MXPA98008974A

MXPA98008974A - Evaporable gas absorbing device with better deviator

Info

Publication number: MXPA98008974A
Application number: MXPA/A/1998/008974A
Authority: MX
Inventors: Martelli Daniele; Urso Giuseppe
Original assignee: Saes Getters Spa
Priority date: 1997-10-30
Filing date: 1998-10-28
Publication date: 2000-10-01

Abstract

An evaporable gas absorbing device consisting of a ring-shaped container open at the top and containing an evaporable gas absorbing material, and a frusto-conical diverter, placed above the free surface of the gas absorber and centrally connected to the container along its smallest base. The diverter has, along its upper margin, an edge parallel to the axis of the device that, by coupling with the magnetic field of activation, results in local heating preventing the barium vapors from condensing, moreover, the smaller base of the diverter has a smaller diameter than the inner diameter of the ring-shaped seat of the evaporating gas absorber material

Description

EVAPORABLE GAS ABSORBING DEVICE WITH IMPROVED DIVERTER DESCRIPTIVE MEMORY The present invention relates to gas absorbing devices and in particular to an evaporable gas absorber device provided with an improved diverter. The gas absorbing materials are known to be used in all applications where it is required to maintain a vacuum for extended periods. In particular? The cathode ray tubes (TRO) used in TV sets and appliances contain gas absorber materials designed to fix traces of gas that may remain in the TRC after evacuation and sealing or that appear from the gas conversion of gas. Component materials The most commonly used gas absorber material in this application is metallic barium deposited in the form of a thin layer on an inner wall of the CRT For this object, dispersers known in the art as evaporable gas absorbers are used. consisting of a metal container »open at the top that contains powders of a barium and aluminum compound and Ni 'ueIr Ni powders» Once the CRT has been evacuated and sealed ^ the device placed inside it is heated by induction by means of a coil arranged on the outside of the tube in a position corresponding to the position where the device is The magnetic induction results in the heating of the metal container that transmits the heat to the packaged powders contained therein. When the temperature of the powder reaches a value of 800QCr a strong exothermic reaction takes place by causing the temperature of the powder to rise to i200 ° Cr temperature at which the evaporation of the barium that is deposited on the walls of the TRC occurs thus forming the However, it may be preferable to prevent the barium from also depositing on the cover and the phosphor layer on the inner surface of the screen, in fact, this results in a reduction of the brightness of the screen due to the fact that electrons have to pass through the barium film before hitting the phosphor »The larger the thickness of the larger film is the attenuation of electrons, in order to direct the evaporation of barium preferably towards the conical surface of the tube »There are known devices provided with a diverter arranged above the free surface of the gas absorber. inclined metal surface positioned above the container of gas absorbing material and spaced far enough away from it to allow discharge of the barium vapors. Various embodiments of this type of device are described by way of example in the patent US 3719433 in the name of the applicant. The main problem with these known devices is that during the evaporation of the barium a part of it is deadened on the diverter. In particular, it is found that the accumulation of barium on the diverter occurs on its upper margin and, to a lesser degree, on the junction area between the diverter and the gas absorber container. The practical effect is that the formation of these barium deposits, sometimes even of large dimensions, causes two types of disadvantages. A first obvious disadvantage is the reduction of the amount of barium currently deposited on the walls of the tube. This results in a reduction in the effectiveness of the total gas absorbing action produced by the device. A second considerable disadvantage is the possible detachment of fragments from the barium deposits during the subsequent "or even worse" operating steps during the use of the CRT. In fact, it is possible that the barium grains »detached from the diverter» end up on the electron gun and / or on the internal cover of the screen. In the first case »they can. occur arcs or circuit breakers »while in the second case avoid the excitation of the phosphorus that cover generating a black area on the screen .. In both cases» the full functionality of the CRT is obviously canceled. The object of the present invention is therefore to provide a device which overcomes the disadvantages mentioned above. This objective is achieved by means of an evaporable gas absorbing device consisting of a diverter provided along its upper margin with a cylindrical edge substantially parallel to the dividing axis and at least 8 mm in height. More advantageous features of the present improved device are specified in the dependent claims. The main advantage of the gas absorbing device according to the invention is that it prevents the deposition of the barium vapors along the upper margin of the diverter. This is obtained thanks to an effective coupling between the magnetic field to activate the device and the axial edge of the diverter. Such coupling results in considerable warming of the edge of the diverter »thus preventing condensation of the barium vapors. The lack of such deposits obviously eliminates the risks of malfunction mentioned above. This and other advantages and features of the device according to the present invention will be apparent to those skilled in the art from the following detailed description of two modalities thereof "with reference to the accompanying drawings" in which? Figure 1 schematically shows the possible positions for mounting the device within a CRT »Figure 2 is a top plan view of a first embodiment of the device; Figure 3 is an enlarged view of a section of the device along the line T-T of Figure 2 »Figure 4 is a schematic perspective view of a second embodiment of the device. The schematic view of Figure 1 shows the three possible mounting positions of the device present within a CRT. The position commonly used is the "antenna" position < A > »In which the device 1 is mounted on the electron gun 2 through an arrow 3. Otherwise the free end of the arrow 3 can be secured to the anodic button 4 (position B) or to the inner cover 5 ( position C). Referring to Figures 2 and 3 »it is seen that the device 1 consists of a container 6 of the evaporable gas absorbing material < G) and a diverter 7 arranged above the free surface of the gas absorber G. The container 6 is ring-shaped and is obtained from a circular sheet »generally made of AISI 304» molded as to obtain an outer wall 6a r a lower wall 6b and a raised central portion. The latter forms the internal portion 6c of the. seat of the gas absorber G and a central plane used for the connection with the diverter 7. The diverter 7 is essentially frustoconically shaped with its smaller base 7a in contact with the plane 6d of the container and having a diameter smaller than the flat? d. The larger base is open and has a cylindrical edge 7b along its margin. The lateral conical surface 7c is flat »but can also be curved so as to have a slight curvature towards the container 6. In this case» the folding radius of the surface 7c must be at least 1.5 times the radius of the deviator 7 »preferably 2 to 5 times the value of said radius. The drawings show a diverter having a larger diameter than the container 6r but the ratio between the diameter of the largest base of the diverter and the diameter of the container 6 can vary from .8 to 1.2. Relationships less than 0.8 result in derailleur dimensions that are unable to effectively prevent the deposition of barium vapors on the screen "while the larger dimensions increase the weight and volume of the deviator without obtaining improvements in its functionality. The edge 7b is at least 0.8 mm in height? it has been found that smaller heights of the cylindrical edge do not result in an effective coupling with the magnetic ca »and therefore the heating of the upper margin of the frusto-conical surface of the diverter is not sufficient to avoid the problems of barium condensation. On the other hand, the maximum height of the edge is limited for practical reasons? Excessive heights »for example greater than 3 mm» increase the weight of the structure without obtaining functional improvements »preferably the height of the barb 7b varies from 1 to 2.5 mm. As stated above, "the edge 7b" which is substantially parallel to the axis of the device "allows intense heating of the upper margin of the conical surface 7c of the diverter 7" where the larger barium deposits are formed in devices of known type . Moreover, the fact that the smaller base 7a has a smaller diameter than the central plane 6d on which it is secured also allows the second barium deposit area to be eliminated. The corner between the base 7a of the diverter and the junction plane is located in the central "shaded area" of the device where the barium vapors do not pass because they are deflected outwardly by the surface 7c. The effectiveness of the solution mentioned above is evident from the comparative tests carried out by the applicant in prior art devices and devices provided with the improved diverter of the present. In these tests it has been discovered that when conventional devices are used, barium deposits are formed in more than half of the cases "while when the device according to the invention is used na formation of such deposits has occurred. Finally »Figure 4 shows a second mode which is different from the previous one in the presence of a screen Q- partially closing the exit space of the barium vapors. The advantage of such partial closure is to limit the avoidance of barium deposition in the area of the electron gun 2 which could result in damaging currents which interfere with the correct operation of the CRT. Therefore »the device is mounted inside the CRT with the screen 8 facing towards the gun 2» that is »with the screen 8 near the supporting arrow 3 in the antenna assembly house (A? O on the handsome side in the other two cases (positions B and C) screen 8 can be provided by "cutting" by pressing and bending a single sheet of metal "integral with the component having the largest diameter between container 6 and diverter 7 (this the last case is shown in figure 4. Otherwise, the screen 8 can be a separate member welded to the diverter 7 and / or to the container 6. Its greater or lesser extent along the circumference of the device obviously depends on the degree The above-described and illustrated embodiments of the device according to the invention are examples obviously subject to many modifications, in particular, the dimensions of the diverter may vary within the ranges An eriorme te and the connection between diverter 7 and container 6 can be obtained in different ways. For example, a central hole can be provided in the plane 6d and have an axial cylindrical edge of proportional size provided in the base of the diverter 7 »inserted therein which would thus be open in its smaller base 7a and consequently in the form of embuda.

Claims

NOVELTY OF THE INVENTION CLAIMS

1 - An evaporable gas-absorbing device consisting of a ring-shaped container (6) open at its upper part and containing an evaporable gas-absorbing material (G) »and a substantially frusto-conical deviator (7) arranged above the free surface of the gas absorber (G) and centrally connected to said container (6) along its smallest base (7a >) characterized in that said diverter (7) has »along its upper margin» a edge (7b) which is substantially parallel to the axis of the device and of at least .8 POT of the ura 2.- A device according to claim 1 »further characterized in that the height of the edge (7b) varies from ia 2.5 3. A device according to claim 1 or 2 »further characterized in that the smaller base (7a) of the diverter (7) has a smaller diameter than the inner diameter of the ring-shaped seat of the evaporable gas absorbing material (G) 4. A device according to one or more of claims 1-3, further characterized in that the ratio between the diameter of the largest base of the deviator (7) and the outer diameter of the container (6) varies from 0.8 to 1. T? 5. A device according to one or more of claims 1-4 »further characterized in that the lateral surface (7c) of the deviator (7) is flat. 6. A device according to one or more of claims 1-4 »further characterized in that the side surface (7c) of the deviator (7) is curved so as to have a convexity facing the container (6)» said convexity having a folding radius of at least 1.5 times the radius of the largest base of the diverter (7). 7. A device according to claim or »further characterized in that the folding radii of the curved side surface (7c) varies from 2 to 5 times the value of the radius of the largest base of the diverter (7). S. - A device according to one or more of the preceding claims »characterized in that it also comprises» along a portion of its perimeter »of a screen (8) integral with the container (6) and / or the deviator ( 7) and substantially parallel to the axis of the device. 9. A device according to claim 8 »further characterized in that the screen (8) is provided» cutting »by pressing and bending a single sheet of metal» integral with the component having the largest diameter between the container (6) and the diverter (7). 10. A device according to claim 10 further characterized in that the screen (8) is a separate member welded to the device.