JPH04277441A - Manufacture of cathode ray tube - Google Patents

Abstract

PURPOSE:To certainly supply getter in an amount enough to hold within a cathode ray tube at a high degree of vacuum for a long period of time, by sensing that amount of getter material which has been evaporated fast while the getter material is left to evaporative attachment process. CONSTITUTION:The input at starting of high frequency heating shall be set so that no excessive amount of getter material 4b will be attached evaporatively. When high frequency heating is commenced and the temp. of a getter vessel 4a has become approx. 800 deg.C, the heat emitting reaction begins in the getter material 4b, whose temp. will immediately rise to around 1300 deg.C. At the same time, the material 4b evaporates and attaches to the getter film thickness measuring part 6a where no interior electroconductive film 6 exists. The getter film thickness is measured by a film thickness sensor element 11, and on the basis of the result from measurement, the output of a high frequency power supply shall be controlled. Thereby the spouting of the getter material 4b can be performed so that excess or shortage in spouting the material 4b will be compensated. That is, the getter can be spouted in a proper amount for maintaining inside of the tube at a high degree of vacuum when the cathode ray tube is 10 practical service.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides a method for installing a sufficient amount of flash getter in a glass bulb, which is a vacuum envelope, and depositing a getter film of an appropriate predetermined thickness inside the tube body of a cathode ray tube. A method of manufacturing a cathode ray tube, in which the gas released into the valve from various parts of the tube after the tube is separated from the exhaust device is adsorbed by the getter film, and the pressure of residual gas in the tube can be maintained at a low value for a long period of time. .

0002

[Prior Art] In general, cathode ray tubes, and color cathode ray tubes in particular, have a large fluorescent surface or shadow mask within the bulb to which a high voltage is applied. Because it is exposed to the impact of a high-density electron beam, even if the degree of vacuum inside the bulb is increased during the evacuation work during the manufacturing process, the phosphor surface Since the occluded and adsorbed gas is gradually released from various parts within the valve, including the electron beam and the shadow mask, the use of a getter is essential to maintain good electron emission characteristics.

[0003] Usually, a flash getter is used for cathode ray tubes, which heats and evaporates the light from outside the bulb using a high-frequency induction heating method. A so-called self-heating getter is used as the getter agent, which has barium, aluminum, and nickel as its main components, and the components of the getter agent undergo an exothermic reaction by external heating. Some getters are designed to stabilize the amount of getter evaporation within the getter itself, but the amount of getter evaporated is usually controlled by adjusting the time from when the getter begins to heat until the getter begins to fly (called the start time ST) and from an external device. This is done using two parameters: the time until heating is stopped (referred to as total time TT). In addition, various proposals have been made regarding the use of a flash getter in a cathode ray tube. For example, in Japanese Patent Publication No. 2-7139, a flash getter is supported by a support piece of an electron gun connected to an internal conductive film of a tube body, The getter device is equipped with a symmetrical getter device having a getter container filled with a getter agent and a flap-like getter shield that expands toward the inside of the tube on the open side of the getter container, and a high frequency of 200 to 350 kHz is applied to an external heating coil. A getter flash method is described in which the getter agent is evaporated from the getter container by heating the getter container by applying current, and the evaporated getter agent is reflected onto the internal conductive film by the getter shield to form a getter film. ing.

0004

[Problems to be Solved by the Invention] The above technology prevents the getter agent from adhering to the fluorescent surface and the metal vapor of the getter from scattering toward the electron gun, thereby preventing short-circuit accidents between the electrodes of the electron gun and valve damage. The purpose is to prevent internal creeping discharge and damage to the bulb, and there is no particular intention to optimize the amount of getter deposition.

[0005] In order to flash the getter, first the getter container is heated, but it is surprisingly difficult to heat the entire container uniformly and with good reproducibility, and parts of the container often end up being overheated. If partial overheating occurs, part of the getter container may melt, or the getter agent in the getter container may float out of the container, and in some cases, the getter may fall out. Contact with the bulb glass may cause the bulb to crack. Furthermore, especially with self-heating getters, the getter metal may evaporate too much and adhere to the electron gun electrode, becoming a source of stray emissions, or a part of the funnel may be made to have a high resistance, reducing the spark current suppression effect when sparks occur. In some cases, an attempt to have this function may be short-circuited and invalidated. It would seem to be a good idea to reduce the external heating input to prevent overheating as described above, but if the heat source and getter are arranged in such a way that a part of the getter container is particularly overheated, the The getter agent begins to fly off, resulting in a cathode ray tube with a small amount of getter agent flying off compared to the so-called ST value.

The present invention was made in order to prevent the gettering agent from being overblown, insufficient, or overheated, which are the causes of the above-mentioned conventional problems, and is sufficient to maintain a high vacuum inside the cathode ray tube for a long period of time. The purpose of the present invention is to provide a getter flash method that can reliably supply a large amount of getter.

[0007]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, during the getter deposition operation, while measuring the amount of getter that has already been deposited (film thickness of the deposited getter agent), Depending on the measurement results, the amount of input power supplied to the heating coil to heat the getter from the outside is controlled in terms of power value or time to prevent the getter film thickness from becoming insufficient or excessive. The amount of vapor deposited was kept constant.

[0008]

[Operation] If the above method is adopted, the thickness of the deposited getter film is constantly monitored during the getter flash, so the getter is deposited so rapidly that the getter container melts due to overheating. Overheating can be prevented by reducing the amount of heating power during the process, and conversely, if the input is too small and the getter film is not being deposited as desired, countermeasures can be taken by increasing the input.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic sectional view of a cathode ray tube according to an embodiment of the present invention. Electron gun 2 installed inside the neck portion 1a of the tube body 1
One end of a support piece 3 (commonly known as an antenna) is attached to the other end of the support piece 3, and a getter device 4 is fixedly supported on the other end of the support piece 3 so as to be in contact with the interior conductive film 6 coated on the funnel portion 1b via a spacer 5. has been done. The interior conductive film 6 has a portion on the opposite side of the portion to which the getter device 4 is fixed, as a getter film thickness measurement portion 6a (window), where no interior conductive film 6 actually exists.

FIG. 2 shows the vicinity of the connection point between the bulb neck portion 1a and the funnel cone portion 1b, the high frequency heating coil 7, and the getter film thickness detector 11 in one embodiment of the present invention.
FIG. 3 is an enlarged cross-sectional view of the arrangement positional relationship.

Getter flash is performed according to the flowchart shown in FIG. The input at the time of starting high frequency heating in the flowchart is set with reference to the conventional ST so that the getter agent is not deposited excessively. When the getter container 4a reaches about 800°C after starting high-frequency heating,
An exothermic reaction begins within the getter agent 4b, and the temperature of the getter agent 4b immediately rises to about 1300° C. At the same time, the getter agent evaporates, and the getter agent is deposited on the getter film thickness measurement portion 6a where the internal conductive film 6 is not present. agent is deposited. Next, the getter film thickness is measured using a film thickness detector, and the output of the high frequency power source is controlled based on the measurement result, so that the excess or deficiency in the amount of getter agent scattered up to that point is just compensated for. Getter agent can be blown away.

[0012] Film thickness meters for metals (for example, measure by the ease with which eddy currents flow due to a predetermined high-frequency magnetic field) usually respond to all metals in the vicinity of the measuring part, so the getter film thickness can be measured at In the case of a color cathode ray tube, keep it away from iron parts such as the shadow mask and inner shield, or the aluminum film covering the fluorescent surface, metal constituting the electrodes of the electron gun, and the getter container. It is necessary to provide In addition, if the vapor deposited film of the getter agent is not a continuous film, the conductivity, which is a characteristic of the metal film, will be significantly reduced, making it impossible to accurately measure the amount of vapor deposited. The interior conductive film 6 is not formed, and the smooth inner wall surface of the bulb glass is exposed.

[0013] In order to evaporate the getter agent, the getter container is usually heated to about 800°C by induction heating using high frequency.
At this time, the reaction heat due to the exothermic reaction occurring in the getter agent and the high-frequency heating together correspond to the heat of evaporation of the getter agent, so if the conditions are such that a part of the getter container is overheated, the ST Although the amount of evaporation of the getter agent is comparatively small, increasing the high-frequency output power value makes the getter container more likely to melt. Under such conditions, it is preferable to control to lengthen the application time of the high frequency output (lengthen TT). That is, the above case corresponds to the case where ST is equivalent to the normal level but the gettering agent film thickness is insufficient.

[0014]

As explained above, according to the present invention, while the getter agent is being vapor-deposited, the amount of the getter agent that has already been vapor-deposited is detected, so that no getter is missed.
It is possible to blow off the getter necessary and sufficient to maintain a high vacuum inside the tube during actual use of the cathode ray tube. Furthermore, at the same time, excessive getter scattering is prevented, so that deterioration of withstand voltage, such as stray emission caused by adhesion of getter metal such as barium, is avoided. Furthermore, since the getter agent contained in the getter container can be efficiently blown away, there is no need to use an extra capacity getter. In other words, the maximum amount of getter agent that can be deposited can be evaporated from a small-capacity getter, so the remaining getter container and getter agent become lighter, and the risk of scraping off the graphite on the internal conductive film due to vibration etc. can be reduced. . At the same time, since a getter with a small capacitance can be used, the cost of materials can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a cathode ray tube according to an embodiment of the present invention equipped with a flash getter.

FIG. 2 is an enlarged cross-sectional view showing the vicinity of the connection point between the bulb neck and the funnel cone of the cathode ray tube according to the embodiment of the present invention, and the arrangement positional relationship of the high-frequency heating coil and the getter film thickness detector.

FIG. 3 is a diagram showing a flowchart of an embodiment of the present invention.

[Explanation of sign]

DESCRIPTION OF SYMBOLS 1... Tube body, 1a... Neck part, 1b... Funnel part, 2... Electron gun, 3... Support piece, 4... Getter device, 4a... Getter container, 4b... Getter agent,
5... Spacer, 6... Internal conductive film, 6a... Getter film thickness measuring section, 7... Coil, 8... Fluorescent film,
9... Shadow mask, 10... Getter film, 11...
Getter film thickness detector.

Claims (1)

[Claims] 1. A method for manufacturing a cathode ray tube in which a getter is installed in a vacuum envelope and is heated from the outside to form a vapor deposited film having a gas adsorption function on the surface of the inner material of the vacuum envelope. A cathode ray characterized in that during the vapor deposition process, the amount of getter that has already been vapor-deposited is measured, and the external heating operation is controlled according to the measurement result to keep the amount of getter vapor-deposited constant. Method of manufacturing tubes.