JP2633592B2 - Withstand voltage test method for color CRT - Google Patents

Description

The present invention relates to a method for testing the withstand voltage of a color cathode ray tube.

(Prior Art) In recent years, an electron gun provided with a first intermediate electrode and a second intermediate electrode between a fifth grid electrode and a sixth grid electrode for the purpose of improving resolution (intermediate electrode insertion type electron gun) Has been developed and used in color cathode ray tubes.

That is, as shown in FIGS. 3 and 4, in this intermediate electrode-insertion type electron gun, the first grid electrode 2, the second grid electrode 3, the third grid electrode 4, and the fourth grid electrode are arranged in this order from the cathode 1 side. 5, a fifth grid electrode 6, and a sixth grid electrode 7 are arranged, and the first grid electrode 6 and the sixth grid electrode 7
An intermediate electrode 8 and a second intermediate electrode 9 are provided.

The sixth grid electrode 7, the first intermediate electrode 8, and the second intermediate electrode 9 are connected to a built-in split resistor 10. The resistance of the built-in split resistor 10 is approximately between point a and point d shown in FIG.
2.4GΩ, about 1.56GΩ between points b and d (65 between points a and d)
%), About 0.96 GΩ between points c and d (40 between points a and d)
%), 65% of the anode voltage to the second intermediate electrode 9,
The first intermediate electrode 8 is configured to supply a voltage of 40% of the anode voltage in a divided manner.

In FIG. 3, reference numerals 11, 12, and 13 indicate a heater, multi-formed glass, and a valve spacer, respectively.

The intermediate electrode insertion type electron gun having the above configuration has the following features. First, by providing the first intermediate electrode 8 and the second intermediate electrode 9 in the electron lens system, the beam spot diameter becomes smaller and the resolution is improved as compared with the conventional electron gun.

Further, it is not necessary to externally supply an operating voltage to the intermediate electrodes by dividing and supplying the anode voltage to the first intermediate electrode 8 and the second intermediate electrode 9 with the built-in dividing resistor 10.

Further, the sixth grid electrode 7 and the fifth grid electrode 6 include:
Each has the same operating voltage as the conventional electron gun, that is, 28KV
Of the anode voltage and a focus voltage of about 8 KV are applied to the second intermediate electrode 9 during that time.
8.2KV), 40% of the anode voltage (11.2KV)
V) is supplied by the built-in split resistor 10,
The potential gradient between the sixth grid electrode 7 and the fifth grid electrode 6 is greatly reduced as compared with the conventional electron gun, and the reliability of the withstand voltage characteristics is greatly improved.

However, as mentioned above, the high resistance built-in split resistor
Since the anode voltage is divided and supplied to the intermediate insertion electrode at 10,
For example, when a leakage current flows from the sixth grid electrode 7 to the second intermediate electrode 9, the impedance between the points b and d of the built-in divided resistor 10 is as high as about 1.56 GΩ, and the operating voltage of the second intermediate electrode 9 is high. Will rise significantly. This degrades the focus lens system of the electron gun, not only impairing the focus characteristics, but also changing the trajectory of the three electron beams, causing convergence deviation. Therefore, it is more important to test the withstand voltage characteristics in the initial stage (manufacturing process) than in the conventional electron gun.

In the case of a color cathode ray tube employing a conventional electron gun, a withstand voltage test in a manufacturing process is performed as follows.
That is, as shown in FIG. 5, in the case of a color cathode ray tube 21 employing a conventional electron gun, the cathode 1, the first grid electrode 2, the second grid electrode 3, the third grid electrode 4, the fourth grid electrode 5, All the electrodes of the five grid electrode 6, the sixth grid electrode 7, and the heater 11 are drawn out to the outside, and each electrode has an appropriate test voltage, for example, a condition in which each electrode has a degree of forcing slightly higher than an actually used operating voltage. The leakage currents ILc ₂ and ILc ₃ between the electrodes are measured by the ammeters 22 and 23, and the stray emission that reaches the phosphor screen (not the regular electron beam emitted from the cathode but each electrode component) Unnecessary light emission due to unnecessary electrons emitted from the field by cathode ray tubes 21
The measurement is performed by the optical sensor 24 provided on the front surface of the device.

In addition, as an example of the voltage applied to each electrode, switching between the anode voltage Eb = 32 KV and the focus voltage Ec ₃ = 10 KV and 5 KV,
The second grid voltage Ec ₂ = 700 V, the first grid voltage Ec ₁ = 0 V, the heater voltage Ef = 6.3 V, the cathode voltage Ek = 200 V, and the like.

However, as shown in FIG. 6, in the cathode ray tube 31 employing the electron gun with the intermediate electrode inserted, the first intermediate electrode 8,
Since the second intermediate electrode 9 is not directly drawn out to the outside, there is a problem that the withstand voltage test of the intermediate electrode cannot be performed by the conventional method.

(Problems to be Solved by the Invention) As described above, in the color cathode ray tube employing the intermediate electrode insertion type electron gun, it is more important to test the withstand voltage characteristics in the manufacturing process than the color cathode ray tube employing the conventional electron gun. However, since the intermediate electrode is not directly drawn out, there is a problem that the withstand voltage test of the intermediate electrode cannot be performed by the conventional method.

The present invention has been made in view of such a conventional situation, and enables a withstand voltage test of an intermediate insertion electrode of a cathode ray tube employing an intermediate electrode insertion type electron gun, and a color that can supply a highly reliable color cathode ray tube. An object of the present invention is to provide a withstand voltage test method for a cathode ray tube.

[Constitution of the Invention] (Means for Solving the Problems) That is, the present invention relates to a method for testing the withstand voltage of a color cathode-ray tube provided with an electron gun having a plurality of electrodes connected via resistors. A step of applying at least two types of voltages of a predetermined test voltage and a low voltage lower than the test voltage between the electrodes via the resistor, and a step of measuring a current flowing through the resistor, A withstand voltage defect between the electrodes is detected from a current value measured when the low voltage is applied and a current value measured when the test voltage is applied.

(Operation) In the method for testing the withstand voltage of a color cathode ray tube of the present invention having the above-described configuration, at least two types of voltages, for example, a predetermined test voltage of about 32 KV and a low voltage of about 10 KV lower than this test voltage, Is applied between the electrodes via.
The low voltage is a low voltage in a region where the withstand voltage failure does not occur. Then, current values are measured when a low voltage is applied and when a test voltage is applied, and a withstand voltage failure between the electrodes is detected from these current values.

Therefore, it is possible to perform a withstand voltage test of the intermediate insertion electrode of the color cathode ray tube employing the intermediate electrode insertion type electron gun in which the intermediate electrode is not directly drawn out to the outside.

(Example) Hereinafter, an example of the withstand voltage test method for a color CRT according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a configuration of a test apparatus used in a withstand voltage test method of a color cathode ray tube according to an embodiment of the present invention. The same parts as those in FIGS. 3 to 6 are denoted by the same reference numerals. is there.

A test apparatus used for the withstand voltage test method of the color cathode ray tube of this embodiment has a predetermined test voltage Eb of about 32 KV, for example.
₂ and a low voltage of, for example, about 10 KV lower than the test voltage Eb ₂
The configuration is such that two types of voltages of Eb ₁ can be switched and applied to the built-in split resistor 10 of the color cathode-ray tube 31 provided with the intermediate electrode insertion type electron gun. Further, the outer pins of the internal dividing resistor 10 is a current meter 32 is connected, a current flows to the low voltage side of the internal dividing resistor 10 when applying the low voltage Eb ₁ Ir
₁ and the internal split resistor 10 when the test voltage Eb ₂ is applied.
It is measurably constituting the current Ir ₂ flowing through the low voltage side of the. Note that a voltmeter 33 that measures the actual applied voltages V ₁ and V ₂ when Eb ₁ and Eb _{2 are} applied is provided to improve the determination accuracy.

In the color cathode ray tube withstand voltage test method of this embodiment using the test apparatus having the above configuration, a withstand voltage characteristic test between the sixth grid electrode 7 and the second intermediate electrode 9 is performed as follows.

That is, first low-voltage Eb ₁ low region withstand voltage failure symptoms do not occur is applied to measure the currents Ir ₁ and the actual applied voltages V ₁ through the low voltage side of the time internal division resistor 10.

Then switch the voltage to the test voltage Eb _2, to measure the current Ir ₂ and the actual applied voltage V ₂ flows in the low voltage side of the time internal division resistor 10.

The above Ir ₁ is Ir ₁ = V ₁ / (total resistance value).

Also, Ir ₂ has poor withstand voltage characteristics, for example, when a stray emission reaching the phosphor screen from the second intermediate electrode 9 or a stray emission reaching the sixth grid electrode 7 from the second intermediate electrode 9 occurs. Due to this stray emission, the sum of the current I GM flowing into the built-in split resistor 10 and the current Ir ₀ flowing through the built-in split resistor 10 due to the anode voltage, that is, Ir ₂ = Ir ₀ + I GM.

On the other hand, because if the withstand voltage characteristics are good is the _{I GM = 0, Ir 2 =} Ir 0 = V 2 / ( total resistance value) = the _{Ir 1 × V 2 / V 1} . This equation is to determine Ir ₀ from the current value Ir ₁ measured in a region where the withstand voltage failure symptom does not occur. That is, as shown in the graph of FIG. 2 where the vertical axis represents the current value and the horizontal axis represents the voltage value, Ir ₁ is the M point, and Ir ₀ is the virtual current value of the N point on the straight line passing through the M point and the origin. It is. The difference between the virtual current value and the current value Ir ₂ i.e. P point measured by test voltage Eb ₂ is a withstand voltage failure fraction I GM of the intermediate electrode.

Therefore, the determination of the withstand voltage quality is performed according to a standard value ≦ Ir ₂ − (Ir ₁ × V ₂ / V ₁ ), and the standard value is, for example, about 0.2 to 0.5 μA.

That is, according to the color cathode ray tube withstand voltage test method of this embodiment, the withstand voltage test of the intermediate electrode of the cathode ray tube 31 provided with the intermediate electrode insertion type electron gun, which was not possible conventionally, can be performed. Reliability can be improved.

[Effects of the Invention] As described above, according to the withstand voltage test method of a color cathode ray tube of the present invention, the withstand voltage test of the intermediate electrode of the color cathode ray tube equipped with the intermediate electrode insertion type electron gun, which was conventionally impossible. This makes it possible to easily supply color CRTs with high resolution as designed with high reliability.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a test apparatus for explaining a withstand voltage test method of a color cathode ray tube according to an embodiment of the present invention, and FIG. 2 is a diagram showing a current flowing to a low voltage side of an internal dividing resistor, an applied voltage, and the like. FIG. 3 is a diagram showing the configuration of the intermediate electrode-insertion type electron gun, FIG. 4 is a diagram showing the main configuration of the intermediate electrode-insertion type electron gun shown in FIG. 3, FIG. 5 and FIG. FIG. 6 is a diagram showing a configuration of a test apparatus for explaining a conventional withstand voltage test method of a color CRT. 6 Fifth grid electrode 7 Sixth grid electrode 8 First intermediate electrode 9 Second intermediate electrode 10 Built-in split resistor 31 Color cathode ray tube with electrode-inserted electron gun 32 … Ammeter 33… Voltmeter Eb ₁ …… Low voltage Eb ₂ …… Test voltage Ir ₁ …… Current when Eb _{1 is} applied Ir ₂ …… Current when Eb _{2 is} applied

Claims (1)

(57) [Claims] 1. A method for testing a withstand voltage of a color cathode-ray tube provided with an electron gun having a plurality of electrodes connected via a resistor, comprising: a predetermined test voltage between said electrodes via said resistor; A step of applying at least two types of low voltages lower than a test voltage, and a step of measuring a current flowing through the resistor, wherein a current value measured when the low voltage is applied and a current value measured when the test voltage is applied A withstand voltage test method for a color cathode ray tube, wherein a withstand voltage defect between the electrodes is detected from the measured current value.