Information
-
Patent Grant
-
6178078
-
Patent Number
6,178,078
-
Date Filed
Thursday, November 12, 199826 years ago
-
Date Issued
Tuesday, January 23, 200124 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Ballato; Josie
- Huynh; Kim
Agents
- Lackenbach Siegel Marzullo Aronson & Greenspan
-
CPC
-
US Classifications
Field of Search
US
- 361 912
- 361 110
- 361 111
- 361 117
- 361 118
- 361 119
- 361 136
- 361 748
- 337 28
-
International Classifications
-
Abstract
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. The discharge gap device functions only as a discharge gap unit and has two conductors. Normally, the conductors are not electrically connected to each other, and upon application of over-voltage, discharge occurs between the conductors; that is, the conductors are electrically connected to each other.
Description
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.
Further, the invention provides a mounting structure of the discharge gap device, wherein a resistor in parallel with the discharge gap device is provided on the printed circuit board.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is an electrical circuit diagram showing an example of a discharge gap device, which constitutes a first embodiment of the invention.
FIG. 2
is an external view showing the discharge gap device.
FIG. 3
is an external view showing the discharge gap device which is covered with resin.
FIG. 4
is an external view showing another example of the discharge gap device, which constitutes a second embodiment of the invention.
FIG. 5
is an external view showing a modification of the discharge gap device shown in FIG.
4
.
FIG. 6
is an electrical circuit diagram showing the discharge gap device applied to a television set.
FIG. 7
is an electrical circuit diagram showing an example of a conventional CR compound part.
FIGS.
8
(
a
) and
8
(
b
) are external views showing the conventional CR compound part.
FIG. 9
is an electrical circuit diagram showing the conventional CR compound part applied to a television set.
FIG. 10
is an electrical circuit diagram showing another example of the conventional CR compound part.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferred embodiments of the invention will be described with reference to the accompanying drawings.
FIG. 1
is an electrical circuit diagram showing a discharge gap device according to the invention.
FIG. 2
is a view showing an external appearance of the discharge gap device of the invention.
The discharge gap device and its mounting structure are employed for AV equipments such as a television set and a television set combined with a video cassette recorder, to protect the equipments from high voltage attributing to ground discharge.
The discharge gap device
1
comprises only a discharge gap unit
2
, and a resistor
3
which is a separate component is formed on a printed circuit board (not shown) . The discharge gap device
1
is substantially rectangular as shown in
FIG. 2
, and it is made up of a pair of soldering patterns (conductors)
5
and
6
on a surface
4
a
of a dielectric
4
of dielectric material such as ceramic base. Further, leadwires
7
and
8
to be inserted into the printed circuit board are connected to the soldering patterns
5
and
6
.
The soldering patterns
5
and
6
are elongated and symmetrical with each other, and their base ends are extended towards each other forming protruded ends
5
a
and
6
a
. The gap G between those protruded ends
5
a
and
6
a
provides a discharge gap unit
2
according to the safety standard.
In this embodiment, in order to meet the UL standard of U.S.A., the gap G for a television set is set to 1.6 mm, and the gap G for a television set combined with a video cassette recorder which needs double insulation is set to 3.2 mm. In this case, the circuit is different from the conventional CR compound part in which the discharge gap unit, the resistor, and the capacitor are connected in parallel to one another. Therefore, as for a television set combined with a video cassette recorder, the discharge gap unit
2
should be such that the gap G between the protruded ends
5
a
and
6
a
is 3.2 mm.
On the other hand, in the UL standard, the discharge voltage between conductors is set to 1.3 KV for safety. Therefore, it is preferable that the discharge gap device be manufactured so that no discharge occurs between the conductors at 2 to 3 KV, also in the case where the discharge gap device is employed for another electrical equipment including a television set.
On the rear surface (not shown) of the dielectric
4
, no silver patterns (conductors in the related art) are printed or bonded.
The soldering patterns
5
and
6
may be any conductor which is printed or bonded on the dielectric. The employment of the soldering patterns
5
and
6
eliminates the step of connecting the lead wires
7
and
8
to the dielectric
4
, and the step of mounting the conductors on the dielectric
4
. Hence, it is preferable that the conductors are the soldering patterns
5
and
6
.
Patterns or the like are not formed on the rear surface of the dielectric
4
, and therefore the dielectric
4
does not work as a capacitor; however, since the dielectric is of ceramic base or the like, discharge is liable to occur between the protruded ends
5
a
and
6
a.
in the discharge gap device
1
having no capacitor, the discharge gap unit
2
is formed on the dielectric
4
. Therefore, the discharge in the gap occurs on the dielectric
4
; that is, the discharge is liable to occur when compared with the discharge occurring in the air or between the insulators. Hence, the distance between the primary power source side and the secondary power source side may be long, and the short-circuiting of the primary and second power source sides is prevented. That is, the discharge gap device serves stably as an over-voltage protective circuit in the case of ground discharge or the like.
If necessary, a resin layer
9
may be formed in such a manner that it covers the substantially whole surface of the dielectric
4
as shown in FIG.
3
. The covering of the dielectric
4
is to prevent the soldering patterns
5
and
6
from peeling off. It is preferable that the protruded ends
5
a
and
6
a
of the soldering patterns
5
and
6
are not covered with the resin layer
9
as shown in
FIG. 3
, because the covering of the protruded ends
5
a
and
6
a
obstructs the discharge.
Now, an example of the formation of the discharge gap device with electrodes will be described.
A discharge gap device
10
shown in
FIG. 4
is formed as follows: Conductor, namely, silver paste is printed on the surface
4
a
of the dielectric
4
by print-etching, and then hardened by baking.
In the discharge gap device
10
, the sides of the sliver paste portions which are confronted with each other are made zig-zag, thus providing five pairs of protrusions. Thus, protruded ends
11
a
and
12
a
are formed. The protruded ends
11
a
and
12
a
form the discharge gap unit
2
. Hence, discharge occurs between a number of protruded ends
11
a
and a number of protruded ends
12
a
, whereby the discharge is stable. Therefore, the burning of the discharge portions is less than in the case of only one pair of protruded ends. Further, the discharge gap device
10
is longer in service life.
In a discharge gap device
13
shown in
FIG. 5
, the sides of conductors which are confronted with each other are made saw-teeth shaped, so that a number of pairs of protruded ends
14
a
and
15
a
are formed. These protruded ends
14
a
and
15
a
provide a number of discharge gaps. Hence, similarly as in the above-described discharge gap device
10
, the discharge is stable.
FIG. 6
is an electrical circuit diagram showing an example of the employment of the above-described discharge gap device
1
in a television set.
In the television set, the discharge gap unit
2
is interposed between the side of the commercial power source
16
and the side of the tuner
19
of the television set. The circuit of
FIG. 6
is equal in fundamental arrangement to the above-described conventional circuit of
FIG. 9
; therefore, in
FIG. 6
parts corresponding functionally to those already described with reference to
FIG. 9
are designated by the same reference numerals or characters.
As shown in
FIG. 6
, the discharge gap device
1
is connected between the commercial power source
16
of the television set and the tuner
19
. Therefore, the discharge gap unit
2
of the discharge gap device
1
is normally held non-conductive; that is, the commercial power source
16
of the primary power source side A is insulated from the tuner
19
of the secondary power source side B.
Now, the prevention of a load circuit from damage at the time of ground discharge will be described.
In the case where, for instance because of the occurrence of ground discharge, high voltage is applied through the antenna (not shown) to the antenna input terminal
19
a
of the tuner
19
, the discharge gap unit
2
of the discharge gap device
1
connected to the tuner
19
becomes conductive through discharge, the high voltage is run to the commercial power source
16
. Hence, the high voltage is not run to the secondary power source side B of the product, which protects the load circuits from damage.
In the above-described embodiment, the discharge gap device
1
is interposed between the side of the commercial power source
16
of the television set and the side of the tuner
19
; however, the invention is not limited thereto or thereby. That is, as a countermeasure against ground discharge, the discharge gap device may be interposed between the circuit (secondary circuit) connected to the secondary power source side and the commercial power source, or between the power lines of the commercial power source.
The discharge gap device designed as described above have the following effects or merits:
The conductors, which are arranged spaced from each other, are normally electrically not connected to each other; however, upon application of over-voltage, discharge is caused to occur between the conductors so that the conductors are electrically connected to each other. Therefore, parts other than the discharge gap unit can be arranged on the side of the printed circuit board as the case may be. Accordingly, when it is required to change parts other than the discharge gap unit, it is not necessary to newly manufacture a discharge gap device. Furthermore, it is not necessary to mount a capacitor or resistor which is not used. This means a reduction in the number of components of the discharge gap device.
Since the resistor, which is in parallel with the discharge gap device, is formed on the printed circuit board, a resistor different in resistance may be employed with ease as the case may be.
Further, in the discharge gap device of the invention, upon application of over-voltage, discharge occurs between at least two conductors on the dielectric, so that two or more lead wires are made electrically connected to one another. Since discharge occurring between the conductors is caused on the dielectric, it is possible to discharge with ease when compared with the discharge in the air or between insulators.
Claims
- 1. A discharge gap device adapted to be mounted on a printed circuit board (PCB), comprising:a dielectric having two opposing surfaces; at least two lead wires each having a portion adapted to be attached to the printed circuit board and another portion attached to one surface of said dielectric; at least two conductors which are connected to said lead wires and provided on said one surface of said dielectric; and a resistor connected between said two lead wires in parallel with said discharge gap device without being directly attached to said at least two conductors or directly mounted on said dielectric, the other surface of said dielectric being free of conductive material to avoid shunting capacitance being formed across said at least two conductors and to prevent passage of high frequency components across the gap device, wherein upon application of over-voltage, discharge is caused to occur between said conductors.
- 2. The discharge gap device as claimed in claim 1, wherein said conductors are of solder.
- 3. The discharge gap device as claimed in claim 1, wherein said conductors are electrodes, and said electrodes are spaced a predetermined distance from each other so that said electrodes are confronted with each other.
- 4. The discharge gap device as claimed in claim 3, wherein said electrodes have protruded ends which are protruded towards each other.
- 5. The discharge gap device as claimed in claim 4, wherein each of said electrodes has a plurality of protruded ends.
- 6. The mounting structure of the discharge gap device as claimed in claim 1, wherein said discharge gap device is provided between a part which produces high voltage and a part which absorbs the high voltage.
- 7. The discharge gap device as claimed in claim 1, wherein said lead wires are connected to said dielectric by welding solder, and the resultant soldering regions are employed as said conductors.
- 8. The discharge gap device as claimed in claim 1, wherein at least a surface of said dielectric to which said lead wires are connected is covered with resin.
- 9. The discharge gap device as claimed in claim 1, wherein said conductors on said dielectric between which discharge occurs are not covered with resin.
- 10. The mounting structure of the discharge gap device as claimed in claim 1, wherein said discharge gap device is provided between a power source line to which a commercial power source is connected and a secondary circuit.
- 11. The mounting structure of the discharge gap device as claimed in claim 10, wherein the secondary circuit is an antenna input terminal of a tuner.
Priority Claims (2)
| Number |
Date |
Country |
Kind |
| 9-310178 |
Nov 1997 |
JP |
|
| 9-359115 |
Dec 1997 |
JP |
|
US Referenced Citations (8)
