Electricity: electrical systems and devices – Safety and protection of systems and devices – High voltage dissipation
Reexamination Certificate
1998-11-12
2001-01-23
Ballato, Josie (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
High voltage dissipation
C361S138000, C337S018000, C337S028000
Reexamination Certificate
active
06178078
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a discharge gap device in which discharge occurs between conductors, and more specifically to a discharge gap device which is provided between an antenna input terminal or a secondary side earth and a commercial power source, or between the power lines of a commercial power source as a ground discharge countermeasure for electrical equipments such as a television set, a video cassette recorder, and a television and video compound device, and to its mounting structure.
2. Description of the Related Art
A CR (capacitor and resistor) compound part
21
whose circuit arrangement is as shown in
FIG. 7
is known as a discharge gap device (for instance, B2R131C131, R1-2M121MF, etc. manufactured by Murata Manufacturing Co., Ltd.).
The CR compound part
21
comprises a discharge gap unit
22
, a resistor
23
, and a capacitor
24
which are connected in parallel to one another.
FIGS.
8
(
a
) and
8
(
b
) are external views of the CR compound part
21
shown in FIG.
7
.
As shown in FIGS.
8
(
a
) and
8
(
b
), in the CR compound part
21
, lead wires
27
and
28
, which are to be inserted into a printed circuit board (not shown) , are welded on a surface
29
a
of a dielectric
29
with soldering patterns
25
and
26
which are conductors, and a resistor
23
is connected between the soldering patterns
25
and
26
. On a rear surface
29
b
of the dielectric
29
, a silver (conductor) pattern
30
is printed or bonded, and the entire rear surface is covered with resin (not shown) so as to cover the silver pattern
30
.
With the discharge gap device thus designed, ends
25
a
and
26
a
of the soldering patterns
25
and
26
form the discharge gap unit
22
, while the dielectric
29
is held between the soldering patterns
25
and
26
and the silver pattern
30
to form the capacitor
24
. Thus, as shown in
FIG. 7
, a discharge circuit has been formed in which the discharge gap unit
22
, the resistor
23
, and the capacitor
24
are connected in parallel to one another.
FIG. 9
is a circuit diagram showing the discharge gap device (CR compound part
21
) applied to a television set.
As shown in
FIG. 9
, the current of a commercial power source
16
is applied to a rectifier circuit
17
, and the current rectified by the circuit
17
is supplied to a power source circuit (or switching power source circuit)
18
. The output current of the circuit
18
is supplied to a variety of load circuits.
A tuner
19
of the television set is connected through the discharge gap device
21
to the aforementioned commercial power source
16
. Normally, the discharge gap unit
22
is in non-conduction state; that is, the tuner
19
is insulated from the commercial power source
16
. A filter
20
is provided between the CR compound part
21
and the tuner
19
. The filter
20
is made up of a coil and the like to cut off high frequency components.
In
FIG. 9
, the one-dot chain line A indicates a primary power source side between the commercial power source
16
and the switch power source circuit
18
, and the other one-dot chain line B indicates a secondary power source side at the rear stage of the switching power source circuit
18
.
An earth (ground) E
1
forming the rectifier circuit
17
, and an earth E
2
which is connected through a capacitor C between the rectifier circuit
17
and the switching power source circuit
18
mean the earth of the primary power source side A, and are at the same potential. Furthermore, an earth E
3
forming the switching power source circuit
18
, and earths E
4
and E
5
of the tuner
19
mean the earth of the secondary power source side B. and are at the same potential.
With the above-described circuit, when ground discharge occurs, the load circuits are prevented from damage as follows:
For instance, when the occurrence of ground discharge causes and high voltage is applied through the antenna (not shown) to the antenna input terminal
19
a
of the tuner
19
, the gap of the discharge gap unit
22
of the CR compound part
1
connected to the tuner
19
is made conductive by the discharge, so that the high voltage is applied to the commercial power source
16
. The high voltage does not go to the side of the secondary power source B, whereby the load circuits are prevented from damage.
FIG. 10
is a circuit diagram showing the case where the two above-described conventional CR compound parts
21
are used.
In this discharge gap device, the two CR compound parts
21
and
21
are connected in series to each other, and one of the CR compound parts
21
is shunted by a capacitor C.
The two compound parts
21
and
21
are used mainly, for instance for a television set combined with a video cassette recorder, to meet the safety standard.
For instance, the UL (Underwriters laboratories) standard in U.S.A. is as follows: In the safety standard for a popular television set, it is necessary that the gap of the discharge gap unit
22
is at least 1.6 mm; and in the safety standard for a television set combined with a video cassette recorder, it is at least 3.2 mm because double insulation is required.
In the discharge gap device of the CR compound part
21
, the gap G (between the ends
25
a
and
26
a
of the soldering patterns
25
and
26
) of the discharge gap unit
22
is set to 2.6 mm. Therefore, in order to provide 3.2 mm, it is necessary to additionally manufacture a CR compound part. Hence, in order to meet the UL standard, two 1.6 mm-gap CR compound parts
21
are used to make the gap 3.2 mm.
Incidentally, in the above-described related art, the CR compound part
21
is employed as the discharge gap device. Hence, in the case where it is required to use a variety of resistances, it is necessary to newly manufacture CR compound parts.
Furthermore, the CR compound part
21
includes the capacitor
24
, and in the case of the ordinary connection, high frequency components pass through the CR compound part through the capacitor
24
, as a result of which high frequency components from the commercial power source is applied to the secondary circuit of the tuner
19
, or high frequency components from the secondary circuit of the tuner
19
are superposed on the power.
Hence, sometimes, it is necessary to connect the CR compound part
21
and a filter
20
to cut off the high frequency components.
Furthermore, in order to meet the safety standard of a television set combined with a video cassette recorder, the two CR compound parts
21
are employed; that is, the number of components is increased as much.
SUMMARY OF THE INVENTION
In view of the foregoing, an object of the invention is to provide a discharge gap device and its mounting structure in which the resistance can be changed with ease, and the passage of high frequency components is less, and in which discharge occurs positively in the gap of the discharge gap unit which provides no problem in safety.
In order to achieve the above object, the invention provides a discharge gap device comprising conductors which are arranged spaced from each other so that a space between the conductors is used as a discharge gap, and which functions only as a discharge gap unit, wherein the conductors are normally held non-conductive to each other, and when over-voltage is applied between the conductors, discharge occurs between the conductors so that the conductor are electrically conductive to each other.
Further, the invention provides a mounting structure of the discharge gap device, wherein a resistor is formed on a printed circuit board which is in parallel to the discharge gap device.
The invention provides a discharge gap device which functions only as a discharge gap unit, comprising: a dielectric; at least two lead wires which are inserted into a printed circuit board; and at least two conductors which are connected to the lead wires and provided on the dielectric, wherein upon application of over-voltage, discharge is caused to occur between the conductors, so that the lead wires are made electrically connected to one another.
Ballato Josie
Funai Electric Co. Ltd.
Huynh Kim
Lackenbach Siegel Marzullo Aronson & Greenspan
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