CRT socket

Details CRT socket CRT socket

2000-01-27

2001-10-23

Sircus, Brian (Department: 2839)

Electrical connectors

With insulation other than conductor sheath

Plural-contact coupling part

Reexamination Certificate

active

06305988

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a cathode ray tube (hereinafter simply referred to as a “CRT”) socket. More particularly, the present invention relates to a CRT socket that includes a structure in which a creeping distance is secured by recessing an engaging portion in the socket. The engaging portion of the CRT socket engages a high voltage contact terminal which couples the CRT focus voltage to the CRT. According to the present invention, creeping distance is increased and the CRT socket height is reduced.
DESCRIPTION OF THE BACKGROUND ART
Conventional CRTs are controlled by a combination of high and low voltages. For example, the focus voltage on a conventional CRT typically receives potentials on the order of 10,000 volts from a flyback transformer, while a video signal is normally on the order of 100 volts. Because of the large differences in potential, a high voltage circuit section perceives potentials in a video signal section to be approximately at the same potential level as ground. If current were to flow from the high voltage section through the signal section, electronic components and circuits in the signal section (i.e. semiconductor devices) are likely to be destroyed. Therefore, the high voltage section and the signal sections in conventional CRTs must be insulated from one another to prevent a high voltage discharge. Creeping distance is required to prevent this destructive high voltage discharge from occurring.
According to the prior art, CRT sockets are available in a variety of shapes. One example of a CRT socket (hereinafter simply referred to as a “socket”) is disclosed in Japanese Laid-Open (Kokai) Utility Model No. 59-173289 which is entitled “a socket for a cathode ray tube”. As shown in
FIGS. 8 and 9
, a socket consists of socket body
10
and insulating cover portion
11
.
Socket body
10
has a generally cylindrical shape. A cylindrical central hole
12
is located in a central portion of socket body
10
. Cylindrical central hole
12
extends through the socket body, from a front to a rear face. A high voltage contact portion
13
and a signal contact portion
14
are arranged on a concentric circle formed along a circumference of cylindrical central hole
12
. High voltage contact portion
13
is spaced apart from signal contact portion
14
. A high voltage contact
15
is located in a substantially central position of high voltage contact portion
13
from a rear side of socket body
10
.
Signal contact portion
14
includes a signal contact
16
and a ground terminal
17
. A CRT signal is communicated to the CRT through signal contact
16
via a terminal (not shown). Ground terminal
17
discharges high voltages which are generated in signal contact
16
. Signal contact
16
includes a connecting terminal
18
which is formed in a sleeved shape and a lead wire connecting terminal
19
. Lead wire connecting terminal
19
is formed with a bent portion oriented perpendicular to socket body
10
in an outward direction. Connecting terminal
18
engages with a terminal (not shown) which couples a signal to a neck of the CRT on an end tip side of signal contact
16
. Ground terminal
17
includes a spherical cap
20
for discharging high voltages. Spherical cap
20
is positioned opposite to an intermediate position of lead terminal
19
of signal contact
16
.
A second example of a prior art CRT socket is shown in FIG.
10
. The second example has approximately the same structure as the first example discussed above. Similar to the first example, signal contact portion
14
is formed in a circumferential shape concentric with cylindrical central hole
12
which extends through socket body
10
to its front and rear faces. The second example differs from the first example in that a ground terminal
17
A, used for discharging high voltage, is stored and arranged within socket body
10
. Namely, signal contact portion
14
includes a signal contact
16
and a ground terminal
17
A. An end portion
21
is formed on a side which is opposite to an engaged end portion of ground terminal
17
A. A discharge gap is formed between signal contact
16
and a bent end portion
21
of ground terminal.
A third example of a prior art CRT socket is disclosed in Japanese Laid-Open (Kokai) Patent No. 2-49091 which is entitled “a cathode ray tube socket”. As shown in
FIGS. 11 and 12
, this example has a structure in which a creeping distance is increased by forming a groove between a high voltage contact
15
and a signal contact
16
. This structure includes a socket body
10
A which is formed in a cylindrical shape and an insulating cover portion
11
A which is formed in a square shape. Insulating cover portion
11
A covers socket body
10
A. A cylindrical central hole
12
A extends through front and rear faces of socket body
10
A. A high voltage contact portion
13
A and a signal contact portion
14
A are formed in a circumferential shape positioned about cylindrical central hole
12
A. The high voltage contact portion
13
A is separated by groove portions
22
and
23
. Groove portions
22
and
23
extend through front and rear faces of socket body
10
A. The groove portions are positioned between high voltage contact portion
13
A and signal contact portion
14
A. A high voltage contact hole
24
stores high voltage contact
15
therein. A barrier fitting groove
25
separates high voltage contact
15
from high voltage contact portion
13
A by a predetermined gap. The barrier fitting groove
25
extends along a commonly connected bottom portion of high voltage contact hole
24
.
A fourth example of a prior art CRT socket is shown in FIG.
13
. This fourth example is structurally similar to the third example discussed above. In this example, a groove portion
22
A extends through front and rear faces of a socket body
10
B. Groove portion
22
A is arranged between a high voltage contact portion
13
B and a low voltage contact portion
26
. High voltage contacts
15
are located within high voltage contact holes
24
. A low voltage contact
29
is located with a low voltage contact hole
28
. Groove portion
22
A separates high voltage contacts
15
from each other. A rib
27
is located in groove portion
22
A in socket body
10
B at an intermediate position. When the socket body
10
B is covered with an insulating cover portion
11
B, rib
27
is inserted in the intermediate position of the groove portion
22
A. Accordingly, it is possible to increase the creeping distance between the high voltage contact
15
and a low voltage contact
29
.
PROBLEMS IDENTIFIED WITH THE PRIOR ART
The CRT sockets shown in each of the preceding examples have structures in which a discharge gap is obtained by setting a ground terminal in a physical position opposite to an intermediate terminal of the signal contact. The ground terminal serves to discharge the signal contact. The above discussed structures do not practicably permit the height of the CRT socket body to be reduced.
Furthermore, creeping distance in the above discussed conventional CRT sockets are insufficient in preventing high voltage discharge phenomenon from occurring. The structures found in prior art CRT sockets tend to result in a discharge state where an end tip side and a high voltage connector tend to short together.
In recent years, there has been a significant increase in the focus voltage for CRTs used in color television units. The increase in focus voltage is predominately due to the need to improve image quality by reducing the aberrations from the electron lens as well as the increasing sizes of conventional television screens. The use of higher focus voltages requires additional care to be taken to prevent the above discussed problems from occurring.
Accordingly, problems exist in that the height of the CRT socket itself cannot be practicably reduced. An improved socket structure is needed in which the position of the ground terminal for discharge is arranged relative to the signal contact and the creeping distance to prevent the discharge state from the high voltage co

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