Television – Video display – Cabinet or chassis
Patent
1995-09-26
1998-08-11
Coles, Sr., Edward L.
Television
Video display
Cabinet or chassis
348805, 348806, 348826, 348830, 348776, 348744, 348284, 348325, 348380, 358507, 358485, 313409, 313411, 313364, 313402, 313441, 315 1, 315 3, H04N 564, H04N 5645, H01J 2950, H01J 2334
Patent
active
057934487
DESCRIPTION:
BRIEF SUMMARY
This invention relates to cathode ray tube packages.
Cathode ray tubes with their fragile glass envelopes and high voltage connections are difficult to handle. In order to mitigate this problem, it is known to provide cathode ray tube packages including the glass envelope, a deflection coil and if necessary a focus coil in a mechanical housing, the housing being provided with the necessary high voltage connections in the form of flying lead electrical connections.
Cathode ray tube packages have been used widely in applications including Head Up Displays, Head Down Displays, Military Vehicle Displays and telecines. The packages are generally encapsulated with, for example, silicone rubber or epoxy and are throw away assemblies. One example of a known cathode ray tube package is shown in FIGS. 1 and 2 in which:
FIG. 1 is a schematic side view of the known cathode ray tube package; and
FIG. 2 is a schematic partly sectioned side view of the cathode ray tube package of FIG. 1.
Referring to FIGS. 1 and 2, the known cathode ray tube package incorporates a cathode ray tube 1 formed with a glass envelope in the usual manner. The cathode ray tube 1 is mounted in a mechanical housing 3 provided with flying lead electrical connections 5, the housing 3 providing protection for the glass envelope of the cathode ray tube 1, and also shielding the cathode ray tube 1 from external magnetic fields. Round the cathode ray tube 1 are provided a deflection coil 7, a focus coil 9 and an astigmatism correction coil 11, the coils 7 and 9 being attached to the inside of the housing 3 by respective mounting tubes 13,15. The front of the housing 3 is provided with a mounting flange 17 to enable the package comprising the cathode ray tube 1, the housing 3 and the coils 7,9,11 to be mounted in the customer's equipment and accurately positioned with respect to the optical system (not shown).
It will be seen that the focus coil 9 must be aligned with the electron beam of the particular cathode ray tube 1 installed in the package in order to optimise the resolution of the cathode ray tube. This alignment procedure is carried out by mounting the focus coil 9 in an external gimbal unit (not shown) enabling the position of the focus coil 9 to be shifted in two mutually perpendicular directions at right angles to the tube axis, and tilted about these two axes. The spot caused by the impact of the electron beam on the phosphor screen of the cathode ray tube with the deflection current switched off, but with either fullwave a.c. current, or d.c. plus a.c. current, passing through the focus coil 9, is then observed by means of a microscope, and the position of the focus coil 9 adjusted by means of the gimbal unit. After alignment of the focus coil 9 has been achieved, the cavity defined between the focus coil 9, the focus coil mounting tube 15 and a pair of seals 19,21 is filled with a gap filling bonding material, for example, a resin 23. When the resin 23 has cured thus fixing the focus coil 9 in position, the external gimbal unit is removed. It will be appreciated that this process of alignment is a relatively lengthy procedure, and must be carried out by skilled personnel.
Because of manufacturing tolerances in cathode ray tube envelopes and/or electron guns, the alignment of the electron optical axis will also vary from tube to tube. Such variations mean that assembly of a replacement tube 1 in the housing 3 by a non-specialist, or specialist without specialist equipment, would lead to poor alignment of the focus coil 9 with respect to the electron beam axis, thus resulting in low resolution of the display on the screen of the cathode ray tube.
In view of the alignment procedure which must therefore be carried out, it is therefore not possible to replace the cathode ray tube in the package at the end of the cathode ray tube's life. Thus, if the cathode ray tube becomes non-functional, the whole package needs to be replaced.
It is an object of the present invention to provide a cathode ray tube package wherein the cathode ray tube may be mo
REFERENCES:
patent: 2456399 (1948-12-01), Gethmann
patent: 3404227 (1968-10-01), Alcala et al.
patent: 3887766 (1975-06-01), Caswell
patent: 4757239 (1988-07-01), Starkey, IV
Ferranti Electronic Display High Resolution Cathode Ray Tube Mounting Unit, Type M400, Issue 2, May 1966.
Ferranti--Microspot Cathode Ray Tubes--Mounting Systems (Apr. 1967).
Ferranti--Microspot Cathode Ray Tubes--Integral Mounting and Collars (Oct. 1974).
Ferranti--Microspot Cathode Ray Tubes--Operating Notes (Jul. 1977).
Ferranti Special Components Department short form catalog (approx. 1970-79).
Ferranti--Microspot Cathode Ray Tubes and Display Equipment short form catalog (1978).
Atkinson George David
Nangle James Francis
Brimar Limited
Coles Sr. Edward L.
Harris Tia M.
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