GB2226492A

GB2226492A - Cleaning sealing portions of panels of colour cathode ray tubes

Info

Publication number: GB2226492A
Application number: GB8929015A
Authority: GB
Inventors: Ki-Taek Lim
Original assignee: Samsung Electron Devices Co Ltd
Current assignee: Samsung SDI Co Ltd
Priority date: 1988-12-22
Filing date: 1989-12-22
Publication date: 1990-07-04
Anticipated expiration: 2009-12-22
Also published as: MY104705A; GB2226492B; JPH0287361U; KR900011672U; JPH0542601Y2; KR910008579Y1; GB8929015D0

Abstract

Residual graphite paste on sealing portion P' of panel P of a colour cathode ray tube is removed by cleaning fluid which is introduced into an annular cleaning tank via inlet 21 and discharged via outlets 22a, 22b. A protective wall 34 may be provided to prevent cleaning fluid from splashing the inner face of the panel. <IMAGE>

Description

CLEANING DEVICE FOR SEALING PORTION OF PANEL OF COLOR CATHODE RAY TUBE Field of the invention The present invention relates to a cleaning device for the sealing portion of the panel of a color cathode ray tube, and particularly to an improved cleaning device for the sealing portion of the panel of a color cathode ray tube, in which the damage of the screen liable to occur due to the spreading of the cleaning chemical can be effectively prevented when the cleaning of the sealing portion is carried out.

Background of the invention On the inner face of the panel of a cathode ray tube, there is formed a black matrix in such a manner that the phosphor stripes should be separated one another at certain intervals, thereby improving the color contrast and color purity as well as absorbing the external light rays. In the process of forming such a black matrix, graphite paste can adhere on the sealing portion of the panel, and such adhered graphite has to be removed through a cleaning step to be followed.

As shown in Figures 1 and 2, the cleaning device for carrying out the cleaning step is constituted such that an outer wall 11 is formed along the edge of a base 10, and, within the outer wall 11, an intermediate wall 12 having a lower height and an inner wall 13 having the same height as the outer wall 11 are formed with certain gaps between them respectively. Further, one or more cleaning fluid inlet tubes 21 are provided on the bottom between the inner wall 13 and the intermediate wall 12, while one or more discharge tubes 22 are provided on the bottom between the intermediate wall 12 and the outer wall 11.

This cleaning device supplies the cleaning fluid through the inlet tube 21, and after the completion of the cleaning by administering the cleaning fluid to the sealing portion P' of a panel P, the cleaning fluid is discharged through the discharge tube 22 so as for the cleaning fluid to be recovered. Under this condition, the means for holding the cleaning fluid is a space formed between the inner wall 13 and the intermediate wall 12 and formed adjacently to the sealing portion P' of the panel, and therefore, if the cleaning fluid is supplied too much, then the excess cleaning fluid overflows over the intermediate wall 12 to be spilled to the bottom formed between the outer wall 11 and the intermediate wall 12.

The introduction of the cleaning fluid through the inlet tube 21 is done when the sealing portion P' of the panel P is received into between the intermediate wall 12 and the inner wall 13, after the panel P is carried by a carrying means to above the cleaning device. One batch of the supply of the cleaning fluid delivered through the inlet tube 21 is of such an amount that it should not be spilled over the inner wall 13 and the outer wall 11, and after the elapsing of a certain period of time, the cleaning fluid is recovered through the discharge tube 22.

In the cleaning fluid supplying manner as described above, the cleaning fluid is delivered by a cleaning fluid supplying means in a large amount at a time into between the inner wall 13 and the intermediate wall 12. The cleaning fluid thus introduced rises up, upon being collided with the inner and outer faces of the sealing portion of the panel, and if the rise reaches a certain height, the cleaning fluid overflows across the intermediate wall. Because the incoming speed of the cleaning fluid is very high, sprinklings of the cleaning fluid occur due to the severeness of the impact of the collision between the cleaning fluid and the sealing portion of the panel.

Further, according as the rising height of the cleaning fluid increases, there is produced a difference between the rising height of the cleaning fluid toward the outer face of the sealing portion exposed to the outside and the rising height of the cleaning fluid toward the inner face of the sealing portion. This difference of the rising heights is attributable to the difference of the atmospheric pressures between the inside and outside of the panel, and this difference increases the sprinklings of the cleaning fluid.

Such sprinkling phenomenon brings the result of damaging the black matrix formed on the inner face of the panel.

Summarv of the invention Therefore it is the object of the present invention to provide a cleaning device for the sealing portion of a panel of color cathode ray tube, in which the damage of the screen, and particularly the damage of the black matrix liable to occur due to the sprinkling of the cleaning fluid can be effectively prevented when cleaning the sealing portion of the panel of color cathode ray tube.

In achieving the above object, the cleaning devices for the sealing portion of the panel of a color cathode ray tube, which is for melt-removing the adhered graphite residuum from the sealing portion by thrust-applying the cleaning fluid to the sealing portion, is characterized in that the cleaning fluid is let to be supplied to the sealing portion of the panel through an inlet tube provided at the outside of the sealing portion of the panel so as for the cleaning fluid to be contacted with the sealing portion, and after the contact of the cleaning fluid with the sealing portion, the cleaning fluid is recovered through discharge tubes which are respectively provided approximately directly below the sealing portion of the panel and at the inside of the sealing portion of the panel.

Thus in the cleaning device according to the present invention, the cleaning fluid is supplied from the outside of the sealing portion of the panel, and is recovered through the discharge tubes provided directly below the sealing portion of the panel and at the inside of the sealing portion of the panel. Therefore, the cleaning fluid which is rushing in can only be sprinkled toward the outer face of the sealing portion of the panel, and accordingly, there is no apprehension that the black matrix might be damaged due to the sprinkling of the cleaning fluid.

Further, there occurs no difference of the atmospheric pressure between the inside and outside of the sealing portion of the panel, and therefore, the sprinkling of the cleaning fluid due to the difference of the atmospheric pressure can be avoided.

Brief descriDtion of the drawings The above object and other advantages of the present invention will become more apparent by describing in detail the preferred embodiment of the present invention with reference to the attached drawings in which: Figure 1 is a schematical sectional view of the conventional cleaning device for color cathode ray tube; Figure 2 is an enlarged view of a part of the cleaning device of Figure 1; Figure 3 is a schematical sectional view of the cleaning device for color cathode ray tube according to the present invention; and Figure 4 is an enlarged view of a part of the cleaning device of Figure 3.

DescriDtion of the Deferred embodiment The preferred embodiment of the present invention will be described in detail referring to Figure 3.

Walls 32, 33 having low heights are formed with a certain distance between them along the edge of a base 30, in such a manner that the walls should closely surround a sealing portion P' of a panel P. At opposite external sides of the low walls 32, 33, high walls 31, 34 are formed, while a flange type skirt 35 is provided at the top of the high wall 34 which is provided in the inside of the panel P.

Meanwhile, a cleaning fluid inlet tube 21 is disposed on the bottom between the low wall 32 and the nearby high wall 31 which is positioned at the outside of the panel P, while cleaning fluid discharge tubes 22a, 22b are respectively disposed on the bottom between the two low walls 32, 33 directly below the sealing portion P' of the panel P on the one hand, and on the bottom between the inner high wall 34 and the nearby low wall 33 on the other hand.

In the cleaning device of the present invention constituted as described above, the cleaning fluid is introduced from the bottom of the base which is isolated from the inside of the sealing portion of the panel, and then, the cleaning fluid flows toward the centre of the base. When the cleaning fluid is supplied in this manner, the impact of the cleaning fluid due to the rush of it is buffered in the region A which is provided between the outer high wall 31 and the nearby low wall 32. Then the cleaning fluid is relatively quietly introduced into the central region B formed between the two low walls 32, 33 and receiving the sealing portion of the panel on the one hand, and also introduced into the region C formed between the low wall 33 and the high wall 34 which is disposed at the inside of the panel on the other hand. When the cleaning fluid which has been introduced into the region A flows again into the regions B and C, if some unexpected impact occurs and if tiny drops of the cleansing fluid are sprinkled onto the inner face of the panel, then the tiny drops of the cleaning fluid are blocked by the skirt 35 which is provided at and extended from the top of the inner high wall 34.

The cleaning device of the present invention as described above assures that the continuous flow of the cleaning fluid should be very quiet, and a skirt is provided across the sprinkling path of the cleaning fluid and in front of the inner face of the panel, so that it should be impossible for the sprinkled cleaning fluid drops to reach the inner face of the panel, thereby effectively preventing the damage of the black matrix.

Claims

CLAIMS:

1. A cleaning device for the sealing portion of the panel of a color cathode ray tube, comprising: step of meltremoving the adhered graphite residuum from said sealing portion by applying a cleaning fluid to said sealing portion, characterized in that said cleaning fluid is let to be supplied to said sealing portion of said panel through an inlet tube provided at the outside of said sealing portion of said panel so as for said cleaning fluid to be contacted with said sealing portion, and after the contact of said cleaning fluid with said sealing portion, said cleaning fluid is recovered through discharge tubes which are respectively provided approximately directly below said sealing portion of said panel and at the inside of said sealing portion of said panel.

2. The cleaning device for the sealing portion of the panel of a color cathode ray tube as claimed in claim 1, wherein high walls are provided on a plate type base in order to surround the inner and outer faces of said sealing portion of said panel, in certain bigger heights and keeping certain distances there between; low walls are provided on said base in order to surround the inner and outer faces of said sealing portion of said panel, in certain lower heights and disposed between said high walls; said cleaning fluid inlet tube is provided on the bottom between one of said low walls and one of said high walls which is facing the former and disposed at the outside of said sealing portion of said panel; and said cleaning fluid discharge tubes are provided respectively on the bottom between said low walls disposed beside said sealing portion of said panel, and on the bottom between one of said low walls and one of said high walls facing the former and disposed beside the inner face of said panel.

3. The cleaning device for the sealing portion of the panel of a color cathode ray tube as claimed in claim 2, wherein, of said high walls, the high wall disposed at the inside of said panel is provided, at the top thereof, with a skirt shaped like a flange so as for said skirt to be approached to said sealing portion of said panel, and so as for said skirt to block off the cleaning fluid drops which are sprinkled from said bottom.

4. Apparatus for cleaning the edge flange of a front panel for a cathode ray tube, the apparatus comprising means defining a peripheral bath for receiving a said edge flange of a panel, means for supplying cleaning fluid into said bath and means for removing cleaning fluid from said bath, said supplying means being arranged so that the fluid flows into the bath from the side thereof disposed outwardly of the edge flange.

5. Apparatus according to claim 4 wherein said supplying means comprises a peripheral reservoir disposed around the bath and separated therefrom by an intermediate peripheral wall which acts as a weir for the flow of cleaning fluid from said reservoir into said bath.

6. Apparatus for cleaning the edge flange of a front panel for a cathode ray tube, the apparatus comprising means defining a peripheral bath for receiving a said edge flange of a panel} means for supplying cleaning fluid into said bath and means for removing cleaning fluid from said bath, wherein there is provide a splash shield above said bath and disposed so as to lie inside said flange thereby to shield the inside face of said front panel from cleaning fluid splashing upwardly from the bath.

7. A cleaning device for the sealing portion of the panel of a cathode ray tube, substantially as hereinbefore described with reference to Figures 3 and 4 of the accompanying drawings.