SE457759B - CRT appts. reducing stray magnetic fields - Google Patents
CRT appts. reducing stray magnetic fieldsInfo
- Publication number
- SE457759B SE457759B SE8601432A SE8601432A SE457759B SE 457759 B SE457759 B SE 457759B SE 8601432 A SE8601432 A SE 8601432A SE 8601432 A SE8601432 A SE 8601432A SE 457759 B SE457759 B SE 457759B
- Authority
- SE
- Sweden
- Prior art keywords
- field
- loop
- picture tube
- compensation
- plane
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
- H04N9/16—Picture reproducers using cathode ray tubes
- H04N9/29—Picture reproducers using cathode ray tubes using demagnetisation or compensation of external magnetic fields
-
- G—PHYSICS
- G12—INSTRUMENT DETAILS
- G12B—CONSTRUCTIONAL DETAILS OF INSTRUMENTS, OR COMPARABLE DETAILS OF OTHER APPARATUS, NOT OTHERWISE PROVIDED FOR
- G12B17/00—Screening
- G12B17/02—Screening from electric or magnetic fields, e.g. radio waves
-
- 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
- H01J29/96—One or more circuit elements structurally associated with the tube
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Magnetic Resonance Imaging Apparatus (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Abstract
Description
457 759 10 15 20 25 30 2 kempensationsslinga, figur 5 visar kompensationsslingan i perspektivvy, figur 6 visar kompensationsslingans elektriska anslutning till bildrörets avlânknings- spole och figur 7 visar en alternativ utzföringsform av kempensationeslingan. 457 759 10 15 20 25 30 2 compensation loop, figure 5 shows the compensation loop in perspective view, figure 6 shows the electrical connection of the compensation loop to the deflection coil of the picture tube and figure 7 shows an alternative embodiment of the compensation loop.
FÖREDRAGEN UTFÜRINGSFORM i figur 1 visas en skiss över en känd magnetisk avlânkningsspole 1 i ett bildrör 3 vars bildyta 3a antytts i figuren. Spelen har en övre halva la och en undre halva lb, vilka är parallellkepplade sasom visas i figur 2. Spelen är mangvarvig men har för enkelhets skull visats med endast ett varv. Spelen är placerad vid bildrörets bakre del utanpå röret och dess trattlike form ansluter till bildrörets form. Elektriska strömmar ll och Iz ispolhalverna, där 11% Iz, alstrar ett vertikalt magnetiskt avlänkningsfålt B i rörets avlänkningszen. En elektron- strale 2 genom avlänkningszonen avlänkas i sidled och träffar bildytan Ba.PREFERRED EMBODIMENT Figure 1 shows a sketch of a known magnetic deflection coil 1 in a picture tube 3 whose picture surface 3a is indicated in the figure. The games have an upper half 1a and a lower half 1b, which are connected in parallel as shown in Figure 2. The games are multifaceted but have been shown with only one turn for the sake of simplicity. The winch is located at the rear of the picture tube outside the tube and its funnel-like shape connects to the shape of the picture tube. Electric currents ll and Iz the half-pole halves, where 11% Iz, generate a vertical magnetic deflection field B in the deflection zone of the tube. An electron beam 2 through the deflection zone is deflected laterally and hits the image surface Ba.
Avlänkningen i sidled, det sakallade linjesvepet, sker med en frekvens 31,7 kHz medan avlänkningen i höjdled, bildsvepet, sker med en frekvens omkring 50 Hz och ombesörja med hjälp av en i figuren icke visad spole.The lateral deflection, the so-called line sweep, takes place at a frequency of 31.7 kHz, while the deflection, the image sweep, takes place at a frequency of around 50 Hz and is provided by means of a coil not shown in the figure.
I figur 3 visas bildröret 3 i genomskärning i ett vertikalt plan genom rörets längsgående symmetriaxel z. Detta plan är parallellt med riktningen för avlänkningsfëltet B och har i figur l betecknats med VP. Bildrörets bakre del Bb omges som nämnts av avlänkningsspolen 1. Denna omges l sin tur av ett skärmande ferrithölje 4 med trattliknande form, vilket avskärmar avlänknings- fältet B mot yttre störningar. Avlânkningsspolen l för det högfrekventa linjesvepet alstrar ett magnetiskt lâckfâlt BL utanför bildröret. Ferrithöljet 4 påverkar detta lâckfält sa att dess fältlinjer 5 huvudsakligen utger fran ferrithöljets framatvânda ytterkent 6. Läckfâltet BL anses, som nämnts ovan, utöva skadlig påverkan på en person som befinner sig i fältet. För att minska denna påverkan kan fältstyrkan hos detta fält enligt föreliggande uppfiming reduceras såsom skall beskrivas nedan.Figure 3 shows the picture tube 3 in section in a vertical plane through the longitudinal axis of symmetry z of the tube. This plane is parallel to the direction of the deflection field B and has in Figure 1 been denoted by VP. The rear part Bb of the picture tube is surrounded, as mentioned, by the deflection coil 1. This in turn is surrounded by a shielding ferrite casing 4 with a funnel-like shape, which shields the deflection field B from external disturbances. The deflection coil 1 for the high-frequency line sweep generates a magnetic leakage field BL outside the picture tube. The ferrite envelope 4 affects this leakage field so that its field lines 5 mainly extend from the forward-facing outer edge 6 of the ferrite envelope 6. The leakage field BL is considered, as mentioned above, to have a detrimental effect on a person who is in the field. To reduce this effect, the field strength of this field according to the present invention can be reduced as will be described below.
Ijfigur 4 visas bildröret 3 uppifrån med avlânkningsspolen 1 och ferrithöljet 4.Figure 4 shows the picture tube 3 from above with the deflection coil 1 and the ferrite housing 4.
Det av avlânkningsspolen alstrade lâckfältet BL motverkas enligt uppfinningen av ett magnetiskt kempensationsfâlt BK som alstras av en kompensationsslinga 7. Slingan är belägen huvudsakligen i ett horisontalt plan HP enligt figur l, vilket innehåller symmetriaxeln z och är vinkelrätt mot riktningen för av- länkningsfältet B. 10 15 20 25 30 457 759 3 Den yta i horisontalplanet HP som ornslutes av kompensatíonsslingan 7 har sin tyngdpunkt TP pa symmetriaxeln z vid den framatvënda ytterkanten 6 hos ferrithöljet 4. Slingan är enligt exemplet utförd med en rektangulär del 'la mellan de strackade linjerna i figuren och tva lober 7b. Dessa lobar sträcker sig fran den rektangulära delen 7a snett framåt utmed bildrörets 3 baksida ut till i jämnbredd med hildytans Ba ytterkant. Slingan 7 har ett flertal tradvarv man är i figuren för ankelhets skull visad med endast ett tradvarv. I figur 5 visas i perspektiv en figur av slíngan 7. I omradet 7a är slingana tradvarv delvis särade för att kunna omfatta farrithöljet 4 och bildröret 3. Slingans övriga delar ligger ihorisontalplanet HP. Slingan 7 är elektriskt ansluten i serie med avlänknings- spolen 1 sasom schematlskt visas i figur 6 och genomflytes av strömmen Il + 12.According to the invention, the leakage field BL generated by the deflection coil is counteracted by a magnetic compensation field BK generated by a compensation loop 7. The loop is located mainly in a horizontal plane HP according to Figure 1, which contains the axis of symmetry z and is perpendicular to the direction of deflection field B. The surface in the horizontal plane HP which is enclosed by the compensation loop 7 has its center of gravity TP on the axis of symmetry z at the forwardly twisted outer edge 6 of the ferrite casing 4. The loop is according to the example made with a rectangular part 'la between the stretched lines in the figure and two lobes 7b. These lobes extend from the rectangular part 7a obliquely forward along the back of the picture tube 3 out to be flush with the outer edge Ba of the full surface Ba. The loop 7 has a plurality of thread turns. Figure 5 shows a perspective view of a figure of the loop 7. In the area 7a, the loops are wire turns partially separated in order to be able to comprise the farry casing 4 and the picture tube 3. The other parts of the loop lie on the horizontal plane HP. The loop 7 is electrically connected in series with the deflection coil 1 as schematically shown in Figure 6 and is traversed by the current II + 12.
Med hjälp av slingan 7 alstras ett magnetiskt kompensationsfâlt BK som sträcker sig i ett omrâde framför bildrörets 3 bildyta 3a. Genom att välja lämplig strörnrikming i slingan 7 blir kompensationsfältet BK motriktat det av avlänkningsspolen l alstrade läckfältet BL såsom visasi figur 4. F ältstyrkan hos kompensationsfältet BK kan varieras genom antalet tradvarv i slingan 7 och genom att förändra slingans ytstorlek. Genom att pa detta sätt anpassa kompensationsslingan 7 kan styrkan hos kompensationsfältet BK anpassas sa att läckfältet BL motverkas och den resulterande fäitstyrkan kraftigt reduceras.By means of the loop 7, a magnetic compensation field BK is generated which extends in an area in front of the image surface 3a of the picture tube 3. By selecting the appropriate current direction in the loop 7, the compensation field BK becomes opposite to the leakage field BL generated by the deflection coil 1 as shown in Figure 4. The field strength of the compensation field BK can be varied by the number of thread turns in the loop 7 and by changing the surface size of the loop. By adapting the compensation loop 7 in this way, the strength of the compensation field BK can be adjusted so that the leakage field BL is counteracted and the resulting flow strength is greatly reduced.
Denna reduktion av fältstyrkan erhålles i ett stort omrade framför bildytan 3e om kompensationsslingansï tyngdpunkt TP förläggas såsom beskrivits ovan.This reduction in field strength is obtained in a large area in front of the image surface 3e if the compensation loop center of gravity TP is located as described above.
Som nämnts ovan är det läckfältets BL tidsförändring som ger upphov till .de strömmar som befaras utöva skadlig påverkan pa kroppen. Den snabbaste fältförândringen erhålles vid atergàngspulsan för llnjesvapat. Mätningar av läckfältet BL fran avlänkningsspolen l vid denna atergangspuls har utförts i ett omrade framför bildytan 3a. I en punkt 30 cm framför bildytan 3a erhölls en maximal fâltförändring av storleken 30 mT/s. Detta värde erhölls för magne- tiskt fält i den i figur 1 markerade y-riktningen. i x- och z-rlktningarna var fältförändringarna 50-500 gånger långsammare. Vid mätningar med kompensa- tipnsslingan 7 inkopplad uppmätes i y-riktningen den maximala fâltförändringen till cirka 1,5 mT/s, medan de svaga fälten i x- och z-riktningarna förändrades i mindre grad.As mentioned above, it is the time field's BL time change that gives rise to the currents that are feared to have a detrimental effect on the body. The fastest field change is obtained at the return pulse for line swap. Measurements of the leakage field BL from the deflection coil 1 at this return pulse have been performed in an area in front of the image surface 3a. At a point 30 cm in front of the image surface 3a, a maximum field change of the size 30 mT / s was obtained. This value was obtained for magnetic field in the y-direction marked in Figure 1. in the x and z directions, the field changes were 50-500 times slower. When measuring with the compensation loop 7 connected, the maximum field change is measured in the y-direction to approximately 1.5 mT / s, while the weak fields in the x- and z-directions were changed to a lesser extent.
En alternativ utföringsform av uppfinningen visas i figur 7. En kompensations- slinga 8 är sammansatt av tva delslingor Ba och Bb, vilka är elektriskt 457 759 4 seriekopplade med varandra och seriekopplade med avlänkningsspolen 1. Del- slingorna är plana och ligger i det horisontella planet HP. De av delslíngorna omslutna ytorna har sin: gemensamma tyngdpunkt TP-l samma punkt som kompensationsslingan 7 vid ferríthöljets 4 framkant. 5 Ovan har beskrivits anordningar för att alstra magnetiskt kompensationsfält BK som motverkar det magnetiska läckfâltet: BL vilket härrör fran avlânkningss- polen 1 för linjesvepet. 'Även ett lâckfält som härrör från en avlänkningsspole för bildsvepet kan motverkas med hjälp av en motsvarande anordning.An alternative embodiment of the invention is shown in Figure 7. A compensation loop 8 is composed of two sub-loops Ba and Bb, which are electrically connected in series with each other and connected in series with the deflection coil 1. The sub-loops are flat and lie in the horizontal plane HP. The surfaces enclosed by the sub-loops have their: common center of gravity TP-1 the same point as the compensation loop 7 at the front edge of the ferrite casing 4. Devices have been described above for generating magnetic compensation field BK which counteracts the magnetic leakage field: BL which originates from the deflection pole 1 for the line sweep. A leakage field originating from a deflection coil for the image sweep can also be counteracted by means of a corresponding device.
Claims (2)
Priority Applications (16)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE8601432A SE457759B (en) | 1986-03-27 | 1986-03-27 | CRT appts. reducing stray magnetic fields |
IN160/DEL/87A IN167955B (en) | 1986-03-27 | 1987-02-24 | |
AU72024/87A AU594145B2 (en) | 1986-03-27 | 1987-03-05 | Reducing leakage magnetic field about cathode ray tube |
JP62501997A JP2525437B2 (en) | 1986-03-27 | 1987-03-05 | Device for reducing the magnetic field strength around a cathode ray tube. |
PCT/SE1987/000109 WO1987006054A1 (en) | 1986-03-27 | 1987-03-05 | Apparatus in cathode ray tubes for reducing the magnetic field strength in the tube environment |
US07/130,463 US4851737A (en) | 1986-03-27 | 1987-03-05 | Apparatus in cathode ray tubes for reducing the magnetic field strength in the tube environment |
AT87902168T ATE52388T1 (en) | 1986-03-27 | 1987-03-05 | ARRANGEMENT FOR CATHODE RAY TUBES FOR REDUCING THE MAGNETIC FIELD IN THE SURROUNDINGS OF THE TUBES. |
EP19870902168 EP0260311B1 (en) | 1986-03-27 | 1987-03-05 | Apparatus in cathode ray tubes for reducing the magnetic field strength in the tube environment |
DE8787902168T DE3762560D1 (en) | 1986-03-27 | 1987-03-05 | ARRANGEMENT OF CATHODE RAY TUBES TO REDUCE THE MAGNETIC FIELD IN THE TUBE ENVIRONMENT. |
IE60587A IE59959B1 (en) | 1986-03-27 | 1987-03-10 | Apparatus in cathode ray tubes for reducing the magnetic field strength in the tube environment |
ES8700829A ES2003240A6 (en) | 1986-03-27 | 1987-03-25 | Apparatus in cathode ray tubes for reducing the magnetic field strength in the tube environment. |
CA000533084A CA1281362C (en) | 1986-03-27 | 1987-03-26 | Compensation loops in cathode ray tubes for reducing the magnetic field strength in the tube environment |
CN87102360.1A CN1007303B (en) | 1986-03-27 | 1987-03-26 | Apparatus in cathode ray tube for reducing the magnetic field strength in the tube environment |
FI874972A FI84864C (en) | 1986-03-27 | 1987-11-11 | ANORDINATION BETWEEN THE REDUCER OF THE MAGNETIC FAILURE STANDARD AND THE IMMUNIZATION. |
NO874896A NO171527C (en) | 1986-03-27 | 1987-11-24 | DEVICE FOR CATHOD RADIATORS FOR REDUCTION OF THE MAGNETIC FIELD STRENGTH IN THE ROOM'S ENVIRONMENT |
DK621087A DK166056C (en) | 1986-03-27 | 1987-11-26 | DEVICE IN IMAGE BOOKS TO REDUCE THE MAGNETIC FIELD STRENGTH IN THE ENVIRONMENT OF THE IMAGE BOOKS |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE8601432A SE457759B (en) | 1986-03-27 | 1986-03-27 | CRT appts. reducing stray magnetic fields |
Publications (3)
Publication Number | Publication Date |
---|---|
SE8601432D0 SE8601432D0 (en) | 1986-03-27 |
SE8601432L SE8601432L (en) | 1987-09-28 |
SE457759B true SE457759B (en) | 1989-01-23 |
Family
ID=20363987
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
SE8601432A SE457759B (en) | 1986-03-27 | 1986-03-27 | CRT appts. reducing stray magnetic fields |
Country Status (1)
Country | Link |
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SE (1) | SE457759B (en) |
-
1986
- 1986-03-27 SE SE8601432A patent/SE457759B/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
SE8601432L (en) | 1987-09-28 |
SE8601432D0 (en) | 1986-03-27 |
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