Dust cleaning apparatus for cleaning cathode ray tubes

A dust cleaning nozzle for cleaning a cathode ray tube comprises a pipe with an axially extending hollow part, and an ejecting angle changing mechanism attached to one end of the pipe. The nozzle, after insertion through the neck of the cathode ray tube, changes the ejecting angle of air ejected from the ejecting angle chainging mechanism with respect to the axis of the pipe so as to be efficient in removing dust from the tube.

FIELD OF THE INVENTION 
The present invention relates to a dust cleaning apparatus for cathode ray 
tubes, and more particularly to a dust cleaning apparatus for cleaning the 
inside of cathode ray tubes. 
BACKGROUND OF THE INVENTION 
Generally, cathode ray tubes are sealed in a high vacuum in order to 
facilitate the movement of free electrons and in order to improve 
withstand voltage characteristics of the tubes. If foreign matter such as 
dust remains inside the tubes, the discharge rate increases and sharp 
pictures cannot be obtained due to scattering of electron beams. 
Accordingly, any dust in cathode ray tubes should be completely removed 
before the electron gun is inserted and before the tubes are sealed. 
A conventional nozzle for cleaning dust from cathode ray tubes is shown in 
FIG. 1. This conventional nozzle is made in such a manner that one or more 
holes 2b communicating with hollow part 2a are formed near the end of thin 
and long pipe 2. This hollow part 2a extends axially in the direction of 
the pipe's length. 
To remove dust in cathode ray tube 30 with the conventional dust cleaning 
nozzle 1, the nozzle 1 is inserted inside cathode ray tube 30 through neck 
30a. After that, dust-free compressed-air is ejected into cathode ray tube 
30 via hollow part 2a and through hole 2b of the nozzle 1. Nozzle 1 is 
simultaneously revolved to blow foreign matter stuck to the inner face of 
the cathode ray tube, the shadow mask, the frame and/or the inner shield 
out neck 30a and from the tube. 
With the conventional nozzle 1, however, all of a high pressure is ejected 
only in a certain direction through holes 2b formed near the end of nozzle 
1 so that only part of the inside area of the cathode ray tube is exposed 
to the high pressure air. Accordingly, dust cleaning is not directly 
performed on the entire inside area of the cathode ray tube. 
SUMMARY OF THE INVENTION 
Therefore, it is an object of the present invention to provide an apparatus 
for cleaning dust from cathode ray tubes which ejects air of a high 
pressure into the inner cavity of the cathode ray tubes in multiple 
directions so as to improve the dust cleaning rate. 
To attain this object, the present invention, comprises: a pipe having a 
hollow part; and an ejecting-angle changing means, attached to one end of 
the pipe, for changing the ejecting direction of air ejected from the 
hollow part.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 2 shows a preferred embodiment of a nozzle for cleaning dust in a 
cathode ray tube according to the present invention. The apparatus 10 for 
cleaning dust in a cathode ray tube comprises a thin long pipe 11 having a 
hollow part 11a and an ejecting angle changing means 20 for changing the 
ejecting direction of air ejected from the hollow part 11a. The 
ejecting-angle changing means 20 is attached to an end of the pipe 11. 
The ejecting angle changing means 20 comprises a shaking plate 21 attached 
to the end of the pipe 11, and a guide portion 22 attached to the shaking 
plate 21 for guiding the air ejected from the hollow part 11a of the pipe 
11 in the right angled direction of the shaking plate 21. 
The guide portion 22 has an aperture 22a in the right angled direction of 
the shaking plate 21 and a shape of square pipe with the face opposed to 
the hollow part 11a open. The guide portion 22 may be made by folding a 
square pipe or cylinder with a certain length by a right angle. The air 
inflow opening of the guide portion 22 should be located directly above 
the hollow part 11a formed in the pipe 11. The shaking plate 21 should be 
made of material with elasticity. Furthermore, it is desirable that a 
nozzle member 12 be provided which is attached to the end of the pipe 11. 
If such a nozzle member 12 is provided, the shaking plate 21 should be 
fixed with a set screw 13 on the peripheral face of the nozzle member 12. 
The nozzle for cleaning dust from a cathode ray tube 10 is, while inserted 
into the tube, variously revolved and lifted by a lifting means and a 
revolving means not shown in the drawings. 
Operation of the nozzle for cleaning dust from cathode ray tubes according 
to the present invention will be described below. 
First, the apparatus for cleaning dust 10 is inserted into a cathode ray 
tube 30 through its neck 30a and dust-free air is supplied with a high 
pressure through the hollow part 11a of the pipe 11. This high pressure 
air is then ejected in the right angled direction of the shaking plate 21 
through the guide portion 22 of the ejecting angle Changing means 20 
attached to the end of the hollow part 11a. As the high pressure air is 
ejected by the guide portion 22 in the right angled direction of the 
shaking plate 21, a force is exerted in the opposite direction of the 
ejecting direction of the air thereby making the shaking plate 21 bend in 
a certain direction so that the guide portion 22 of the shaking plate 21 
deviates from the vertically upper part of the hollow part 11a the from 
which air of a high pressure is ejected. If the guide portion 22 deviates 
from the vertically upper part of the hollow part 11a, the inflow quantity 
of the air of a high pressure ejected from the hollow part 11a into the 
guide portion 22 is reduced and the force exerted on the shaking plate 21 
is reduced. The guide portion 22 therefore recovers so that it is directly 
above part of the hollow part due to the restoring force of the shaking 
plate 21. Accordingly, the inflow quantity of air into the guide portion 
22 increases, and the force exerted on shaking plate 21 becomes stronger. 
The sequence described above is repeated so that the ejecting angle 
changing means 20 is shaken back and forth at a high speed. The degree of 
shaking of the ejecting angle changing means 20 depends on the quantity 
and the ejecting speed of the air applied to the guide portion 22 from the 
hollow part 11a. 
In addition to the ejecting angle changing means being shaken at a high 
speed, and in addition to the varying of the ejecting angle from the guide 
portion 22, the nozzle is also revolved a number of times by a revolving 
means and is also lifted by a lifting means. The revolving means and 
lifting means are not shown in the drawings. As a result, foreign matter 
in cathode ray tubes is cleanly removed. Especially, the apparatus for 
cleaning dust can eject high pressure air to the corners of the panel of 
cathode ray tubes so that the apparatus is very efficient in removing dust 
from these corners. 
As described above, the apparatus for cleaning dust from cathode ray tubes 
according to the present invention removes dust from cathode ray tubes by 
varying the ejecting angle of air inside the tubes. Accordingly, the 
number of tubes rendered inferior by foreign matter can be reduced with 
this invention.