JPS6324530A - Crt aging treatment - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the aging of cathode ray tubes, and more particularly to an improved aging process that significantly reduces darkening of the center of the cathode due to aging of the focusing electrode.

In manufacturing cathode ray tubes for use in televisions and other displays, various cathode ray management processes are implemented to enhance the lifetime of reliable operation.

This process begins after the cathode ray tube components are assembled; the process involves evacuating the tube, firing it to create a vacuum in the envelope, and
degassing the components of the cathode ray tube; flushing getter onto the interior surfaces of the cathode ray tube and the components so as to continuously getter any residual foreign matter that generates gas during operation of the cathode ray tube; and heating. activating the electron gun cathode to promote the formation of low work function elements in the electron emitting layer; and aging the electron gun cathode and the grid element below it to bring the cathode to an active state. and conditioning the electron gun voltage at a high voltage to remove particles and protrusions that may cause internal electrode arcing.

The rate of degassing is time and temperature dependent, and due to the throughput demands of manufacturing processes and the limited temperature stability of some cathode ray tube components, complete degassing is not possible during evacuation and firing. Extraction cannot be performed. therefore,
Certain residual gases and gas-forming foreign substances, such as hydrocarbons, remain within the cathode ray tube after sealing the exhaust pipe.

Getter flushing typically introduces additional hydrocarbon contaminants into the cathode ray tube. These hydrocarbons cannot be effectively absorbed by the uncalcined barium getter commonly used in many types of color television display tubes. However, during subsequent aging, these hydrocarbons are dissociated and introduced into the getterable components, thus reducing the residual gas within the cathode ray tube to an acceptable level.

It has also been found that, undesirably, the aging process described above produces a condition known as a "darkened center cathode." Analysis confirmed that this condition was due to carbon being deposited in the center of the emissive layer of the cathode. Surprisingly, this deposit does not significantly reduce cathode electron emission.

However, this limits electron emission in the area around the emissive layer, thereby creating a hollow beam that prevents proper focusing and resolution at the screen.

In U.S. Pat. No. 4,457,731, the problem of darkened cathodes in the center is addressed in a reprocessed cathode ray tube. Cathode ray tubes rejected due to electron gun-related defects can be refurbished by ``reguning,'' in which the defective electron gun is replaced with a new one. This regunning process necessarily reopens the envelope to its surroundings, requiring the cathode ray tube to be reprocessed. This US patent describes that flushing the getter after aging, so-called "bost-flushing", can significantly reduce darkening in the center of the cathode. If this happens, unacceptably high gas levels will result.

It is an object of the present invention to reduce the formation of a dark center cathode so that unacceptably high gas levels do not occur.

Another object of the invention is to age a cathode ray tube without the formation of a darkened cathode after sealing and getter flushing, while reducing residual gas to acceptable levels.

The present invention is a processing method for aging a cathode ray tube after evacuating the cathode ray tube, sealing it, getter flushing, and activating the cathode. A method for aging a cathode ray tube, in which a predetermined voltage is applied to cause electrons to be emitted from the cathode, and then a predetermined voltage higher than the voltages of the cathode electrode and grid electrode G1 is sequentially applied to grid electrodes G2 and G3 of an electron gun. In, the grid electrode G
3 is smaller than the voltage of the grid electrode G2.

In the present invention, grid Gl during aging.

By applying a sufficiently high voltage to G2 and G3, the electrons emitted from the cathode are focused into an electron beam that dissociates the residual hydrocarbons present in the cathode ray tube after evacuation, firing and getter flushing, and this dissociation causes the aforementioned They found that a beam of positive carbon ions moving in the opposite direction of the electron beam was formed and that this beam became deposited on the cathode.

Furthermore, according to the invention, by reducing the potential of grid G3 during aging to a critical level above the threshold required for effective aging of this grid G3, but well below the potential of grid G2, It was confirmed that by forming a potential barrier that prevents a beam of positive carbon ions from reaching the cathode, the aging effect of grid G3 can be sufficiently maintained, and the possibility of forming a cathode with a darkened center can be significantly reduced.

In an embodiment of the process according to the invention, the voltage of grid G3 is at least 100V and is at least 50V lower than the voltage of grid G2.

In another embodiment of the process according to the invention, grid electrode G2
and G3 were connected to the same potential source, and the voltage of grid electrode G3 was lowered by inserting a resistor between these two electrodes.

The drawings are explained in detail below.

FIG. 1 is a cross-sectional view showing the essential elements of a multi-beam in-line color cathode ray tube 11 that has been aged by the process of the present invention. This cathode ray tube 11 has a central longitudinal axis 1
4 and an X perpendicular to this longitudinal axis 14.

It is configured to have a Y axis. The surrounding cathode ray tube envelope includes a neck R13, a funnel part 15,
This is a glass structure consisting of an assembly in which a panel portion 17 is hermetically sealed. Disposed on the inner surface of this panel section is a patterned cathodoluminescent screen 19 consisting of strips or dots of colored phosphor material.

A patterned screen 1 is provided inside the panel portion.
A porous structure 21, in this example, a perforated mask, is arranged spaced apart from the porous structure 9. A unitized multi-beam in-line electron gun assembly 23 is housed inside the neck portion 13 of the envelope.
3 to 3 electron beams, namely the central beam 25;
Two side beams 27, 29 are emitted in a common in-line plane. These beams are emitted, focused through a perforated mask 21 and concentrated on a screen 19 to excite the colored phosphors.

On the outside of the cathode ray tube, in the front region of the funnel part 15, a conductive coating 31 is applied, which coating 31 is maintained at ground potential during use of the cathode ray tube.

The multi-beam electron gun assembly 23 is arranged such that the three in-line beams 27, 25 and 29 are in a common horizontal "in-line" plane approximately coincident with the X-axis of the tube.
It is located within the neck portion 13. The electron gun assembly is a plurality of elongated structures of in-line perforated electrode members unitized in spatial relationship. These electrodes are provided in a spaced sequential array in front of the individual electron-emitting cathode elements to form, focus and accelerate each individual electron beam. The electron gun assembly terminates forwardly by a convergence cup 39, the entire structure being integrated by at least two mutually opposed insulating polymorphic members, only one of which 41 It is illustrated. A getter container 35 is supported by elastic strips 37 attached to a convergence cup 39. A thin layer of getter material (not shown) is flashed from the getter container 35 by induction heating, which covers some of the inner surfaces of the envelope, mask, and other cathode ray tube components.

The unitized two-potential electron gun assembly in FIG. 2 has individual cathode elements: K2. It has a plurality of unitized in-line perforated electrode members arranged sequentially in front of K3. The two-potential electrode array has an initial beam forming grid G1, an initial beam accelerating grid G2, a main focusing grid G3 having a longitudinal dimension defined by front and rear perforated ends, and a final accelerating grid G4.

In FIG. 3, the unitized four-potential in-line electron gun assembly has individual cathode elements of 1°K2. K
3, a plurality of electrodes arranged in front of the grid, namely an initial beam forming grid G1, an initial beam acceleration grid G2, a first high potential focusing grid G3, and a low potential focusing grid electrically connected to the grid G2. G4 and grid G
3 and a final acceleration grid G6. grid G3
．． G4 and G5 each have a longitudinal dimension defined by the front and rear open ends.

In manufacturing cathode ray tubes, it is common to subject the cathode of the electron gun and the low potential focusing element to an acing process subsequent to evacuation, firing, sealing and getter flashing of the cathode ray tube. Such aging treatment is performed immediately after activating the cathode and before conditioning to a high voltage. In addition to conditioning the electron-emitting layer itself, aging has at least two purposes: to maintain the cathode in an active state, thereby ensuring proper emission of electrons from the cathode. belongs to.

The primary purpose of aging is to "condition" the surfaces of adjacent grid elements, ie, to heat the grids to remove particles, adsorbed gases, and other residues that are potential sources of cathode contamination.

A second purpose of aging is to convert residual gases, primarily hydrocarbons, into getterable types. This conversion is accomplished by selecting the voltages on the cathode and the various grid elements such that an electron beam of sufficient energy is obtained to separate these residual gas molecules into smaller components.

A typical prior art procedure for activating the cathode and aging the cathode ray tube for a 19V mini-neck color display tube with a four-potential electron gun is diagrammatically shown in FIG.

Ep, εGll EG2 and E, respectively, expressed in volts
heater filament and grid Gl labeled G3;
The potentials of G2 and G3 are plotted against time in minutes. As is clear from this FIG. 4, a relatively low potential E of about 6.5 V is initially applied to these heater filaments to preheat the cathode.

is applied for about 1 minute, and then this potential is increased to about 9.5V for about 1 minute.
to activate the cathode. Aging begins immediately after this activation. A voltage of approximately 8.5 V is maintained on the cathode heater filament during the 33 minute aging cycle. At the beginning of aging, grid G1 is applied with a potential of approximately 8v, which is slightly lower than the heater filament. After about 4 minutes, the potential of grid G1 is increased to about 15V, and a much higher potential of about 300V is applied to grid G2. After another 4.5 minutes, the potential of grid G2 is increased to about 350V, and after 11 minutes, potential EGI of grid G1 is decreased to IOV. At this instant, 19 minutes after the start of aging, a potential of about 350 V is applied to grid G3 for about 13 minutes.

Heater filament potential BP is potential EGII EG2
and maintained for 1 minute after EG3 turns off.

The voltage EF is then reapplied for 2 minutes to ensure that no harmful deposits form on the cathode from these grids and to further reduce any contamination on the cathode surface.

A conventional circuit for accomplishing the activation and aging procedure described above is diagrammatically shown in FIG. In this figure, a potential source ε supplies power to the cathode ray heater filament, and a potential source E
. 1 powers grid G1 and potential source E. 2 feeds grids G2 and G3. The actual potential for aging each electron gun element is controlled by the resistance value. resistance 1
hl~R. Typical resistance values are, for example, 150 Ω each.
, Rc is 100Ω, and RG2 is 5000Ω. Since there is no resistance between grids G2 and 63, the same potential is applied to these grids.

As mentioned above, when grid G3 is given a potential similar to that of grid G2, positively charged carbon particles are formed in the beam due to the dissociation of residual hydrocarbons;
It is directed back towards the cathode to form a dark center cathode similar to that shown in FIG. That is, the cathode 90 has a carbon deposit 92 in the center of the electron emitting layer 94. In order to eliminate such harmful deposits, the potential of grid G3 needs to be lowered so as to form a barrier to the positively charged particle beam.

However, if the potential of grid G3 is lowered too much, at least two adverse effects may occur. First, by reducing the energy of the X-n beam, the effectiveness of gas dissociation is reduced. Second, reducing the temperature caused by energy consumption in grid G3 reduces the conditioning effectiveness of grid G3. Both residual gas and contaminants on grid G3 can reach the cathode during subsequent operation of the cathode ray tube, reducing the emission of electrons and thus shortening the lifetime of the cathode ray tube.

To eliminate these drawbacks, during aging the potential of grid G3 is high enough to achieve effective gas dissociation and conditioning within a critical range and also form a barrier against carbon deposits on the cathode. It needs to be kept low enough that it does. In this respect, the potential of grid G3 must be determined to be at least 100V and at least 50V lower than the potential of grid G2, preferably at least 150V and at least 100V lower than the potential of grid G2.

Examples are given below to confirm the advantages of the invention.

Three sets of samples of 26VCFF color display tubes were divided into two groups. This first group was aged using a prior art procedure similar to that described above for mini-neck tubes, and the second group was aged using the inventive procedure shown in FIG. These samples were compared in terms of electron emission, dark center cathode, and emitted electron reduction.

A circuit similar to that shown in FIGS. 7 and 8 was used. For prior art aging (FIG. 7), the values of voltage BG2 and resistor R62 are 600v and 5000Ω, respectively, which provides 51V for both grids G2 and G3.
A potential of 5V was obtained. The currents flowing through grids G2 and G3 were 0.8 mA and 17 mA, respectively.

In the aging procedure of the process according to the invention, the potential E. 2 was reduced to 400v and a 500 Ω resistor (R03 in Figure 8) was inserted in the circuit between grid G2 and grid G3, thereby obtaining potentials of 325v and 255v on grids G2 and G3, respectively. Grid G2
The current flowing through G3 and G3 is 0.5mA and 15mA, respectively.
It was A.

The results are shown in the table below.

The amount of electron emission and the amount of reduction in emitted electrons are shown for each of the red electron gun, green electron gun, and blue electron gun. The amount of electron emission is expressed in microamperes as the average value (X) of 10 to 12 samples, and its standard deviation is expressed as S. The amount of decrease in emitted electrons is expressed as a percent decrease after 5 seconds when the filament potential is 5V and the bias is zero. The condition of the cathode after aging was visually evaluated as zero deposit, low deposit, moderate deposit, and high deposit, representing no distinction between individual electron guns.

As is clear from this result, the aging procedure of the treatment according to the present invention (group ■) results in a good electron emission level and considerably good stability as expressed by a low reduction in emitted electrons. , and the probability of the center of the cathode becoming dark has been sufficiently reduced.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view showing a sealed and getter flushed cathode ray tube to be aged by the process of the present invention; FIG. 2 is a cathode and grid of a two-potential electron gun to be aged by the process of the present invention. The partial sectional view of the neck of the cathode ray tube shown in FIG. 1 showing the device, and FIG. 3 similar to the sectional view of FIG. 4 is a diagram showing potential in volts versus time in minutes for a typical prior art cathode activation and cathode ray tube aging procedure; FIG. FIG. 6 is an enlarged plan view of a cathode with a darkened center resulting from a prior art aging procedure; FIG. 7 is a diagrammatic circuit diagram of a prior art circuit that accomplishes the procedure of FIG. 4; FIG. 8 is a diagram of a circuit diagram of a prior art circuit that accomplishes the procedure of FIG. 1 is a diagrammatic circuit diagram of an inventive circuit; FIG. 11...Color cathode ray tube 13...Neck part 14...Central longitudinal axis 15...Funnel part 17...Panel part 19.
...Cathodeluminescent screen 21...Porous structure 23...Electron gun assembly 25...Central beam 27.29...Side beam 31...Conductive coating 35...Geck container 37.・Elastic strips
39... Convergence cup 41... Insulating member 90... Cathode 92... Dark spot in the center (
carbon deposit) 94...electron emission layer 61~G6・
...1 to 3 to grid...Cathode element RK+ to R
K,...resistance-hifro = αfuhyft■ Oko(ri)

Claims (1)

[Claims] 1. A treatment method for aging a cathode ray tube after evacuating the tube, sealing it, getter flushing, and activating the cathode, which treatment method comprises Applying a predetermined voltage to the grid electrode G1 of the gun,
In this aging treatment method for a cathode ray tube, electrons are emitted from the cathode, and then a predetermined voltage higher than the cathode voltage and the voltage of grid electrode G1 is sequentially applied to grid electrodes G2 and G3 of the electron gun. A method for aging a cathode ray tube, characterized in that the voltage of the grid electrode G2 is made smaller than the voltage of the grid electrode G2. 2. A method for aging a cathode ray tube according to claim 1, characterized in that the voltage of the grid electrode G3 is set to at least 100V. 3. A cathode ray tube aging treatment method according to claim 1 or 2, characterized in that the voltage of the grid electrode G3 is lowered by at least 50V than the voltage of the grid electrode G2. Aging treatment method for pipes. 4. A method for aging a cathode ray tube according to claim 2, characterized in that the voltage of the grid electrode G3 is set to at least 150V. 5. A method for aging a cathode ray tube according to claim 3, characterized in that the voltage of the grid electrode G3 is lowered by at least 100 V than the voltage of the grid electrode G2. . 6. A method for aging a cathode ray tube according to claim 1, characterized in that the heater voltage is within a range of approximately 5 to 10V. 7. A method for aging a cathode ray tube according to claim 1, characterized in that the voltage of the grid electrode G1 is set within a range of about 5 to 20V. 8. A method for aging a cathode ray tube according to claim 1, characterized in that the voltage of the grid electrode G2 is within a range of about 250 to 400V.