JPH09134674A - Emission characteristic inspection method of cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an emission characteristic inspection method by which even a cathode-ray tube unremovable by a conventional inspection method while having a defect in an emission characteristic can be easily inspected. SOLUTION: This method is provided with an electron gun 7 composed of a cathode K, a heater H and plural electrodes G1 to G4, and prescribed voltage is impressed on its cathode, the heater and the electrodes, and an emission characteristic is inspected. In this case, voltage lower than a rating is impressed on the heater, and bias voltage is impressed on the cathode, or its both are impressed, and the emission characteristic is inspected.

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 emission characteristics of a cathode ray tube such as a color picture tube.

[0002]

2. Description of the Related Art Generally, in a cathode ray tube, an electron gun is provided in the neck of an envelope, and an electron beam emitted from the electron gun is deflected by a deflecting device to produce fluorescent light provided on the inner surface of an image display section. The body screen is horizontally and vertically scanned to form an image display structure.

As an example thereof, FIG. 4 shows a color picture tube. This color picture tube has an envelope composed of a panel 1 and a funnel-shaped funnel 2, and a phosphor screen 4 composed of a three-color phosphor layer is provided on the inner surface of the panel 1 so as to face the shadow mask 3. Has been. On the other hand, in the neck 5 of the funnel 2, an electron gun 7 that emits the three electron beams 6 is arranged.

The electron gun 7 has three cathodes K, three heaters H for heating the cathodes K separately, and a plurality of the electron guns 7 arranged in this order from the cathode K toward the phosphor screen 4 (4 in the illustrated example). Individual) electrodes. In the electron gun 7, the final accelerating electrode and the like located on the phosphor screen 4 side are provided with an anode terminal 9 provided on the large diameter portion of the funnel 2 through a conductive film 10 provided on the inner surface of the funnel 2. A high voltage is applied, but to the electrodes other than the final accelerating electrode located on the cathode K, the heater H, and the cathode K side, through the stem pin 12 penetrating the stem 11 that seals the end of the neck 5. , And a predetermined voltage is applied to each.

Generally, in such a cathode ray tube, various tube inner members such as a phosphor screen are provided in the envelope, and then the electron gun is sealed in the neck. The sealed envelope of the electron gun. After performing a getter flash to evacuate the inside of the envelope to a high vacuum, high pressure treatment to increase the withstand voltage between the electrodes of the electron gun, and cathode aging to stabilize the electron emission capacity of the cathode, and then perform a characteristic inspection. Is performed. As one item of this characteristic inspection, there is an emission characteristic inspection.

The quality of this emission characteristic is judged by the ratio φ (cathode quality factor) of the maximum emission current MIK of a good cathode and the actually measured cathode current IK. Since the maximum emission current MIK is proportional to the 3/2 power of the cutoff voltage EKCo of the electron gun as shown in the equation (1), φ is represented by the equation (2). ^{MIK = k · EKCo 3/2 .................. (} 1) φ = IK / MIK = IK / k · EKCo 3/2 ............... (2) Thus, the cathode current IK of the manufactured cathode ray tube By measuring the cut-off voltage EKCo and the cut-off voltage EKCo, it is possible to judge the quality of the emission characteristics.

The cathode current IK is measured by applying a rated voltage to the heater and each electrode and setting the cathode to 0V. The cut-off voltage EKCo is obtained by decreasing the cathode current IK and measuring the bias voltage when the cathode current IK becomes 0.1 μA, for example.

[0008]

As described above, the emission characteristic inspection performed as one item of the characteristic inspection of the cathode ray tube is performed by applying a rated voltage to the heater and each electrode and setting the cathode to 0V to make the cathode current. Measure IK,
Further decrease the cathode current IK, and measure the bias voltage at 0.1 μA,
It is determined by the φ value obtained from the equation (2). If the φ value is smaller than the predetermined value, it is determined to be defective.

However, the cathode is set to 0 as in the above-mentioned inspection method.
When the cathode current IK is measured at V, as shown in FIG. 5, the area S for taking out the emission from the cathode K has substantially the same area as the electron beam passage hole 14 of the first grid G1. Even if a foreign substance 16 smaller than the emission area S is attached to the central portion of 15 or a portion deteriorated due to ion bombardment, etc., due to the emission emitted from around it,
There is a problem that φ is equal to or larger than a predetermined value and is determined as a non-defective product.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to easily detect even a cathode ray tube which has a defect in the emission characteristic but cannot be removed by the conventional emission characteristic inspection method. The purpose is to obtain an emission characteristic inspection method.

[0011]

A cathode, a heater for heating the cathode, and an electron gun composed of a plurality of electrodes arranged in the phosphor screen direction from the cathode are provided, and a predetermined voltage is applied to the cathode, the heater and the plurality of electrodes. In the emission characteristic inspection method for a cathode ray tube, in which the emission characteristic is inspected by applying a voltage, a voltage lower than the rated voltage is applied to the heater to inspect the emission characteristic.

Further, a bias voltage is applied to the cathode to inspect the emission characteristic.

Further, a voltage lower than the rated voltage is applied to the heater and a bias voltage is applied to the cathode to inspect the emission characteristic.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a method of inspecting the emission characteristics of a color picture tube, which is one form thereof. The color cathode ray tube in this one mode includes a cathode K, a heater H for heating the cathode K, and first to fourth electrodes sequentially arranged in the direction of the phosphor screen 4 formed on the inner surface of the panel 1 from the cathode K. An electron gun 7 composed of G1 to G4 is provided. The fourth electrode G4 (final accelerating electrode) located on the phosphor screen 4 side is provided with an anode terminal 9 provided on the large diameter portion of the funnel 2 and a conductive film 10 formed by coating on the inner surface of the funnel 2. High voltage is applied to the fourth electrode G
The heater H, the cathode K, and the first to third electrodes G1 to G3 other than 4 have a predetermined voltage (rated voltage) through a plurality of stem pins (not shown) that penetrate the stem at the end of the neck 5. Is formed in a structure to which is applied. In FIG. 1, 3 is a shadow mask.

The emission characteristic is inspected by the fourth electrode G4
Power source 20 through the anode terminal 9 and the conductive film 10 and the like.
The rated high voltage is applied to the second and third electrodes G2 and G3.
A rated voltage is applied from the power sources 21 and 22 to the first electrode G1 via the stem pin, and the first electrode G1 is connected to the ground via the stem pin. Then, a voltage of 70 to 80% of the rated voltage is applied to the heater H from the power source 23 via the stem pin. Further, a voltage of about 50% of the cutoff voltage is applied as a bias voltage from the power supply 24 to the cathode K via the stem pin. Then, the cathode current Ik at this time is measured.

When the voltage of the heater H is lowered as described above,
The temperature of the cathode K drops, and the cathode current Ik drops significantly. That is, as shown in FIG. 2 which shows the relationship between the heater voltage and the cathode current for a good cathode without defects and a cathode with defects, as compared with the good cathode without defects shown in the curve 26, the cathode with defects is ,
As shown by the curve 27, when the rated voltage is applied to the heater H, there is no great difference in the cathode current Ik, but when the rated voltage is reduced to 70 to 80%, a large difference occurs.

On the other hand, the cathode K has a cutoff voltage of 50.
When a bias voltage of about% is applied, as shown in FIG. 3, the area S for extracting the emission from the cathode K becomes narrower than in the case where the cathode K is set to 0 V and the cathode current is measured (see FIG. 5). Therefore, even if a small foreign matter 16 adheres to the central portion of the electron emission portion 15 of the cathode K or a minute portion deteriorated due to ion bombardment or the like, the cathode current Ik extremely decreases.

Therefore, as described above, a voltage of 70 to 80% of the rated voltage is applied to the heater H, and a voltage of about 50% of the cutoff voltage is applied to the cathode K as a bias voltage to measure the cathode current Ik. As a result, it becomes possible to easily detect defects that could not be detected by the conventional emission characteristic inspection method, and it is possible to significantly reduce the occurrence of emission defects in the set maker and the market.

In the above embodiment, a voltage lower than the rated voltage is applied to the heater and a bias voltage is applied to the cathode to measure the cathode current. However, the heater voltage is lowered or the cathode is biased. Similar effects can be obtained by only applying a voltage.

Further, although the color picture tube has been described in the above embodiment, the present invention is applied not only to the color picture tube but also to the inspection of the emission characteristics of other cathode ray tubes, and the same effect can be obtained. can get.

[0022]

In the emission characteristic inspection method for a cathode ray tube, a voltage lower than the rated voltage is applied to the heater, a bias voltage is applied to the cathode, or a voltage lower than the rated voltage is applied to the heater and the cathode is By applying a bias voltage to the IC and inspecting the emission characteristics, it becomes possible to easily detect defects that could not be detected by conventional emission characteristics inspection methods, greatly reducing the occurrence of emission defects in set manufacturers and the market. can do.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an emission characteristic inspection method for a color picture tube according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a heater voltage and a cathode current for a good cathode having no defect and a cathode having a defect.

FIG. 3 is a diagram for explaining an emission extraction area of the cathode when a voltage lower than the rated voltage is applied to the heater and a bias voltage is applied to the cathode.

FIG. 4 is a diagram showing a configuration of a color picture tube.

FIG. 5: The rated voltage is applied to the heater and the cathode is set to 0V.
FIG. 3 is a diagram for explaining an emission extraction area of a cathode when a cathode current is measured as described above.

[Explanation of symbols]

 4 ... Phosphor screen 7 ... Electron gun 15 ... Electron emission part 16 ... Foreign substance G1 ... First electrode G2 ... Second electrode G3 ... Third electrode G4 ... Fourth electrode H ... Heater K ... Cathode

Claims (3)

[Claims] 1. An electron gun comprising a cathode, a heater for heating the cathode and a plurality of electrodes arranged in the phosphor screen direction from the cathode, and a predetermined voltage is applied to the cathode, the heater and the plurality of electrodes. A method for inspecting emission characteristics of a cathode ray tube, comprising: applying a voltage lower than a rated voltage to the heater to inspect the emission characteristics. 2. An electron gun comprising a cathode, a heater for heating the cathode, and a plurality of electrodes arranged in the phosphor screen direction from the cathode, and applying a predetermined voltage to the cathode, the heater and the plurality of electrodes. A method of inspecting emission characteristics of a cathode ray tube, comprising: applying a bias voltage to the cathode to inspect the emission characteristics of the cathode ray tube. 3. An electron gun comprising a cathode, a heater for heating the cathode, and a plurality of electrodes arranged in the phosphor screen direction from the cathode, and applying a predetermined voltage to the cathode, the heater and the plurality of electrodes. In the emission characteristic inspection method of the cathode ray tube for inspecting the emission characteristic by applying a voltage lower than the rated voltage to the heater,
A method of inspecting an emission characteristic of a cathode ray tube, characterized by applying a bias voltage to the cathode to inspect the emission characteristic.