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US3086138A - Television and like camera tubes - Google Patents

Television and like camera tubes Download PDF

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Publication number
US3086138A
US3086138A US290160A US3086138A US 3086138 A US3086138 A US 3086138A US 290160 A US290160 A US 290160A US 3086138 A US3086138 A US 3086138A
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Prior art keywords
mesh
tube
potential
multiplier
section
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Expired - Lifetime
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Hendry Eric Douglas
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e2v Technologies (UK) Ltd
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e2v Technologies (UK) Ltd
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00Cathode ray tubes; Electron beam tubes
    • H01J31/08Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/26Image pick-up tubes having an input of visible light and electric output
    • H01J31/28Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen
    • H01J31/34Image pick-up tubes having an input of visible light and electric output with electron ray scanning the image screen having regulation of screen potential at cathode potential, e.g. orthicon
    • H01J31/36Tubes with image amplification section, e.g. image-orthicon

Description

April 16, 1963 E HENDRY TELEVISION AND LIKE CAMERA TUBES Filed Jan. 18, 1960 I lx/ /1/ 1/1 11'? III INVENTOQ ATTORNEYS United States atent 3,086,138 TELEVISION AND LIKE CAMERA TUBES Eric Douglas Hendry, Chelmsford, England, assignor to English Electric Valve Company Limited, London, England, a company of Great Britain Filed Jan. 18, 1960, Ser. No. 2,901 Claims priority, application Great Britain July 15, 1959 2 Claims. (Cl. 315-11) This invention, which is for improvements in or modifications of the invention forming the subect of co-pending application No. 818,186, now Patent No. 3,054,019, granted September 11, 1962, relates, like the said co-pending application, to systems including the television and like camera tubes generally known as image orthicon camera tubes. More specifically the invention relates to systems including image orthicon camera tubes of the kind in which, in order to ensure that the electron beam scanning the target shall always be incident thereon at right angles thereto in all positions of cathode ray deflection, there is provided an electro-static field-terminating mesh which is mounted substantially parallel to and adjacent the target on the gun side thereof. -In the usual present day tubes of the kind referred to, this field-terminating mesh is electrically connected to the normally provided internal wall coating on the inside of the tube envelope. This field-terminating mesh is for the purpose of correcting the electro-static field in the neighbourhood of the target and increasing the strength of the declerating field in front of the target. This reduces or eliminates distortion due to deflection of the ray by the electrostatic field due to the charge pattern stored on the target.

As is explained in the co-pending application 818,186, operating defects occur with known image orthicon camera tubes of the kind referred to, because of secondary electron emission from the field-terminating mesh. One such defect is that such secondary electrons released from the mesh as a result of bombardment by electrons of the ray on its way to the target cause an undesirably high DC. output. Also a distorting out-of-phase signal occurs due to secondary electrons released from the mesh returning to the electron multiplier section of the tube. Since these electrons start from the mesh with very low velocity they will arrive at the input of the multiplier section a little later than (i.e. a little displaced in time with respect to) the main signal; in other words they cause an out-of-phase and therefore a distorting signal component to be included in the output from the tube. The invention of co-pending application No. 818,186, which seeks to eliminate or substantially reduce the above-mentioned defects, consists, in its broadest aspect, in providing means for establishing, in the neighbourhood of the entrance to the electron multiplier section of the tube, a potential surface which is negative with respect to the potential of the field-terminating mesh adjacent the target structure of the tube, whereby secondary electrons emitted by said mesh are substantially prevented from entering said multiplier section. In the preferred embodiments of the invention of co-pending application No. 818,186 the means for establishing the potential surface are constituted by a ring electrode (or its equivalent, such as a number of interconnected electrodes in a ring) mounted on the normally provided electron gun and multiplier section structure of the tube at the end of said structure nearer the target, and means for applying a predetermined operating potential to said ring electrode.

The present invention also seeks to eliminate or substantially reduce the above-mentioned defects but to do so without having to provide any electrodes additional to those already present in a known image orthicon tube of the kind referred to.

According to the system of this invention the fieldterminating mesh adjacent the target structure of an "ice image orthicon tube of the kind referred to i.e. of the kind in which, in order to ensure that the electron beam scanning the target shall always be incident thereon at right angles thereto in all positions of cathode ray deflection, there is provided an electro-static field-terminating mesh which is mounted substantially parallel to and adjacent the target on the gun side thereof, is provided with its own independent connection lead, extending to a point outside the envelope of the tube whereby a potential which is positive with respect to the potential of the first dynode of the electron multiplier section of the tube, may. be applied to said mesh. When such a positive potential of suitable value is applied to the mesh it results in the production of a negative potential gradient between the mesh and the electron multiplier section of the tube and thus prevents secondary electrons emitted from the mesh from reaching the said multiplier section. The normally provided wall coating of the tube (to which, in a known tube of the kind referred to the field-terminating mesh is directly connected) is, in using the present invention, operated in the normal way, i.e. adjusted in potential until the required beam focus is obtained. In a tube in accordance with this invention, however, such adjustment of wall coating potential is effected independently of the adjustment of the potential of the field-terminating mesh which has its own independent connection lead.

The invention is illustrated in the accompanying drawing which is a highly simplified schematic representation of a preferred embodiment of the invention. The drawing shows only those parts of the tube necessary to an understanding of this invention.

Referring to the drawing, an image orthicon tube of the kind referred to has an envelope 1 with a photocathode 2 on the inside of the end wall thereof. 3 represents the usual internal coating on the inner wall of the tube. This coating has its own connection lead 3 shown for simplicity as going straight through the envelope wall, by means of which a suitably adjustable potential may be applied to the coating to obtain beam focus. 4 is a fieldterminating mesh adjacent and parallel to the customary target structure conventionally represented at 5. This mesh has its own independent connection lead 4 which, again for simplicity, is represented as passing straight through the wall coating and envelope being, of course, insulated from the coating. In practice the leads 3' and 4 would probably be brought out of the tube envelope via the customary plug connector (not shown) at the neck end of the tube. The electron gun is at the end of the neck of the tube, its cathode being given the reference 6. Arranged around the gun, as in the usual way, is a secondary electron multiplier section comprising a number of dynodes conventionally represented at 7, the first dynode being referenced 7 The electron gun and electron multiplier section are parts of a single mechanical unit or structure as in the customary way.

In use a suitable potential, positive with respect to the first dynode 7 is applied to the mesh 4 via the lead 4 To give typical operating potentials by way of example only, the mesh 4 might be held at about 300 volts and the first dynode 7 at about 250 volts making the mesh about 50 volts positive to the first dynode. In typical present day known practice, with the mesh connected to the coating 3, the mesh would normally be about to 200 volts and the first dynode at about 250 to 300 volts with the result that secondary electrons from the mesh reach the electron multiplier section of the tube to produce the operating defects hereinbefore mentioned.

I claim:

1. A system including an image orthicon tube having an electron gun, a multiplier section adjacent said gun, said multiplier section including at least one dynode, a

target, and an electrostatic field terminating mesh mounted substantially parallel to and adjacent the target, whereby the beam scanning the target shall always be incident at right angles thereto in all directions of beam deflection,

said system further including a source of potential which is positive with respect to the potential of said dynode, and means to apply said positive potential to said field terminating mesh, the voltage from said source being of such magnitude as to establish a predetermined negative potential gradient between the mesh and said electron multiplier section, whereby secondary electrons emitted from the mesh are prevented from reaching said multiplier section.

2. A system including an image orthicon tube as set forth in claim 1, said tube having an electrically conductive coating on the inside of the envelope Wall of the tube, a connecting lead for said coating independent of the lead from the field terminating mesh, said lead having a connection outside the tube envelope, said system further including means to apply to the connection to said Wall coating a predetermined potential of such magnitude as to produce the required beam focus.

References Cited in the file of this patent UNITED STATES PATENTS 2,548,405 Synder Apr. 10, 1951 2,747,131 Sheldon Oct. 12, 1951 2,598,919 Jensen June 3, 1952 2,652,515 McGee Sept. 15, 1953

Claims (1)

1. A SYSTEM INCLUDING AN IMAGE ORTHICON TUBE HAVING AN ELECTRON GUN, A MULTIPLIER SECTION ADJACENT SAID GUN, SAID MULTIPLIER SECTION INCLUDING AT LEAST ONE DYNODE, A TARGET, AND AN ELECTROSTATIC FIELD TERMINATING MESH MOUNTED SUBSTANTIALLY PARALLEL TO AND ADJACENT THE TARGET, WHEREBY THE BEAM SCANNING THE TARGET SHALL ALWAYS BE INCIDENT AT RIGHT ANGLES THERETO IN ALL DIRECTIONS OF BEAM DEFLECTION, SAID SYSTEM FURTHER INCLUDING A SOURCE OF POTENTIAL WHICH IS POSITIVE WITH RESPECT TO THE POTENTIAL OF SAID DYNODE, AND MEANS TO APPLY SAID POSITIVE POTENTIAL TO SAID FIELD TERMINATING MESH, THE VOLTAGE FROM SAID SOURCE BEING OF SUCH MAGNITUDE AS TO ESTABLISH A PREDETERMINED NEGATIVE POTENTIAL GRADIENT BETWEEN THE MESH AND SAID ELECTRON MULTIPLIER SECTION, WHEREBY SECONDARY ELECTRONS EMITTED FROM THE MESH ARE PREVENTED FROM REACHING SAID MULTIPLIER SECTION.
US3086138A 1958-08-29 1960-01-18 Television and like camera tubes Expired - Lifetime US3086138A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
GB2778358A GB847320A (en) 1958-08-29 1958-08-29 Improvements in or relating to television and like camera tubes
GB2430359A GB867955A (en) 1958-08-29 1959-07-15 Improvements in or relating to television and like camera tubes

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US3086138A true US3086138A (en) 1963-04-16

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US3054019A Expired - Lifetime US3054019A (en) 1958-08-29 1959-06-04 Television and like camera tubes
US3086138A Expired - Lifetime US3086138A (en) 1958-08-29 1960-01-18 Television and like camera tubes

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US3054019A Expired - Lifetime US3054019A (en) 1958-08-29 1959-06-04 Television and like camera tubes

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US (2) US3054019A (en)
DE (1) DE1096405B (en)
FR (2) FR1229364A (en)
GB (2) GB847320A (en)
NL (2) NL242771A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3136916A (en) * 1961-05-17 1964-06-09 Gen Electric Image orthicon tube having specially coated decelerating field electrode
US3179840A (en) * 1961-02-10 1965-04-20 Westinghouse Electric Corp Method of obtaining uniform response from a television camera device
US3413514A (en) * 1964-02-04 1968-11-26 Csf Storage tube

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB958009A (en) * 1962-04-13 1964-05-13 English Electric Valve Co Ltd Improvements in or relating to television and like camera tubes
US3427490A (en) * 1967-02-13 1969-02-11 Westinghouse Electric Corp High contrast cathode ray tube
US3751705A (en) * 1971-08-10 1973-08-07 Goodyear Aerospace Corp Electron image data processing apparatus

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2548405A (en) * 1945-07-24 1951-04-10 Rca Corp Electron tube
US2598919A (en) * 1950-06-30 1952-06-03 Rca Corp Barrier grid storage tube
US2652515A (en) * 1946-12-18 1953-09-15 Emi Ltd Negative charge image television transmission tube
US2747131A (en) * 1951-10-12 1956-05-22 Sheldon Edward Emanuel Electronic system sensitive to invisible images

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2749463A (en) * 1951-10-24 1956-06-05 Bell Telephone Labor Inc Solid state television pick-up tube

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2548405A (en) * 1945-07-24 1951-04-10 Rca Corp Electron tube
US2652515A (en) * 1946-12-18 1953-09-15 Emi Ltd Negative charge image television transmission tube
US2598919A (en) * 1950-06-30 1952-06-03 Rca Corp Barrier grid storage tube
US2747131A (en) * 1951-10-12 1956-05-22 Sheldon Edward Emanuel Electronic system sensitive to invisible images

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3179840A (en) * 1961-02-10 1965-04-20 Westinghouse Electric Corp Method of obtaining uniform response from a television camera device
US3136916A (en) * 1961-05-17 1964-06-09 Gen Electric Image orthicon tube having specially coated decelerating field electrode
US3413514A (en) * 1964-02-04 1968-11-26 Csf Storage tube

Also Published As

Publication number Publication date Type
FR1229364A (en) 1960-09-06 grant
NL242771A (en) 1964-01-27 application
US3054019A (en) 1962-09-11 grant
DE1096405B (en) 1961-01-05 application
GB847320A (en) 1960-09-07 application
NL248285A (en) 1964-03-10 application
FR77281E (en) 1962-02-09 grant
GB867955A (en) 1961-05-10 application

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