Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/64—Constructional details of receivers, e.g. cabinets or dust covers
  • H04N5/645—Mounting of picture tube on chassis or in housing
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
  • H01J29/86—Vessels; Containers; Vacuum locks
  • H01J29/87—Arrangements for preventing or limiting effects of implosion of vessels or containers

Definitions

• the present invention relates to cathode ray tube (CRT) vibration and shock isolation apparatus, and more particularly, to the tailoring of a vibration isolation mounting module to the model of CRT.
• CRT cathode ray tube
• a CRT envelope is evacuated to a very low internal pressure and accordingly is subjected to the possibility of implosion due to the stresses produced by atmospheric pressure acting on the surfaces of the tube and to impact forces.
• This problem has been addressed in the art by providing the CRT with an implosion protection band that extends around the peripheral sidewall of the faceplate panel.
• Such a band is used to apply a compressive force to the sidewall of the CRT to redistribute some of the faceplate panel forces as well as improving the impact resistance of the tube, because glass in compression is stronger than glass which is in tension, and the band causes compression in faceplate panel areas which otherwise would be in tension.
• Mounting lugs either integral with or attached to the implosion protection band, or captivated between the band and the tube sidewall, are used to secure and support the tube within the cabinet.
• the mounting lugs are positioned at the corners of the tube and are aligned along the rectangular faceplate panel diagonals, although other placements of the mounting lugs are known.
• the mounting lugs extend outwardly from the band and typically have a mounting aperture or slot therein for accepting a screw for securing the tube to the cabinet. Once the CRT is properly aligned within the cabinet, the screws are driven through the holes in the lugs and are tightened to provide a secure attachment of the CRT to the cabinet.
• a color CRT uses a shadow mask suspended over the inner surface of the faceplate panel.
• This shadow mask can be exposed to vibrations matching the mechanical resonant and/or harmonic/subharmonic frequencies of the mask structure. These vibrations are primarily caused by sound transmitted within the cabinet by loudspeakers also mounted to and within the cabinet. Such resonance of the mask frame structure will cause undesirable visual effects on the CRT picture, e.g., microphonics.
• the shadow mask structures can be vibrated by hundreds of micrometers, causing the color producing electron beams and the shadows of the shadow mask, to be shaken causing further undesirable visual effects on the CRT, e.g., color banding, chromatic aberration. Accordingly, it is desirable to minimize vibrations transmitted to the CRT from the cabinet through the CRT mounting arrangement.
• CRT mounting hardware be provided for each of the family of CRTs so that the particular model of CRT can be installed in different cabinets without any special vibration design considerations being given about the cabinet. In other words, it is desirable that mounting hardware be designed for the model of CRT regardless of the cabinet where the CRT will be installed.
• a base member has two shaped high compliance members mounted at diametrically opposite sides of the base member, with coaxial apertures in the three members.
• the base member is secured to the CRT.
• the apertures accept an elongated securement member, such as a screw, for securing the module and CRT to the cabinet.
• the two shaped high compliance members in combination with the base member, minimize the passage of vibrations from the housing to the CRT.
• the parameters of the high compliance members are selected to minimize the transmission of specific vibration frequencies, in combination with a predetermined screw tightening torque.
• the drawing figure shows a representative side, partially cut-away view of the CRT mounting arrangement according to aspects of the present invention.
• a cathode ray tube is typically mounted to a cabinet or housing by means of four mounting lugs having apertures, with fasteners inserted through each aperture.
• the mounting lugs are positioned at the corners of the tube and are aligned along diagonals of the rectangular faceplate. Such an arrangement is well known in the art.
• CRT 10 is provided with an implosion band 12 having a mounting lug 14 secured thereto, as discussed hereinabove.
• Lug 14 is provided with an aperture 16 for securingly receiving a cylindrical base member 18 therein.
• Diametrically opposite sides 20, 22 of base member 18 are provided with recesses 24 which each have resilient members 26a, 26b disposed therein.
• Base member 18 and each of members 26a, 26b have coaxial cylindrical apertures 28 through which passes retainer screw 30 to secure the CRT to a chassis/housing 32.
• a washer 34 is concentrically disposed about screw 30 between screw head 36 and member 26a.
• a second washer 37 is concentrically disposed about screw 30 between and in contact with member 26b and housing 32.
• Members 26a, 26b are made of elastomeric resilient material, e.g., neoprene, PVC.
• the stiffness of members 26a, 26b are selected to have a predetermined dynamic stiffness capable of attenuating vibrations and shock dynamic G forces when under compression.
• members 26a, 26b are semi- hemispheric in shape and snuggly nest in respective recess 24, but it is within the contemplation of the present invention that other shapes can be used for achieving the desired reduction of vibration frequencies, e.g., conical, cylindrical, etc., and that the two members 26a, 26b need not be the same shape, size, or dynamic stiffness.
• the tightening torque of screw 30 determining the amount of compression of members 26a, 26b, and the durometer stiffness, shape and dimensions of members 26a, 26b are chosen to tune the system to prevent transmission of harmful frequencies from cabinet/housing 32 to CRT 10, with the typical frequencies of interest being within the range of 80 Hz to 90 Hz for soft-tension true-flat CRTs and somewhat higher for conventional formed shadow mask CRTs.
• the clearance 38 between the washers 34, 37 and base member 18, housing/cabinet 32 respectively ensures that vibrational energy must pass through the resilient members before engaging the tube, but the clearance is limited to provide shock resistance in the Z plane along the longitudinal axis of the CRT.
• the disclosed vibration insulation mounting will trap undesirable frequencies, dissipate vibrational energy and provide some shock protection.
• Base member 18 can be secured to mounting lug 14 within aperture 16 by a number of ways, e.g., welding, force fit, the sizing of aperture 16 and the outside diameter of base member 18 to be close fitting so that when base member 18 is frozen, thermal expansion of base member 18 will lock base 18 to lug 14 at ambient temperature, or that the outside diameter of base member 18 is threaded and a pair of locking nuts are threaded onto base member 18 along its axial length and tightened on both sides of lug 14 (not shown).
• ways e.g., welding, force fit, the sizing of aperture 16 and the outside diameter of base member 18 to be close fitting so that when base member 18 is frozen, thermal expansion of base member 18 will lock base 18 to lug 14 at ambient temperature, or that the outside diameter of base member 18 is threaded and a pair of locking nuts are threaded onto base member 18 along its axial length and tightened on both sides of lug 14 (not shown).
• such a disclosed module of base member 18 and resilient members 26a, 26b can be determined for the characteristics of a particular CRT with a predetermined tightening torque for screw 30, and such a module can then be used with various cabinets/chassis independent of the vibrational characteristics of the cabinet/chassis.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Vibration Prevention Devices (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Casings For Electric Apparatus (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (2)

Family

ID=24883734

Family Applications (1)

Country Status (5)

Cited By (2)

Citations (1)

Family Cites Families (2)

• 2001
  • 2001-11-08 CN CNA018189814A patent/CN1475075A/zh active Pending
  • 2001-11-08 KR KR10-2003-7006886A patent/KR20040020043A/ko not_active Application Discontinuation
  • 2001-11-08 WO PCT/US2001/046858 patent/WO2002043380A2/en active Application Filing
  • 2001-11-08 JP JP2002544973A patent/JP3822566B2/ja not_active Expired - Fee Related
  • 2001-11-08 AU AU2002227267A patent/AU2002227267A1/en not_active Abandoned

Patent Citations (1)

Non-Patent Citations (2)

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