US2505011A - Magnetic deflecting system for cathode-ray tubes - Google Patents

Magnetic deflecting system for cathode-ray tubes Download PDF

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Publication number
US2505011A
US2505011A US769552A US76955247A US2505011A US 2505011 A US2505011 A US 2505011A US 769552 A US769552 A US 769552A US 76955247 A US76955247 A US 76955247A US 2505011 A US2505011 A US 2505011A
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US
United States
Prior art keywords
coils
scanning
cathode
ray tubes
currents
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US769552A
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English (en)
Inventor
Smyth Charles Norman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Application granted granted Critical
Publication of US2505011A publication Critical patent/US2505011A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/76—Deflecting by magnetic fields only
    • H01J29/762—Deflecting by magnetic fields only using saddle coils or printed windings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/96—Circuit elements other than coils, reactors or the like, associated with the tube
    • H01J2229/964—Circuit elements other than coils, reactors or the like, associated with the tube associated with the deflection system

Definitions

  • This invention relates to magnetic deflecting systems for cathode ray tubes for use for example in television receivers.
  • two crossed magnetic fields are caused to vary simultaneously to give a resultant field for deflection in one direction and are also caused to vary simultaneously but in a different relative sense to give a superposed resultant field for deflection in the transverse direction.
  • the invention in one aspect resides in a coil structure with or without a magnetic core in which the coils are arranged and inter-connected to permit the required fields to be set up when suitably excited.
  • the invention in another aspect resides in a supply circuit adapted to feed the necessary currents to a coil structure to set up the required magnetic fields.
  • Fig. l of the drawings is shown a cross section of the cathode ray tube and deflector coil windings taken through the centre of the deflector coils.
  • the coils A and B could be used for frame scanning and the coils C and D, for line scanning.
  • These windings comprise four separate elements each shown in Fig. 4. tributed around the neck of the tube in the manner shown, in order to provide a uniform magnetic field throughout the useful cross sectional area of the neck.
  • Fig. 2 which comprises two coils LI and L2 (each as shown in Fig. 4) arranged around the neck of the tube as shown in Fig. 3.
  • the active length of each coil is in practice substantially the same although the spacing between the end loops has been exaggerated in Fig. 3 for the sake of clarity.
  • two coils each as shown in Fig. 5 could be employed if absolute symmetry of the end turns was in special instances found necessary. In this case the end loops are distributed on both sides of the neck.
  • the fields in the several coils due to the line currents should be equal and those due to the frame currents should also be equal.
  • the coils should therefore be as like as The windings are disto practical considerations can be neutralised in effect by increasing or reducing the number of turns in one of the coils.
  • the two coils, section as shown in Fig. 2 were fed separately with scanning currents of line and frame frequency, the resultant raster wouldbe very distorted due to the curvature of the deflecting field near the edges of the cathode ray tube between the two coils. It is proposed, therefore, to overcome this difiiculty and produce a field identical with that produced by the coils of Fig. 1 and still to maintain the simplification of the coils described by using both coils in Fig.
  • a suitable circuit for feeding the coils is shown in Fig. 6.
  • the deflector coils LI and L2 are connected in series across a line scanning transformer Ti which has a split secondary.
  • the coils are fed in parallel for frame deflection by the transformer T2 connected between the centre tap of the coils and the centre of the line transformer secondary.
  • a tapped resistance (or reactance) R is included to obtain exact balance of the two halves of the circuit. It is noteworthy that from the point of view of line scanning voltages the two ends of the secondary of the frame scanning transformer T2 are at the same potential and so no line scanning currents influence the frame scanning circuit. Additionally the frame scanning currents pass through the two halves of the line scanning transformer secondary equally and oppositely and therefore produce no resultant M. M. F. in this quarter: consequently it is only the resistance and not the inductance of the line transformer secondary which is a series inefficiency in the frame scanning circuit, and the core of the line scanning transformer is not disturbed from its normal magnetic working point by the fluctuating frame scanning currents.
  • the line scanning currents may be fed in parallel and the frame scanning currents in series.
  • the coils may be connected in series and symmetrically in the output circuit of a pushpull amplifier, to which the scanning waves for one direction are fed in push-pull and the scanning waves for the other direction in parallel.
  • a common amplifier can be used for both line and frame currents.
  • the turns may be distributed over the neck to modify the distribution of the lines of force within the tube.
  • coil structures of the kind at present in use such as that referred to with reference to Fig. 1 can be interconnected and excited to function in accordance with the invention.
  • An electromagnetic system for deflecting an electron beam in a cathode ray tube in two directions at substantially right angles comprising a coil structure in which two coils are arranged around the neck of said tube, means to feed said coils in series to deflect said beam in one direction, a second means to feed said coils in parallel to deflect said beam in the other direction, said two means being interconnected.
  • a deflector coil structure for the system of claim 1 comprising two crossed series-connected coils adapted to embrace the neck of the cathode ray tube with their axes perpendicular to the tube axis.

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  • Details Of Television Scanning (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US769552A 1939-08-09 1947-08-19 Magnetic deflecting system for cathode-ray tubes Expired - Lifetime US2505011A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB22979/39A GB533301A (en) 1939-08-09 1939-08-09 Improvements in or relating to magnetic deflecting systems for cathode ray tubes

Publications (1)

Publication Number Publication Date
US2505011A true US2505011A (en) 1950-04-25

Family

ID=10188134

Family Applications (1)

Application Number Title Priority Date Filing Date
US769552A Expired - Lifetime US2505011A (en) 1939-08-09 1947-08-19 Magnetic deflecting system for cathode-ray tubes

Country Status (7)

Country Link
US (1) US2505011A (zh)
BE (1) BE440984A (zh)
CH (1) CH260753A (zh)
DE (1) DE862203C (zh)
FR (1) FR867293A (zh)
GB (1) GB533301A (zh)
NL (1) NL57501C (zh)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2612622A (en) * 1950-12-14 1952-09-30 Sylvania Electric Prod Scanning system for cathode-ray tubes
US2661443A (en) * 1949-12-30 1953-12-01 Du Mont Allen B Lab Inc Television keystone balance control circuit
US2722621A (en) * 1949-10-04 1955-11-01 Hartford Nat Bank & Trust Co Device for deflecting the cathode-ray in cathode-ray tubes

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2780749A (en) * 1955-02-09 1957-02-05 Rca Corp Raster centering control

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2007380A (en) * 1932-11-30 1935-07-09 Rca Corp Cathode ray apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2007380A (en) * 1932-11-30 1935-07-09 Rca Corp Cathode ray apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2722621A (en) * 1949-10-04 1955-11-01 Hartford Nat Bank & Trust Co Device for deflecting the cathode-ray in cathode-ray tubes
US2661443A (en) * 1949-12-30 1953-12-01 Du Mont Allen B Lab Inc Television keystone balance control circuit
US2612622A (en) * 1950-12-14 1952-09-30 Sylvania Electric Prod Scanning system for cathode-ray tubes

Also Published As

Publication number Publication date
CH260753A (de) 1949-03-31
BE440984A (zh)
FR867293A (fr) 1941-10-10
NL57501C (zh)
GB533301A (en) 1941-02-11
DE862203C (de) 1953-01-08

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