JPH0561741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a seasoning method applied to improve the withstand voltage characteristics of a cathode ray tube.

[Prior Art] Generally, a color cathode ray tube has a
It has a glass bulb 4 consisting of a panel part 1, a funnel part 2, and a neck part 3, and an inner conductive film 5 and an outer conductive film 6 are formed on the inner and outer surfaces of the glass bulb 4.
is provided. The internal conductive film 5 extends to the inner surface of the neck portion 3, and the funnel portion 2 accommodates a multi-step focus electron gun structure (hereinafter referred to as "electron gun structure") 9. As shown in FIG. 3, an anode 11, a fifth lattice 12, a fourth lattice 13, a third lattice 14, a second lattice 15, a first lattice 16, a cathode 17, and a bead glass that holds each of these electrodes together. 18, a cup-shaped body 19, and a valve spacer 20. The anode 11 and the fourth lattice 13 are connected to the connector 21
a, and a high voltage is applied from the outside through the anode terminal 8, the internal conductive film 5, and the valve spacer 20. Further, the fifth lattice 12 and the third lattice 14 are connected by a connector 21b, and an auxiliary high voltage is applied from the outside through a lead wire 24 planted in the stem 23. Similarly, the second grating 15, the first grating 16, and the cathode 17 are connected to the lead wire 24 through separate connectors, and respective voltages are applied from the outside. The operating voltage of the multi-step focus electron gun configured in this way is determined by the third grid 1.
Since 9KV is applied to the second grid 4 and several hundred V to the second grid 15, a voltage nearly twice that of the conventional bipotential electron gun is applied between the second grid 15 and the third grid 4.

FIG. 4 is an enlarged sectional view of the vicinity of the third grating 14 and the second grating 15, and shows the electron beam passing hole 2 of the first grating 16.
A cathode 17 is arranged below 7, and the cathode 1
A cathode powder layer 25 is formed at the tip of the cathode 17, and a heater 26 is provided inside the cathode 17.
is located.

When a current is applied to the heater 26 of the color cathode ray tube configured in this way to heat it, the cathode 17 and the cathode powder layer 25 are heated by the heat, and thermoelectrons are emitted from the surface of the cathode powder layer 25. Electron beam passing holes 27 and 2 of the first grating 16, the second grating 15, and the third grating 14, respectively
8 and 29, the electron beam 30 collides with a fluorescent screen (not shown). In the manufacturing process and aging process of cathode ray tubes, the heater 26 is
Nearly twice as much voltage is applied. Therefore, the temperature of the cathode 17 increases, and barium oxide (hereinafter referred to as BaO) evaporates from the cathode powder layer 25, causing the electron beam passing holes 2 of the first, second, and third lattices to evaporate.
7, 28, 29, BaO vapor deposition layer 3
1 is formed.

On the other hand, the electron beam passing holes such as the second grating 15 are
In the manufacturing process, since the product is formed by punching using press processing, many protrusions 32 with a size of 1 μm or less may be formed due to burrs, burrs, etc.
If present in the grating 15, unnecessary electrons 33 may be emitted from the tips of the projections 32 due to the electric field from the third grating 14 during operation of the cathode ray tube.
The unnecessary electrons 33 are affected by the sharpness of the tip of the protrusion 32 and the work function of this portion.

The sharpness of the tip of the protrusion 32 is generally expressed by the magnitude of the electric field multiplication coefficient, and in the case of a cathode ray tube that has not been subjected to high voltage processing, the value is about 500 to 800.
Furthermore, the work function at the tip of the protrusion 32 is approximately 4.4 eV because the material is stainless steel, but
If it is attached, the voltage drops to about 2.5eV. In other words, since the electric field multiplication factor is large and the work function is small, the amount of unnecessary electrons increases as determined by the Fowler-Norldheim relation, causing the phosphor (not shown) to emit light when unnecessary, which improves the image quality of the cathode ray tube. This contributes to a decrease in

In order to eliminate such problems, seasoning is conventionally applied by applying a high voltage of 20 to 50 KV between the second grating 15 and the third grating 14, and the projections 32
The aim was to reduce unnecessary electrons 33 emitted from the

[Problems to be Solved by the Invention] However, in the conventional seasoning method, before discharge occurs between the protrusions 32 and the third lattice 14, the second lattice 15 is formed to increase mechanical strength. has been done. A discharge occurs between the embossing 34 and the third grid 14, or a creeping discharge occurs between the straps of the second grid 15 and the third grid 14 planted on the bead glass 18, and the applied voltage is increased. However, there was a problem in that the number of cracks in the bead glass 18 increased and the protrusions 32 could not generate discharge, and the emission of unnecessary electrons could not be sufficiently suppressed.

The present invention was made to solve the above-mentioned problems, and aims to provide a seasoning method that can sufficiently remove the protrusions 32 and reduce the emission of unnecessary electrons.

[Means for Solving the Problems] The seasoning method according to the present invention includes an activation step of applying a voltage between the second grid and the cathode to flow a second grid current, and after performing this activation step. This is a seasoning method in which a seasoning step of applying a high voltage between the second grating and the third grating is repeated multiple times.

[Function] The activation step in this invention activates the BaO vapor deposited layer adhering to the protrusions of the second lattice,
In the subsequent seasoning step, electrons are intensively emitted from the activated portions, and the protrusions are heated and melted to smooth them. By repeating this process multiple times, the tips of the protrusions are smoothed in descending order of the electric field multiplication factor and work function, resulting in a cathode ray tube that emits fewer unnecessary electrons.

[Embodiment of the Invention] An embodiment of the invention will be described with reference to FIG.
In the figure, the same reference numerals as in FIG. 4 indicate the same components.

First, the BaO vapor deposition layer 31 adhering to the protrusions 32 of the second lattice 15 is activated. In this activation process, a voltage of 100 to 2000 V is applied to the second grid 15, and the voltage of the first grid 16 is adjusted in the range of -100 to 0 V to generate a second grid current that does not cause the second grid 15 to become red hot. flow. As shown in the figure, this second lattice current flows intensively around the electron beam passage hole 28, activates the BaO vapor deposition layer 31, and lowers the work function to about 1.5.

Next, between the second lattice 15 and the third lattice 14,
Seasoning is applied by applying a high voltage of 20 to 50KV. Then, since the work function has been lowered by the activation process performed previously, large unnecessary electrons are emitted from the plurality of protrusions 32 in the order of their electric field multiplication coefficient and work function. It melts due to heat, or gas is released to generate a vacuum discharge, and the Joule heat of the discharge current causes it to melt and become smooth. Therefore, the electric field multiplication factor in this part becomes small, and even if the work function in this part remains low at 1.5 eV,
This prevents unnecessary electrons from being emitted.

Seasoning as described above is more effective than conventional treatments even if done only once, but even better results can be obtained by repeating it multiple times. The reason is,
In one process, as a large number of protrusions 32 are smoothed, the gas released from the previously smoothed protrusions 32 is absorbed into the BaO vapor deposited layer 31 of the protrusions 32 that have not yet been smoothed. Since it acts on the activated portion to inactivate it, unnecessary electrons are no longer emitted from the protrusion 32, and the smoothing effect is no longer progressed. Therefore, if the activation treatment is performed again and then the seasoning is performed, the protrusions 32 that could not be smoothed in the first seasoning treatment can be smoothed, and this seasoning treatment is repeated 4 to 5 times. Therefore, all of the protrusions 32 that cause problems during operation of the cathode ray tube can be smoothed out, so that a cathode ray tube with sufficient withstand voltage characteristics can be obtained.

In this case, the conditions for the second and subsequent activation treatments and seasoning may be the same as the conditions for the first time.

According to this example, the occurrence rate of cutoff adjustment defects among users of high-resolution color cathode ray tubes was almost 0%, which was a significant effect compared to the failure rate of several percent with conventional seasoning. Obtained.

[Effects of the Invention] As described above, according to the present invention, the activation process for activating the BaO vapor deposited layer attached to the second lattice and the application of a high voltage between the second lattice and the third lattice are performed. Since the application of seasoning is repeated multiple times, the seasoning of the second lattice can be applied without causing discharge between the embossing formed on the second lattice and the third lattice, or creeping discharge of the bead glass. It is possible to obtain a cathode ray tube having high reliability and high quality withstand voltage characteristics.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of the vicinity of the second grid of an electron gun for explaining the operation of an embodiment of the present invention, FIG. 2 is a partially cutaway side view of a color cathode ray tube, and FIG. FIG. 4 is a side view of the electron gun assembly, and FIG. 4 is a partially enlarged sectional view of the vicinity of the second grid of the electron gun. 9...Electron gun structure, 14...Third grid, 15...
...Second grid, 16...First grid, 17...Cathode, 25...Cathode powder layer, 27, 28, 2
9...Electron beam passing hole, 30...Electron beam,
31... BaO vapor deposition layer, 32... protrusion. In addition,
In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. An activation step in which a voltage is applied between the second grid and the cathode of the cathode ray tube to flow a second grid current, and after this activation step, a high voltage is applied between the second grid and the third grid. A method for seasoning a cathode ray tube, in which a seasoning step of applying an electric current is repeated multiple times.