JP2003016941A - Inspection method for cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection method for a cathode-ray tube allowing an accurate inspection without damaging a cathode electrode heretofore damaged in a so-called impregnated cathode with barium oxide impregnated in a tungsten base to constitute a cathode electrode structure, which has a defect of being weak to gas poisoning in property compared with an oxide cathode, thereby causing large damage by the collision of positive ion generated by the collision between residual gas and electrons, which impedes the accurate state inspection of the cathode electrode and damages the cathode electrode even if carrying out the inspection. SOLUTION: In inspecting the state of the cathode electrode K of the cathode- ray tube having an electron gun 18 provided with a grid electrode G6 supplied with anode voltage, and a grid electrode G5 supplied with focus voltage, the inspection is performed by setting the focus voltage higher than the anode voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a cathode ray tube, and particularly to an inspection for a cathode ray tube which is suitable for inspecting a cathode ray tube using a cathode electrode formed by impregnating a tungsten base with barium oxide. Regarding the method.

[0002]

2. Description of the Related Art At present, a color cathode ray tube which is generally used in a color television receiver, a color terminal display, etc., has a substantially rectangular face panel 41 as shown in FIG. Having an envelope made of funnel-shaped funnels 42 that are joined together and having a stripe-shaped or dot-shaped three-color phosphor layer that emits blue, green, and red on the inner surface of the face panel 41 A screen 43 is formed, and a shadow mask 44 having a large number of apertures formed therein is mounted via a mask frame 45 so as to face the phosphor screen 43. The mask frame 45 includes a skirt portion 47 of the face panel 41 via an elastic support 46.
An inner shield 49 is attached to the stud pin 48 provided on the inner surface, and an inner shield 49 is attached to the skirt portion 47. A lug piece 51 for attaching to an explosion-proof band 50 and a housing (not shown) is further provided on the outer periphery of the skirt portion 47. Is provided.

On the other hand, in the neck 52 of the funnel 42, an in-line type electron gun 54, which emits the three electron beams 53B, 53G and 53R, is arranged in a line in the horizontal direction, and is emitted from the electron gun 54. The three electron beams 53B, 53G, and 53R are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 55 mounted outside the funnel 42, and the phosphor screen 43 is horizontally and vertically scanned through the shadow mask 44. By doing so, a color image is reproduced and displayed on the phosphor screen 43. A predetermined voltage is supplied to each of the electrodes of the electron gun 54 through a plurality of stem pins 57 implanted in a stem 56 arranged at the end of the neck 52.

In such a color cathode ray tube, especially the center beam 53 in which the electron gun 54 passes on the same horizontal plane.
G, and a pair of side beams 53B and 53R on both sides thereof
Is configured as an in-line type electron gun 54 that emits light, and the positions of the side beam passage holes (not shown) of the electrodes on the low-voltage side and the high-voltage side of the main lens portion of the electron gun 54 are eccentric to thereby make the phosphor screen 43 At the center, the three electron beams 53B, 53G, and 53R are concentrated, and the deflection yoke 5
The horizontal deflection magnetic field generated by No. 5 is a pincushion type, and the vertical deflection magnetic field is a barrel type, so that the three electron beams 53B, 53G, 53R arranged in a row are self-focused over the entire screen. The pipe is widely used.

The electron gun 54 of this color cathode ray tube is constructed, for example, as shown in FIG. That is, in order to correspond to the three electron beams 53B, 53G, and 53R, three cathode electrodes K (only one cathode electrode is shown in the figure) having heaters (not shown) installed therein are provided in a row in the horizontal direction. In the tube axis direction of the cathode electrode K, the first
The grid electrode G1 to the sixth grid electrode G6 and the convergence cup CV are coaxially arranged. These cathode electrode K to sixth grid electrode G6 are planted and fixedly supported on an insulating support (not shown) made of bead glass.

In such an electron gun 54, when it is normally operated, for example, in the cathode electrode K,
A voltage of about 100 to 150 V is applied, and the first grid electrode G1 is grounded. Further, the second grid electrode G
The second and fourth grid electrodes G4 have about 60 from the power source E1.
A voltage of about 0 to 800 V is applied to the third grid electrode G3 and the fifth grid electrode G5 from the power source E2 to about 6
A focus voltage of about 9 kV is applied. If necessary, a dynamic focus voltage synchronized with the deflection magnetic field with a focus voltage of about 6 to 9 kV as a reference is supplied from the AC power source E3 via the capacitor C1. The sixth grid electrode G6 is supplied with about 25 to 30 power from the power supply E4 to the convergence cup CV.
An anode voltage of about kV is applied at the same time.

In the thus configured electron gun 54, electron beam generators for generating electron beams 53B, 53G and 53R are formed between the first grid electrode G1 to the third grid electrode G3, respectively. Further, a focusing lens unit is formed between the third grid electrode G3 to the sixth grid electrode G6.

By the way, in the manufacturing process of such a color cathode ray tube, various cathode ray tube characteristics of the color cathode ray tube are measured and inspected. During the inspection step, the adhered state of foreign matter on the cathode electrode K is inspected. There is an inspection process. In this inspection method, for example, as shown in FIG. 6, an operating voltage of 6.3 V is applied to the heater of the color cathode ray tube, the first grid electrode G1 is set to the ground potential, and the second grid electrode G2 and the fourth grid electrode G4 are used. Is applied to the third grid electrode G3 and the fifth grid electrode G5 with a voltage of 4 kV as a focus voltage.
An inspection is carried out by applying an anode voltage of 5 kV to each of them.

Each grid electrode G of the electron gun 54 as described above
1 to G6 and the heaters are respectively applied with predetermined set voltages, the cathode voltages of the three cathode electrodes K are sequentially decreased to further reduce the cutoff voltage of the cathode ray tube from about 55 V. In the case of a cathode ray tube of about inch, as shown in FIG. 7, circular images each having a diameter 1 of about 6 cm are individually projected on the phosphor screen 43 corresponding to the three cathode electrodes K respectively. .

By observing this reproduced image, when the surface of the cathode electrode K is clean and no foreign matter is attached, the image as shown in FIG. 7 is reproduced. However, if a foreign substance adheres to the surface of the cathode electrode K, electrons are not emitted from the surface of the cathode electrode K, and the image reproduced on the phosphor screen 43 is as shown in FIG. , A shaded part (black part) occurs due to the adhered state of foreign matter. Therefore, by observing these reproduced and displayed images, the presence or absence of foreign matter on the surface of the cathode electrode K, that is, the quality of the cathode electrode K can be easily identified.

[0011]

By the way, a cathode electrode K which constitutes an electron gun of such a color cathode ray tube.
As a cathode electrode K, which has been referred to as an oxide cathode, in which a cathode base metal surface containing nickel as a main component is coated with an oxide mainly containing barium oxide.
The structure was mainly used. However, recently, a cathode base K structure has been constructed by impregnating a tungsten base that can be operated at a high current density with barium oxide.
A cathode electrode K structure called a so-called in-cathode has become mainstream.

In the case of this oxide cathode, when inspecting the state of the cathode electrode K, the inspection is carried out under the conditions of the applied voltage as shown in FIG. When a color cathode ray tube equipped with an imprint cathode is inspected, the electrons emitted from the cathode electrode K are accelerated by the second grid electrode G2 and the focus voltage and reach the phosphor screen 43. At this time, The electrons will repeatedly collide with the residual gas in the envelope. The residual gas in the tube, which has been hit by the electrons, is ionized to be positively ionized.

If positive ions generated between the cathode electrode K and the third grid electrode G3 are i3 and positive ions generated between the sixth grid G6 and the anode A2 are i4, positive ions i3, i4 Will be accelerated toward the lower potential, the positive ions i3 will reach the cathode electrode K as they are, and the positive ions i4 will reach the third grid electrode G3 and the fourth grid electrode G as shown by the arrow in the figure.
There is a potential barrier of less than 4 kV between 4 and the positive ion i4, which has a higher potential, has enough energy to overcome the potential barrier. It will reach the cathode electrode K together with i3. The fact that the positive ions i3, i4 reach the cathode electrode K means that the positive ions i
3, i4 impinges on the cathode electrode K, and positive ions i3 generated before the third grid electrode G3 and positive ions i4 generated between the fifth grid electrode G5 and the anode electrode A2 are applied to the cathode electrode K. Since it arrives, the cathode electrode K will be damaged.

The above-mentioned impregnated cathode is characteristically weak against gas poisoning as compared with the oxide cathode, and in particular, the cathode electrode K is greatly damaged by collision of positive ions,
Not only is it difficult to perform an accurate inspection, but there is also a problem that the cathode electrode K is damaged by the inspection.

The present invention has been made in view of these problems, and a cathode ray tube using an impregnated cathode electrode assembly in which a tungsten base is impregnated with barium oxide does not damage the cathode electrode. An object of the present invention is to provide an inspection method for a cathode ray tube capable of inspecting the state of electrodes.

[0016]

SUMMARY OF THE INVENTION The present invention provides a substantially rectangular face panel, a funnel-shaped funnel connected to the face panel, a phosphor screen formed on the inner surface of the face panel, and a funnel neck. An electron gun having a plurality of grid electrodes including a cathode electrode arranged to form an electron beam and focus it on a phosphor screen, a grid electrode supplied with at least an anode voltage, and a grid electrode supplied with a focus voltage. With respect to the relationship between the voltage and the focus voltage, the focus voltage is set higher, and the voltage is supplied to the corresponding grid electrode to inspect the cathode electrode state.

By adopting such an inspection method, by suppressing the positive ions that collide with the cathode electrode to a minimum, it is possible to reduce damage to the cathode electrode and perform an accurate inspection. Therefore, it is possible to obtain a method for inspecting a cathode ray tube capable of avoiding damage to the cathode electrode due to inspection.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing a color cathode ray tube according to the present invention, which is a substantially rectangular face panel 11 and the face panel 1.
1 has an envelope composed of a funnel-shaped funnel 12 integrally joined to 1, and on the inner surface of the face panel 11,
A phosphor screen 13 including a stripe-shaped or dot-shaped three-color phosphor layer that emits blue, green, and red is formed, and a large number of apertures 14 are formed inside the phosphor screen 13 so as to face the phosphor screen 13. Shadow mask 15
Is installed.

On the other hand, in the neck 16 of the funnel 12, an in-line type electron gun 18 which emits the three electron beams 17B, 17G and 17R and which is arranged in a line in the horizontal direction is arranged. The three electron beams 17B, 17G, and 17R are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 19 mounted on the outer side of the funnel 12, and the phosphor screen 13 is horizontally and vertically scanned through the shadow mask 15. By doing so, a color image is reproduced and displayed on the phosphor screen 13.

In such a color cathode ray tube, in particular, the electron beam 18 is passed through the center beam 17 passing on the same horizontal plane.
G, and a pair of side beams 17B and 17R on both sides thereof
Is configured as an in-line type electron gun 18 that emits light, and the positions of the side beam passage holes of the electrodes on the low-voltage side and the high-voltage side of the main lens portion of the electron gun 18 are eccentric, so that three lines are formed in the center of the phosphor screen 13. Electron beam 17B,
By concentrating 17G and 17R, the horizontal deflection magnetic field generated by the deflection yoke 19 is formed into a pincushion type, and the vertical deflection magnetic field is formed into a barrel type, so that the three electron beams 17B, 17G, and 17R arranged in a row can be distributed over the entire screen. It is configured as a self-focusing, self-convergence color cathode ray tube. A stem 21 having a plurality of stem pins 20 electrically connected to the respective electrodes of the electron gun 18 is sealed at the end of the neck 16.

The electron gun 18 used in this color cathode ray tube has a three-electron beam 17B, as shown in FIG.
Corresponding to 17G and 17R, three cathode electrodes K each containing a heater H (only one cathode is shown in FIG. 2) are provided in a row in the horizontal direction, and the tube axes of the cathode electrodes K are provided. Direction, the first grid electrodes G1 to
The sixth grid electrode G6 and the convergence cup CV welded and fixed to the sixth grid electrode G6 are coaxially arranged. These cathode electrode K to sixth grid electrode G
6 is planted and fixedly supported on an insulating support (not shown) made of bead glass, and the convergence cup CV is electrically connected to the inner conductive film 22 formed by the inner surface of the funnel 12 and the inner surface of the neck 16. A plurality of contacts 23 for electrical continuity are attached.

When the electron gun 18 is operated normally, the cathode electrode K is
A voltage of about 100 to 150 V is applied, and the first grid electrode G1 is grounded. Further, the second grid electrode G
The second and fourth grid electrodes G4 have about 60 from the power source E1.
A voltage of about 0 to 800 V is applied to the third grid electrode G3 and the fifth grid electrode G5 from the power source E2 to about 6
A focus voltage of about 9 kV is applied. If necessary, a dynamic focus voltage synchronized with the deflection magnetic field with a focus voltage of about 6 to 9 kV as a reference is supplied from the AC power source E3 via the capacitor C1. The sixth grid electrode G6 is supplied with about 25 to 30 power from the power supply E4 to the convergence cup CV.
An anode voltage of about kV is applied at the same time.

In the electron gun 18 thus constructed, electron beam generators for generating electron beams 17B, 17G and 17R are formed between the first grid electrode G1 to the third grid electrode G3, respectively. Further, a focusing lens unit is formed between the third grid electrode G3 to the sixth grid electrode G6.

When inspecting the state of the cathode electrode K of the color cathode ray tube constructed as described above, for example, as shown in FIG. 3, an operating voltage of 6.3 V is applied to the heater of the color cathode ray tube, and 1 grid electrode G1 is set to ground potential, 300V is applied to the second grid electrode G2 and the fourth grid electrode G4, and a voltage of 5.2 kV is applied to the third grid electrode G3 and the fifth grid electrode G5 as a focus voltage, Further, an inspection is performed by applying an anode voltage of 4.7 kV to the sixth grid electrode G6.

Each grid electrode G of the electron gun 18 as described above
1 to G6 and the heater H are respectively applied with a predetermined set voltage, the cathode voltages of the three cathode electrodes K are sequentially decreased to set the cut-off voltage of the cathode ray tube to, for example, 5
If the voltage is further lowered below about 5 V, in the case of a cathode ray tube of about 17 inches, as shown in FIG.
Circular images of cm are individually projected on the phosphor screen 13 corresponding to the three cathode electrodes K, respectively.

With this structure, the electrons emitted from the cathode electrode K are accelerated by the grid electrodes G1 to G6 so as to strike the phosphor screen 13.
Although it is focused, the residual gas is ionized and positively ionized by repeatedly colliding with the residual gas in the envelope at this time, and as shown in FIG. 3, from the cathode electrode K to the third grid electrode G3. When the positive ions generated during the period up to i are i1 and the positive ions generated between the sixth grid G6 and the anode A2 are i2, the positive ions i1 and i2 are accelerated toward the lower potential, As shown by the arrow in the figure, the positive ions i1 reach the cathode electrode K as they are, and the positive ions i2 are generated between the fifth grid electrode G5 and the sixth grid electrode G6 by this grid voltage difference (5.2 kV-
There is a potential barrier of 500 [eV], which is 4.7 kV). Since the positive ion i2 has a lower potential, it does not have enough energy to overcome this potential barrier,
Therefore, the potential barrier cannot be overcome and the cathode electrode K is not reached. Similarly, positive ions generated between the third grid electrode G3 and the fifth grid electrode G5 cannot similarly overcome the potential barrier existing between the third grid electrode G3 and the fourth grid electrode G4.

Therefore, the positive ions i1, i generated in the tube
Only positive ions i1 reach the cathode electrode K, and only the positive ions i1 collide with the cathode electrode K. Moreover, the positive ion i1 is targeted for the space area (volume) before the third grid electrode G3 in the neck 16 as compared with the positive ion i2, whereas the positive ion i2 is
Since the inside of the funnel 12 is also targeted, and the spatial area (volume) thereof becomes overwhelmingly large, the positive ion i1 becomes i2
The probability that positive ions are generated is extremely low as compared with the above, and therefore, the influence of the positive ions i1 on the cathode electrode K is lessened in each step. Therefore, the cathode electrode K can be inspected without damaging the cathode electrode K. It becomes possible to carry out.

In the present invention, the case of application to the cathode electrode K structure of the impression type has been described.
There is no problem even if it is applied to the cathode electrode K in the form of an oxide cathode, and various applications and modifications are possible without being limited to the configurations described in the above embodiments. It goes without saying that it is possible to take other measures, and it is possible to adopt depending on the form.

[0029]

As described above, according to the present invention, when the cathode electrode is inspected, it is possible to reduce the damage due to the collision of positive ions on the cathode electrode due to this inspection, so that the inspection can be performed accurately. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view showing a color cathode ray tube applied to an inspection method for a cathode ray tube according to the present invention.

FIG. 2 is a configuration diagram similarly showing an example of the electron gun.

FIG. 3 is an explanatory diagram that similarly illustrates the bias state of the electron gun.

FIG. 4 is a sectional view showing a conventional general color cathode ray tube.

FIG. 5 is a configuration diagram similarly showing an example of the electron gun.

FIG. 6 is an explanatory view for explaining the bias state of the electron gun.

FIG. 7 is an explanatory diagram showing an image similarly reproduced in the inspection process.

FIG. 8 is an explanatory diagram showing an image reproduced in the same inspection process.

[Explanation of symbols]

11: Face panel 12: Funnel 13: Phosphor screen 16: Neck 18: Electron gun K: cathode electrode G5: Fifth grid electrode G6: Sixth grid electrode E2: Focus voltage power supply E4: Power supply for anode voltage

Claims (2)

[Claims] 1. A substantially rectangular face panel, a funnel-shaped funnel connected to the face panel, a phosphor screen formed on an inner surface of the face panel, and an electron beam formed in a neck of the funnel. And an electron gun having a plurality of grid electrodes including a cathode electrode for focusing on the phosphor screen, a grid electrode to which at least an anode voltage is supplied, and a grid electrode to which a focus voltage is supplied, the anode voltage and the focus. An inspection method for a cathode ray tube, characterized in that a relationship with a voltage is set higher on a focus voltage side. 2. The method for inspecting a cathode ray tube according to claim 1, wherein the cathode ray tube comprises a cathode electrode assembly in which a tungsten base is impregnated with barium oxide.