US3794876A - Deflection circuit for an electron beam in a cathode-ray tube - Google Patents

Deflection circuit for an electron beam in a cathode-ray tube Download PDF

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US3794876A
US3794876A US00284966A US3794876DA US3794876A US 3794876 A US3794876 A US 3794876A US 00284966 A US00284966 A US 00284966A US 3794876D A US3794876D A US 3794876DA US 3794876 A US3794876 A US 3794876A
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circuit
deflection
resistors
bridge
voltage
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US00284966A
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English (en)
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Alphen W Van
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/26—Modifications of scanning arrangements to improve focusing
    • 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
    • H01J29/465—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement for simultaneous focalisation and deflection of ray or beam
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
    • H04N3/24—Blanking circuits

Definitions

  • ABSTRACT 1 A deflection circuit for an electron beam formed with [3O] Fore'gn Application Pnomy Data an electrode system suitable for both focussing and Sept. 4, 1971 Netherlands 7112210 deflection, which System includes an electrode divi 1 1 v dend in segments. The electrode segments are incor- [52] U.S. Cl. 315/17, 3l 5/27 R porated in a bridge circuit built up from resistors while [5l 1 II!!- Cl. H01J 29/70 two deflection Signal generators are each connected to [58] held of searchm' 335/213; 161 two bridge connection points. A focussing voltage 315/171 27 R source is connected to a central connection point of a bridge cross branch so that the source and the genera- [56] References Cted tors are mutually decoupled.
  • the invention relates to a deflection circuit for an electron beam in a cathode-ray tube, which circuit is provided with an electrode system suitable for both focussing and deflecting the electron beam for which purpose the system comprising an electrode divided in segments is connected to a focussing voltage source and to two deflection signal generators for deflection in two transverse directions relative to the tube axis.
  • U.S. Pat. No. 2,91 1,563 describes a cathode-ray tube which is formed with a system of electrodes for both focussing and deflecting the electron beam. Since one of the electrodes of the system is divided in segments, different voltages can be applied to the electrode segments. The mean value of these voltages across the electrode segments relative to the voltage across a different electrode in the system determines focussing. The difference between the voltages across the segments yields a field strength at right angles to the axis of the tube so that the electron beam is deflected.
  • An object of the invention is to provide a deflection circuit with which a satisfactory focussing and a satisfactory deflection can be obtained, while the control of the electrode system is as simple as possible without mutually unwanted influences of the various voltage sources and signal generators.
  • the deflection circuit according to the invention is characterized in that when a bridge circuit having bridge branches between four bridge connection points is used for the deflection, of which points each facing pair is connected between two connection terminals of each different deflection signal generator and in which the branches include resistors and further connection points focussing is effected by providing at least a cross branch formed with resistors and connection points in the bridge, which cross branch has a central connection point for connection to the focussing voltage source.
  • FIG. 1 diagrammatically shows a cathode-ray tube, which is provided with a system of electrodes for both focussing and deflecting and with control means therefor,
  • FIG. 2 shows a schematic circuit diagram of the control means formed according to the invention, suitable for use with an electrode divided in eight segments.
  • FIG. 3 shows, likewise as FIG. 2, a bridge circuit with which deflection error corrections can be performed
  • FIG. 4 shows, likewise as FIG. 2, a bridge circuit which is suitable for use with an electrode divided in six segments.
  • FIG. 1 shows a partial diagrammatic cross section of a cathode-ray tube K,.
  • a so-called target plate is denoted by K in tube K,.
  • the target plate K is scanned by an electron beam not shown which is generated by an electron gun K K, denotes a tube axis of the tube K,.
  • a system of electrodes E consisting of three electrodes E,, E and E is provided.
  • the electrode E is divided in eight segments S, S, some of which are shown in FIG. 1.
  • FIG. 2 all segments S, S of the electrode E, are shown in a cross-section which is at right angles to that of FIG. 1.
  • the electrode segments S, S, are
  • FIG. 1 shows that a voltage U, is applied to the electrodes E and E,, which voltage is supplied by a direct voltage source (u) denoted by D
  • the electrodes E and B may alternatively receive different voltages. In case of a more positive voltage across the electrode E the electrons are accelerated between the electrodes E and E3.
  • the eight segments S, S of the electrode E are connected to a cable L provided with eight leads L, L All eight leads L, L, are connected to a resistive network N
  • Two deflection signal generators denoted by G and G are connected to network N which generators provide voltages U H and U respectively, varying in accordance with a sawtooth function.
  • Some leads, namely L,, L L, and L, are connected to a resistive network N to which a direct voltage source D applies a focussing voltage Up.
  • the difference between the voltages U, and Up determines focussing of the electron beam. If the voltages U, and Up were equal, focussing would not take place and the electrodes E and B, would only be operative as anodes. A satisfactory focussing may be obtained, for example, with U, 500 V and U V.
  • a voltage +U and U is impressed on, for example, two segments such as S, and S, which are pairwise located and face each other relative to the tube axis K., which voltage U has a sawtooth variation with an amplitude of 50 V peak-to-peak.
  • the combination of focussing and deflection then results in, for example, the segment S, conveying a voltage of 100 25 V and the segment 8, conveying a voltage of 100 25 V.
  • the cathode-ray tube K is operative with its target plate K which is formed, for example, with photosensitive material, as a television camera tube in which a scene to be picked up is displayed through an objective lens not shown on the target plate K Any other embodiment of the tube K, is possible.
  • the electrodes 15,, E and E shown in the electrode system E may alternatively exchange positions.
  • FIG. 2 shows that the resistive networks N and N of FIG. 1 are formed as a combined bridge circuit N.
  • the reference R denotes resistors
  • B denotes branches
  • P denotes connection points.
  • P,, P P and P denote four bridge connection points with the points P, and P and P, and P.,, respectively, facing each other being connected to two connection terminals and of the deflection signal generators G and G respectively.
  • Bridge branches B,, B B and B are provided between the points P, and P P and P P and P P, and P, respectively, which branches are each provided with two resistors R in series denoted susccessively by R,, R R R
  • the bridge circuit N according to FIG. 2 is provided with two cross branches which are located between points P, and P and P and P,,, respectively, and are denoted by B and B
  • the branches B and B are each provided with four resistors in series R R,, and R R respectively.
  • the branches B, B are provided with connection points P at the areas where two resistors R are connected together.
  • connection points P,,, P,.,, P, and P,, of the branches 3,, 8-,, B, and B are connected to the segments 8,, 8,, S and 8,, respectively.
  • Two connection points P,, and P of branch 8 are connected to the segments S, and S respectively, while two connection points P,, and P of branch B are connected to segments 5,, and S,.
  • Central connection points P and P of the branches B and B are connected together and are connected to the connection terminal of the focussing voltage source D which provides the focussing voltage U!- It is found that the network N according to FIG. 1 corresponds to the resistors R,,,, R,,, R,., and R, of the bridge circuit N.
  • the remaining resistors R of the bridge circuit N are incorporated in the network N
  • the bridge circuit N ensures that a required combination of the voltages provided by voltage source D and by one or both signal generators G and Gy is impressed on each of the electrode segments S, S while the source D and the generators G and G do not influence each other without extra steps being necessary therefor.
  • the focussing voltage Up is impressed as a bias on the bridge circuit N, which voltage thus reaches all segments S, 8,, through the resistors R, R Relative to the focussing (bias) voltage 'lUp, the generators G and G decoupled through the bridge circuit N provide sawtooth varying voltages V,, and U whose mean value corresponds to the voltage U
  • the starting point is a deflection of the electron beam in which the landing spot on the target plate K, as seen from the axis K, in the tube K, writes a line from the right to the left and in which a television raster corresponds to a deflection from the top to the bottom. Seen from the outside of the tube K, the deflection ofa raster thus commences in the top-left corner of the target plate K,. It is assumed that in order to deflect the electron beam landing spot to the top, a voltage +U,/ across the segment S, is required and U across segment 5,, is required. For the deflection to the right there follows that a voltage +U across the segment 8,, is required and U,,, across segment S, is required.
  • the segments 8,, S4, S and SB located on the circumference of a circle are provided and a combination of the voltages U and U is to be impressed on these segments.
  • resistors R, and R are equal and may have a value of, for example, k.ohms.
  • resistors R R Resistors R and R,, must have a value such that a voltage division from U ⁇ /2 to U, is effected, hence R R 1: V2-l
  • resistor R is given a value of 65 k.ohms, approximately 27 k.Ohms is the value for resistor R,,.
  • the focussing voltage +U is impressed onall electrode segments S, S, with the aid of the bridge circuit N and each segment separately receives a different deflection voltage without any mutual unwanted influence taking place.
  • the position of the generators G, and 6, may be interchanged without further steps.
  • the bridge circuit N ensures in its simplicity a satisfactory focussing and deflection when the electrode system E and the electron gun K, as such do not cause deflection errors. Due to, for example, symmetry errors in the configuration of the system E and the gun K, relative to each other and to the tube axis I(.,, noticeable deflection errors may occur in practice.
  • FIG. 3 shows a bridge circuit N in which some deflection error corrections can be performed while there are no principal deviations relative to the bridge circuit N according to FIG. 2.
  • two cross branches B and B are provided beyond the bridge branches B B. and the two cross branches B and B6.
  • the cross branches B and B provided between the connection points P and P of the bridge branches B and B and P and P respectively, of the bridge branches B and 8, include two resistors R and R and R and R respectively.
  • the segments S S S and S are connected to both a bridge branch B B B or B and to a cross-branch B, or B Unlike the bridge circuit N according to FIG. 2, the points P and P in FIG.
  • potentiometers R and R are not directly connected together but are connected together through a potentiometer R Furthermore the points P and P are connected together through two series-arranged resistors R and R while the junction of resistors R and R is connected to ground through a resistor R Branches B and B have connection points P and P respectively, between the resistors R R and R R As described with reference to points P and P 21 ptentiometer R two resistors R and R in series and a resistor R to ground are provided near points P and P The wipers on potentiometers R and R are both connected to the output terminal of the focussing voltage source D The potentiometers R and R form part of a bridge circuit R R R and R R respectively.
  • points P and P convey the same positive voltage which is active as a focussing voltage.
  • this focussing voltage of, for example I00 V
  • the points P and P convey, for example, a more positive and a less positive voltage, respectively, of 25 V which are brought about by voltages +U and -U
  • points P and P which under the influence of the voltages +U' and 'U, convey the voltages 125 V and 75 V respectively.
  • the potentiometer R of FIG. 3 generates a quadripolar field as a function of the displacement from the centre, while the polar axes of this field are located in the direction of the segments 8,, S and of the segments S S (FIG. 2).
  • the intensity of the quadripolar field and the polarity is dependent on the magnitude and the direction of the displacement of the wiper on potentiometer R
  • the branches 8, and B and the bridge circuit R R R are provided in FIG. 3.
  • potentiometer R In the same manner as described with reference to potentiometer R a second quadripolar field with the polar axes in the direction of the segments 8 S and S S can be generated therewith (FIG. 2).
  • any quadripolar field for which given polar axis directions are required may be realized dependent on the direction and the extent of the displacement of potentiometers R and R It is found that the potentiometer R and the resis tors R R and R constitute a distributing circuit R R with which the focussing voltage across points P and P may be made different, while the mean value remains the same.
  • the provision of the cross branches B and B according to FIG. 3 has a further advantage when a correction is required for a barrel or pincushion distor tion which may occur in a raster shown on the target plate K of FIG. 1.
  • a correction is required for a barrel or pincushion distor tion which may occur in a raster shown on the target plate K of FIG. 1.
  • resistors R, R R R and R As already de scribed a value of 50 k.ohms has been taken for resistors R R R and R It follows from calculations that the voltages given in FIG. 2 occur in the segments S if the resistors R R likewise have a value of 50 k.ohms.
  • the voltage across the segments S S and S 5 may be modified in such a manner that the distortion which becomes clearly manifest in the corners near the segments S S S and S is influenced.
  • the deflection near the corners is to be attenuated relative to the linear deflection i.e., the segments S S S and S are to receive less voltage which may be satisfied by giving the resistors R R a lower value than resistors R R R and R
  • a direct voltage source which includes a direct voltage source D and a potentiometer R is connected in parallel with resistors R and R A displacement of the wiper on the potentiometer R;,, which is connected to the resistor R provides the shift direct current through the branches B B and B A direct current is not produced by the bridge circuit configuration in the branch B, as is evident in a simple manner from FIG. 2.
  • an adjustable direct voltage source (D R R in parallel with the bridge connection points P and P., a horizontal shift direct current through the branches B B and B may be obtained while no direct current is produced through branch B
  • the required direct voltage may alternatively be derived directly from the focussing voltage Up.
  • FIG. 3 shgwsth atcapagitors Q C, are arranged in parallel with the resistors R R R,,, R R, and R,,,. These capacitors C C are not principally required for the invention, but they are to be provided when, as is shown in FIG. 1, the cable L is used.
  • the leads L, L, of the cable L have their own capacitance which together with the capacitance of the segment S connected thereto in tube K, may yield a composite capac itance of approximately 50 pF. Since as shown in FIG. 2 the generator G provides a low frequency sawtooth voltage of, for example, 50 or 60 Hz for the deflection in the vertical direction, the influence of the composite capacitance at this low frequency is negligible.
  • the cable L of FIG. 1 were to have a negligibly low capacitance or if it were absent because, for example, the bridge circuit N shown in FIG. 2 is provided in an integrated form on or neae the tube I(,, capacitors C, C of FIG. 3 could be omitted.
  • resistors R of the bridge circuit N may be provided in or outside the tube K, on its wall near the electrode E,.
  • FIG. 4 likewise as in FIG. 2, shows a bridge circuit N which is, however, suitable for use with an electrode E, which is built up from six segments S. As compared with FIG. 2 it is found that the segments S and S, are omitted and the remaining six segments 5,, S S S S and S, as seen along the circumference of a circle have a longer form. Since the segments 8,, and S of FIG. 2 are absent, the cross branch 8,, is likewise absent.
  • the angle d) relates to formula (1) given with reference to the description of FIG. 2. Angles which are an integral multiple of 60 are associated with the subsequent segments 5,, S S and 8,. While using the manner shown in FIG. 2 of calculating the required various voltages in the bridge circuit N at which the voltage U is fictitiously present, because the segments 8,, and S, are absent in FIG. 4, it follows for the segment 8, that: U cos 60 U sin 60 /2U,- /zU,,. n. By drawing a tangent in point P,, to the circumference of the circle on which the segment S2 is located, the voltages can be calculated which are to be impressed on the points P, and P so as to obtain the desired voltages across the segments S.
  • the required ratios of the resistors R in the bridge circuit N can be calculated in a simple manner, dependent on the number of segments S of the electrode E,.
  • the segments S, and S of FIG. 2 are absent, the segments S, and 8;, might be omitted in FIG. 2 although the deflection will be effected less linearly even when enlarging the remaining segments 5,, S S and S Dependent on the imposed requirements this may be allowed.
  • the segments 5,, S.,. S, and S are present the cross branches B, and B, are
  • the use of only the segments S S S and S which are located between the said deflection directions has the advantage that at the area where the greatest problems for a linearly varying deflection field occur, namely in the corners, the presence of the segments at that area reduces the problems.
  • An electrostatic deflection and focussing circuit for a cathode ray tube including a plurality of opposite electrode segments symmetrically arranged about a central axis, comprising in combination, a bridge circuit having two pairs of opposite junctions connected to assigned pairs of electrode segments, two sources of deflection signals each connected to a pair of said junctions, a crossed connection of four resistances having a common point and four terminal points connected to said junctions, respectively, and a source of a focusing voltage having a terminal connected to said common point.
  • a circuit as claimed in claim 4 characterized in that capacitors are arranged in parallel with the resistors which are connected to those bridge junctions and are connected to the deflection signal generator which provides a volrage of a higher frequency.
  • a cathode-ray tube provided with a deflection circuit as claimed in claim 6, characterized in that the resistors are provided in an integrated form on the wall of the cathode-ray tube.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Details Of Television Scanning (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
US00284966A 1971-09-04 1972-08-30 Deflection circuit for an electron beam in a cathode-ray tube Expired - Lifetime US3794876A (en)

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Application Number Priority Date Filing Date Title
NL7112210A NL7112210A (de) 1971-09-04 1971-09-04

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US00284966A Expired - Lifetime US3794876A (en) 1971-09-04 1972-08-30 Deflection circuit for an electron beam in a cathode-ray tube

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US (1) US3794876A (de)
JP (1) JPS5520431B2 (de)
CA (1) CA983160A (de)
DE (1) DE2243217C3 (de)
FR (1) FR2151122B1 (de)
GB (1) GB1407223A (de)
NL (1) NL7112210A (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0132522A2 (de) * 1983-07-28 1985-02-13 International Business Machines Corporation Ionenstrahl-Ablenkgerät
US4808890A (en) * 1985-09-20 1989-02-28 Hitachi, Ltd. Cathode-ray tube

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4142132A (en) * 1977-07-05 1979-02-27 Control Data Corporation Method and means for dynamic correction of electrostatic deflector for electron beam tube
DE3478261D1 (en) * 1984-02-18 1989-06-22 Leybold Ag Device for the examination of crystal surfaces according to the leed-technique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2911563A (en) * 1957-04-24 1959-11-03 Westinghouse Electric Corp Electrostatic lens and deflection system
FR1368473A (fr) * 1963-09-03 1964-07-31 Philips Nv Tubes cathodiques
US3688156A (en) * 1969-03-17 1972-08-29 Sony Corp Electron beam deflection system utilizing a yoke having a plurality of separate windings toroidally wound theron

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2911563A (en) * 1957-04-24 1959-11-03 Westinghouse Electric Corp Electrostatic lens and deflection system
FR1368473A (fr) * 1963-09-03 1964-07-31 Philips Nv Tubes cathodiques
US3688156A (en) * 1969-03-17 1972-08-29 Sony Corp Electron beam deflection system utilizing a yoke having a plurality of separate windings toroidally wound theron

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0132522A2 (de) * 1983-07-28 1985-02-13 International Business Machines Corporation Ionenstrahl-Ablenkgerät
US4556823A (en) * 1983-07-28 1985-12-03 International Business Machines Corporation Multi-function charged particle apparatus
EP0132522A3 (en) * 1983-07-28 1986-08-20 International Business Machines Corporation Ion beam deflecting apparatus
US4808890A (en) * 1985-09-20 1989-02-28 Hitachi, Ltd. Cathode-ray tube

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DE2243217A1 (de) 1973-03-08
DE2243217C3 (de) 1979-10-25
GB1407223A (en) 1975-09-24
FR2151122B1 (de) 1977-12-23
DE2243217B2 (de) 1979-03-08
NL7112210A (de) 1973-03-06
CA983160A (en) 1976-02-03
FR2151122A1 (de) 1973-04-13
JPS4837017A (de) 1973-05-31
JPS5520431B2 (de) 1980-06-02

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