US3505559A

US3505559A - Electron beam line scanner device

Info

Publication number: US3505559A
Application number: US762557A
Authority: US
Inventors: Lester A Jeffries; Bobby L Landrum; Robert J Quinn
Original assignee: Northrop Grumman Corp
Current assignee: Northrop Grumman Corp; Northrop Grumman Systems Corp
Priority date: 1968-09-25
Filing date: 1968-09-25
Publication date: 1970-04-07
Anticipated expiration: 1987-04-07

Description

April 7, 197G JEFFRIES ET AL 3,505,559

ELECTRON BEAM LINE SCANNER DEVIGE' Filed Sept. 25, 1968 2 Sheets-Sheet l CONTEOL. EIGMAL. SOUQCE ADDRESSING LO6\ C BEAM )NTEN 3i TY CONTROL.

WINE/Woes LESTER A.JEFFV2\E$ BOBBY L. LANDRUM 5Q QOBEET 3. QUINN April 7,, 1970 JEFFRlEs ET AL 3,505,559

ELECTRON BEAM LINE SCANNER DEVICE Filed Sept. 25. 1968 2 Sheets-Sheet z l/VVEA/TOES LE5TEI2 A. JEFFQIES BOBBY L. LANDQUM 205x521 :17 aumm United States Patent US. Cl. 31512 2 Claims ABSTRACT OF THE DISCLOSURE The path of an electron beam between a cathode and a target plate is controlled in response to a random addressing signal by means of a plurality of dynode members interposed between the cathode and the target. Random linear scan is achieved by means of the dynodes which provide a plurality of electron beam channels arranged in a line. Such channels are formed by apertures in the dynode members, each dynode aperture being alined with a corresponding aperture on each of the other dynode members. Each dynode member has conductive portions thereon forming fingers which are electrically insulated from each other and which are arranged in a predetermined coded configuration. Digital control means are connected to the conductive portions of each dynode and are appropriately excited to provide a control potential to selected finger portions to permit the electron beam to pass completely through only one of the electron beam channels at a time.

This invention relates to an electron beam line scanner device and more particularly to such a device capable of providing random electronbeam scanning of a target in response to digital control signals.

Electron beam scanning techniques are used extensively for applications such as video display, video pickup, and for memory and storage functions. Most such prior art devices utilize cathode ray tubes which have the disadvantage of a relatively bulky and elongated configuration and which are readily subject to ambient electrostatic and electromagnetic fields which can impair their linearity and focus. Also, cathode ray tube devices are generally adapted to scan in a relatively cyclical fashion and cannot randomly be addressed to any desired point on the target without sacrificing resolution and speed of operation.

The device of this invention overcomes the shortcomings of prior art cathode ray tube scanning devices by providing a relatively flat thin and compact electron beam scanner capable of providing a line scan having high linearity and definition which is relatively unaffected by ambient electrostatic and electromagnetic fields. Further, the device of this invention operates in response to a digital control signal and is capable of random addressing as well as cyclical scanning.

The device of the invention will now be described in connection with the accompanying drawings of which,

FIG. 1 is a schematic view illustrating a preferred embodiment of the device of the invention,

FIG. 2 is a perspective view showing the general structure of one embodiment of the device of the invention,

FIG. 3 is an exploded view schematically illustrating the operation of the embodiment shown in FIG. 2,

FIG. 4 is a perspective view partially in section illustrating a second embodiment of the device of the invention, and

FIG. 5 is a perspective view illustrating one of the dynode half sections of the embodiment of FIG. 4.

Briefly described, the device of the invention comprises a plurality of dynode members interposed between an electron emitting cathode which provides a supply of electrons along a strip and a target plate. The dynode members each have a plurality of linear arranged apertures therein, each dynode aperture being alined with corresponding apertures on each of the other dynode members to form a plurality of electron beam channels between the cathode and the target. Each dynode member further has a pair of separate conductive portions thereon which are arranged in a coded tfinger pattern. Binary addressing means are connected between the conductive portions of each dynode such that one of the conductive portions i is given an electron accelerating potential, while the other conductive portion is given an electron retarding potential. The dynode conductive portions are addressed in response to digital control signals to permit an electron beam to pass through only one of the electron beam channels at a time.

Referring now to FIG. 1, the general aspects of one embodiment of the device of the invention are schematically illustrated. The flow of electrons between cathode 1-1 and target plate 12 is controlled by means of grid 13 and control dynodes 14-18. The electron beam is accelerated between cathode 11 and target 12 by means of potential source 20 and which is connected therebetween. The intensity of the beam may be controlled by means of beam intensity control 22 which is connected to control grid 13. The addressing of the beam is accomplished by means of dynode control 27 which is utilized to control the conductive portions on each of the dynodes.

Dynode control 27, which may comprise a fiipflop circuit for each of the dynodes, alternatively connects an electron accelerating or an electron retarding potential to each of the conductive portions of each dynode, such potential being obtained from voltage divider 26 which is connected across power source 20. Such a gradation of potential is require to provide increasingly higher potentials as we go from the cathode to the target to provide the desired electron accelerating potential therebetween. Dynode control 27 operates in response to addressing logic 28 which may comprise conventional digital addressing circuitry, which in turn responds to a control signal source 25.

Referring now to FIG. 2, a first embodiment of the device of the invention is illustrated. Cathode member 11 and target member .12 have a control grid 13 and control dynodes 14-18 sequentially, placed therebetween to provide a plurality of electron beam channels as to be described in connection with FIG. 3. Cathode 11 may be of the cold cathode type having a radioactive or photoemissive surface, or may be a thermionic cathode. Target 12 in the case of a display device has :a phosphorescent coating 29 thereon, or may have a coating to provide an appropriate storage or memory medium. A vacuum environment is provided for the electron beam channels by means of casing 34 which is sealed to target member 12 and the backing 30 of cathode 11, the compartment thus formed being appropriately evacuated.

Referring now to FIG. 3, the operation of the device of the invention is schematically illustrated. Successively positioned between cathode 11 and target 12 are control grid 13 and control dynodes 114-18. Each of the control dynodes has a first conductive portion 14a18a and a second conductive portion 14b-18b, respectively, such conductive portions being deposited as films on the dynodes by vacuum deposition or other conventional techniques. The dynodes 14 1 8 and control grid 13 are formed from a non-conductive substrate material such as glass, and each has a plurality of linearly arranged apertures 42 formed therethrough, the apertures of each dynode being alined with corresponding apertures on each of the other dynodes thereby forming a plurality of linearly arranged channels extending from cathode 11 to target 12. The

walls of the substrate at apertures 42 are coated with a secondary emitting material such as tin oxide or lead oxide, to provide secondary electrons to the electron beams.

Connected between each pair of conductive portions 14a, 14b-18a, 18b is a flipflop circuit 37-41 respectively. Each of the flipflops 37-41 receives a potential from voltage divider 26 which is connected across voltage source 20, the potential provided increasing as we go from cathode 11 totarget 12. As already has been noted in connection with FIG. 1, flipflops 3741 are controlled in response to addressing logic to excite the conductive sections between which they are connected in any predesired pattern. The details of flipflop control circuitry which may be utilized to perform the functions of flipflops 3741 are shown, for example, in FIG. 6 of copending application Ser. No. 511,747, now Patent No. 3,408,532, for Electron Beam Scanning Device, filed Dec. 6, 1965.

To illustrate the operation of the device of the invention, the dynodes of FIG. 3 have been shown with their conductive portions excited in a particular pattern, the portions 14a-18a ,(without stippling) having electron accelerating potentials thereon, while the conductive portions 14b18b (with stippling) have an electron retarding potential thereon. For this particular excitation pattern, it can be seen that only a single beam, i.e., the one indicated by :beam line 47, will pass through all of the dynodes to the target, all of the other beams, such as that indicated by beam line 48 encountering an electron retarding potential in one or the other of the dynodes. Thus it can be seen that any portion of the target can be excited at a time in response to the digital address, such addressing being possible in a completely random fashion.

Referring now to FIGS 4 and 5, a second embodiment of the device of the invention is illustrated. In the second embodiment, the basic configuration and operation is the same as the first. The construction,'however, of the dynode structure is significantly diflerent. In the second embodiment, the dynode assembly is formed from a pair of half-

sections

50 and 51, which may be formed of a substrate of a dielectric material such as glass. The electron beam channels 54 in this embodiment are formed by appropriately etching each of the half-

sections

50 and 51 to form semicircular channel walls 55. The dynode members 14'18 are formed by etching separating grooves 56 in the

plate members

50 and 51 with the conductive finger portions 14a18a and 14b18b being located in the grooves as coatings along the ends of the associated The device of this invention thus provides a simple electron beam line scanner having more compact construction than cathode ray tube devices of the prior art which provides improved linearity thereover and is capable of random addressing.

. We claim:

1. An electron beam line scanner comprising:

a cathode member for providing a supply of electrons along a strip;

a target plate for receiving the electrons from said strip;

means for supplying a potential between said cathode member and said target plate for accelerating the flow of electrons there-between;

a plurality of dynode members interposed between said cathode member and said target plate for controlling said flow of electrons,

each of said dynode members having a plurality of linearly arranged apertures therein, each dynode aperture being aligned with corresponding apertures on the others of said dynode members to form an electron beam channel between said cathode member and said target plate,

each of said dynode members further having a pair of separate conductive portions formed thereon, said conductive portions being arranged in a coded finger pattern, each conductive portion of a pair being positioned to affect the electron flow through half of the apertures,

said dynode members comprising a pair of oppositely positioned plates having longitudinal grooves therein forming said apertures and transverse grooves therein separating said dynode members from each other, and

binary addressing means connected between the paired conductive portions of each dynode to provide an electron accelerating potential to one of said conductive portions and an electron retarding potential to the other of said conductive portions.

2. The scanner of claim 1 wherein said conductive portions are located in said grooves.

References Cited UNITED STATES PATENTS 3,408,532 10/1968 Hultberg et a1. 3l512 RICHARD A. FARLEY, Primary Examiner M. F. HUBLER, Assistant Examiner US. Cl. X.R. 3 l3105