Patent Publication Number: US-6670746-B2

Title: Cathode ray tube electrical connector with through passage and leaf springs

Description:
FIELD OF THE INVENTION 
     The present invention generally relates to cathode ray tubes and specifically to a cathode ray tube having an improved electrical connector. 
     BACKGROUND OF THE INVENTION 
     This invention relates to cathode ray display tubes, and is particularly concerned with the electrical connection of such tubes at the neck region that provides for passing and isolating a number of electrically conductive pins that convey operating voltages into the tube envelope. 
     Cathode ray tubes used in television picture tubes, and in CRT monitors displaying a variety of information, typically have a narrow neck terminated by a plurality of electrically conductive pins extending axially from the electron gun through the neck of the tube. The pins may comprise a number of closely spaced, low-voltage pins, and at least one high-voltage pin spaced from the low-voltage pins. Electrical connection to the pins is typically made by a socket which provides for connecting by means of a plurality of frictional members which slidably contact each pin. The members are attached to a plurality of lead wires which in turn make connection to various components of the ancillary electrical chassis, such as the power supply and scanning circuits. 
     It has become desirable to manufacture tubes that allow for the design of televisions and monitors with a slim profile. That is, televisions and monitors with cabinets having reduced depth. A conventional socket as discussed above, has one objectionable characteristic and that is that it extends the overall length of the tube, as measured by the front to back dimension. This single geometrical dimension results in the increased depth of the tube cabinet. A well known approach to decreasing the overall length of the tube is to increase the deflection angle of the electron gun beam trajectory relative to the tube longitudinal axis thereby permitting the electron gun to be brought closer to the viewing screen of the tube and thus shortening the overall length of the tube. For example, a typical twenty-inch diagonal CRT has a 90 degree deflection angle. Increasing the deflection angle to 110 degrees decreases the overall length of the tube approximately three-inches. Further increase in deflection angle is possible, however, the marginal gain in length reduction of the tube progressively decreases as the angle of deflection increases. For example, increasing the deflection angle from 110 degrees to 130 degrees of a 20-inch diagonal CRT results in a depth reduction of approximately 2.3 inches. Increasing the electron beam deflection angle also tends to create other challenges including an increase in the deflection frequency and current supplied to the deflection yoke resulting in increase power consumption of the CRT. 
     Therefore, it is desirable to provide additional means for reducing the overall length of the tube. 
     SUMMARY OF THE INVENTION 
     A cathode ray tube electrical connector is provided for detachably coupling an electrical lead to the electron gun. The connector has a through passage defined by a diameter greater than the diameter of the neck which surrounds and is secured to the outer surface of the neck. Adjacent the passage is a plurality of integral resilient leaf springs extending toward the stem at a plurality of circumferentially spaced locations. The leaf spring elements include base elements for terminal engagement and tip ends projecting and bias toward the electrical leads of the electron gun to provide electrical connection to the cathode ray tube. The passage of the connector is preferably defined by an opening in a printed circuit board or other electrical terminal contact from which the leaf springs extend. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the present invention will be described below in more detail, with reference to the accompanying drawings, in which: 
     FIG. 1 is a cross-sectional side view showing an example of a cathode ray tube with an electron gun connected therein according to the prior art; 
     FIG. 2 is a partial cross-sectional side view of a cathode ray tube showing the connection of an electron gun according to the prior art; 
     FIG. 3 is a partial cross-sectional side view of the present invention as taken along line  3 — 3  of FIG. 4; 
     FIG. 4 is a plan view of the present invention as shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION 
     As shown in FIG. 1, a known cathode-ray tube  10  is usually composed of a hermetically sealed, evacuated glass envelope  12  including a neck  14 , a funnel  16  and a faceplate panel  18 . The funnel  16  has an internal conductive coating (not shown) that extends from an anode button  20  toward the faceplate panel  18  and the neck  14 . A three-color phosphor screen  22  is carried by the inner surface of the faceplate panel  18 . A shadow mask frame assembly  24  is removably mounted in predetermined spaced relation to the screen  22 . An internal magnetic shield  26  is fastened to the shadow mask frame assembly. Centrally mounted within the neck  14  is an electron gun  22  to generate and direct three inline electron beams (not shown), a center beam and two side or outer beams, along convergent paths through the tension mask frame assembly  24  to screen  22 . 
     The CRT  10  is designed to be used with an external magnetic deflection yoke  28  shown in the neighborhood of the funnel-to-neck junction. When activated, the yoke  28  subjects the three beams to magnetic fields which cause the beams to scan horizontally and vertically in a rectangular raster over the screen  22 . 
     As illustrated in FIG. 2, a typical electron gun  22  includes a plurality of spaced electrodes centrally mounted within the neck  14  of the tube. Electrical connections between the outside and the inside of the above described envelope is the anode button  20  and stem pins  29 . The stem pins  29  include closely spaced, low-voltage pins, and at least one high-voltage pin spaced from the low-voltage pins. The potentials conducted by the low-voltage pins may range from less than one volt to one kilovolt, for example. The potentials conducted by the high-voltage pin are typically in the range of six to twelve kilovolts, or greater. In certain television tube applications, an additional very high potential termed the “anode potential” is in the range of 25-32 kilovolts, and is introduced through the tube envelope by means of the anode button  20 . Electrical connection to the pins is typically made by a socket  30  which provides for connecting by means of a plurality of frictional members therein (not shown) which slidably contact each stem pins  2829 . The frictional members of the socket  30  are attached to a plurality of lead wires which in turn make connection to various components of the ancillary electrical chassis, such as the power supply and scanning circuits  32 . 
     FIG. 3 is a detail sectional side view, partial cutaway, of a cathode ray tube and electrical connector in accordance with the present invention. The cathode ray tube includes neck  14  with an electron gun  22  centrally positioned therein and an associated electrical leads  34  extending axially from the neck  14 . The end of the neck  14  terminates at a closed end stem  36  through which electrical leads  39  extend to the outside surface of the tube. The electrical leads  34  include contact buttons  38  on the outer surface of the stem  36 . It is to be understood that the electrical leads  39  and associated contacts  38  may comprise more than those depicted for exemplary purposes. Typically, the number of electrical leads may be as many as six or more in a single gun. The scope of the invention is not limited to the number of electrical leads or contacts shown, but is intended to cover both standard and unusual gun configurations to which the invention has applications. An electrical connector  40  embodying the invention is secured to the outside surface of the neck  14  near the stem for making electrical contact with the electron gun leads in a manner to be described. 
     Turning to FIGS. 3 and 4, the electrical connector  40  has a through passage  42  defined by a diameter greater than the outside surface diameter of the neck and extending away from the stem  36  toward the front faceplate panel  18  of the tube. The electrical connector  40  includes a cylindrical clamp  44  formed along the through passage surrounding the outside surface of the neck  14  for securing the connector  40  adjacent the proximal end, or stem  36 , of the neck. It will be understood that the electrical connector  40  may also be secured to the outside surface of the neck with an adhesive or the like in lieu of the clamp  44 . A plurality of integral resilient leaf springs  46  extend from the connector  40  at a plurality of circumferentially spaced locations to the contacts  38 . The leaf springs  46  have base elements  48  for terminal engagement with various electrical components of the tube, and tip ends  50  which project and are biased toward the longitudinal axis of the connector for mating engagement with the contacts  38  of the electrical leads  39 . The resilient leaf springs  46  extend from the base elements  48  at a plurality of spaced circumferential locations in accordance to the number and location of the electron gun leads  39  and associated contacts  38 . The springs  46  and contacts  38  operate over a large range of voltage and can be electrically insulated from each other and from ground to prevent arcing that can damage the surrounding components of the tube. Several approaches can be used to achieve the insulation such as, for example, placing an insulating material having a high electrical breakdown voltage per unit thickness of material between the springs. In addition, contacts  38  and springs  46  operating at different voltages may be spaced apart or individually insulated so that arcing is suppressed. Since the connector  40  is secured to the neck, the overall axial length of the tube is reduced by the contour of the leaf springs  46  and the extension of the contacts  38  above the surface of the stem  36 . 
     Preferably, the electrical connector  40  forms a printed circuit board with base elements  48  acting as an integral terminal contact with the various electrical components. It will also be understood as being within the purview of the invention to fabricate a modified electrical connector  40  such that the circuit board is separate from the connector wherein the leaf springs are secured to the outer surface of the neck  14  as described above but with the base elements  48  connected to a separate printed circuit board  32  by suitable means. 
     While foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.