Abstract:
A video shield for a monitor is disclosed, which includes a video shield engaged at a rear end portion of the electron gun and having a predetermined shaped through hole through which the electron gun passes and having a plurality of snap holes formed around the through hole, a bracket being separable from the video shield wherein a circle hole is formed at a portion corresponding to the through hole, a plurality of displaceable distal members are formed on an inner surface of the circle hole at a certain distance from each other and are protruded in the front direction and pass through the through hole and surrounds an outer surface of the electron gun, and a plurality of snap members are protruded at a portion neighboring with the circle hole and are engaged with the snap holes, a first means for fixing the video shield at the electron gun by pressing the outer surfaces of the displaceable distal members at an outer surface of the electron gun by a snap method, and a second means for stably fixing the video shield at the electron gun by generating a certain friction force between an outer surface of the electron gun and the inner surfaces of the displaceable distal members in the case that the video shield is detachable in the interiors of the displaceable distal members, for implementing a simpler assembling process and decreasing an assembling time based on a snap method.

Description:
CLAIM OF PRIORITY 
     This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for VIDEO SHIELD FOR MONITOR earlier filed in the Korean Industrial Property Office on the 13 th  of February 1999 and there duly assigned Ser. No. 5278/1999. 
     BACKGROUND OF THE INVENTION 
     1 . Field of the Invention 
     The present invention relates to a video shield for a monitor, and in particular to a video shield for a monitor, the video shield easily assembled at and disassembled from the monitor. 
     2. Description of the Background Art 
     Video shields are used in a monitor. Typically, the video shield is mounted on the electron gun of the cathode ray tube (CRT) of the monitor. The monitor is directed to display a certain character, symbol, graphic, etc., on the screen of the cathode ray tube by amplifying a video signal from a printed circuit board and emitting on electron beam from an electron gun of the cathode ray tube. Electromagnetic waves are generated from the electron gun during operation of the cathode ray tube. An external shock may cause damage to the cathode ray tube of the monitor. Therefore the video shield is sometimes used to shield the electromagnetic waves and prevent any external shock to the cathode ray tube. 
     We have noticed, however, that in conventional electron guns and video shield structures, a plurality of screws are used for attaching the bracket to the front casing, and a clamp is tightened with threaded fasteners. In addition, since surface tape may be attached on the outer surface of the electron gun, the assembly is complicated, and the assembly time is substantial. Moreover, conventional apparatus and techniques are not adequate to absorb and reduce the force exerted by an external shock to the election gun. Furthermore, we have found that during the process of fixing the bracket at the front casing and displaceable distal member, tightening the screws may cause damage to the election gun of the cathode ray tube. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved apparatus and process able to shield electromagnetic waves generated by a cathode ray tube. 
     It is another object to provide an apparatus and process able to prevent an external shock to an electron gun of a cathode ray tube. 
     It is yet another object to provide an apparatus for providing a video shield suitable for easy installation during assembly of a monitor. 
     It is still another object to provide an improved video shield for decreasing that decreases the assembly time of the video shield and a cathode ray tube. 
     It is still yet another object to provide an improved video shield able to absorb an external shock applied to an electron gun. 
     These and other objects may be achieved by providing a video shield for a monitor that includes a front cover, a cathode ray tube engaged to a rear surface of the front cover, and has an electron gun mounted an end portion of the cathode ray tube. The video shield unit is engaged at a rear end portion of the electron gun and includes a snap ring, a rubber collar, a front casing, a bracket, a printed circuit board with a socket, and a rear casing. The front casing includes a shaped through hole through which the electron gun passes and a plurality of snap holes formed around the through hole. The bracket that is separable from the video shield and a circular hole is formed at a portion of the front casing corresponding to the through hole and includes a plurality of displaceable distal members formed on an inner surface of the circular hole at a spaced apart from each other and protruding in a frontal direction, passing through the through hole and surrounding an outer surface of the electron gun. A plurality of snaps protrude from snap holes formed around the circular hole and engage the snap holes. The shield includes snap ring tightening the video shield at the electron gun by pressing the outer surfaces of the displaceable distal members at an outer surface of the electron gun and a rubber collar the video shield at the electron gun by generating a friction force between an outer surface of the electron gun and the inner surfaces of the displaceable distal members so that the video shield is detachable from the interiors of the displaceable distal members. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
     FIG. 1 is an exploded perspective view illustrating an inner structure of a video shield; 
     FIG. 2 is a cross-sectional view illustrating a structure of a video shield attached to a cathode ray tube; 
     FIG. 3 is an exploded perspective view illustrating an inner structure of a video shield constructed according to the principles of the present invention; 
     FIG. 4 is a cross-sectional view illustrating a structure with a video shield engaging an end portion of a cathode ray tube according to the principles of the present invention; 
     FIG. 5 is a partially cut-away and enlarged perspective view illustrating the assembled state of a video shield according to the present invention; 
     FIG. 6 is a perspective view illustrating a silicon rubber collar constructed according to the principles of the present invention; 
     FIG. 7 is a perspective view illustrating an open snap ring constructed according to the principles of the present invention; and 
     FIG. 8 is a schematic view illustrating the closure of an elastic portion of a snap ring during an assembly process according to the principles of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Turning now to the drawings, FIG. 1 is an exploded perspective view illustrating an inner structure of a shield, and FIG. 2 is a cross-sectional view illustrating a structure that a video shield is engaged at a cathode ray tube. 
     As shown therein, a monitor  1  includes a front cover  2 , a cathode ray tube  3  engaged with inner back surface of the front cover  2 , an electronic gun  4  engaged with a rear portion of the cathode ray tube  3  that emits electron beams, a video shield  5  positioned at an end portion of the electron gun  4 , and a rear cover (not shown) integrally engaged with a rear portion of the front cover  2 . A plurality of neck pins  14  are installed at an end portion of the electron gun  4  for receiving video signals, and a surface tape  4   a  is wrapped around an outer surface of the electron gun  4 . In addition, the video shield  5  includes a rear casing  7  integrally engaged with the front casing  6 , and a video printed circuit board  8  positioned within an inner space formed between the front and rear casings  6  and  7 . 
     The front casing  6  is formed in a rear side opened box shape, and a through hole  9  having a certain shape is formed at one side of casing  6 , and a plurality of first holes  11  for fasteners are formed around through hole  9 . A plurality of holes  10  perforate casing casings  6 ,  7  for air ventilation. A socket  12  is formed on an upper surface of the video printed circuit board  8 . This socket  12  is cylindrical, and a plurality of holes  13  are formed at one surface of the socket  12 . Therefore, a plurality of connecting pins  14  of the electron gun  4  pass through the through hole  9  and are inserted into the holes  13  of the socket  12 . When the video shield  5  is engaged to the electron gun  4  in the interior of the video shield  5 , the video shield  5  is held against the electron gun  4  with a bracket  16 . 
     The bracket  16  has a certain shape structure similar to the through hole  9  of the front casing  6 , and a circular hole  17  is formed on an upper portion of bracket  16 . A plurality of displaceable displaceable distal members  18  are formed on an inner surface of the circular hole  17  at a certain distance from each other extend axially outwardly from hole  17  and toward through hole  9 . A plurality of second holes  19  for fasteners are formed at a certain portion of the bracket  16 . 
     Bracket  16  is integrally engaged at a back surface of the front casing  6  in such a manner that engaging screws  20  pass through the first engaging holes  11  of the front casing  6  and the second engaging holes  19  of the bracket  16  and are engaged. The displaceable distal members  18  pass through the through hole  9  of the front casing  6  and protrude in the front direction. Therefore, when the displaceable distal members  18  are inserted into the socket  12  of the video printed circuit board  8  via the circular hole  17  of the bracket  16 , the displaceable distal members contact an outer surface of the electron gun  4 . 
     A clamp  21  is used for pressing and fixing the displaceable distal member  18  at the outer surface of the electron gun  4  after the electron gun  4  is engaged to the socket  12 . The clamp  21  is formed in the shape of an omega “Ω”. An engaging hole  22  is formed at both ends of the clamp  21 , respectively. The engaging screw  23  passes through the engaging hole  22  and is engaged with a nut  24 . Elastic distally extending members  18  contact the outer surface of the electron gun  4  screw  23  is tightened after the clamp  21  encircles with the outer surfaces of the displaceable distal members  18  thereby attaching the video shield at the electron gun  4 . The surface tape  4   a  is wound around an outer surface of the electron gun  4 , and the inner surfaces of the elastic plates  18  contact the surface tape  4   a  based on a certain force, so that the video shield  5  is securely mounted upon the electron gun  4 . 
     The embodiments of the present invention will be explained with reference to the accompanying drawings, beginning with FIG. 3, which illustrates an inner structure of the monitor in which a video shield is engaged according to the present invention, and FIG. 4 is a cross-sectional view illustrating a structure with a video shield engaged at an end portion of the cathode ray tube. 
     Monitor  51  includes a front cover  52 , a cathode ray tube  53  engaged at a rear portion of the front cover  52 , an electron gun  54  engaged at an end portion of the cathode ray tube  53  for emitting electron beams, a video shield  55  engaged at an end portion of the electron gun  54  for shielding electromagnetic waves and preventing damage to the electron gun due to externally applied forces, and a rear cover (not shown) integrally engaged at a rear portion of the front cover  52 . A plurality of neck pins  64  protrude from an end portion of the electron gun  54  and serve as electrical conductors for receiving video signals. 
     The video shield  55  includes a front casing  56 , a rear casing  57  integrally engaged with the front casing  56 , a video printed circuit board  58  engaged in the interior space when the front and rear casings  56  and  57  are engaged, and a bracket  66  fixing the video shield  55  at the electron gun  54  when the video shield  55  is engaged at the electron gun  54 . The front casing  56  is formed in a box shape having an end portion opened. A through hole  59  having a certain shape is formed at one side of the same. In addition, a plurality of snap holes  61  are formed around the through hole  59 . 
     A cylindrical socket  62  is formed on an upper surface of the video printed circuit board  58 . A plurality of pin holes  63  are formed on one surface of socket  62 . Neck pins  64  of the electron gun  54  are inserted into the pin holes  63 . 
     Bracket  66  has a shape similar to the through hole  59  in the front casing, and circular hole  67  is formed on the upper portion of bracket  66 . A plurality of displaceable distal members  68  are formed on an inner surface of the circular hole  67  to extend a certain distance toward front casing  56 . A certain displaceable distal member  68  among a plurality of displaceable distal members  68  has an engaging shoulder portion  99  extending from an outer end portion of the displaceable distal member  68 . In addition, a plurality of snap members  69  are installed at a certain portion of the bracket  66 . The snap members  69  protrude from one side of the bracket  66 , and each end portion of each of the snap members  69  is curved in the vertical direction and is formed parallel to one surface of bracket  66 . 
     As shown in FIG. 5, when the bracket  66  is engaged to the front casing  56 , the snap members  69  of bracket  66  are inserted into the snap hole  61  of the front casing  56 . The snap members  69  are inserted into the snap hole  61  by rotating the bracket in the counterclockwise direction at a certain angle. Therefore, the bracket  66  is integrally engaged at the rear surface of the front casing  56 . When removing bracket  66  from the front casing  56 , the bracket  66  is rotated in the clockwise direction for thereby escaping the snap members  69  from the snap hole  61 , so that the bracket  66  is separated from the front casing  56 . 
     As shown in FIGS. 3 and 4, when the bracket  66  is attached to the front casing  56 , a plurality of displaceable distal members  68  pass through the through hole  59  in the front casing  56  and protrude beyond through hole  59  by a certain distance. Therefore, the electron gun  54  passes through the through hole  59  in the front casing  56  and a plurality of displaceable distal members  68 , and socket  62  of the video printed circuit board  58  and the inner surface of displaceable distal member  68  surround the neck of electron gun  54 . 
     A snap-action adjustable ring  80  is positioned on an outer surface of the displaceable distal members  68  for tightening displaceable distal members  68  against the outer surface of the electron gun  54  to attach the video shield  55  to the electron gun  54  when the electron gun  54  passes between displaceable distal members  68  and is engaged with the socket  62 . 
     As shown in FIGS. 7 and 8, the snap ring  80  includes a band  83  having a ring shape, an elastic portion  84  rotatably connected with a first end portion  81  of the band  83 , and an engaging portion  85  rotatably engaged at a second end portion  82  of the band  83  and connected with the elastic portion  84 . The band  83  is made of elastic material and includes first and second rectangular holes  87  and  86  formed at the first and second end portions  81  and  82 . In addition, a rectangular groove  88  is formed at a circumferential portion of the band  83 . 
     The engaging portion  85  includes a ring shaped end portion  89  that is rotatably connected at a portion of the second rectangular hole  86  formed at the second end portion  82  of the band  83 . In addition, the other end portion  90  opposite to end portion  89  curved at a certain angle is a free end and operates as a handle. An intermediate portion  85   a  between end portion  89  and the other end portion  90  is cut in order to form an arcuate protrusion  91  that passes through opening  95  and loosely engages end portion  93 . A second end portion  93  of the displaceable distal member  84  is connected to the engaging protrusion  91 . 
     The displaceable distal member  84  is formed in an inverted U shape. The first end portion  92  is a ring-shaped end portion  94  which is rotatably connected to a portion of the first rectangular hole  87  of the first end portion  81  of the band  83 . In addition, a rectangular hole  95  is formed at the second end portion  93  opposite to the first end portion  81 . The rectangular portion  95  engages the protrusion  91  of the portion  85 . Therefore, the displaceable distal member  84  is connected to the band  83  and the engaging portion  85 . When the engaging portion  85  is pressed in the direction of a first arrow  96 , the first and second end portions  92  and  93  which are initially spaced-apart, are drawn closer to each other. Therefore, the displaceable distal member  84  may allow the band  83  to engage the electron gun  54  with a diameter that is different from that of the electron gun  54  by a certain range. Namely, when a band is tightened to an element having a diameter larger than the diameter of the band, since the first and second end portions  92 ,  93  of the displaceable distal member  84  are spaced-apart by a certain distance based on the diameter of the band  83 , so that it is possible for the band to tighten the element. 
     The engaging portion  85  is pressed in the direction of a first arrow  96 , the end portion  89  of the engaging portion  95  pulls the second end portion  82  of the band  83  in the direction of a second arrow  97 . The intermediate portion  85   a  pulls the second end portion  93  of the displaceable distal member  84  is a direction of a third arrow  98 . Therefore, when both ends of the displaceable distal member  84  are spaced-apart by a certain distance, the second end portion  93  of the displaceable distal member  84  presses the engaging portion  85 , so that the engaging portion  85  elastically contacts the outer surface of the band  83 . 
     Therefore, the band  83  of the snap ring  80  tightens against an outer surface of the displaceable distal member  68  when the engaging portion  85  is pressed in the direction of first arrow  96  and the snap ring  80  engages the displaceable distal member  68  as is shown in FIG.  5 . 
     At this time, the groove  88  formed at the band  83  engages one displaceable distal member  68  shown in FIG. 5 among the displaceable distal members, and prevents a free rotation of the snap ring  80  on an outer surface of the displaceable distal member  68  shown in FIG.  5 . In addition, the snap ring  80  engages the engaging shoulder portion  99  formed at an end portion of the displaceable distal member  68  as shown in FIG. 5, so that it is possible to prevent the snap ring  80  from slipping from the displaceable distal member  68 . 
     As shown in FIGS. 3 and 4, the rubber collar  70  serves as a shock absorber, a buffer, and a damper by engaging the interior of the through hole  59  of the front casing  56 . When the rubber collar  70  is inserted in the circular hole  67  of the bracket  66 , the rubber collar  70  is positioned between an outer surface of the electron gun  54  and an inner surface of the displaceable distal member  68 , so that the video shield  55  is stably positioned around the outer surface of the electron gun  54 . As shown in FIG. 6, the rubber collar  70  can be made of silicone. Therefore, the shape of the rubber collar  70  may be changed within a certain range and has a certain friction coefficient. The rubber collar  70  includes a cylindrical body  71 , and first and second flanges  72  and  73  extended from each circumferential surface of the openings  74  of the cylindrical body  71 . 
     As shown in FIG. 5, when the rubber collar  70  engages the interior of the displaceable distal members  68 , the first flange  72  is positioned at a rear surface of the bracket  66 , and the cylindrical body  71  passes through the interiors of the displaceable distal members  68 , and the second flange  73  is supported by the end portions of the displaceable distal members  68 . When the snap ring  80  contacts with the outer surfaces of the displaceable distal members  68 , the displaceable distal members  68  press the rubber collar  70 . Since the rubber collar  70  presses an outer surface of the electron gun  54 , the video shield  55  is stably fixed at the electron gun  54 . 
     The operation of the video shield according to the present invention will be explained by reference to FIGS. 3,  5  and  7 . When a user attaches the video shield  55  to the electron gun  54  of the cathode ray tube  53 , bracket  66  is first attached to a rear surface of the front casing  56 . Namely, the snap members  69  of the bracket  66  are inserted into the snap holders  61  of the front casing  56  and are rotated in a counterclockwise direction by a certain angle, and bracket  66  integrally engages a rear surface of the front casing  56 . At this time, the displaceable distal members  68  of the bracket  66  extend through the through hole  59  of the front casing  56  by a certain distance. 
     After the bracket  66  engages the front casing  56 , the rubber collar  70  is inserted into the inside of the displaceable distal members  68 . Therefore, the first flange  72  of the rubber collar  70  contacts with the rear surface of the bracket  66 , and the cylindrical body  71  of the rubber collar  70  contacts with the inner surfaces of the displaceable distal members  68 , and the second flange  73  engages an end portion of the displaceable distal member  68 . 
     After the snap ring  80  is inserted onto the displaceable distal members  68  via the second flange  73  and the engaging portion  85  of the snap ring  80  does not engage the band  83 , the openings  74  of the rubber collar  70  are arranged to engage the electron gun  54 , and the video shield  55  is pushed in the direction of the electron gun  54 . The video shield  55  is pushed by a certain force until the neck pins  64  engage socket  62  of the video printed circuit board  58 . When the neck pins  64  of the electron gun  54  fully engage pin holes  63  of socket  62 , groove  88  formed in the periphery of one side of band  83  of the snap ring  80  is inserted onto engaging shoulder portion  99  formed on a corresponding displaceable distal member  68  among a plurality of the displaceable distal members  68 . This prevents free rotation of the snap ring  80  against the outer surface of the elastic plate  68 . 
     When the engaging portion  85  is pushed in the direction of first arrow  96 , one end  89  of the engaging portion  85  pulls the second end portion  82  of the band  83  in the direction of second arrow  97 . At the same time, the intermediate portion  85   a  pulls the second end portion  93  in the direction of third arrow  98 . Therefore, when both ends  92  and  93  of the displaceable distal member  84  are spaced-apart from each other by a certain distance based on the diameters of the displaceable distal members  68 , the second end portion  93  of the displaceable distal member  84  presses the engaging portion  85 , so that the engaging portion  85  elastically contacts the outer surface of the band  83 . Since both ends of the elastic portion  84  are easily deformable by a certain distance, various diameters of electron guns may be adaptable. Therefore, the snap ring  80  tightens the displaceable distal members  68 , and the displaceable distal members  68  press the rubber collar  70  and is stably positioned around an outer surface of the electron gun  54 . As a result, the video shield  55  is integrally attached to an end portion of the electron gun  54 . 
     As described above, with the video shield of the monitor according to the present invention, the bracket is engaged at the front casing of the video shield by the snap-action, and the video shield is connected to the electron gun by using the snap ring placed around the silicone rubber, so that it is possible to implement a simpler assembly line process while decreasing the time, required for assembly. Moreover, snap ring having an elastic portion and an engaging portion tightens the shield on the electron gun without giving too much tension to the electron gun and breaking the neck of cathode ray tube. Furthermore, the absorber formed in a single body absorbs the external shock and provide an implementation of a simpler assembly line process.