US3519867A

US3519867A - Electric discharge tube for displaying alphanumeric character symbols

Info

Publication number: US3519867A
Application number: US730976A
Authority: US
Inventors: Arthur Tisso Starr
Original assignee: Rank Precision Industries Ltd
Current assignee: Rank Precision Industries Ltd
Priority date: 1964-01-27
Filing date: 1968-05-03
Publication date: 1970-07-07
Anticipated expiration: 1987-07-07
Also published as: FR1421089A; DE1514334B1; NL6500742A; GB1096193A

Description

A. T. STARR ELECTRIC DISCHARGE TUBE FOR DISPLAYING .Fuiy 7, 1970 ALPHANUMERIC CHARACTER SYMBOLS Original Filed Jan. 26, 1965 2 Sheets-Sheet 1 Pia. I

R l m A w Q NW. I MG wig S L Q Q E I w w 3 4 R P w MATR'X CATHODE clbcda SELECT.2.

INVENTOR. ARTHUR T. STARR July 7, 1970 I A. T. STARR ELECTRIC DISCHARGE TUBE FOR DISPLAYING ALPHANUMERIC CHARACTER SYMBOLS Original Filed Jan. 26, 1965 2 Sheets-Sheet 2 INVENTOR. ARTHUR T. STARR C; AfiO/PNEV United States Patent 4 Int. 01. B613 29/50, 31/16 U.S. Cl. 313-70 7 Claims ABSTRACT OF THE DISCLOSURE An electric discharge tube for the displaying of alphanumeric character symbols. A control circuit is utilized in conjunction with said electric discharge tube for controlling in a predetermined pattern a plurality of electron beams therein.

This application is a division of application Ser. No. 662,195, filed Aug. 22, 1967, now abandoned, which is a continuation of application Ser. No. 428,166, filed Jan. 26, 1965, now abandoned.

Background of the invention There is disclosed in the copending US. patent application Ser. No. 104,916, filed Apr. 24, 1961, now Pat. No. 3,198,976, an electric discharge tube in the form of an image-forming cathoderay tube. The tube basically comprises a cathode, a matrix member with a plurality of apertures, a fluorescent screen for impingement of electron beams after passage of said beams through the matrix and beam accelerating means disposed between the matrix and the screen. Each matrix aperture is surrounded by a conductive annulus and by applying a suitable beam switching potential to individual selected annuli, portions of the electron beam flooding the matrix from the cathode are allowed to pass through the respective matrix apertures and impinge upon the screen.

It will be appreciated that apart from the usual external connections to the cathode and acceleration anode, the above described electric discharge tube requires one conductor to be taken to the outside of the tube for each matrix annulus. For a 7 x 9 matrix this means 63 conductors, and for a 10 X 14 matrix this means 140 conductors. Production of a tube having so many external connections is diflicult and expensive.

Brief summary of the invention The present invention consists of a control circuit in combination with an electric discharge tube as set forth in the copending patent application, Ser. No. 312,901, filed Oct. 1, 1963, now Pat. No. 3,264,638. There is disclosed therein an electron beam production means for providing a plurality of elemental electron beams ar ranged in a row, means being provided for accelerating said elemental electron means, intercepting means being provided for impingement of the elemental electron beams thereon, the elemental electron beams being positionable generally transversely of said row by beam deflecting means.

The electron beam production means in the last named copending application comprises a plurality of cathodes arranged in a row, the cathodes being adapted to be heated by filaments.

A plurality of rows of cathodes may be provided with each row of cathodes serving to produce a character on the screen. In this way, a plurality of characters can be displayed. The control circuit of the present invention is operative to jointly deflect the elemental electron beams in a step by step manner in the said transverse direction. If for each deflection step, selected ones of the cathodes are switched into the circuit, a character or some other element of data representation can be displayed as an array of bright spots on the fluorescent screen. The individual electron beams of the row being present or not present at each deflection step depends on whether the cathodes corresponding thereto have been switched in.

Objects Accordingly, a primary object of the present invention is to provide an improved apparatus and methods for the display of alphanumeric character symbols.

Another object of the present invention is to provide an improved apparatus and methods for producing a plurality of elemental beams in an electric discharge tube in a predetermined pattern under the control of input signals.

Description of the drawings Further objects of the present invention will be apparent to those skilled in the art from a reading of the specification and claims thereof taken in conjunction with the drawings in which:

FIG. 1 is a diagram of a character formed by elemental squares;

FIG. 2 is a circuit diagram of a matrix arrangement for selectively energizing the circuits for the production of a character;

FIG. 3 is a diagram showing the formation of a block of six characters by six vertical rows of beam modulating electrodes;

FIG. 4 is a diagram showing the formation of a block of six characters by two horizontal rows of beam modulating electrodes;

FIG. 5 is a perspective view of a cathode ray tube; and

FIG. 6 is an exploded view of the cathode structure of the cathode ray tube of FIG. 5.

Detailed description of the invention Referring now to FIG. 1 there is shown a simulated character display, such as a cathode ray tube screen hav ing vertical rows a to e. Various squares are shown shaded, so that the numeral 2 represented in response to the control circuit of FIG. 2, as explained hereinafter. The squares 1 to 7 of each of the rows a to e correspond to the cathodes 1 to 7 of an electric discharge tube.

The electric discharge tube may have the form shown in FIG. 5, the cathodes 1 to 7 being accommodated in a neck portion 8 of the tube envelope 9, the tube having a fluorescent screen 10. Beam deflection may be effected by vertical and

horizontal deflection plates

45 and 47. These plates would be connected to appropriate sources ohf deflection potential, not shown, as is well known in t e art.

With specific reference to FIG. 6, array 20 includes a number of cathodes 1-7 as elemental areas of electron emitting source. The array of cathodes faces a modulator plate 21 containing an equal number of apertures 22, each aperture being in register with one of the cathodes 1-7. Each of the cathodes 1-7 has an input lead 19a-19g through the tube envelope 8. Further, each cathode 1-7 can be selectively rendered active or inactive by driving its lead by a suitable electrical potential, as described hereinafter. By thus activating predetermined cathodes, electron beams are made to impinge on fluorescent screen 10 in a predetermined pattern to form, for example, a bright display of alphanumeric character symbols.

In operation, the modulator plate 21 of the tube is held at a potential negative with respect to an inactive cathode 1-7, and by applying a suitable negative potential to a cathode 1-7 in the usual manner an elemental beam 25 is produced.

The cathodes 12 consist of pins of metal, and on the tip of each pin is deposited a small coating of emissive material, that is, a material 23 which emits electrons when heated. The cathodes 1-7 are mounted in a block 27 of ceramic or other insulating material. The ceramic insulator block 27 containing the cathodes 1-7 is surrounded by a heating coil 29 having a voltage supplied thereto in the usual manner from a low-voltage electrical supply. The heating coil 29 in the tube is surrounded by heat shield 30 in order to conserve the amount of power required to keep the cathodes 1-7 at the appropriate temperature.

The circuit diagram of FIG. 2 shows a resistance matrix having seven horizontal wires Ila-11g and five vertical Wires 12a-12e, resistors 13 being connected at crossing point of the wires in a coding corresponding to the shaded squares of FIG. 1.

Each horizontal wire 11 is connected through a diode 14a-14g to an amplifier 15a-15g and thence to the respective cathode 1 to 7. Each horizontal wire 11a-11g is moreover connected through a diode 16 to a common wire 17. The vertical wires 12a-12e are connected to out put terminals of a sequential pulse generator 18 which is so arranged that output pulses appear sequentially on the various vertical wires 12a-12e. Thus, when a vertical wire 12o12e receives a pulse, pulses are fed to those amplifiers 15a-15g having its associated wires 11a-11g connected by resistors to the vertical wire 12w-12e receiving the pulse. It will readily be seen that if the elemental beams from the cathodes 1 to 7 are jointly deflected in a direction transverse to the direction of extension of the row of cathodes, in a step by step manner, with one step for each pulse oft he sequential pulse generator 18 then the resistor arrangement shown in FIG. 2 will result in the numeral 2 being displayed on the fluorescent screen 10 of the tube, the numeral being formed by bright spots on the screen.

For each different character which can be selected for display, a resistance matrix is provided, the resistors being arranged in the correctly coded locations. The wires 12a- 12e and the sequential pulse generator 18 are common to all of the resistance matrices, as also are the amplifiers 15a-15g. Each matrix has its own set of horizontal wires, connected to the amplifiers through diodes analogous to the diodes 14w-14g of FIG. 2 and also its own set of diodes connecting the horizontal wires to a control wire analogous to the control wire 17 of FIG. 2. For selecting the character to be displayed, the respective control wire is made positive.

In the embodiment shown in FIGS. 1 and 2, a 7 x display matrix results, this requiring seven amplifiers 15, which are common to all displayable characters, and fourteen diodes and fourteen resistors for each displayable character. For a 14 x matrix, up to twenty eight resistors would be needed for each displayable character, and fourteen common amplifiers.

A different number of cathodes, of course, may be employed and more than one row of cathodes or beam modulating electrodes can be provided, so that more than one character can be displayed at a time. FIG. 3 shows the provision of six rows each of seven cathodes 31 the electron beams from which are displaceable jointly in a step by step manner through five steps in the X-direction, so as to enable the display of a block of six characters, each character having a matrix of 7 x 5. FIG. 4 shows the provision of two rows each of fifteen cathodes 41, the electron beams from which are jointly displaceable in a step by step manner through seven steps in the Y-direction, so as to enable the display of a block of six characters. The rows of cathodes in FIGS. 3 and 4 are necessarily spaced apart from each other by an amount greater than the spacing between adjacent ones of the elemental cathodes to allow the step by step deflection of the electrons for the generation of the selected character. The 7 x 5 matrix may be extended within the scope of the invention to include In number of cathodes with m number of steps.

FIGS. 3 and 4 also show an additional cathode 32 or 42 respectively, which provides a cathode ray beam which can be used for some purpose other than character display. Thus, the tube may be a radar display tube, the beam from the additional cathode serving for displaying target echoes on the tube screen. If, in addition to the deflection which the elemental beams undergo in displaying the characters, the elemental beams are also deflected with the target echo display beam, then the displayed characters can be located adjacent to a given target echo and may serve as an identification indication.

What is claimed is:

1. A display tube for simultaneously generating a plurality of characters each in the form of a combination of elemental dots within a m n dot array comprising:

(a) an envelope;

(b) a fluorescent screen at one end of said envelope;

(0) a source of emitted electrons at the other end of said envelope opposite said one end;

(d) deflection means for causing said emitted electrons to be deflected in a predetermined direction across said fluorescent screen;

(e) said source of emitted electrons including a plurality of substantially parallel rows of spaced apart elemental cathodes, said rows being arranged substantially perpendicular to said predetermined direction and spaced apart from each other by an amount greater than the spacing between adjacent ones of said elemental cathodes.

2. A display tube as defined in claim 1 wherein there are m number of elemental cathodes in each of said rows.

3. A display tube as defined in claim 1 wherein there are multiple groups of elemental cathodes in at least one of said rows, each of said groups having m number of elemental cathodes.

4. A display tube as defined in claim 2 wherein the spacing between said rows is at least an 11 multiple of said spacing between adjacent ones of said elemental cathodes.

5. A display tube as defined in claim 3 wherein the spacing between said rows is at least an n multiple of said spacing between adjacent ones of said elemental cathodes.

6. A display tube for generating a plurality of characters simultaneously comprising:

(a) an envelope;

(b) a fluorescent screen at one end of said envelope;

((1) deflection means for causing said emitted electrons to be deflected in a predetermined direction across said fluorescent screen;

(e) said source of emitted electrons comprising a plurality of substantially parallel rows of elemental cathodes, said rows being arranged substantially perpendicular to said predetermined direction and apart from each other by an amount sufficient to permit deflection of said emitted electrons in said predetermined direction to generate at least one character for each row of elemental cathodes.

7. A display tube as defined in claim 6 wherein the spacing between said adjacent rows is greater than the spacing between adjacent ones of said elemental cathodes in one of said rows.

References Cited UNITED STATES PATENTS 5 ROBERT SEGAL, Primary Examiner V. LAFRANCHI, Assistant Examiner US. Cl. X.R.