KR20010084815A - Cathode ray tube having an internal voltage-dividing resistor - Google Patents

Abstract

PURPOSE: A cathode ray tube comprising an embedded voltage dividing resistor is provided, which has a voltage-resistant characteristics by increasing a spot knocking effect by preventing the generation of cracking penetrating layers of the embedded voltage dividing resistor during a spot knocking process. CONSTITUTION: An in-line type 3 beam electron gun(9) includes a cathode(K), grid electrodes(G1-G6) and a medium electrode(GM). The grid electrodes and the medium electrode are fixed by inserting peripheral flanges of the grid electrodes and the medium electrode on a pair of glass beads(23) or by inserting a support tab attached to the grid electrodes and the medium electrode in the glass beads. A bulb spacer(24) controls an axis of the electron gun in a neck part(2). An embedded voltage dividing resistor(25) is mounted on a side of the glass beads toward the neck part. A high voltage terminal(26) of the voltage dividing resistor is connected to a shield cup(12) attached to the sixth grid electrode(G6) and a medium voltage terminal(27) is connected to the medium electrode and a low voltage terminal(28) is grounded through one of stem pins(15). A discharge-suppressing shield wire(29) is arranged to surround the embedded voltage dividing resistor and one of the glass beads and is connected to the fifth grid electrode(G5).

Description

Cathode ray tube with built-in voltage divider resistor {CATHODE RAY TUBE HAVING AN INTERNAL VOLTAGE-DIVIDING RESISTOR}

The present invention relates to a cathode ray tube, and more particularly, to a color cathode ray tube having an electron gun using a built-in voltage divider resistor.

Colored cathode ray tubes used in TV receivers or information terminals are electron guns for emitting multiple (generally three) electron beams at one end of the vacuum envelope, multiple (usually three colors) at the other end of the vacuum envelope. A fluorescent screen formed of a phosphor coated on an inner surface of the vacuum envelope to emit light of a color, and a shadow mask installed in close proximity to the fluorescent screen and operating as a color selection electrode. The electron beams emitted from the electron gun are deflected to irradiate the fluorescent screen horizontally and vertically to form a rectangular raster by a magnetic field generated by a polarization yoke mounted to the outside of the vacuum envelope to produce a predetermined image on the fluorescent screen. Is displayed.

FIG. 8 is a cross-sectional view illustrating an exemplary configuration of a color cathode ray tube. In FIG. 8, reference numeral 1 denotes a panel portion, and reference numeral 2 denotes a neck for accommodating an in-line type electron gun 9. Part 3 is a funnel part for connecting the panel part 1 and the neck part 2, 4 is a fluorescent screen, 5 is a shadow mask, 6 is a mask frame, and 4 is a funnel part 7 is magnetic shield, 8 is mask suspension mechanism, 10 is deflection yoke, 11 is inner conductive film, 12 is shield cup, 13 is contact spring, 14 is Denotes jitter and stem pins.

In this color cathode ray tube, the vacuum envelope is formed by the panel portion 1, the neck portion 2 and the funnel portion 3, and the electron beam emitted from the electron gun 9 housed in the neck portion 2 ( 16 scans the fluorescent screen 4 two-dimensionally by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 10.

The electron beam 16 is modulated by a video signal applied through the stem pin 15 and color selected by a shadow mask 5 placed directly in front of the fluorescent screen 4 to be projected onto the intended primary phosphor. Play a predetermined color image.

These cathode ray tubes utilize multiple focusing lens systems to obtain sufficiently small electron beam spots throughout the entire fluorescent screen.

Japanese Patent Laid-Open No. 10-255682 (published on September 25, 1999) discloses that a main lens is formed of an "extended filed lens" by providing an intermediate electrode between an anode and a focusing electrode. Fig. 9 is a schematic longitudinal cross-sectional view of the electron gun of the cathode ray tube disclosed in Japanese Patent Laid-Open No. 10-255682, and Fig. 10 is a cross-sectional view taken along the line XX of the electron gun shown in Fig. 9. Three cathodes 309 arranged on the same plane, and the first electrode 301, the second electrode 302, and the third electrode arranged in sequence on the same axis as the cathode 309. 303, fourth electrode 304, fifth-first electrode (focus electrode) 305, fifth-second electrode (focus electrode) 306, intermediate electrode 310, sixth electrode (anode electrode) A field expanding electron gun comprising a 307 and a shield cup 308, wherein the cathode and electrodes are small by a pair of glass beads 311. It is fixed in relation to the distance.

In order to obtain the voltage to be supplied to the intermediate electrode 310 in the cathode ray tube, the cathode ray tube has a voltage divider resistor 312 fabricated on a ceramic substrate, which is one of the glass beads 311. Stuck in As shown in FIG. 10, the metal wiring 314a surrounds the glass beads 311 and the voltage dividing resistor 312 and is welded to the intermediate electrode 310.

The electrons emitted from the cathode 309 are prefocus lenses formed by the cathode 309, the first electrode 301, the second electrode 302, and the third electrode 303, and then the third electrode. 303, a pre-main lens formed by the fourth electrode 304 and the fifth-first electrode 305, followed by the fifth-second electrode 306, the intermediate electrode 310, and the sixth The main lens formed by the electrode 307 is focused on the fluorescent screen to form an image on the viewing screen of the cathode ray tube.

The voltage applied to the intermediate electrode 310 is selected lower than the anode voltage and higher than the voltage applied to the focusing electrode by dividing the anode voltage using the voltage divider 312. The installation of the intermediate electrode 310 forms an electric field-expandable lens in which the potential distribution on the tube axis is smooth from the anode electrode to the focusing electrode, thereby reducing spherical aberration, thereby reducing the diameter of the electron beam spot.

On the other hand, as shown in FIG. 10, the neck glass 317 is attached by attaching the metal wiring 314a to the intermediate electrode 310 so that the metal wiring 314a surrounds the glass crystal 311 and the voltage divider resistor 312. Collect the amount of charge accumulated on the inner wall.

After inserting the completed electron gun into the neck glass 317, an external radio frequency introduction heater is used to evaporate a part of the metal contained in the metal wiring 314a to form a more stable electric potential on the inner wall of the neck glass 317. The metal wiring 314a is heated to form a metal thin film (not shown) on the inner wall of the neck glass 317 and the surface of the voltage dividing resistor 312 and the glass beads 311.

In the manufacture of cathode ray tubes, the so-called spot-knocking (high pressure stabilization), in which the gas is exhausted and sealed in the cathode ray tube, and then a voltage of about twice the normal operating voltage of the cathode ray tube is applied to the anode. By forcibly generating a spark between the electrodes and between the electrodes and the inner wall of the neck to remove the projections and / or foreign matter at the electrode of the electron gun in the cathode ray tube, thereby eliminating the cathode ray tube during normal operation of the finished cathode ray tube. Sparks can be prevented from occurring.

However, in a cathode ray tube using an electric field expansion lens formed by applying a voltage divided from an anode voltage to an intermediate electrode by using a built-in voltage divider resistor and a metal wire for discharge suppression attached to a focusing electrode on the upper side than the intermediate electrode, the anode When spot-knocking, for example, applying a high voltage of, for example, about 60 mA to the anode, to all other electrodes and the grounded intermediate electrode, the discharge inhibiting metal wiring surrounding the voltage divider resistor is grounded. As a result, a voltage difference of about 30 kV occurs between the metal wiring and the resistance element of the voltage divider resistor, causing cracking to pass through the layers of the built-in voltage divider resistor, and thus, between the anode electrode and the adjacent intermediate electrode. And between the intermediate electrode and another electrode facing the cathode side of the intermediate electrode. There is a problem that a sufficient high voltage is not generated for spot knocking, and as a result, a sufficient spot knocking effect cannot be obtained and a satisfactory withstand voltage characteristic in the cathode ray tube cannot be guaranteed.

It is an object of the present invention to provide a cathode ray tube with improved breakdown voltage characteristics by incorporating a built-in voltage divider resistor and preventing the occurrence of cracking through the layers of the built-in voltage divider resistor during the spot knocking process, thereby increasing the spot knocking effect.

In order to achieve the above object, according to an embodiment of the present invention, a vacuum envelope including a panel portion having a fluorescent screen formed on the inner surface, a neck portion and a funnel portion connecting the panel portion and the neck portion; At least one cathode, a first grid electrode, a second grid electrode, a plurality of focusing electrodes, and an anode arranged in the named order, the at least one electron beam emitted from the at least one cathode An electron gun embedded in the neck portion for focusing on a screen, wherein the at least one cathode, the first grid electrode, the second grid electrode, the plurality of focusing electrodes and the anode are formed by at least two glass beads Fixed at an interval in the axial direction; A voltage divider resistor attached to one of the at least two glass beads to divide the voltage applied to the anode to generate an intermediate voltage to be applied to a first one of the plurality of focusing electrodes adjacent to the anode; And a metal conductor attached to a second electrode of the plurality of focusing electrodes so as to surround the voltage divider resistor and one of the at least two glass beads, wherein the second electrode of the plurality of focusing electrodes includes: One of the plurality of focusing electrodes disposed above the first electrode, wherein the voltage divider may include a first overcode insulating film, a resistor, an insulating substrate, and a second overcode insulating film, wherein the one of the at least two glass beads The first overcode insulating film facing each other is stacked and included in the named order, and the portion of the second overcode insulating film including a region facing the metal conductor is the remaining portion of the second overcode insulating film. It provides cathode tubes that are made thicker locally.

1 is a partially cut away front view of a cathode ray tube of a first embodiment according to the present invention;

FIG. 2 is a side view partially cut away of the cathode ray tube along line II-II of FIG. 1; FIG.

3 is a top view of a voltage divider resistor used in the cathode ray tube of the present invention.

4 is a side cross-sectional view of the voltage divider resistor of FIG. 3.

FIG. 5 is a partially cut back view of the voltage divider resistor of FIG. 3. FIG.

6 is a schematic illustration of the electrical configuration of the color cathode ray tube of the invention of FIG. 1 in operation;

FIG. 7 is a schematic diagram of an electrical configuration for spot-knocking the cathode ray tube of the present invention of FIG.

8 is a cross-sectional view of an exemplary conventional colored cathode ray tube.

9 is a schematic longitudinal cross-sectional view of an electron gun of a conventional cathode ray tube.

10 is a cross-sectional view taken along the line X-X of the electron gun of FIG. 9.

<Explanation of symbols for the main parts of the drawings>

1: Panel part

2: neck

3: funnel

4: fluorescent screen,

5: shadow mask

9: electron gun

10: deflection yoke

15: stem pin

16: electron beam

23: glass beads

24: Bulb spacer

K: cathode

G1: first grid electrode

G2: second grid electrode

G3: third grid electrode

G4: fourth grid electrode

G5: fifth grid electrode

G6: 6th grid electrode

GM: middle electrode

An embodiment according to the present invention will now be described in detail with reference to the accompanying drawings. In the drawings, parts having the same or similar functions are denoted by the same reference numerals.

1 and 2 are basic drawings of an electron gun for explaining a first embodiment of a color cathode ray tube according to the present invention, in which FIG. 1 is a partially cut away front view of the cathode ray tube, and FIG. 2 is a line II of FIG. Partially cut side view of the cathode ray tube along -II.

The in-line three-beam electron gun 9 includes a cathode K, a first grid electrode G1, a second grid electrode G2, a third grid electrode G3, a fourth grid electrode G4, and a fifth The grid electrode G5, the intermediate electrode GM, and the sixth grid electrode G6 are included. The first to sixth grid electrodes G1-G6 and the middle electrode GM insert the peripheral flanges of the grid electrodes and the intermediate electrodes on the pair of glass beads (polymorphic glass beads) 23, or Or it is fixed in a predetermined order by inserting a support tab attached to the grid electrodes and the intermediate electrode in the pair of glass marbles (23). The bulb spacer 24 is adjusted so that the axis of the electron gun 9 in the neck portion 2 may be centered. The electron gun 9 is supported on the stem pin 15 via leads (not shown) and the cathode K is heated by a heater H embedded in the cathode K.

The built-in voltage divider resistor 25 has the side of the ceramic substrate of the built-in voltage divider resistor 25 on which the resistor element 32 is formed faces the glass beads 23, that is, the coated glass film 33 is coated with the glass beads 23. Is mounted on the side of the glass beads 23 facing the neck 2. The high voltage terminal 26 of the built-in voltage divider resistor 25 is connected to the shield cup 12 attached to the sixth grid electrode G6, and the intermediate voltage terminal 27 is connected to the intermediate electrode GM, and the low voltage terminal 28 is grounded through one of the stem pins 15.

The discharge suppression shield wiring 29 is arranged to surround one of the built-in voltage divider 25 and the glass beads 23 equipped with the resistor 25 and is connected to the fifth grid electrode G5. The discharge suppressing shield wiring 29 may be made of nickel, stainless steel, or the like. In the discharge suppression conductive film 29A shown in FIG. 2, after the spot-knocking step, the shield wiring 29 is heated by using a radio frequency introduction heater (not shown) outside the neck part 2 to heat the neck part. It forms in the inner wall of the neck part 2 by evaporating a part of metal contained in the shield wiring 29 on the inner wall of (2).

The built-in voltage divider resistor 25 of the present invention will be described in detail. 3, 4 and 5 are top, side and partially cut back views of the voltage divider 25, respectively. The built-in voltage divider 25 has a low voltage and a high voltage terminal 26 disposed at both ends of the resistance element 32 and the resistance element 32 formed on the alumina ceramic substrate 31 based on ruthenium oxide. An intermediate voltage terminal 27 disposed at an intermediate point between the terminal 28 and the both ends. The resistance element 32 is covered with an overcode glass film 34 (for example, made of lead-containing glass), and the upper surface of the ceramic substrate 31 is formed of an overcode glass film (for example, of lead-containing glass). 34).

The ceramic substrate 31 is formed by molding an Al ₂ O ₃ paste into a predetermined shape having a predetermined size and sintering it. Since the substrate 31 itself manufactured in this manner is strictly a porous state, partial electric field concentration may occur in the ceramic substrate 31. Thus, the overcode glass film 34 is formed on the side of the ceramic substrate 31 on the opposite side of the resistive element 32 so as to suppress the spark from the shield wiring 29 where charge is concentrated in the resistive element 32 and thereby complete. The breakdown of the voltage divider resistor 25 is prevented during normal operation of the cathode ray tube.

In general, the total length M and width W of the built-in voltage divider 25 and the thickness ST of the ceramic substrate 31 are about 50 mm to 100 mm, 5 mm to 10 mm, and 0.6 mm to 1, respectively. , 0 mm range.

3 and 4, portions corresponding to the discharge suppression shield wirings 29 are shown in dashed lines. In the present invention, as shown in Figs. 3 and 4, the thickness UT1 of a portion 34A of the overcode glass film 34 having a width L and a portion of which is directed toward the discharge suppression shield wiring 29. Becomes thicker than the thickness UT2 of the remaining portion of the overcode glass film 34, so that occurrence of cracking through the layers in the portion of the overcode glass film 34 facing the discharge suppressing shield wiring 29 can be prevented. have.

An embodiment of the built-in voltage dividing resistor 25 according to the present invention will be described when the voltage difference between the lowering element 32 and the discharge suppression shield wiring 29 in the spot-knock process is about 30 kV.

The dielectric strengths of the ceramic substrate 31 and the overcode glass film 34 are about 15 kPa / mm and about 85 kPa / mm, respectively, and the thickness ST1 of the ceramic substrate 31 is in the range of about 0.6 mm to 1.0 mm.

When the thickness ST of the ceramic substrate 31 is 0.6 mm and the thickness UT1 of the thick portion 34A of the overcode glass film 34 is at least 0.25 mm, and the thickness ST is 1.0 mm, the thickness UT1 ) Is preferably at least 0.19 mm. Since the voltage divider resistor 25 is mounted on the glass beads 23 of the electron gun 9, the maximum value of the thickness UT1 is about 0.45 mm. The length L of the thick portion 34A measured in the longitudinal axis direction of the cathode ray tube is preferably 3 to 8 times the length of the discharge suppression shield wiring 29 measured in the longitudinal axis direction of the cathode ray tube.

The thickness UT2 of the overcode glass film 34 except for the thick portion 34A is about 0.05 mm.

An exemplary method of making thick portion 34A will now be described with reference to FIGS. 3 and 4. First, a first glass powder layer is applied on one surface of the ceramic substrate 31 with a uniform thickness, and then a second glass powder layer having a pattern corresponding to the thick portion 34A on the first glass powder layer is glass. The paste containing the powder is printed by silk screening. Then, the dry powder layer is fired to complete the overcode glass film 34 including the thick portion 34A. The silk screen of the pattern corresponding to the thick portion 34A is repeatedly executed so that the thick portion 34A has a predetermined value thickness UT1 in the completed voltage divider resistor 25.

FIG. 6 is a schematic diagram showing the electrical configuration of the color cathode ray tube of the present invention in FIG. 1 in operation.

Electrons emitted from the cathode K heated by the heater H are formed in the beam by the first grounded electrode G1 (grounded) and the second grid electrode G2 (eg 650V) and Then, the third grid electrode G3, the fourth grid electrode G4, the fifth grid electrode G5, the middle electrode GM, and the sixth grid electrode G6 (anode) (for example, 7V). Is focused and collides with the fluorescent screen 4.

In the electron gun 9 of this type, the anode voltage Eb (for example, 30 mA), which is the highest voltage, is applied to the sixth grid electrode G6, and the voltage divider 25 is used for the intermediate electrode GM. A voltage divided by the anode voltage Eb (for example, 16.5 kV, which corresponds to 55% of the anode voltage) is applied, and the fifth grid electrode G5 and the third grid electrode G3 are connected to each other in the cathode ray tube. And the same voltage (for example, 7 kW) is applied, and the fourth grid electrode G4 and the second grid electrode G2 are also connected to each other in the cathode ray tube so that a direct current voltage (for example, 650 V) is applied. The first grid electrode G1 is grounded. Video signals are applied to the cathodes K, respectively.

In FIG. 6, the discharge suppression shield wiring 29 attached to the fifth grid electrode G5 is indicated by a dotted line. The discharge suppressing conductive film 29A heats the shield wiring 29 using a radio frequency introduction heater outside the neck portion 2 after the spot-knocking step, thereby shielding the wiring 29 from the inner wall of the neck portion 2. It is formed by evaporating a part of the metal contained in).

The following describes the spot-knock process. FIG. 7 is a schematic diagram illustrating an electrical configuration for spot-knocking the color cathode ray tube of the present invention in FIG. 1 in a manufacturing process. Since the discharge suppressing conductive film 29A is scattered in the spot-knocking step, the conductive film 29A is not yet formed in the inner wall of the neck portion 2 in the spot-knocking step.

First, for comparison, consider a case in which a built-in voltage divider resistor 25 is installed in a cathode ray tube without the thick portion 34A of the overcode glass film 34 according to the present invention. After the cathode ray tube is evacuated and sealed, all electrodes except for the sixth grid electrode G6 and the middle electrode GM are grounded, a high voltage of 60 mA is applied to the sixth grid electrode G6, and the voltage divider resistor 25 is applied. A voltage of 33 kV divided from a high voltage of 60 kV is applied to the intermediate electrode GM through.

The purpose of the spot-knocking step is to apply 27 μs and 33 μs between the sixth grid electrode G6 and the intermediate electrode GM and between the intermediate electrode GM and the fifth grid electrode G5, respectively. Between the sixth grid electrode G6 and the middle electrode GM, between the middle electrode GM and the fifth grid electrode G5, between the sixth grid electrode G6 and the inner wall of the neck part 2, and the middle electrode ( By forcibly generating a spark between GM) and the inner wall of the neck part 2, projections in the electrodes of the electron gun are removed, and unwanted particles in the cathode ray tube are also removed.

During the spot-knocking step, the voltage divider 25 is applied with a high voltage of 60 mA and the fifth grid electrode G5 to which the shield wiring 29 is electrically connected is grounded, so that the ceramic substrate 31 and the overcode glass film are grounded. Sparks are generated between the discharge suppression shield wiring 29 and the voltage dividing resistor 25 through the 34, and as a result, cracking through the ceramic substrate 31 and the overcode glass film 34 occurs. Thus, between the sixth grid electrode G6 and the middle electrode GM, between the middle electrode GM and the fifth grid electrode G5, between the sixth grid electrode G6 and the inner wall of the neck part 2, and Between the intermediate electrode GM and the inner wall of the neck part 2, a voltage difference large enough to generate a spark cannot be obtained, and a sufficient spot-knocking effect cannot be obtained.

Consider now the case where the cathode ray tube as shown in FIG. 7 incorporates a built-in voltage divider resistor 25 having a thick portion 34A in the overcode glass film 34 according to the present invention. After the cathode ray tube of the present invention is exhausted and sealed, all electrodes except for the sixth grid electrode G6 and the middle electrode GM are grounded, a high voltage of 60 kV is applied to the sixth grid electrode G6, and the partial pressure is applied. A voltage of 33 kV divided from a high voltage of 60 kV is applied through the resistor 25 to the intermediate electrode GM.

In the cathode ray tube of the present invention, a thick portion 34A of the overcode glass film 34 is provided between the high voltage resistance element 32 and the grounded discharge suppression shield wiring 29 to discharge the resistance element 32 and the discharge. The breakdown voltage between the suppressing shield wirings 29 is increased and sparks are generated between the high voltage resistance element 32 and the grounded shield wiring 29. As a result, 27 kV and 33 kV are applied between the sixth grid electrode G6 and the intermediate electrode GM and between the intermediate electrode GM and the fifth grid electrode G5, respectively, and the sixth grid electrode G6 And between the middle electrode GM, between the middle electrode GM and the fifth grid electrode G5, between the sixth grid electrode G6 and the inner wall of the neck portion 2, and between the middle electrode GM and the neck portion 2 A strong enough spark can be generated between the inner walls of the C) to sufficiently remove unwanted particles in the projections or cathode ray tube from the electrode of the electron gun.

After the spot-knocking step, as shown in FIG. 2, during the normal operation of the completed cathode ray tube, the discharge inhibiting conductive film 29A is shielded by using a radio frequency introduction heater outside the neck portion 2. ) Is formed on the inner wall of the neck part 2 by evaporating a part of the metal contained in the shield wiring 29 to the inner wall of the neck part 2.

In the above-described embodiment, the present invention has been applied to a three beam in-line electron gun, but is of course also applicable to one beam electron gun.

The present invention provides the following advantages. The built-in voltage divider according to the present invention includes a first overcode insulating film, a resistor, an insulating substrate, and a second overcode insulating film, which are sequentially stacked from a first overcode insulating film facing one of the glass beads to fix the electrodes of the electron gun. And a voltage element of a voltage divider resistor to which a high voltage is applied during the spot-knocking step so as to locally thicken a portion including a region facing the discharge suppression metal conductor of the second overcode insulating film to increase the spot-knocking effect. Spark generation between the grounded metal conductors can be prevented, thereby improving the breakdown voltage characteristics during normal operation of the finished cathode ray tube.

Claims (6)

In the cathode ray tube, A vacuum envelope including a panel portion having a fluorescent screen formed on an inner surface thereof, a neck portion, and a funnel portion connecting the panel portion and the neck portion; At least one cathode, a first grid electrode, a second grid electrode, a plurality of focusing electrodes, and an anode arranged in the named order, the at least one electron beam emitted from the at least one cathode An electron gun embedded in the neck portion for focusing on a screen, wherein the at least one cathode, the first grid electrode, the second grid electrode, the plurality of focusing electrodes and the anode are formed by at least two glass beads Fixed at an interval in the axial direction; A voltage divider resistor attached to one of the at least two glass beads to generate an intermediate voltage to apply to a first one of the plurality of focusing electrodes adjacent to the anode by dividing a voltage applied to the anode; And A metal conductor attached to a second electrode of the plurality of focusing electrodes to surround the voltage divider resistor and one of the at least two glass beads Including; The second electrode of the plurality of focusing electrodes is disposed above the first electrode of the plurality of focusing electrodes, The voltage divider is formed by stacking a first overcode insulating film, a resistance element, an insulating substrate, and a second overcode insulating film in the named order from the first overcode insulating film facing the one of the at least two glass beads. Including, And a portion of the second overcode insulating film including a region facing the metal conductor is locally made thicker than the remaining portion of the second overcode insulating film. The cathode ray tube according to claim 1, wherein the locally thick portion of the second overcode insulating film extends at a distance of 3 to 8 times the width of the metal conductor when measured in the axial direction of the cathode ray tube. . 2. The insulating substrate of claim 1, wherein the insulating substrate has a thickness of 0.6 mm to 1.0 mm, the second overcode insulating film is made of glass, and the thickness of the locally thick portion of the second overcode insulating film is 0.19 mm to 0.45. A cathode ray tube, which is in the range of mm. 3. The insulating substrate of claim 2, wherein the insulating substrate is ceramic having a thickness of 0.6 mm to 1.0 mm, the second overcode insulating film is made of glass, and the thickness of the locally thick portion of the second overcode insulating film is 0.19 mm. Cathode ray tube, characterized in that in the range of 0.45 mm. The cathode ray tube according to claim 3, wherein the second overcode insulating film is made of lead-containing glass. The cathode ray tube according to claim 4, wherein the second overcode insulating film is made of lead-containing glass.