Display apparatus

Information

  • Patent Grant
  • 6384874
  • Patent Number
    6,384,874
  • Date Filed
    Friday, February 12, 1999
    25 years ago
  • Date Issued
    Tuesday, May 7, 2002
    22 years ago
Abstract
The present invention provides a display apparatus for discharging and removing needless cooling liquid consistently when the display apparatus for cooling a cathode ray tube with cooling liquid is fabricated and relates to a display apparatus for cooling cathode ray tubes with cooling liquid is provided with a cooling liquid container for containing cooling liquid for cooling the cathode ray tubes, a sealing member for sealing cooling liquid in the cooling liquid container by plugging a cooling liquid charging hole formed on the cooling liquid container after cooling liquid is charged into the cooling liquid container, and a residual cooling liquid discharging outlet provided with connection to the sealing member and the cooling liquid container for discharging residual cooling liquid in the space between the sealing member and cooling liquid container to the outside though the space between the sealing member and the cooling liquid container.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




This invention relates to an display apparatus for projecting an image displayed on a cathode ray tube, and more particularly relates to improvement of a display apparatus having a structure for cooling a cathode ray tube with cooling liquid.




2. Description of Related Art




Recently, with popularization of multi-media apparatuses and computers, demand for a display apparatus having a large screen has risen increasingly. Various types of television receivers, image monitors, and image projectors which use a cathode ray tube (CRT) have been proposed as display apparatuses for displaying images of this sort. Among these display apparatuses, a type of display apparatus having structure for enlarging an image displayed on a cathode ray tube and displaying the enlarged image on a screen has been known. A display apparatus of this type can project the light of an image onto the front side of the screen or display an enlarged image on the screen by projecting the light of the image from the back side of the screen.




A projection type display apparatus for forming an image by projection is provided with three cathode ray tubes corresponding to a red (R) image, a green (G) image, and a blue (B) image to be projected on the screen side. These images displayed by these cathode ray tubes are subjected to optical processing through lenses and projected on the screen side. Because the respective cathode ray tubes generate heat, the cathode ray tubes should be cooled with cooling liquid. Cooling liquid used for cooling a cathode ray tube is usually a liquid mixture which is non-volatile under a normal temperature containing mainly, for example, ethylereglycol, and such cooling liquid is apt to stay without evaporation.





FIG. 1

shows a conventional projection type display apparatus. This display apparatus has three cathode ray tubes


1000


,


1001


, and


1002


; the respective cathode ray tubes


1000


,


1001


, and


1002


form images of monochromatic colors namely red (R), green (G), and blue (B), and the respective images are projected on the screen


1004


through lenses


1003


to form a color image on the screen


1004


. Cooling mechanisms


1005


for holding cooling liquid are provided between these cathode ray tubes


1000


,


1001


, and


1002


and corresponding lenses


1003


.





FIG. 2

shows a cathode ray tube


1000


(


1001


, and


1002


) and the cooling mechanism


1005


. The cooling mechanism


1005


has a metal box


1006


, and a metal box


1006


has the structure for containing cooling liquid


1007


in the metal box


1006


. Cooling liquid


1007


is charged from a hole


1008


, and a sealing screw


1009


is tightened after charging so that the cooling liquid


1007


does not leak through the hole


1008


.




FIG.


3


and

FIG. 4

show a screw


1009


tightened in the hole


1008


of the metal box


1006


. An O-ring


1011


for sealing is provided between the screw


1009


and the groove


1010


of the metal box


1006


.




Application of such structure causes problems as described hereafter. In

FIG. 2

, when cooling liquid


1007


is charged into the metal box


1006


though the hole


1008


and thereafter the screw


1009


is screwed into the hole


1008


, as shown in

FIG. 4

, a part


1007


A of the cooling liquid


1007


is confined in a space defined by the groove


1010


, the O-ring


1011


, and the screw


1009


, because cooling liquid remains in the groove


1010


when cooling liquid is charged.




The needless liquid


1007


A confined as described herein above leaks slowly with time to the outside from the space defined by the screw


1009


, the groove


1010


, and the O-ring


1011


. Thus cooling liquid


1007


A leaks though there is no structural defect and fabrication defect. The cooling liquid which leaks to the outside remains on the metal box


1006


because cooling liquid is non-volatile under a normal temperature.




OBJECT AND SUMMARY OF THE INVENTION




It is an object of the present invention to provide a display apparatus having a structure for discharging and removing needless cooling liquid consistently when a display apparatus having a structure for cooling a cathode ray tube with cooling liquid is fabricated.




The present invention is accomplished by using a display apparatus having a structure for projecting and displaying an image displayed on a cathode ray tube and having a structure for cooling the cathode ray tube with cooling liquid provided with a cooling liquid container for containing cooling liquid for cooling the cathode ray tube, a sealing member for sealing cooling liquid in the cooling liquid container by plugging a cooling liquid charging hole formed on the cooling liquid container after cooling liquid is charged into the cooling liquid container, and a residual cooling liquid discharge outlet provided with connection to the sealing member and the cooling liquid container for discharging residual cooling liquid in the space between the sealing member and the cooling liquid container to the outside through the space between the sealing member and the cooling liquid container.




In the present invention, the cooling liquid container contains cooling liquid used for cooling a cathode ray tube. The sealing member seals cooling liquid in the cooling liquid container by plugging the cooling liquid charging hole formed on the cooling liquid container after charging of cooling liquid into the cooling liquid container. The residual cooling liquid discharging outlet provided with connection to the sealing member and the cooling liquid container functions to discharge and remove residual cooling liquid remaining in the space between the sealing member and the cooling liquid container to the outside though the space between the sealing member and the cooling liquid container. Thereby, residual cooling liquid remaining in the space between the sealing member and the cooling liquid container is discharged to the outside easily through the cooling liquid discharge outlet, the problem of confined cooling liquid is solved, and liquid leakage is eliminated.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a plan view for illustrating a conventional display apparatus.





FIG. 2

is a side view for illustrating a cathode ray tube and a metal box for containing cooling liquid of a conventional display apparatus of FIG.


1


.





FIG. 3

is a plan view for illustrating a screw attached to the conventional metal box.





FIG. 4

is a cross sectional view along a, line


4





4


, in FIG.


3


.





FIG. 5

is a side view of a preferred embodiment of the display apparatus of the present invention.





FIG. 6

is a plan view for illustrating cathode ray tubes, a cooling mechanism, a projection lens, and a screen of the display apparatus of the present invention in FIG.


5


.





FIG. 7

is a side view for illustrating components of the structure shown in FIG.


6


.





FIG. 8

is a side view for illustrating one cathode ray tube and the cooling mechanism.





FIG. 9

is a plan view for illustrating a vicinity of an charging hole and a sealing member shown in FIG.


8


.





FIG. 10

is a cross sectional view along the line


10





10


in FIG.


9


.





FIG. 11

is an exploded perspective view for illustrating the structure shown in FIG.


9


and FIG.


10


.





FIG. 12

is a plan view for illustrating the vicinity of a sealing member and a charging hole in another embodiment of the display apparatus of the present invention.





FIG. 13

is a cross sectional view along the line


13





13


in FIG.


12


.





FIG. 14

is a perspective view for illustrating the sealing member and O-ring shown in FIG.


13


.





FIG. 15

is a diagram for illustrating another embodiment of the display apparatus of the present invention.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Preferred embodiments of the present invention will be described in detail with reference to the drawings.




Because the embodiments described hereinafter are detailed examples of the present invention, though the embodiments are described with various technically preferable restrictions, the scope of the present invention is by no means limited to these embodiment unless otherwise specified to limit the present invention in the description hereinafter.





FIGS. 5

to


12


show a preferred embodiment of the present invention. A display apparatus


10


shown in

FIG. 5

is a so-called back projection display apparatus, which projects the projection light


16


of an image to the back side


14


of a screen


12


.




The display apparatus


10


is provided with a cabinet


20


, a signal generation unit


22


disposed in the cabinet


20


, cathode ray tubes (CRT)


30


,


32


, and


34


, a cooling mechanism


40


, and the screen


12


.




The cathode ray tubes


30


,


32


, and


34


are cathode ray tubes of the same type, and the cathode ray tube


30


forms a red (R) image, the cathode ray tube


32


forms a green (G) image, and the cathode ray tube


34


forms a blue (B) image. In other words, these cathode ray tubes


30


,


32


, and


34


form monochromatic images respectively, and form an overlapped color image on the screen


12


.




The cooling mechanism


40


in

FIG. 6

is provided to cool the cathode ray tubes


30


,


32


, and


34


, and disposed between the cathode ray tubes


30


,


32


, and


34


and projection lenses


50


,


52


, and


54


.




The projection lenses


50


,


52


, and


54


shown in

FIG. 6

project the respective color images formed by the cathode ray tubes


30


,


32


, and


34


on an image forming area


12


A on the screen


12


to form a color image.




In

FIG. 6

, the cathode ray tube


32


is disposed in the perpendicular direction to the screen


12


, and the cathode ray tube


30


and the cathode ray tube


34


are disposed with an inclination angle θ respectively. The cathode ray tubes


30


,


32


, and


34


are viewed overlapped in the side view as shown in FIG.


7


and

FIG. 5

, and the cathode ray tubes


30


,


32


, and


34


are viewed separately with an angle θ in the top view as described herein above as shown in FIG.


6


.





FIG. 8

shows the cathode ray tube


30


(


32


and


34


) in FIG.


6


and one example of a cooling mechanism


40


. Because the cathode ray tubes


30


,


32


, and


34


have the same structure, the structure of the cathode ray tube


30


is described as an example. The cathode ray tube


30


has a panel


60


and funnel


62


, and the funnel


62


is provided with an electron gun not shown in the drawing.




Based on a signal supplied from the signal generation unit


22


in

FIG. 5

, the electron gun forms an image on the panel


60


side in the normal manner.




The cooling mechanism


40


is disposed facing to the panel


60


and the side


63


of the funnel


62


. The cooling mechanism


40


is a component for cooling preferably the front face of the cathode ray tube


30


, namely the panel


60


and preferably the side


63


of the side member of the cathode ray tube


30


, namely the funnel


62


. The cooling mechanism


40


has a metal box


42


and a front panel


44


, and has a structure having a sealed space for containing cooling liquid


70


between the metal box


42


and the front panel


44


, and the front panel


44


and the metal box


42


form a cooling liquid container


72


.




For charging cooling liquid into the cooling liquid container


72


, cooling liquid is charged from a charging hole


74


formed on the metal box


42


. A sealing member


76


is inserted into the charging hole


74


to plug the charging hole after cooling liquid


70


is charged in the cooling liquid container


72


so that the cooling liquid


70


in the cooling liquid container


72


does not leak to the outside.




The metal box


42


in

FIG. 8

, the charging hole


74


, the sealing member


76


, and their vicinities are shown enlarged in FIG.


9


and FIG.


10


. On the end


42


A of the metal box


42


, for example, a circular hole


42


B is formed. The size of the hole


42


B is larger than the size of the sealing member


76


. A plurality of grooves


78


are preferably formed between the hole


42


B and the charging hole


74


.





FIG. 11

shows the grooves


78


, the charging hole


74


, the sealing member


76


, and an O-ring


80


.




The grooves


78


comprise four grooves formed, for example, with a 90 degree phase interval, and the grooves


78


are communicated to a circular groove


82


having a size for accepting the head


76


A of the sealing member


76


. In other words, four grooves


78


extend radially from the circular groove namely ring groove


82


, and the grooves


78


and the groove


82


form a residual cooling liquid discharge outlet


90


.




The grooves


78


are disposed along two orthogonal straight lines L


1


and L


2


.




On the inside surface of the charging hole


74


, a female thread


74


A is formed.




The sealing member


76


shown in

FIG. 11

has a head


76


A and a male thread


76


B. On the head


76


A, for example, a tool hole


76


C for accepting a cruciate tool is formed.




The male thread


76


B of the sealing member


76


is screwed into the female thread


74


A of the charging hole


74


with interposition of the O-ring


80


. Thereby, as in

FIG. 10

, the O-ring


78


ensures sealing between the bottom of the head


76


A of the sealing member


76


and the inside bottom


87


of the metal box


42


so that cooling liquid


70


does not leak from the inside of the metal box


42


shown in

FIG. 8

to the outside through the charging hole


74


. The O-ring is preferably made of material which maintains its durability and elasticity in the cooling liquid


70


.




The residual cooling liquid discharge outlet


90


shown in

FIG. 11

is provided to discharge cooling liquid


70


A shown in

FIG. 10

to the outside easily and consistently. In detail, the residual cooling liquid discharge outlet


90


is structured so that needless cooling liquid


70


A which is residual in the space between the bottom of the head


76


A of the sealing member


76


, the inside bottom


87


, and the O-ring


80


is discharged to the outside along the direction of the arrow A shown in FIG.


10


.




Next, cooling liquid charging work into the cooling mechanism


40


of the above-mentioned display apparatus


10


, removing work of needless cooling liquid


70


A, and an exemplary use of the display apparatus


10


shown in

FIG. 5

are described. The cooling mechanism


40


shown in FIG.


5


and

FIG. 8

is disposed on the panel


60


side of the cathode ray tube


30


. Cooling liquid


70


is charged into the cooling liquid container


72


though the charging hole


74


for filling. After the filling, the male thread


76


B of the sealing member


76


is screwed into the female thread


74


A of the charging hole


74


shown in FIG.


10


. In this case, the O-ring


80


is placed between the head


76


A and the inside bottom


87


. Thereby, the sealing member


76


and the O-ring


80


function to prevent cooling liquid


70


in the cooling liquid container


72


shown in

FIG. 8

from leaking through the charging hole


74


.




During the charging work described herein above, needless cooling liquid


70


A remains on the bottom of the head


76


A of the sealing member


76


shown in

FIG. 10

, near the inside bottom


87


, and near the O-ring


80


. In the case that ethyleneglycol is used as the cooling liquid


70


, the needless cooling liquid


70


A is dissolved, for example, in water easily by charging water from the outside. By blowing high pressure air against the mixture of the residual cooling liquid and water, the needless cooling liquid


70


A is blown away with water to the outside along the direction of the arrow A.




As described herein above, by providing the plurality of grooves


78


and the groove


82


of the residual cooling liquid discharge outlet


90


, needless cooling liquid, which is confined in the inside conventionally, is discharged to the outside completely prior to fabrication work. Therefore, cooling liquid will not leak consistently from the product later.




In the fabricated display apparatus shown in

FIG. 5

, the cathode ray tubes


30


,


32


, and


34


project R, G, and B images respectively onto the image forming area


12


A of the screen


12


through the lenses


50


,


52


, and


54


in

FIG. 6

when signal image forming signals are transmitted from the signal forming unit


22


. Thereby, a dynamic or static color image is formed on the screen


12


. In this case, because the panel


60


which is the front side of the cathode ray tubes


30


,


32


, and


34


shown in FIG.


8


and the side vicinity


63


of the funnel


62


are cooled, the operation of the respective cathode ray tubes


30


,


32


, and


34


is stabilized, and also heat is prevented from being enclosed in the cabinet shown in FIG.


5


.




Next, FIG.


12


and

FIG. 13

show another embodiment of the display apparatus of the present invention wherein, particularly FIG.


12


and

FIG. 13

correspond to FIG.


9


and

FIG. 10

of the previous embodiment respectively. The same components shown in FIG.


12


and

FIG. 13

as those shown in FIG.


9


and

FIG. 10

are given the same characters, and the description is omitted.




In the embodiment shown in FIG.


12


and

FIG. 13

, the shape of the residual cooling liquid discharge outlet


190


is different from the residual cooling liquid discharge outlet


90


shown in FIG.


9


and FIG.


10


. In detail, the residual cooling liquid discharge outlet


190


in

FIGS. 12 and 13

has grooves


178


formed on the bottom of the head


176


A of the sealing member


176


. The grooves


178


are components for discharging residual cooling liquid


70


A. The needless residual cooling liquid


70


A in a space defined by the bottom of the head


176


, the O-ring, inside bottom


87


, and side


99


is discharged to the outside in the direction of the arrow A or through the plurality of grooves


178


in the same manner as described hereinbefore.




As shown in FIG.


12


and

FIG. 14

, the grooves


178


are formed radially with a 90 degree interval on the bottom of the head


176


A. The head


176


A has a tool hole


176


C for accepting a cruciate tool.





FIG. 14

shows the sealing member


176


and the O-ring


80


. The sealing member


176


has the head


176


A and a male thread


176


B. The male thread


176


B is screwed into the female thread


74


A of the charging hole


74


shown in FIG.


13


.




The display apparatus


10


shown in

FIG. 5

is a display apparatus of so-called back projection type which projects projection light


16


onto the back side


14


of the screen


12


. On the other hand, the display apparatus shown in

FIG. 15

is a so-called front face projection type display apparatus


110


which projects projection light


16


of an image onto the front face (front side) of the screen


112


. In the display apparatus


110


, the cooling mechanism and the sealing member described hereinbefore in the embodiment of the present invention may be used.




The present invention is by no means limited to the above-mentioned embodiments.




In the above-mentioned embodiments, the case that a color image is obtained using arranged three monochromatic cathode ray tubes is described, the present invention is by no means limited to such case. Alternatively, a cathode ray tube which projects R, G, and B color image light onto a screen from a single cathode ray tube may be used. The cooling mechanism can be applied to such cathode ray tube. The thread type sealing member is employed, but the present invention is by no means limited to the type. Alternatively the type in which a sealing member is fitted with a pressure simply, instead of screwing, may be used to prevent cooling liquid from leaking.



Claims
  • 1. A display apparatus for projecting and displaying an image displayed on a cathode ray tube and for cooling said cathode ray tube with cooling liquid comprising:a cooling liquid container for containing cooling liquid for cooling said cathode ray tube; a sealing member for sealing cooling liquid in said cooling liquid container by plugging a cooling liquid charging hole formed on said cooling liquid container after cooling liquid is charged into said cooling liquid container; and a residual cooling liquid discharge outlet provided with connection to said sealing member and said cooling liquid container for discharging residual cooling liquid in a space between said sealing member and said cooling liquid container to the outside through the space between said sealing member and said cooling liquid container.
  • 2. A display apparatus as claimed in claim 1, wherein said residual cooling liquid discharge outlet is a groove formed on said cooling liquid container.
  • 3. A display apparatus as claimed in claim 1, wherein said residual cooling liquid discharge outlet is a groove formed on said sealing member.
  • 4. A display apparatus as claimed in claim 2, wherein said sealing member has a male thread and has a head provided on the end of said male thread, and a female thread for accepting said male thread of said sealing member is formed on said cooling liquid container.
  • 5. A display apparatus as claimed in claim 3, wherein said sealing member has a male thread and has a head provided on the end of said male thread, and a female thread for accepting said male thread of said sealing member is formed on said cooling liquid container.
  • 6. A display apparatus as claimed in claim 1, wherein cooling liquid contained in said cooling liquid container cools the front and side faces of said cathode ray tube.
  • 7. A display apparatus as claimed in claim 1, wherein said display apparatus is provided with the first cathode ray tube for projecting a red image, the second cathode ray tube for projecting a green image, and the third cathode ray tube for projecting a blue image, and images projected by said cathode ray tubes are projected onto a target through projection lenses.
  • 8. A display apparatus as claimed in claim 1, wherein an image projected from a cathode ray tube is projected onto a target on the back side of a screen namely a target.
  • 9. A display apparatus as claimed in claim 1, wherein an image projected from a cathode ray tube is projected onto a target on the front side of a screen namely a target.
Priority Claims (1)
Number Date Country Kind
10-031485 Feb 1998 JP
US Referenced Citations (3)
Number Name Date Kind
4777532 Hasegawa Oct 1988 A
5409337 Muyskens et al. Apr 1995 A
5877583 Meglio et al. Mar 1999 A
Foreign Referenced Citations (2)
Number Date Country
2-177228 Jul 1990 JP
6-89656 Mar 1994 JP