JPH07211255A - Color image receiving tube - Google Patents

Abstract

PURPOSE:To prevent degradation in the focusing characteristic generated when a leakage current flows to a dividing resistor. CONSTITUTION:A color image receiving tube has an electron gun composed of a focusing electrode G5 in which main lens parts are serially arranged in the phosphor screen direction, one or plural intermediate electrodes Gm1 and Gm2, and a final accelerator electrode G6 to which an anode voltage is applied. The anode voltage is divided into specific voltages by means of a dividing resistor and the specific voltages are supplied to the intermediate electrodes Gm1 and Gm2 from an intermediate terminal part. In this color image receiving tube, plural dividing resistors 27a and 27b are provided, and connection resistors 43a, 43b, and 45a, and 45c are interposed between the intermediate terminal port and the intermediate electrode of each dividing resistor. The direction of each dividing resistor from the intermediate electrode is defined as the direction of the positive current flow, and rectifiers 44a, 44b, 46a, and 46b are interposed in parallel to the connection resistors between the intermediate terminal port of each dividing resistor and the intermediate electrode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly to a color picture tube constructed to prevent deterioration of focus characteristics.

[0002]

2. Description of the Related Art Generally, a color picture tube deflects three electron beams emitted from an electron gun by horizontal and vertical deflection magnetic fields generated by a deflecting device, and a phosphor consisting of a three-color phosphor layer through a shadow mask. It is formed in a structure for displaying a color image by scanning the screen. In such a color picture tube, the electron gun is an electron gun that emits three electron beams arranged in a row passing through the same horizontal plane, and the horizontal deflection magnetic field generated by the deflection device is distorted into a pincushion type and the vertical deflection magnetic field into a barrel type. No, the self-convergence in-line type color picture tube constructed so as to self-focus the three electron beams arranged in a row by this non-uniform magnetic field is currently the mainstream of the color picture tube.

Generally, in order to improve the quality of an image drawn on a phosphor screen of a color picture tube, it is necessary to improve the shape of the beam spot on the phosphor screen to improve the resolution. However, the self-convergence in-line type color picture tube has a problem in that the shape of the beam spot on the screen is distorted and the resolution is deteriorated because the deflection magnetic field is non-uniform. That is, as shown in FIG. 5, the beam spot 1a in the central part of the screen is almost a perfect circle, but the beam spot 1b in the peripheral part of the screen extends vertically to the elliptical high-brightness core part 2 elongated in the horizontal direction. Further, the image is distorted into a shape having the low-brightness halo portion 3, and the resolution in the peripheral portion of the screen is significantly reduced. The distortion of the beam spot 1b on the periphery of the screen is shown in FIGS. 6 (a) and 6 (b).
As shown for one of the three electron beams 4B, 4G, and 4R, one side beam 4B,
This is because when G and 4R pass through the horizontal and vertical deflection magnetic fields 5H and 5V, the focusing is weakened in the horizontal direction and conversely the focusing is strengthened in the vertical direction.

As one means for improving the deterioration of resolution due to such deflection distortion, Japanese Patent Laid-Open No. 64-38 of the present inventor has proposed.
Japanese Patent No. 947 discloses an electron gun 7 having the structure shown in FIG. The electron gun 7 has three cathodes KB, KG, KR arranged in a line in the horizontal direction (X direction), three heaters (not shown) for heating the cathodes KB, KG, KR, respectively. Two intermediate electrodes arranged between the first to sixth grids G1 to G6, the fifth grid G5 and the sixth grid G6, which are sequentially arranged from the cathodes KB, KG and KR at predetermined intervals in the phosphor screen direction. Gm1, Gm2
And a shield cup SC attached to the phosphor screen side of the sixth grid G6.

In each electrode of the electron gun 7, three electron beam passage holes are formed corresponding to the three cathodes KB, KG and KR. The electron beam passage holes are electron beam passage holes 8B, 8G, 8R on the surface of the fifth grid G5 made of a cylindrical electrode facing the intermediate electrode Gm1, and the electron beam passage holes of the sixth grid G6 facing the intermediate electrode Gm2. Passage hole 9
The electron beam passage holes 8B, 8G, 8R and 9B, 9G, 9R are circular except for B, 9G and 9R, but are formed in horizontally long non-circular holes which are long in the horizontal direction or thin circular holes. Has been done.

In this electron gun 7, the fifth grid G5, 2
The intermediate lenses Gm1 and Gm2 and the sixth grid G6 form a main lens part for finally focusing the emitted three electron beams on the phosphor screen, and the fifth grid G5 as the focusing electrode includes The dynamic focus voltage Vd, which changes in synchronization with the deflection of the electron beam of the deflector, is applied, and the sixth grid G6, which is the final accelerating electrode.
A high anode voltage Eb is applied to the. A dividing resistor 10 arranged close to the electron gun 7 divides the anode voltage into the intermediate electrodes Gm1 and Gm2, and a predetermined voltage is applied to each of them.

When the electron gun 7 is constructed as described above, the main lens portion of the electron gun 7 has the fifth grid G5 and the intermediate electrode Gm1 adjacent to the fifth grid G5, which strongly intensifies the three electron beams in the vertical direction relative to the horizontal direction. A first quadrupole lens for focusing is formed, and a sixth grid G6 and an intermediate electrode Gm2 adjacent to the sixth grid G6 are formed.
As a result, a second quadrupole lens that strongly diverges in the vertical direction relative to the horizontal direction is formed. These first and second quadrupole lenses are balanced when the three electron beams are directed to the center of the screen, and a beam spot having a substantially circular shape is obtained at the center of the screen. On the other hand, when the three electron beams are directed to the peripheral part of the screen, the potential difference between the fifth grid G5 and the intermediate electrode Gm1 becomes small due to the rise of the dynamic focus voltage of the fifth grid G5, and the first quadrupole lens The focusing effect of is weakened. As a result, the diverging action of the second quadrupole lens becomes relatively strong, and the three-electron beam is diverged mainly in the vertical direction and cancels the deflection distortion that is strongly focused in the vertical direction due to the deflection magnetic field. It is possible to improve the shape of the beam spot of the portion.

To that end, the electrodes forming the main lens,
Above all, it is an essential condition to stabilize the voltage of the intermediate electrodes Gm1 and Gm2. When the voltage applied to the intermediate electrodes Gm1 and Gm2 changes, the balance of the first and second quadrupole lenses is lost, the beam spot at the center of the screen becomes non-circular, and the focus characteristic deteriorates. Further, the change of the beam spot at the center of the screen also affects the peripheral part of the screen, so that desired characteristics cannot be obtained.

One of the causes of changes in the voltage applied to the intermediate electrodes Gm1 and Gm2 is a short circuit of the dividing resistor 10. This dividing resistor 10 is placed close to the electron gun 7 having an electrode to which a high voltage is applied and is exposed to a strong electric field, so that it is under severe conditions in terms of withstand voltage. In particular, intermediate terminal portions 11 and 12 connected to the intermediate electrodes Gm1 and Gm2
Is an electrode (sixth grid G) to which a high anode voltage is applied.
Since it is located relatively close to 6), dust and burrs are attached and formed between the anode terminal portion 13 to which the anode voltage of the dividing resistor 10 is applied and the intermediate terminal portions 11 and 12, A leak current may flow through the dividing resistor 10. In this case, the resistance value between the anode terminal portion 13 and the intermediate terminal portions 11 and 12 apparently becomes small, the potentials of the intermediate electrodes Gm1 and Gm2 become higher than a predetermined potential, and the focus characteristic is to degrade.

[0010]

As described above, in the self-convergence in-line type color picture tube, the horizontal and vertical deflection magnetic fields generated by the deflecting device are non-uniform.
Especially, there is a problem that the beam spot around the screen is distorted and the resolution is deteriorated. As one means for improving the deterioration of resolution due to this deflection distortion, the main lens portion of the electron gun is formed of a focusing electrode (fifth grid), two intermediate electrodes and a final accelerating electrode (sixth grid), and the focusing electrode is formed. The dynamic focus that changes in synchronization with the deflection of the electron beam is applied to the final accelerating electrode, and the anode voltage is applied to the two intermediate electrodes by the dividing resistors arranged close to the electron gun. There is an electron gun which is configured to divide the voltage into a predetermined voltage and apply a predetermined voltage.

In this electron gun, the focusing electrode and the intermediate electrode adjacent thereto form a first quadrupole lens which strongly focuses the three electron beams in the vertical direction relative to the horizontal direction, and the final accelerating electrode. The second quadrupole lens that strongly diverges in the vertical direction relative to the horizontal direction is formed by the and the intermediate electrode adjacent thereto. These first and second quadrupole lenses are balanced when the three electron beams are directed to the center of the screen, and a beam spot having a substantially circular shape is obtained at the center of the screen. On the other hand, when the three electron beams are directed to the peripheral portion of the screen, the potential difference between the focusing electrode and the intermediate electrode adjacent to the focusing electrode decreases due to the increase in the dynamic focus voltage of the focusing electrode, and the first quadrupole lens Of the second quadrupole lens becomes relatively strong. As a result, the three electron beams diverge mainly in the vertical direction, and the deflection distortion that is strongly focused in the vertical direction due to the deflection magnetic field is canceled out, and the shape of the beam spot in the peripheral portion of the screen can be improved.

However, this electron gun is under severe conditions in terms of withstand voltage because the dividing resistor is arranged close to the electron gun 7 and is exposed to a strong electric field. Especially, since the intermediate terminal part connected to the intermediate electrode is located relatively close to the final acceleration electrode to which the anode voltage is applied, dust, burrs, etc. may occur between the anode terminal part and the intermediate terminal part of the dividing resistor. May be adhered and formed, and a leak current may flow through the dividing resistor. In this case, the resistance value between the anode terminal portion and the intermediate terminal portion apparently becomes small, the potential of the intermediate electrode becomes higher than the predetermined potential, and the focus characteristic deteriorates.

The present invention has been made in order to solve the above problems, and a color image is formed in which the balance of the quadrupole lens formed in the main lens portion is not deteriorated even if a leak current flows through the dividing resistor. The purpose is to construct a tube.

[0014]

There is a main lens unit for finally focusing an electron beam from an electron beam generating unit on a phosphor screen, and the main lens unit is sequentially arranged in the phosphor screen direction. An electron gun having an electrode, one or more intermediate electrodes and a final accelerating electrode to which an anode voltage is applied. The intermediate electrode is divided into a predetermined voltage by a dividing resistor on the intermediate electrode. In the color picture tube supplied from the company, there are a plurality of dividing resistors, and a connecting resistor is inserted between the intermediate terminal part and the intermediate electrode of each dividing resistor. A rectifier was inserted in parallel with the connecting resistor between the intermediate terminal portion and the intermediate electrode of each dividing resistor with the direction of the resistor as the forward direction of the current.

Further, the reverse resistance of the rectifier is made larger than the resistance value of the connecting resistor.

[0016]

As described above, a plurality of dividing resistors are provided, a connecting resistor is inserted between the intermediate terminal portion and the intermediate electrode of each dividing resistor, and the dividing electrodes are divided from each other. When the rectifier is inserted in parallel with the connecting resistor between the intermediate terminal portion and the intermediate electrode of each dividing resistor with the direction of the resistor as the forward direction of the current, for example, two dividing resistors are arranged. In this case, a leak current flows between the anode terminal portion of one of the first dividing resistors and the intermediate terminal portion connected to the intermediate electrode,
The potential of the intermediate terminal portion rises. As a result, a connecting resistor inserted between the intermediate terminal portion and the intermediate electrode → the intermediate electrode →
A current flows in the route of the rectifier inserted between the second dividing resistor and the intermediate electrode → the second dividing resistor. In this case, since the current flowing through the rectifier inserted between the second dividing resistor and the intermediate electrode is in the forward direction, the resistance of the rectifier can be ignored and the potential of the intermediate electrode is the second dividing resistor. The predetermined potential obtained from the resistor is reached, and the amount of increase in the voltage at the intermediate terminal portion of the first dividing resistor is inserted between the intermediate terminal portion and the intermediate electrode of the first dividing resistor. It is absorbed by the connecting resistor and a predetermined voltage can be applied to the intermediate electrode.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 2 shows a self-convergence in-line type color picture tube which is one of the embodiments. This color picture tube has an envelope consisting of a panel 20 and a funnel-shaped funnel 21 integrally joined to the panel 20, and the inner surface of the panel 20 has a striped shape that emits blue, green, and red light. Phosphor screen 2 consisting of three-color phosphor layers
2 is formed, facing the phosphor screen 22,
A shadow mask 23 is arranged inside thereof. On the other hand, inside the neck 24 of the funnel 21, the center beam 25G and the pair of side beams 2 that pass on the same horizontal plane.
5B and 25R arranged in a row in a three-electron beam 25B,
An electron gun 26 that emits 25 G and 25 R is arranged, and a pair of dividing resistors 27 a and 27 are arranged close to the electron gun 26.
b is placed. Also, the large-diameter portion 28 of the funnel 21
Is provided with an anode terminal 29. Also funnel 21
An inner conductive film 30 is formed by coating from the inner surface of the large diameter portion 28 to the inner surface of the adjacent portion of the neck 24, and is connected to the anode terminal 29.

Reference numeral 31 is a deflection device mounted outside the funnel 21 for generating a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field.

As shown in FIG. 1, the electron gun 26 has three cathodes KB, KG, K arranged in a line in the horizontal direction.
R, three heaters (not shown) for heating the cathodes KB, KG, KR separately, the cathodes KB, KG,
First to sixth grids G1 to G6, which are sequentially arranged from KR in the direction of the phosphor screen, at predetermined intervals, and 2 arranged between the fifth grid G5 and the sixth grids G5 and G6.
The intermediate electrodes Gm1 and Gm2 and the shield cup SC attached to the phosphor screen side of the sixth grid G6 have cathodes KB, KG and KR, heaters, first to sixth grids G1 to G6 and 2 One intermediate electrode Gm1,
Gm2 is formed in a structure integrally fixed by a pair of rod-shaped insulating supports (not shown).

The first and second grids G1 and G2 are
From the plate-shaped electrodes having a relatively thin plate and having an integrated structure to the third, fourth, fifth and sixth grids G3, G4, G5, G6, respectively.
From the cylindrical electrode of the integral structure to the intermediate electrode Gm1,
Each Gm2 is composed of a plate-shaped electrode having a relatively thick plate and having an integral structure. The first, second, third, fourth, grid G1
, G2, G3, G4, G4, fourth of the fifth grid G5
Three cathodes KB, KG, KR are provided on the surface facing the grid G4, the intermediate electrode Gm2, the surface facing the shield cup SC of the sixth grid G6 and the surface facing the sixth grid G6 of the shield cup SC. Corresponding to, 3 in one row
A circular electron beam passage hole is provided. The fifth
On the surface of the grid G5 facing the intermediate electrode Gm1, the horizontally long non-circular holes or the plate thickness that is long in the horizontal direction in a row is thinned to 1.0 mm or less in correspondence with the three cathodes KB, KG, and KR. Three electron beam passage holes 33B consisting of circular holes,
33G and 33R are also the intermediate electrodes G of the sixth grid G6.
Also on the surface facing m2, corresponding to the three cathodes KB, KG, KR, there are three electron beam passage holes 34B, 34G, 34 each having a similar non-circular hole or a circular hole with a reduced plate thickness.
R is provided. The three electron beam electron beam passage holes are coaxial with each other except the pair of side beam passage holes 35B and 35R of the intermediate electrode Gm2.
The pair of side beam passage holes 35B and 35R of m2 are eccentric to the pair of side beam passage holes of the intermediate electrode Gm1 in a direction away from the center beam passage hole 35G.

The pair of dividing resistors 27a, 27a
b is formed in a structure having the same shape and almost the same resistance characteristics, and is symmetrically arranged on both sides of the electron gun 26 with the electron gun 26 interposed therebetween. Preferably, the electrodes of the electron gun 26 are integrally fixed to a rod-shaped insulating support. It is placed in close contact with the back of the body (the surface facing the inner surface of the neck). These dividing resistors 27a, 27
In b, anode terminal portions 37a and 37b and ground terminal portions 38a and 38b are provided at both ends, and two terminals are provided at an intermediate portion.
The individual intermediate terminal portions 39a, 39b, 40a, 40b are provided. Anode terminal portions 37a and 37b at one end thereof
Are connected to the anode terminal 29 through an inner conductive film or the like applied from the inner surface of the large-diameter portion of the funnel to the inner surface of the adjacent portion of the neck, and the ground terminal portion 3 at the other end.
8a and 38b are stem pins 41 at the neck end, respectively.
(See FIG. 2) and variable resistors 42a and 42b. Also, each of the above two intermediate terminal portions 39a,
One of the intermediate terminals 39a, 39b, 40a, 40b
And 40a, and the other intermediate terminal portions 39b and 40b are formed to have the same potential when the anode voltage is applied to the anode terminal portions 37a and 37b, respectively.

Two intermediate terminal portions 39a and 39b are provided.
, 40a, 40b, one of the intermediate terminal portions 39a,
39b are connection resistors 43a, 43a,
43b and the rectifiers 44a and 44b connected in parallel with these resistors 43a and 43b are connected to the intermediate electrode Gm1, and the other intermediate terminal portions 40a and 40b are similarly connected resistors 45a having the same resistance value, respectively. , 45b and rectifiers 46a, 46b connected in parallel with these resistors 45a, 45b are connected to the intermediate electrode Gm2. A rectifier 44a in parallel with the resistors 43a and 43b,
44b and rectifier 46 in parallel with resistors 45a and 45b
a and 46b are from the intermediate electrodes Gm1 and Gm2 to the intermediate terminal portions 39a and 39b of the dividing resistors 27a and 27b, respectively.
The directions of 40a and 40b are the forward direction of the current. The rectifiers 44a, 44b, 46a, and 46b have the reverse resistances of the rectifiers 44a, 44b, 46a, and 46b.
connecting resistors 43a, 43b, 45 connected in parallel to b
It is larger than the resistance of a and 45b.

In the electron gun 26 to which the dividing resistors 27a and 27b are connected in this way, a video signal is superimposed on a DC voltage of about 180 V on each of the cathodes KB, KG and KR via the stem pin at the neck end. Voltage is applied, the first
The grid G1 is grounded, the second grid G2 and the fourth grid G4 are connected in a pipe, and a DC voltage of about 800 V is applied to the second and fourth grids G2 and G4, and the third grid G3 and the fifth grid G5. It is connected to the (focusing electrode) in the tube, and the third and fifth grids G3 and G5 have about 8 to
A dynamic focus voltage Vd in which a parabolic voltage which changes in synchronization with the deflection of the electron beam of the deflector is superimposed on the DC voltage of 9 kV is applied. On the other hand, for the intermediate electrode Gm1, the dividing resistors 27a and 27b divide the anode voltage Eb supplied to the anode terminal portions 37a and 37b at one end thereof to divide the anode voltage Eb from the intermediate terminal portions 39a and 39b. A voltage of about 40% is applied to the intermediate electrode Gm2 by the dividing resistors 27a and 27b, and a voltage of about 65% of the anode voltage Eb is applied from the intermediate terminal portions 40a and 40b. An anode voltage Eb of about 30 kV is applied to the sixth grid G6 (final accelerating electrode) via the anode terminal 29 provided on the funnel and the inner conductive film.

When such a voltage is applied to each electrode of the electron gun 26, an electron beam generator is formed by the three cathodes KB, KG and KR and the first, second and third grids G1, G2 and G3. And each cathode KB, KG, KR
The three electron beams emitted from the first and second grids G
After forming a crossover near 1, G2, diverge,
Prefocusing is performed by a prefocus lens formed by the second and third grids G2 and G3. Then, it is further focused by an auxiliary lens formed by the third, fourth and fifth grids G3, G4 and G5, and then the fifth grid G5, the two intermediate electrodes Gm1, Gm2 and the sixth grid G6.
Finally, it is focused on the phosphor screen by the main lens portion formed by.

In the electron gun 26, the main lens portion for finally focusing the three electron beams on the phosphor screen is the fifth grid G5 and the intermediate electrode Gm1 adjacent to the fifth grid G5.
And a second quadrupole lens formed by the sixth grid G6 and the intermediate electrode Gm2 adjacent to the sixth grid G6. The first quadrupole lens strongly focuses the three electron beams in the vertical direction relative to the horizontal direction, and the second quadrupole lens conversely strongly focuses the vertical direction in the horizontal direction. Diverge. Moreover, these first and second quadrupole lenses are balanced when the three electron beams are directed to the center of the screen, and a substantially circular beam spot is obtained at the center of the screen. Further, when the three electron beams are directed to the peripheral portion of the screen, the potential difference between the fifth grid G5 and the intermediate electrode Gm1 becomes small due to the increase in the dynamic focus voltage applied to the fifth grid G5, and
The focusing action of the quadrupole lens is weakened, and the diverging action of the second quadrupole lens is relatively strengthened, and the deflection distortion of the deflecting device which causes relatively vertical overfocusing is offset to cancel the deflection distortion of the peripheral portion of the screen. The beam spot should also be almost circular.

By the way, when the color picture tube is constructed as described above, the dividing resistors 27a, 27a,
Even if a leak current flows between any one of the anode terminal portions 37a and 37b of 27b and the intermediate terminal portions 39a and 39b or 40a and 40b, it is possible to suppress the rise of the potentials of the intermediate electrodes Gm1 and Gm2. The intermediate electrodes Gm1 and Gm2 can be maintained at a predetermined potential to prevent the focus characteristics from deteriorating.

Now, the anode voltage Eb is supplied to the respective anode terminal portions 37a and 37b of the dividing resistors 27a and 27b, and either one of the dividing resistors 27a or 27b, for example, one of the first dividing resistors. Anode terminal part 37 of container 27a
It is assumed that a leak current flows between a and the intermediate terminal portion 40a, and that no leak current flows between the anode terminal portion 37b and the intermediate terminal portion 40b of the other second dividing resistor 27b.
In this case, as shown in FIG.
The resistance value between a and the intermediate terminal portion 39a is R1, the resistance value between the intermediate terminal portion 39a and the intermediate terminal portion 40a is R2, and the resistance value between the intermediate terminal portion 40a and the anode terminal portion 37a is R3.
, The resistance value of the variable resistor 42a is Rv1, the dividing resistor 2
When the normal current flowing through 7a is IR1, the potential V12 of the intermediate terminal portion 40a is V12 = (R1 + R2 + Rv1) IR1 in the normal state. On the other hand, as shown in (b), when the leak current IL flows through the dividing resistor 27a, the potential V12 'of the intermediate terminal portion 40a becomes V12' = (R1 + R2 + Rv1) (IR1 + IL), The potential rises above the normal potential V12.

At this time, the other second dividing resistor 27
Since no leak current flows through b, as shown in FIG. 4, the potential V of the intermediate terminal portion 40b of the dividing resistor 27b is V.
Reference numeral 22 designates the resistance value of the variable resistor 42b as Rv2, the resistance value between the ground terminal portion 38b and the intermediate terminal portion 39b as R1,
The resistance value between the intermediate terminal portion 39b and the intermediate terminal portion 40b is R2, and the resistance value between the intermediate terminal portion 40b and the anode terminal portion 37b is the same as that of the dividing resistor 27a.
If R1, R2 and R3 and the current flowing through the dividing resistor 27b are IR2, then V22 = (R1 + R2 + Rv2) IR2 and the potential is about 65% of the anode voltage.

That is, in a normal state in which the leak current does not flow through the first dividing resistor 27a, the dividing resistors 27a are divided.
, 27b have slightly different resistance characteristics, the variable resistors 42a, 42b of the dividing resistors 27a, 27b are adjusted so that V12 = V22, and the intermediate terminal portions 40a, 40b are
It becomes a predetermined divided potential. However, when the leak current IL flows through the first dividing resistor 27a, V12 '> V22, and a potential difference is generated between the intermediate terminal portion 40a of the dividing resistor 27a and the intermediate terminal portion 40b of the dividing resistor 27b. A current I2 flows from the intermediate terminal portion 40a to the connecting resistor 43a to the intermediate electrode Gm2 to the rectifier 46b to the intermediate terminal portion 40b. Since the current I2 flows in the forward direction of the current flowing in the rectifier 46b, the resistance of the rectifier 46b can be ignored, and the potential of the intermediate electrode Gm2 becomes equal to that of the dividing resistor 27b.
Is kept at the same normal potential as the potential V22 of the intermediate terminal portion 40b. That is, the dividing resistor 27 due to the leak current IL
The increase in the voltage of the intermediate terminal portion 40a of a is absorbed by the connecting resistor 45a and does not affect the potential of the intermediate electrode Gm2.

The intermediate terminal 4 of the dividing resistor 27a
Rectifier 46a interposed between 0a and the intermediate electrode Gm2
Is in the opposite direction to the current flow. The connecting resistor 45b inserted between the intermediate terminal portion 40b of the dividing resistor 27b and the intermediate electrode Gm2 is short-circuited by the rectifier 46b connected in parallel. Almost no current flows through the resistor 45b.

As described above, the intermediate terminal portion 4 of the dividing resistor 27a
The increase in the potential of 0a has been explained, but the dividing resistor 2
Similarly, with respect to the intermediate terminal portion 39a of 7a, the potential V11 of the intermediate terminal portion 39a in the normal state (see FIG. 3A) is V11 = (R1 + Rv1) IR1. On the other hand, when the leak current IL flows, the potential V11 'of the intermediate terminal portion 39a (see FIG. 3B) becomes V11' = (R1 + Rv1) (IR1 + IL), which is higher than the potential V11 in the normal state. To do. However, as in the case of the intermediate terminal portion 40a, the increase in the voltage of the intermediate terminal portion 39a of the dividing resistor 27a due to the leak current IL is absorbed by the connecting resistor 43a and affects the potential of the intermediate electrode Gm1. The intermediate electrode Gm1 is not provided and the dividing resistor 2
The potential V21 of the intermediate terminal portion 39b of 7b is maintained at the same normal potential as V21 V21 = (R1 + Rv2) IR2.

In the above embodiment, the case where the number of dividing resistors is two has been described. However, the number of dividing resistors is not limited to two, and any number of dividing resistors may be used. Good.

In the above embodiment, the electron gun having two intermediate electrodes has been described, but the number of the intermediate electrodes may be one or more, and the number thereof is not limited.

Further, in the above embodiment, the QPF (Quadra P
Although the color picture tube provided with the otential focus type electron gun has been described, the present invention is also applied to a color picture tube provided with an electron gun having another configuration.

[0036]

The present invention has a main lens portion for finally focusing the electron beam from the electron beam generating portion on the phosphor screen, and the main lens portion is sequentially arranged in the phosphor screen direction. A color having an electron gun composed of a plurality of intermediate electrodes and a final accelerating electrode to which an anode voltage is applied, and dividing the anode voltage into a predetermined voltage by a dividing resistor and supplying it from the intermediate terminal portion to the intermediate electrode. In the picture tube, there are a plurality of dividing resistors, the connecting resistor is inserted between the intermediate terminal portion and the intermediate electrode of each dividing resistor, and the direction of each dividing resistor from the intermediate electrode. A rectifier is inserted in parallel with the connecting resistor between the intermediate terminal portion and the intermediate electrode of each dividing resistor as a current forward direction, and preferably the reverse resistance of the rectifier is the resistance value of the connecting resistor. Greater than For example, when two dividing resistors are arranged, a leak current flows between the anode terminal portion of one of the first dividing resistors and the intermediate terminal portion connected to the intermediate electrode, and the potential of the intermediate terminal portion is increased. , And the connecting resistor inserted between the intermediate terminal and the intermediate electrode → intermediate electrode →
A current flows in the route of the rectifier inserted between the second dividing resistor and the intermediate electrode → the second dividing resistor. In this case, since the current flowing through the rectifier inserted between the second dividing resistor and the intermediate electrode is in the forward direction, the resistance of the rectifier can be ignored and the potential of the intermediate electrode is the second dividing resistor. The predetermined potential obtained from the resistor is reached, and the amount of increase in the voltage at the intermediate terminal portion of the first dividing resistor is inserted between the intermediate terminal portion and the intermediate electrode of the first dividing resistor. It is absorbed by the connecting resistor and a predetermined voltage can be applied to the intermediate electrode.

That is, the potential of the conventional intermediate electrode rises,
The problem of deterioration of focus characteristics is solved by a relatively simple means, and even if a leak current flows between the anode terminal and the intermediate terminal of the splitting resistor, the intermediate electrode is stabilized at a predetermined potential. The color picture tube can be maintained and the focus characteristic does not deteriorate.

[Brief description of drawings]

FIG. 1 (a) is a front view showing in section a structure of an electron gun of a color picture tube which is an embodiment of the present invention, and FIG. 1 (b).
[Fig. 3] is a side view similarly showing in section.

FIG. 2 is a diagram showing a configuration of a color picture tube which is an embodiment of the present invention.

3 (a) and 3 (b) are equivalent circuit diagrams of a first dividing resistor shown for explaining the operation of the color picture tube which is one embodiment of the present invention.

FIG. 4 is an equivalent circuit diagram of first and second dividing resistors shown for explaining the operation of the color picture tube which is the one embodiment.

FIG. 5 is a diagram showing a shape of a beam spot on a screen of a conventional self-convergence in-line type color picture tube.

6A is a diagram for explaining the distortion of an electron beam due to a pincushion type horizontal deflection magnetic field, and FIG. 6B is a diagram for explaining the distortion of an electron beam due to a barrel type vertical deflection magnetic field. Is.

FIG. 7 (a) is a front view showing a cross section of the structure of a conventional electron gun of an in-line type color picture tube, and FIG. 7 (b) is a side view showing the same cross section.

[Explanation of symbols]

 21 ... Funnel 22 ... Phosphor screen 25B, 25G, 25R ... 3 Electron beam 26 ... Electron gun 27a, 27b ... Dividing resistor 31 ... Deflection device 37a, 37b ... Anode terminal 38a, 38b ... Ground terminal 39a, 39b ... intermediate terminals 40a, 40b ... intermediate terminals 43a, 43b ... connecting resistors 44a, 44b ... rectifiers 45a, 45b ... connecting resistors 46a, 46b ... rectifiers KB, KG, KR ... cathode G1 ... first grid G2 ... second grid G3 ... third grid G4 ... fourth grid G5 ... fifth grid G6 ... sixth grid Gm1 ... intermediate electrode Gm2 ... intermediate electrode

Claims (2)

[Claims] 1. A focusing lens having a main lens section for finally focusing an electron beam from an electron beam generating section on a phosphor screen, the main lens section being sequentially arranged in the phosphor screen direction. An electron gun including one or more intermediate electrodes and a final accelerating electrode to which an anode voltage is applied, and a plurality of dividing resistors for dividing the anode voltage into predetermined voltages and supplying the intermediate electrodes to the intermediate electrodes. A resistor, a connecting resistor inserted between the intermediate terminal portion of each of the dividing resistors and the intermediate electrode, and a direction of the dividing resistor from the intermediate electrode as the forward direction of the current A color picture tube comprising a rectifier interposed in parallel with the connecting resistor between the intermediate terminal portion of each dividing resistor and the intermediate electrode. 2. A focusing lens having a main lens section for finally focusing the electron beam from the electron beam generating section on the phosphor screen, the main lens section being sequentially arranged in the phosphor screen direction. An electron gun including one or more intermediate electrodes and a final accelerating electrode to which an anode voltage is applied, and a plurality of dividing resistors for dividing the anode voltage into predetermined voltages and supplying the intermediate electrodes to the intermediate electrodes. A resistor, a connecting resistor inserted between the intermediate terminal portion of each of the dividing resistors and the intermediate electrode, and a direction of the dividing resistor from the intermediate electrode as the forward direction of the current Between the intermediate terminal portion of each split resistor and the intermediate electrode is inserted in parallel with the connecting resistor, and the reverse resistance is greater than the resistance value of the connecting resistor inserted in parallel. And a large rectifier A color picture tube.