DE1279213B - Cathode ray tube - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 4507WW PATENTAMT Int. α .:

HOI j

EDITORIAL

German class: 21g-13/21

Number: 1279 213

File number: P 12 79 213.1-33 (W 34263)

Filing date: April 8, 1963

Open date: October 3, 1968

The invention relates to a cathode ray tube with electrostatic lenses for forming and Focusing an electron beam on a target, primarily on a screen.

The invention relates to a cathode ray tube with at least three equiaxed one behind the other Grids which are provided with diaphragms that focus the cathode ray, the diaphragm opening of the second grid is smaller than the aperture of the first, it closely adjacent grid.

With television receivers and other electronic devices that hit a screen of an electron beam is made to light up, it is very desirable to have as large a modulation as possible the light output of the cathode ray tube as a function of a given change in amplitude of the control signal supplied to the device. Succeeds in getting a cathode ray tube too create a relatively large change in the beam current with a relatively small change in the supplied Control signal results, the circuit structure of the device can be significantly simplified. It is then z. B. possible to make a video amplifier dispensable in televisions and also others Make circuit simplifications, especially in the network connection of the television set. Expressed differently, the cathode ray tube should have a high steepness, without that for normal Television required brightness and image resolution are impaired.

It is known that at a certain control voltage, increased cathode and beam currents can be achieved by modulating the cathode of the electron gun, but not the control grid, which is normally the grid closest to the cathode, hereinafter referred to as the first grid G ₁ is designated.

This grid G ₁ as well as the grids G ₂ , G ₃ , G ₄ and G ₅ listed below can also be referred to as electrodes. For the sake of consistency, they are referred to as grids throughout. When using cathode modulation, minimal control voltages and high steepness can only be achieved if the potential of the second grid G _{2 is} less than 100 V positive when the first grid G _{1 is grounded.} Prior to using this low voltage operated second grid, this grid was normally operated with a voltage of 300 volts positive. The cathode ray tubes, which operate with a lower voltage on the second grid, have a higher steepness. The higher the slope, the lower the control voltage with which the cathode ray tube can be

Applicant:

Westinghouse Electric Corporation,

East Pittsburgh, Pa. (V. St. A.)

Representative:

Dipl.-Ing. G. Weinhausen, patent attorney,

8000 Munich 22, Widenmayerstr. 46

Named as inventor:

Melvin V. Duerr, Elmira, N.Y. (V. St. A.)

Claimed priority:

V. St. v. America April 13, 1962 (187 257) - -

Signals are fed. A known cathode ray tube of this type has at least three equiaxed ones one behind the other grid, which are provided with the cathode ray focusing diaphragms, the The aperture of the second grid (anode) is smaller than that of the first grid that is closely adjacent to it is.

The known cathode ray tubes have third and fifth grids G ₃ and G ₆ , which operate with a high positive potential of about 16000V, and a fourth grid G _{4 in between} , to which a voltage of about 300V is applied. These gratings form the main focusing lens of the electron optical system. It is therefore important for radiators with a second grid G ₂ under low voltage that the high voltages of the third and further grids do not penetrate to the cathode, since otherwise a higher control voltage would be necessary to switch off the tube.

One disadvantage of the known cathode ray tubes, which is primarily the electrostatic structure attributing the radiator is a defect known as point blooming. It manifests itself in a considerable Increase in the point size on the screen or even as an halo when the potential increases

of the control grid approaches the value zero. Through this

a disturbing blurring arises in the lighter areas of the television picture.

It has now been found that this disadvantage by a special adjustment of the strength of the between the second and the third grid located lens can be largely avoided. This is based on

809 619/440

presumably mainly for the following reason. Approaches to creating a beam tube that is at high steepness and With cathode modulation, the control voltage of the high beam current only shows small light points on the the value zero, the beam angle of the triode, screen is generated.

the cathode and the first two grids G ₁ with the cathode ray tube according to the invention

and G ₂ consists, great. In addition, the electrons, 5 at least three equiaxed one behind the other, if the cathode has the control voltage zero, can be provided on grids _{which are provided with the cathode ray bundling diaphragms on the earthed or de-energized side of the grid G 1} , the diaphragm opening of the second impinging. These electrons are then reflected lattice smaller than the aperture of the first, close to it and penetrate into the main lens of the cathode ray tube adjacent lattice, is characterized, at rather strongly diverging angles of inclination, that the opening of the second lattice is closer to the first. They will therefore not lie in the same image plane of the grid as the rest of the diaphragm part of the same that is focused as the desired electrons that are emitted by the second grid at its center of the radiation source from the cathode _{The lens 15 located between the grids G 2} and G ₃ is now connected to the second grid in an electrically conductive manner and with its aperture of the pre-appropriate shape, and if the aperture of the second grid is switched on, the aperture in particular is brought into the this grille provided an opening If the distance is smaller than the diameter in the vicinity of the electron beam, one can adjust the aperture of the insert, the aperture of which corrects the electrons striking the edge, but has an aperture larger than the aperture and prevents it from being out of the beam axis The diameter of the aperture of the second grating is strong, diverge in that they cause the described image error, while the subsequent third grating is one of the causes. It has been found that, in the case of a second grating, a tapered tubular turn of a tubular protruding grating is used as the entrance part, the entrance opening of which in the third grating G ₃ achieves better image reproduction. Diameter at least three times larger than the diameter should actually be expected that when using 25 the diaphragm opening of the diaphragm insert is in such a grille as a result of increased penetration of the second grille.

Field of the third grid G ₃ through the opening of the cathode ray tube according to the invention

second grid G ₂ the reverse voltage in a considerably improved sensitivity of the cathode _{modulus of the potential of the third grid G 3} ab- lation and a structure that would be subject to a high penetration. This would of course have provided for a connection of the second grid. This high penetration leads to a reduction in the modulation sensitivity. You would occur if the penetration of the field between the cathode and the first two grids of the third grid G _{3 were} too large. G ₁ and G ₂ and those provided in these grids. It is therefore an object of the invention to achieve the grid assembly aperture openings. In addition, a network should be designed so that the size of the penetration 35 improved luminous spot limitation of the radiator and one of the field of the third grid G _{3 is} limited if the stronger beam current through a special interposition of the second and third grid G ₂ and G ₃ aisle part of the third Grating G ₃ and optimally located lens on a good light spot reproduction dimensioning of the distances between the second and is set so that the good modulation _{sensitivity of the third grating G 2} or G ₃ and the size of their speed is not eliminated. 40 apertures achieved.

The known cathode ray tubes have a cathode ray tube in the drawing Penetration of the third and the wide grid measure of the invention shown for example, namely up to the cathode, so that the reverse voltage essentially shows

borrowed is determined by the second grid G ₂ . In- F i g. 1 a partially cut open cathode

consequently, it is necessary to maintain the plan view of the cathode ray tube,

modulation improved modulation sensitivity F i g. 2 shows a longitudinal section through part of the grove, to the second grid G ₂ a low potential of the tube on a larger scale and
tial of about 100 V or less. So far, F i g. 3, 4 and 5 characteristics of this tube in comparison

it is generally believed that such cathodes are the same as the characteristics of those previously used the radiant tubes with low voltage on the second 5 ° tubes.

Grid G ₂ a certain penetration of the field of the third tube part illustrated in FIGS. 1 and 2

Grid G _{3 is} required in order to avoid too weak a focus, has an evacuated piston 13 with an image, and that the requirement of a screen 15 and an electron arranged in the neck 17 does not have good sensitivity for the cathode module electron beam generating system 20. The electron retention by reducing penetration on the one hand and beam generating system20 consists of an electron source, on the other hand, to achieve good focus, and means for controlling, accelerating and speaking. It has been found, however, that these two bundles of the electron beam, the factors leading to the screen, do not necessarily have to contradict each other. is directed and by a deflection device, e.g. B. Rather, it has been found that on the one hand an electromagnetic deflection yoke 21 influences low penetration with consequently high sensitivity. The screen 15 will achieve the same as the last speed of the cathode modulation and, on the other hand, the grid of the electron gun, depending on the simultaneous use of a strongly projecting application, will be held at a potential of about 14 to lens between the second grid G ₂ and the third 18 kilovolts. This high potential accelerating grid G ₃ holds the electron beam together and lowers the electrodes to such a high speed, halo-like bright spots with strong scattering at 65, that they can reduce the fluorine-high control voltages when they hit the screen. make the decorative layer of the picture light up. North

Accordingly, the invention on which the invention is based is the high voltage for the screen Task primarily aimed at attaching a cathode and the last grid to an anode terminal 23.

5 6

placed. An electrically conductive inner layer 25 of the distance S ₁ as well as through the distance S _{2 of} the conical part of the piston 13 extends after the grille G _{2 has passed} through. Because of this back into the neck 17 of the tube and the high high penetration actuator leads to the cathode reverse voltage voltage to the last grid, namely by means of _{contact tongues 27, largely due to the tension of the grid G 2} , which agrees against the inner layer which is usually 20 to 50 volts. The remaining grids of the tube receive theirs while the voltage of the grid G _{1 is} zero. Covered by lines which are inserted into the tube neck 17 through the rear boundaries for the minimum distances between the end caps 29. The edges of the opening result from the fact that these

The beam generation system 20 has several equal thermal expansions occurring spacing changes axially one behind the other grids G ₁ to G ₅ , which would stand with the manufacturing tolerances and which must be compatible with rod-shaped insulating bodies 31 in a known manner so that short circuits and sparks are fixed in The longitudinal direction of the tube formation can be avoided with certainty. The necks extend. In the first grid G ₁ , which works as a control order of the opening 53 in the protruding part of the grid, a tubular, indirectly heated screen surface makes it possible to arrange the distance S _z cathode 33, which is in an annular 15 between the opening edges very to keep small and ceramic holder 35 sits and a relatively large grid spacing 39 is nevertheless provided with a heating wire. Maintain the screen 15 facing S ₃ , so that short circuits are prevented. The end of the cathode 33 is closed and wears out. In order to maintain the high penetration and the high slope of an electron-emitting coating 41. called the grid G ₂ , the distances

The control grid G ₁ is cup-shaped and 20 S ₁ and S _{2 are} not greater than 0.17 d _x . Limits open to the rear. It consists of a tubular of diameter d _{2 of} the advanced diaphragm sleeve 38 and a diaphragm 40, the opening 42 of which the opening 53 is based on the fact that despite the enlargement, the emitting coating 41 overlaps the cathode 33. of the reach- through actuator D _{1 of} the grating G ₂ through a The diameter d _{x of} the diaphragm opening 42 is the beam current consumption and a small opening is about 0.9 mm. The wall of the diaphragm 40 has, at its 25 corresponding decrease in steepness, a minimum outer surface facing away from the cathode 33, which results in value. A considerable reduction in the concave recess surrounding the aperture 42. Penetration actuator D _{1 also} occurs when the penetration is a small possible distance between knife d ₂ approximately equal to the diameter d _{x of} the opening of the surface of the emission layer 41 and the opening 42 of the control grid G ₁ or larger than this ge screen facing surface the aperture 40 makes 30. The tube was found to be secured in the area of opening 42. The distance S _{1 has} a ratio d ₂ / d ₁ smaller than 0.9 and larger than 0.7 works best between the diaphragm 40 and the emission layer 41. The penetration actuator D ₁ des is about 0.01 mm. The wall thickness of the cover plate second grid G ₂ results from the ratio is also about 0.01 mm. Fo ₁ / F ₂ , where F _{2 is} the voltage difference between the

In the beam direction close behind the grid G ₁ is 35 cathode 33 and G ₃ and Fei is the negative voltage,

there is the second grating G ₂ , it also consists of _{what is required on the grating G 1} to deflect the beam.

a metal tube which, however, switches to the screen when the end grids G ₃ and G _{6 are} de-energized

is. The grid G ₂ has a sleeve 51 and a screen. The penetration actuator D _{1 of} the grid G ₂ is

52, the opening 53 of which with the aperture 42 in the example shown is approximately 5.

of the grid G _{1 is} aligned. The middle part 54 of the aperture 40 that is located behind the grille G ₂ in the direction of the beam.

denwand is to the grid G ₁ concavely or conically Liehe grid G ₃ is composed of a stepped sleeve 61,

deformed. The diameter d _{z of} the opening 53 is that at the exit end of the beam with a diaphragm 62

about 0.7mm. The distance S _{z is provided} between the rear one, the opening 63 of which has a diameter d _s

Edge of this opening and the front edge of about 2.3 mm. The outer sleeve 61 sets

Opening 42 is about 0.1 mm. 45 consists of a larger diameter part 64 and

The grid G ₂ also contains an insert sleeve with a smaller part 65 together. The part 64 has

57, which with its sleeve 47 in the sleeve 51 of the grid G _{2 has} approximately the same outer diameter as the sleeves

fits and also open to the front of the screen 38 and 51 of the grids G ₁ and G ₂ . In the part 65 of the

is. The insert sleeve has a screen 58, the sleeve 61 of the grid G ₃ is a tubular one

with the grid G ₂ electrically and mechanically connected 50 insert 67, the tele with a cylindrical part 68

is bound. The diaphragm 58 contains an opening 59, which fits into the sleeve part 65 in a scopically displaceable manner. At

whose diameter is denoted _{by d 3.} The from this cylindrical part 68 closes to the rear

stood S _t between the mutually facing edges to a conical part 69, which consists of the part 64 of

the openings 53 and 59 is about 0.25 mm, and the sleeve 61 protrudes backwards and at its end

Distance S ₃ between the outer parts of each other 55 has an inlet opening 70. The distance S ₅ the

facing surfaces of the diaphragms 40 and 52 has approximately the outer edge of this opening of the diaphragm disk 58

the same size. The outer diameter of the grid of the insert 57 of the grid G ₂ is about 4.3 mm,

G ₁ and G ₂ are about 12.5 mm. the diameter d _{t of} this opening is about 3.0 mm.

The arrangement described represents a triode, by adjusting the grid spacing S ₅ and the

in which the penetration of the grid G _{2 is} high. The 60 size of the inlet opening 70 of the conical part

The maximum penetration value is mainly due to the 69 a significant improvement in the light

The distances between the grids are limited, and spot size characteristics can be achieved. The maximum

which are necessary to spark formation and short- achievable improvement is of course dependent on

Avoid drawing conclusions. what access is still permissible before it is

In general, it is desirable to switch the distance S ₁ 65 where the electron beam comes. At the high one

between the cathode 33 and the grid G ₁ so to modulation sensitivity, which with a triode

choose that the desired reverse voltage achieved execution of the type described is achieved is a

will. In the arrangement shown, the excessively high penetration of the grid G ₃ can cause very un-

The insert socket 57 arranged in the grid G ₂ limits or determines the height of the high-voltage _{penetration of G 3.} The insert socket 57 and the other parts of the grid G ₂ act as a screen, the 4s from the cathode 33, the first grid G ₁ and the triode section consisting of the protruding part 54 of the grid G ₂ shields against the tension of the grid G _3. The diameter J _{3 of} the opening 59 of the insert socket 57 is essentially a compromise resulting from the increased penetration actuator D _{1 of} the grid G ₂ , the Experience has shown that a reduction in the diameter J _{3 of} the opening 59 results in a slight increase in the penetration D _{1 of} the grid G ₂ and a considerable reduction in the penetration D _2. The penetration actuator D _{2 of} the grid G _{3 is} calculated is derived from the fraction V _cm IV _a and is approximately 0.0075, where K _{3 is} the voltage difference between the cathode 33 and the grids G ₃ and G ₅ and V _{cm is} the negative voltage which must be applied to the grid G _{1 in} order to switch off the beam when the grid G _{2 is} de-energized. Because of the reduction in penetration D _{2, it} could be expected that the spot size would increase with high beam currents. However, this is prevented by appropriate adjustment of the focusing lens located _{between the grids G 2} and G _3. The limitation of the diameter J _{3 of} the aperture 59 of the grating G ₂ is necessary because experiments have shown that if the penetration is increased by changing the distance S _5, the resulting increase in the strength of the focusing lens may lead to an increase in the light spot size on the screen 15 leads. The diameter d _s must therefore remain in a range that ensures the highest possible penetration D _{1 of} the grating G ₂ and still allows a sufficient high voltage penetration so that the increase in the size of the light spot and the overexposure can be controlled without undue amplification of the focusing lens. This is achieved by making the diameter d _{3 of} the opening 59 approximately as large as the diameter J _{1 of} the opening 42 of the first grid G ₁ and the distance S ₄ , between the edges of the openings 53 and 59 not greater than 0, 6 d _s selects. The diameter J _{4 of} the opening 70 must also be smaller than the diameter of the outer sleeve 51 of the grid G ₂ and the distance S _{5 must be} just as large or greater than 3 J ₃ .

A sleeve-shaped grid G ₄ , the sleeve of which is designated 75 and is fastened to the insulating rod 31 by means of part 18, is connected behind the grid G ₃ in the direction of the beam. This is followed by a grating G ₅ , the part 80 of which is closed on the beam entry side by a diaphragm 82, the opening 84 of which has a diameter J ₆ of approximately 2.8 mm.

The following dimensions and applied voltages have been found to work well for cathode ray tubes proven according to the invention:

Opening diameter

J ₁ 0.9 mm

J ₂ 0.7 mm

J ₃ 0.9 mm

J ₄ 3.0 mm

J ₅ 2.3 mm

J ₆ 3.8 mm

distances

1S ₁ 0.1 mm

S ₂ 0.1mm

5 ₃ 0.25 mm

5 ₄ 0.25 mm

5 ₅ 4.3 mm

Tensions

Cathode 33 0 to + 60 V.

Grid G ₁ OV

Grid G ₂ . + 45 V

Grid G ₃ + 16 kV

Grid G ₄ + 200V

Grid G ₅ + 16 kV

The curves according to FIG. 3, 4 and 5 show the performance of a cathode ray tube according to the invention compared to the performance of conventional cathode ray tubes whose grids are fed with low voltages, the curves referring to the known ones, the curves B referring to tubes according to the invention. Fig. 3 shows .that a considerable increase in the slope and consequently a considerable improvement in control compared to the conventional tubes is achieved. It is important that, in addition to this improvement, a considerable improvement in the size of the light spot is also achieved. F i g. 4 also illustrates the increased steepness and also reveals that the. achievable with the tube maximum jet current is much stronger than with the known tubes. F i g. 5 shows the improvement in the size of the light spot on the screen and also the achievable increase in the beam current intensity.

Claims (2)

Patent claims: 1. Cathode ray tube with at least three equiaxed grids one behind the other, which are provided with the cathode beam focusing aperture, the aperture of the second grid is smaller than the aperture of the first, closely adjacent grid, dadurchgekennzeichn et that the opening (53) of the second grid (G ₂₎ closer to the first grating (G ₁₎ is the same as the rest of the screen member (54), in that the second grating (G ₂₎ at its the radiation source (33, 41) facing away side contains an additional panel insert (57) is electrically conductively connected to the second grid and with its aperture (59) from the upstream aperture (53) of the second grid at a distance (S ₄ ) which is smaller than the diameter (J ₃ ) of the aperture (59) of the insert is, the aperture of which _{is larger in diameter (J 3} ) than the aperture diameter (J ₂ ) of the aperture of the second grating (G ₂ ), and that the subsequent third grating (G ₃ ) has a tubular inlet part (69) tapering towards the second grid, the inlet opening (70) of which in diameter (J ₄ ) is at least three times larger than the diameter (J ₃ ) of the aperture (59) of the aperture insert (47) in the second grid (G ₂ ) is. 2. Cathode ray tube according to claim 1, characterized in that the two first grids (G ₁ and G ₂ ) each have a cylindrical sleeve (38 or 51) and these sleeves at their ends facing each other through the associated diaphragm (40 or 52) are closed on one side, wherein the aperture insert (57) of the second grille (G ₂ ) is arranged within its sleeve (51) so that the distance (S ₄ ) between the two openings (53 and 59) of the apertures (52 and 58) of the second grille and its insert is smaller than 0.6 of the diameter (J ₃ ) of the aperture (59) of the insert - (57). 3. Cathode ray tube according to claim 2, characterized in that the wall thickness of the diaphragm (40) of the first grid (G ₁ ) in the region of the diaphragm opening (42) is smaller than in the outer edge region. 4. Cathode ray tube according to claim 2 or 3, characterized in that the cylindrical sleeve (51) of the second grid (G ₂ ) has the same outer diameter as the cylindrical sleeve (38) of the first grid (G ₁ ). 5. Cathode ray tube according to claim 2, 3 or 4, characterized in that the middle part (54) of the diaphragm (52) of the second grid (G ₂ ) tapers towards the first grid (G ₁ ) in the shape of a truncated cone. 6. Cathode ray tube according to claim 2, 3, 4 or 5, characterized in that the diameter 04) of the inlet opening (70) of the third grid (G ₃ ) is smaller than the diameter of the cylindrical sleeve (51) of the second grid (G ₂ ). 7. Cathode ray tube according to one of the preceding claims, characterized in that 10 the distance (S ₁ ) of the cathode (33) forming the radiation source from the diaphragm (40) of the first grid (G ₁ ) as well as the distance (S ₂ ) of the opening (42) of this diaphragm from the adjacent diaphragm opening (53) of the second grid is not larger than 0.17 of the diameter (^ ₁ ) of the aperture (42) of the first grid (G ₁ ). 8. Cathode ray tube according to one of the preceding claims, characterized in that the diameter (J ₃ ) of the opening (59) of the insert (57) of the second grid (G ₂ ) is approximately equal to the diameter (^ ₁ ) of the aperture (42) of the first grid (G ₁ ) is. 9. Cathode ray tube according to one of the preceding claims, characterized in that the ratio (I ₂ Id ₁ between the diameters of the aperture openings (53, 42) of the second and first grids is greater than 0.7 and less than 0.9. Considered publications:
German interpretative document No. 1 071 238. 1 sheet of drawings 809 619/440 9.68 © Bundesdruckerei Berlin