,000 volts or more with respect to the cathode. 'I'his introduces considerable difficulties in the construction of a I0 a high potential difference.

With the foregoing in mind, it is one of the objects of my invention to provide an improved method of making a cathode ray device provided with a pair of plates for deflectng the ray in one 5 direction, without incurring any of the diiliculties and disadvantages referred to.

Other objects and advantages will hereinafter appear.

In accordance with my invention, a tube blank ll is used in which both the large and the small ends are open. The electron gun is assembled as a unit, and is inserted into the small end of the tube and then sealed in place. The deecting plates are assembled as a unit which is in- 5 serted into the large bulbous end of the tube and press to withstand such 1934, Serial N0. 722,863 (Cl. Z50-27.5)

aligned with the electron gun, for which purpose an insulating collar provides a supporting connection between the two units. Connecting leads extending through the wall of the tube at the large end thereof are then secured to the respective plates, and these rigidly support and hold them in position. The end wall piece, in the form of a glass plate provided screen, is then applied to the tube and sealed in place.

My invention resides in the improved construction and method of the character hereinafter described and claimed.

For the purpose of illustrating my invention, an embodiment thereof is shown in the drawing, wherein Figure 1 is a static ray-deflecting unit;

Fig.- 2 is a perspective View of the electron gun; and

Fig. 3 is a central, longitudinal, sectional view, illustrative of the manner in which the various parts and units are assembled to make the complete tube.

'I'he deflecting plates I0 and I2 are secured by wire sections I3 and I4, joined by glass beads I5, to a collar I6 of insulating material which is bored to receive the wire sections I3, as shown in Fig. 3. A diaphragm I8, provided with a central aperture 20, is disposed over one end of the collar I6, as more clearly .shown in Fig. 3, and is provided with openings 2| through which the wire sections I3 pass. '

g Leads

22 and 24 are connected, respectively, to the plates II) and I2, and the latter are supported in fixed relation to each other lat their outer ends by struts 26 comprising sections of wire and an interposed glass bead, as shown.

With reference to Fig. 2, the electron gun or means for developing the ray of electrons, is assembled as a unit on a press 28, in the sam`e manner as in the copending application by John C. Batchelor, Serial No. 584,924, filed January 6, 1932.4 The gun comprises a cathode 30 and its associated heater 32, a tubular grid 34 to which the picture signals are applied for controlling the intensity of the ray, and a tubular anode 36 to which a relatively high potential is applied for accelerating the electrons to a high velocity after they have' passed beyond the influence of the controlgrid 34.

An insulating collar 38 receives the adjacent ends of the

tubes

34 and 36, and operates to space and maintain alignment of these parts. Wire sections 40 and an interposed glass bead 42 hold large end of the with a fluorescent.

perspective View of the electro- 58 is applied to the ray-deflecting the

tubes

34 and 36 and the collar 38 together.

Connection to the anode tube 36 is made by a lead M which extends through the press. The connections to the grid 34, the cathode 30 and the heater 32 are also made through the press, as shown.

In assembling the parts, the electron gun unit is inserted into the small end of the tube blank 46, both ends of which are open. The adjacent edges of the press 28 and the tube blank are then sealed at 4B, with the axis of the gun unit coincident with that of the tube.

The ray-defiecting unit i's then inserted into the large bulbous portion of the tube, with the end of the anode 38 extending into the collar I6 with a snug fit, whereby the deflecting unit is supported by and maintained in alignment with the electron gun unit.

Lead wires

22a and 24a, which are sealed through the Wall of the tube, are then connected respectively to the

lead wires

22 and 24. These wires support the deflecting unit rigidly at the outer end thereof.

A lead wire 50, extending through the wall of the tube, is connected to a lead wire 52 previously secured to the diaphragm I8.

An end wall piece 54, in the form of a glass disc provided with a fluorescent screen 56, is then applied and sealed to the large open end of the tube, after which the latter is evacuated and treated in the usual manner.

As an alternative, it is proposed to assemble the ray-defiecting unit and the electron gun unit together, insert this entire assembly into the large open end of the tub-e blank, and then seal the press 28 to the small end of the tube, as before, with the axis of the assembly coincident with that of the tube. The connections to the plates I0 and I2 and the diaphragm I8 are then made as before, after which the end wall piece 54 is sealed in place.

If desired, the fluorescent screen 58 can be applied to the end Wall 54 through a suitable opening in the tube blank; after the latter has been sealed in place.

In operation, electrons of secondary emission leave the screen 56 as the latter is scanned by the cathode ray. These electrons are collected by the deflecting plates and are removed by way of the

leads

22a and 24a. It is also proposed to collect and remove at least some of the secondary electrons by an auxiliary electrode 58 in the form of an open ring supported from the deecting plates by wire sections 60 and the interposed ,glass beads 62 which insulate this electrode from the plates. A suitable operating potential is applied to the electrode 58 by a lead 64 sealed through the tube wall. When used, the electrode unit before the latter is placed into the tube.

From the foregoing it will be seen that, in carrying out my improved method, a tube blank is used having at one end thereof a bulbous portion in which the deflecting plates are disposed, and which is provided with a tubular portion in which the electron gun unit is disposed. The deflecting plates are placed in position through the large open end of the tube blank, which facilitates centering and adjustment of the structure after the electron gun unit has been sealed in. The fluorescent screen is sealed in place after the ray-deflecting unit and the electron gun unit have been properly placed within the tube, without affecting the alignment of these units. The diaphragm I8, to which is applied a potential positive with respect to the anode 36. operates to focus the ray on the screen 56. By disposing this diaphragm as shown, between the end of the electron gun and the deilecting plates, the distance between the screen andthe gun can be made substantially smaller lthan this distance in constructions proposed heretofore. It is thereby possible to obtain a. sharper focus of the ray on the screen 58.

Furthermore, by reason of my improved construction and method, the sensitivity of deflection is substantially greater than in the various constructions proposed heretofore due to the feasibility of bringing the defiecting plates closer together and extending them for a substantial distance along the tube between the end of the electron gun and the screen. Since the raydeilecting plates are assembled through the large open end of the tube blank, they can be made substantially larger than has been possible heretofore. The plates are, therefore, effective for collection of the electrons of secondary emission from the screen, which removes the necessity of silvering the interior surface of the tube. This allows the heat and light from the fluorescent screen to radiate through the clear glass, thereby preventing undesirable heating of the screen. For this reason, burning of the fluorescent material is less likely, and the tube can be operated at higher power than those proposed heretofore.

'The possibility of using the deflecting plates for the collection of electrons of secondary emission, rather than a bright silver coating on the inside surface of the tube, as heretofore, also eliminates the necessity of blackening the inner surface of the tube blank, since practically no light is reflected back to the screen from the transparent walls of the tube. Another advantage of my improved construction resides in elimination of the contact for connection with the second anode required in the various constructions proposed heretofore.

While but one embodiment of my invention has been disclosed, it will be understood that various modifications are possible without departing from the spirit of my invention or the scope of the claims.

vI claim as my invention:

1. The method of making a cathode ray device comprising a tube having at one end thereof a bulbous portion provided with a screen, a tubu lar portion in which is disposed a unit for developing a ray of electrons and directing the ray at said screen, and a pair of plates; said method comprising placing said plates into said tube by way of the screen end thereof which is open for this purpose, locating the plates both within the tubular and bulbous portion of the tube, supporting the plates both from the tube and the ray developing and directing unit, and subsequently afiixing an end wall piece to the screen end of said tube to close the same.

2. The method of making a cathode ray device comprising a tube having at one end thereof a bulbous portion provided with a screen, a tubular portion in which is disposed a unit for developing a ray of electrons and directing the ray at said screen, and a pair of plates disposed at least partly in said bulbous portion for dellecting the ray; said method comprising assembling said plates with respect to each other to form a. ray-deflecting unit complete in itself, placing said ray-developing unit into said tube by way of one of the ends thereof which is open for this purpose, placing said ray-deflecting unit into said tube by way of posed within said the open screen-end ot the tube with said umts aligned and with their adiacent ends engaging to maintain the alignment and to support the raydeiiecting unit by means of the ray-developing unit, and subsequently aillxing an end wall piece to the screen end of said tube to close the same.,/`

3. A cathode ray device comprising a tube proscreen, means disposed within said tube for developing a ray of electrons and directing the same at said screen, a pair of plates distube between said screen and said ray-developing means for rdeilecting the ray, a collar oi' insulating material engaging the electron-emitting erid o1' said ray-developing means 'ends of said plates with the aperture in line with of the tube blank.

5. A cathode ray device comprising a tube having a bulbous portion at one end and a stem and press member-at the opposite end, a cathode support from said press member, a hollow cylindrical electrode positioned coaxially with and surrounding said cathode and also supported from said press member, an apertured insulator mounted upon the cylindrical electrode at theend thereof remote from the cathode, a second hollow cylindrical electrode held in predetermined space relationship by the apertured' insulator and supported from both the press member and the rst cylindrical electrode, and a second apertured insulator the second cylindricalelectrode.

6. A cathode ray device comprising a cylindrical tube flaring out to form a bulbous portion at one end and a press at the other end, an electronI gun mounted upon and supported' by the press within the cylindrical tube, a pair of deiiecting plates, means to support the plates from both the electron `gun and the bulbous portion of the tube, independent means for maintaining the plates in spaced relation with each other, an annular disk electrode, means to support the disk in register and coaxial with the electron gun from the deecting plates, and a uorescent screen supported from the bulbous portion of the tube, said annular electrode being supported intermediate the deilecting plates and the fluorescent screen.

VLADIMLIR K. ZWORYKIN.