US3146305A

US3146305A - Cathode ray tube protective front panel device

Info

Publication number: US3146305A
Application number: US159315A
Authority: US
Inventors: Anthony T Monaco; Richard S Sobie
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 1961-12-14
Filing date: 1961-12-14
Publication date: 1964-08-25
Anticipated expiration: 1981-08-25

Description

8- 1964 A. T. MONACO ETAL 3,146,305

CATHODE RAY TUBE PROTECTIVE FRONT PANEL DEVICE Filed Dec. 14. 1981 INVENTOR. Anthony T. Monaco Richard S. Sobie 14% (M United States Patent Office 3,146,305 Patented Aug. 25, 1964 3,146,305 CATHODE RAY TUBE PROTECTIVE FRONT PANEL DEVICE Anthony T. Monaco, Skokie, and Richard S. Sobie, Glen Ellyn, Ill., assignors to Motorola, Inc., Chicago, 11].,

a corporation of Illinois Filed Dec. 14, 1961, Ser. No. 159,315 3 Claims. (Cl. 178-732) This invention relates generally to cathode ray tubes and more particularly to a protective front panel for a cathode ray tube.

Many devices, such as Oscilloscopes and television receivers employ cathode ray tubes, the proper operation of which requires evacuation of the interior of the tubes. Because of the virtual vacuum inside these tubes, rupture of the glass shell may cause a sudden and violent shattering of the tube with resultant flying glass.

To protect a viewer from injury in the event of such an occurrence, these devices are generally provided with a protective cover of transparent material over the face of the tube. One method of doing this is to bond a transparent cover directly to the outer surface of the oathode ray tube screen. Such procedure however, is expensive and necessitates replacement of the protective cover every time the picture tube is replaced. Another method of guarding against implosion forces is to provide a transparent cover mounted over the face of the cathode ray tube and separated therefrom to leave a space between. Because of the violence of implosion forces, such an arrangement has required the use of relatively thick glass or other transparent material, which may be expensive. Furthermore, an effective seal must be provided to prevent moisture and dust from entering the space between the screen and the cathode ray tube which might cause deterioration of viewing quality.

An object of this invention is to provide an implosion guard for a cathode ray tube which is low in cost.

Another object of this invention is to provide an improved implosion guard for a cathode ray tube which is readily separable from the tube.

It is a further object of this invention to provide a removable implosion guard for a cathode ray tube, with an effective seal against the entrance of moisture and dust into the dead air space between the implosion guard and the cathode ray tube.

Another object of this invention is to permit the use of a relatively thin protective transparent panel for a cathode ray tube.

A feature of the invention is the provision of a mounting gasket of dual tubular construction surrounding the periphery of a transparent implosion panel for effectively floating the panel over the viewing face of a cathode ray tube.

A further feature of the invention is the provision in the first mentioned feature of a resiliently mounted flexible frame member for holding the gasket against the periphery of the face of the picture tube to aid absorption of implosion forces.

Another feature of the invention is the provision in the above-mentioned gasket of serrations along the bearing surfaces of the gasket to facilitate the gripping and sealing functions.

In the drawing:

FIG. 1 is a perspective view of a cathode ray tube and support frame utilizing the invention;

FIG. 2 is a perspective view of a television receiver in which the invention may be used;

FIG. 3 is a cross-sectional view of the gasket as shown in FIG. 4, but in unassembled relationship; and

FIG. 4 is a sectional view along the line 4-4 of FIG. 2.

In brief the invention includes a gasket of resilient material, preferably polyvinyl chloride, stretched to fit about the outer edge of a glass protective panel. The gasket is held on the panel by means of a channel provided in the gasket which receives the edge of the panel therein. The gasket contains two hollow tubular portions, continuous throughout, which are formed on either side of the channel. The panel and gasket are held over the viewing face of a cathode ray tube by means of a flexible frame and resilient mounting. The frame fits over the gasket applying pressure thereto so that the gasket provides an effective seal for the space between the transparent panel and the viewing face of the picture tube. When the gasket and panel are held against the tube in this manner, one of the tubular portions is disposed between the transparent panel and the viewing face of the tube, and the other tubular portion is disposed between the frame and the transparent panel. Thus, the gasket provides a cushion of air on either side of the transparent pane, effectively floating the panel in front of the tube to form a resilient implosion guard that will absorb implosion forces while at the same time reduce the required thickness of the glass panel.

Referring to FIG. 1, a cathode ray tube 11 is mounted on a chassis frame 13 by means of a mounting assembly 15. Chassis frame 13 may have mounted thereon a chassis containing various electrical circuit elements for the apparatus in which tube 11 is used. Mounting assembly 15 includes a strap or support member 17, on which the bottom of tube 11 bears. Also included in mounting assembly 15 is side member 21 which is clipped to openings 23 in support member 17 by tabs 25. Side member 21 is secured to chassis frame 13 by screws 26, the opposite side of assembly 15 being identical. A band or strap 27 extends across the top of tube 11 and secures the tube against support member 17 by means of screw 29 extending through bearing portion 31 on strap 27, and threaded into tapped bracket 33 on side member 21. An identical arrangement is used on the opposite side of tube 11.

With this arrangement, tube 11 is secured to chassis frame 13 as follows. The tube is placed so that the bottom rests on support member 17, which is suspended from side member 21 by tabs 25 clipped in openings 23. Side member 21 is fastened to chassis frame 13, as is the corresponding member on the opposite side of tube 11. Thus, tube 11 is at this point suspended from chassis frame 13. Screw 29, and its opposite, are then tightened, causing strap 27 to force tube 11 down on support member 17, placing the viewing face of tube 11 in compression for added strength. Finally, support member 17 is secured to chassis frame 13 with a threaded fastener through bracket 19, and with an identical means on the opposite side.

The general appearance of tube 11 as viewed from the outside of a typical device in which it is used, e.g. a television receiver, is depicted in FIG. 2. Receiver cabinet 35 has on the exterior thereof an escutcheon plate 36, controls 37, and a grill cloth covered opening 39 for a loudspeaker. T.e screen of tube 11 is visible through transparent implosion panel 41, with the viewing face being framed by a bezel 42.. As may be seen from this view, it is necessary that implosion panel 41 be sufliciently strong to withstand implosion forces to reduce the likelihood of a viewer being struck by flying glass. Panel 41 may be made of tempered glass curved to follow the contour of the viewing face of tube 11.

Implosion panel 41 is mounted over the face of cathode ray tube 11 by means of a flexible frame 43. Flexibility of frame 43 aids in providing a cushioning effect for implosion panel 41 in the event of implosion of tube 11. Frame 43 is secured on both sides to chassis frame 13 by bracket portions 45. Frame 43 is secured to mounting assembly 15 at the top thereof by means of a resilient spring 47 captured in clip 49 which is attached to frame 43, and also captured behind stop portions 51 on the mounting assembly. The bottom is resiliently mounted in identical fashion. Such an arrangement furthermore prevents the center of frame 43 from flexing outwardly to break the seal of the gasket, described subsequently.

Implosion panel 41 is effectively float mounted by means of gasket 53. Gasket 53, the cross-section of which is best seen in FIG. 3, is comprised of two hollow

tubular portions

55 and 57, the former being the larger of the two. Connecting

tubular portions

55 and 57 is web portion 59. The arrangement of the various portions is such as to form a channel 61 therebetween.

Gasket 53 is stretched and fitted around the periphery of the shaped panel 41. The larger tubular portion 55 is arranged on the interior side of the panel 41, so that when panel 41 is placed against the viewing face of the cathode ray tube 11, the larger tubular portion 55 of gasket 53 will bear against the viewing face of tube 11, cushioning panel 41. against it and suspending panel 41 a short distance from the viewing surface of tube 11 to leave a space 66 therebetween. Physical contact of panel 41 with the viewing face of tube 11 is avoided so that direct transmission of implosion forces from the tube to the panel is avoided.

The smaller tubular portion 57 of gasket 53 is arranged on the outside of panel 41 to isolate the panel from flexible frame 43. As seen in FIG. 4, when flexible frame 43 is placed in position to secure panel 41 over the face of tube 11, gasket 53 is compressed compliantly to form a cushion for panel 41 and in addition to provide an effective seal for space 66. Such a seal is necessary to prevent dust and moisture from entering the space and causing cloudiness to obscure viewing. Serrations or longitudinal ridges 63 provided along appropriate surfaces of gasket 53 (see also FIG. 3) facilitate the gripping of panel 41 and tube 11 by the gasket, and also aid in maintaining the sealing of the dead space 66. As frame 43 is mounted, the hump on the top of tubular portion 55 is rolled out flat along the top of tube 11 to isolate the tube from the frame.

From FIG. 4 it may readily be seen that hollow

tubular portions

55 and 57 of gasket 53 enable panel 41 to be effectively floated from the tube 11 on a cushion of air. This floating effect permits the use of much thinner glass in the implosion panel while still maintaining the equivalent implosion protection of conventional devices.

Gasket 53 is preferably made of a substance called polyvinyl chloride which provides the economical optimum of strength and flexibility. In addition, it is further desirable that the polyvinyl chloride substance be of low plasticizer content to avoid emission of gasses into space 66 as temperatures increase during operation of the device. This is to reduce the likehood of the gases fogging to impair viewing quality. To further reduce this possibility space 65 is filled with dry nitrogen gas under pressure during assembly just prior to sealing. The introduction of a relatively inert gas such as nitrogen into space 66 forces out the air occupying the space, along with any moisture contained therein. Furthermore, such a gas will not cause any problems due to reaction with the materials surrounding the space.

It may therefore be seen that the invention provides an effective guard against implosion forces which requires relatively less thickness of the implosion panel due to resiliency of the mounting arrangement. In addition, the air space between the cathode ray tube and the implosion panel is effectively sealed against moisture and dust.

We claim:

1. An implosion guard for a cathode ray tube including in combination, a transparent panel for covering the viewing face of the tube, a mounting gasket of compressible material surrounding the periphery of said panel, said gasket having a channel formed therein to receive the edge of said panel, a structure for supporting the tube in view ing position, a flexible frame engaging said gasket, first means rigidly mounting said frame at both sides thereof to said structure, and second means resiliently mounting said frame at the top and bottom thereof to said structure so that said gasket is pressed against the viewing face of the tube, thereby suspending said panel a short distance in front of the viewing face of the tube to seal the region between said face and said panel from foreign matter and to form a resilient guard for absorbing implosion forces.

2. The combination of claim 1 wherein a dry, inert gas is introduced in the region between said face and said panel.

3. An implosion guard for a cathode ray tube including in combination, a transparent panel for covering the viewing face of the tube, a mounting gasket of compressible material surrounding the periphery of said panel, said gasket having a channel formed therein to receive the edge of said panel, a structure for supporting the tube in viewing position, a flexible frame engaging said gasket, said frame having a bracket portion on each side thereof secured to said structure, said frame further having a hook portion at the top and bottom thereof, a pair of projections on the top and bottom of said structure, and a pair of elongated resilient members having their ends engaging said projections on the opposite side thereof from said frame, said resilient members further being displaced in the center thereof to be captured in said hook portion so that said frame is resiliently mounted at the top and bottom thereof to said structure, said frame compressing said gasket against the viewing face of the tube so that said panel is suspended a short distance in front of the viewing face of the tube thereby forming a seal and a resilient guard for absorbing implosion forces.

References Cited in the file of this patent UNITED STATES PATENTS 2,456,399 Gethmann Dec. 14, 1948 2,559,353 Fisch July 3, 1951 2,870,438 Solheim J an. 20, 1959 2,936,448 Marholz May 10, 1960 3,084,217 Fiore et al Apr. 2, 1963 FOREIGN PATENTS 792,478 Great Britain Mar. 26, 1958

Claims

1. AN IMPLOSION GUARD FOR A CATHODE RAY TUBE INCLUDING IN COMBINATION, A TRANSPARENT PANEL FOR COVERING THE VIEWING FACE OF THE TUBE, A MOUNTING GASKET OF COMPRESSIBLE MATERIAL SURROUNDING THE PERIPHERY OF SAID PANEL, SAID GASKET HAVING A CHANNEL FORMED THEREIN TO RECEIVE THE EDGE OF SAID PANEL, A STRUCTURE FOR SUPPORTING THE TUBE IN VIEWING POSITION, A FLEXIBLE FRAME ENGAGING SAID GASKET, FIRST MEANS RIGIDLY MOUNTING SAID FRAME AT BOTH SIDES THEREOF TO SAID STRUCTURE, AND SECOND MEANS RESILIENTLY MOUNTING SAID FRAME AT THE TOP AND BOTTOM THEREOF TO SAID STRUCTURE SO THAT SAID GASKET IS PRESSED AGAINST THE VIEWING FACE OF THE TUBE, THEREBY SUSPENDING SAID PANEL A SHORT DISTANCE IN FRONT OF THE VIEWING FACE OF THE TUBE TO SEAL THE REGION BETWEEN SAID FACE AND SAID PANEL FROM FOREIGN MATTER AND TO FORM A RESILIENT GUARD FOR ABSORBING IMPLOSION FORCES.