Socket and base for picture tubes

A novel space-saving socket and base assembly for high-voltage picture tubes is disclosed. The inventive socket, which does not project over the base in the direction of the longitudinal axis of the picture tube, is obtained by optimizing the air and creepage paths of the socket and base through the use of an aperture positioned in the base for locating the high-voltage lead. This effectively reduces the overall length requirements for mounting these tubes inside equipment housings, and the size of these housings thereby.

The invention relates to a socket and a base of the type as set forth in 
the preamble of the claim. 
For picture tubes operating at high focusing voltages, it is known to use 
bases in which the focusing voltage pin is arranged in a chamber or hollow 
body structure, i.e. the so-called "silo". In such a conventional type of 
base a high-voltage plug with an insulation filling out the interior of 
the hollow body structure, serves as the high-voltage lead from the power 
supply unit. Such a high voltage plug may also be combined with the 
further plugs of the socket to form one structural unit. In that case, the 
one half of the base or of the socket is provided for this particular high 
voltage terminal whereas all other terminals are arranged on the other 
half of the base. In this way it is possible to provide sufficiently 
dimensioned air paths and creepage paths between the leads, which in size 
exceed the protective gap. In one base as known from DE-OS No. 27 18 966 
the hollow body structure is almost as long as the base. 
Accordingly, the socket or the additional high voltage connector must 
project over the base in the direction of its longitudinal extension 
parallel in relation to the axis of the picture tube. This, however, is of 
a disadvantage in so far as the mounting size of the picture tube is still 
enlarged beyond the base. In order to be able to keep the depth of the 
equipment in which the picture tube is to be installed, as small as 
possible, the socket must be prevented from protruding over the base. The 
form of construction of the conventional bases is to be maintained as far 
as possible. 
It is the object of the invention to further develop the hitherto 
well-proven form of construction in such a way as to prevent the socket 
from protruding over the base. 
According to the invention, this object is achieved by the combination of 
features set forth hereinbelow. 
The novel base differs from the conventional base in that a slot in the 
outer wall of the base which extends from one edge of the hollow body 
structure parallel in relation to the axis of the base, opens the hollow 
body structure throughout 30--60% of its length. Into this slot, during 
placement of the socket, there is inserted a lead-in conductor extending 
to the high-voltage terminal, which then extends from the connecting 
spring on the inside, radially towards the outside. By this way of leading 
out the high-voltage lead towards the side, the length of the socket can 
be kept so small that it, including the dimension necessary for the 
terminals of all leads, is still shorter than the base itself. There are 
various ways of embodying the terminals, quite depending on whether the 
leads are printed conductors or cables. All types of leads, however, are 
required to maintain the air and creepage paths provided for with respect 
to both the base and the socket. The fact that, according to the 
invention, the leads are led out on one side of a short socket provides a 
good condition to this end.

FIG. 1 shows the base 5 as seen from the bottom (rear) side of the picture 
tube with the socket 9, 10 inserted and with the board 11 designed as a 
printed circit board comprising the connecting line conductors 8. The 
ground connection is indicated by the reference numeral 12 and the 
protective gaps are indicated by the reference numeral 13. The chamber or 
hollow body structure (silo) 4 comprises a slot 2 through which the lead 3 
extending to the connecting spring 6, establishing the contact with the 
contact pin 7, is guided. Although it is beneficial not to have slot 2 
extend the entire length of base 5, it has been found that it is easier to 
assemble base 5 and socket 9, 10 when slot 2 is between 30 and 60% of the 
length of base 5. further, it has been found to be particularly easy to 
assemble base 5 and socket 9, 10 when high voltage lead 3 is located, when 
assembled, in the middle third of base 5. The cutout portion 17 in the 
bottom part 10 of the socket can be enlarged so that the creepage path 14 
is greater than the one also existing with the conventional types of 
combinations of base and socket, i.e. than the smallest creepage path 15 
existing on the base. 
FIG. 2 shows the embodiment of FIG. 1 as seen in the direction indicated by 
the arrow S. From this drawing it can be seen how the lead 3 is led 
through the slot 2 between the jacket part 9 and the bottom part 10 of the 
socket, toward the outside. 
The neck 18 of the picture tube carries the base 5. A sealing compound 
between the neck of the picture tube and the base prevents the development 
of air and creepage paths. Between the jacket part 9 and the bottom part 
10 of the socket, the lead 3 extends in the radial direction through the 
slot 2 laterally towards the outside. The lead 3 is arranged in the middle 
third of the length of the base. 
Another preferred space-saving embodiment is shown in FIG. 3. The terminals 
19 of the leads are led out horizontally and connected to the conductors 8 
arranged on the top side of the p.c. board. 
FIG. 4 shows that the arrangement according to the invention of both the 
base and the socket does not absolutely require the connections to be made 
with the aid of a board 11 designed as a printed circuit board. In this 
example of embodiment, the electrical connections are established with the 
aid of one or more connectors 8 on the circumference of the jacket and 
bottom parts 9, 10 of the socket connected in a flange-like manner. 
The creepage path 15 extends from the contact pin 7 to the next one of the 
other contact pins along the surface of the base, as indicated by the 
dashlines in FIGS. 1 and 2. The length of the base 5 is so dimensioned, 
and the contact pins are arranged in niches, such that creeping currents 
are prevented from developing. A creepage path 14 dimensionally 
corresponding to the creeping path 15, and extending on the socket, 
extends along the bottom part 10 of the socket and is indicated by the 
dotted line in FIGS. 1 and 2. When the same surface quality of materials 
is used for both the socket and the base with respect to the 
creeping-current resistance, the critical creepage path 14 on the socket 
does not need to be longer than the creepage path 15 which is decisive for 
the base. The invention discloses an arrangement in which, by avoiding an 
excessively long creepage path 14, a shorter socket is realized in that 
the hollow body structure of the base is partially opened towards the 
outside. This provides favorable constructional possibilities for 
embodying a space-saving socket of which three examples of embodiment are 
shown in FIGS. 2 to 4. Thus it is seen how novel space-saving sockets can 
be fashioned which are shorter than their corresponding bases by as much 
as 20 to 40%. It is of particular advantage to design terminals 19 of the 
leads extending to the connecting springs 6 in such a way that they can be 
bent from the radial direction into the axial direction, or vice versa. A 
socket consisting of the jacket part 9 and of the bottom part 10 may then 
be easily adapted to various types of p.c. boards, connectors, etc. 
Instead of the two-part design of both the jacket and the bottom part, 
both may also be designed as one part, in which case the p.c. board may 
likewise be integrated.