JP2531221Y2 - Discharge type surge absorbing element with security mechanism - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge type surge absorbing element with a security mechanism for absorbing surges such as induced lightning applied to telephone lines and the like to prevent electronic equipment from being damaged.
In particular, the present invention relates to a discharge-type surge absorbing element with a security mechanism that can flatten the element, form a trigger discharge electrode film with a voltage non-linear resistor, and can cut off continuous overcurrent.

[0002]

2. Description of the Related Art Conventionally, as a surge absorbing element for protecting an electronic circuit of an electronic device from a surge such as an induced lightning, a varistor composed of a high-resistance element having a voltage non-linear characteristic,
An arrester or the like in which a discharge gap is accommodated in an airtight container is widely used.

Although the varistor has excellent surge absorption responsiveness, it has a relatively small current withstand capacity per unit area, and thus it is difficult to efficiently absorb a large surge current. Further, the arrester can increase the current withstand capability by generating an arc discharge in the discharge gap. However, it takes a long time from the application of a surge to the arc discharge, and there is a problem in its responsiveness.

Therefore, as shown in FIGS. 8 and 9, a conductive thin film b is applied to the surface of a substantially cylindrical insulator a, and the conductive thin film b has a width of about 0.1 mm. The conductive thin film b is divided by forming a small discharge gap c in a circular shape, and the discharge electrodes e, e are fitted to both ends of the insulator a with a main discharge gap d therebetween to form the conductive thin films b, b. And the discharge electrode e,
and a surge absorbing element h in which the external terminals g and g are connected to each other and sealed in an airtight container f together with a discharge gas.

When a surge is applied to the surge absorbing element h, first, conductive thin films b, b separated by a minute discharge gap c
A potential difference is generated between them, whereby electrons are emitted to the minute discharge gap c and a creeping discharge occurs. Next, a transition is made to a glow discharge due to the priming effect of electrons generated by the creeping discharge. Then, the glow discharge is transferred to the main discharge gap d due to an increase in the surge current, and shifts to an arc discharge as the main discharge to absorb the surge.

[0006]

As described above, since the surge absorbing element h uses a creeping discharge originally having a high response speed generated in the minute discharge gap c as a trigger discharge, the surge absorbing element h is smaller than the arrester. Since high responsiveness can be realized and surge is absorbed by arc discharge as a main discharge generated in the main discharge gap d, a large current withstand capability can be realized as compared with the varistor.

However, in the conventional surge absorbing element h, as shown in FIG. 8, since the hermetic container f has a bulky and substantially cylindrical shape, a considerable space is required when mounting inside various electronic devices. This is contrary to recent demands for downsizing of electronic devices.

Further, since the conductive thin films b, b facing each other via the minute discharge gap c are formed of ordinary resistors, there are the following disadvantages. That is, since a current proportional to the voltage value starts to flow at the same time as the application of the voltage, it is difficult to stably set a voltage value that shifts to the main discharge gap, and when an overvoltage such as a surge is applied steeply. However, there is a possibility that the main discharge will start only when the rated voltage of the surge absorbing element h is far exceeded. In addition, since no surge is absorbed until the main discharge is started, the surge is applied to the electronic circuit during that time, and there is a risk of damaging the electronic circuit.

Further, when an overvoltage equal to or higher than the rated voltage of the surge absorbing element h is continuously applied by an overvoltage test based on safety standards such as UL and CSA assuming a contact accident with a power line or such a situation. Has a main discharge gap d
, The overcurrent conduction by the main discharge is maintained.
Then, the heat generated by the continuous energization of the overcurrent melts the hermetic container f and burns the circuit board in which the surge absorbing element h is incorporated. As a result, the passing criteria for the overvoltage test cannot be satisfied. Of course, there was a risk of causing a fire under actual use conditions.

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and has a compact outer shape, can achieve a stable transition characteristic to a main discharge gap, and an improvement in surge responsiveness. An object of the present invention is to prevent a burnout accident by interrupting continuous energization of an overcurrent, and to realize a discharge type surge absorbing element with a safety mechanism conforming to various safety standards.

[0011]

In order to achieve the above object, a discharge type surge absorbing element with a security mechanism according to the present invention comprises:
An insulating substrate, a lid member that hermetically covers the surface of the insulating substrate, forms a discharge space filled with a discharge gas between the surface, and a voltage non-linear resistor; A pair of trigger discharge electrode films formed so as to face each other with a minute discharge gap therebetween, and formed on the surface of the insulating substrate so as to face each other with a main discharge gap therebetween, and electrically connected to the trigger discharge electrode film. A pair of main discharge electrode films, and legs protruding from opposite side edges of the back surface of the insulating substrate, and a continuous overcurrent flows through the trigger discharge electrode film. In this case, the insulating substrate is crushed by the heat generated by the trigger discharge electrode film due to the application of the overcurrent, and the crushed portion of the insulating substrate is depressed downward.

Further, the discharge type surge absorbing element with a security mechanism according to the present invention hermetically covers an insulating substrate and a surface of the insulating substrate, and forms a discharge space filled with a discharge gas between the surface. A pair of trigger discharge electrode films formed by a lid member, a voltage non-linear resistor, and formed on the surface of the insulating substrate so as to face each other with a minute discharge gap therebetween; and a main discharge gap formed on the surface of the insulating substrate. And a pair of main discharge electrode films that are formed so as to face each other and electrically connected to the trigger discharge electrode film, and are electrically connected to the main discharge electrode film on both opposite end surfaces of the insulating substrate. And an external terminal protruding and fixed to the back side of the insulating substrate, and when a continuous overcurrent flows through the trigger discharge electrode film, Trigger discharge electrode film generates heat The insulating substrate is 砕裂, insulating substrate of crushed portion is configured to collapse downwards.

More specifically, the thickness, material, etc. of the insulating substrate are appropriately selected in consideration of the resistance value, the amount of current, and the like of the voltage non-linear resistor forming the trigger discharge electrode film at the time of discharge (that is, the thickness). , The cracking of the insulating substrate is adjusted). The expression “continuous” means “continuous for a certain period of time”, and “continuous overcurrent” includes not only direct current but also alternating current whose current value changes over time. Is naturally included. The same applies to the following.

When a voltage less than a predetermined voltage value set in advance is applied to the voltage non-linear resistor, the resistance value is very high, so that current does not flow. When a voltage is applied, the resistance value suddenly drops and has a property of passing a large current at a stretch. The above-mentioned predetermined voltage value (a voltage value at which current starts to flow) is called a clamp voltage. The clamp voltage is, for example, 10V to 100V.
It is set within the range of 0V. Further, as the voltage non-linear resistor, for example, ZnO, SiC, TiO ₂ , Fe ₂
O ₃ or the like is used.

Further, the discharge type surge absorbing element with a security mechanism according to the present invention forms an upper discharge space filled with a discharge gas between the insulating substrate and the surface of the insulating substrate in an airtight manner. An upper lid member, a lower lid member that hermetically covers the back surface of the insulating substrate and forms a lower discharge space filled with a discharge gas between the lower surface and the voltage non-linear resistor. A pair of trigger discharge electrode films formed so as to face the surface of the substrate with a minute discharge gap therebetween, and the trigger discharge electrode film formed so as to face the surface of the insulating substrate with a main discharge gap therebetween. A pair of main discharge electrode films electrically connected to the film, and, on both sides of the trigger discharge electrode film and the main discharge electrode film on the insulating substrate, substantially parallel to the direction of current flow of the trigger discharge electrode film. To form a pair of through grooves Therefore, when a continuous overcurrent flows through the trigger discharge electrode film, the heat generated in the trigger discharge electrode film due to the application of the overcurrent causes the trigger discharge electrode film to move in a direction substantially orthogonal to the direction of current flow of the trigger discharge electrode film on the insulating substrate. A plurality of cracks were generated, and the portion of the insulating substrate surrounded by the cracks and the through-groove was configured to fall into the lower lid member.

[0016]

The trigger discharge electrode film opposing the micro discharge gap and the main discharge electrode film opposing the main discharge gap are formed on the surface of the insulating substrate. The shape of the type surge absorbing element is entirely flattened, and it is easy to reduce the size.

In the above-mentioned discharge type surge absorbing element with a security mechanism,
When a surge equal to or higher than the clamp voltage of the voltage non-linear resistor constituting the trigger discharge electrode film is applied via an external terminal connected to the main discharge electrode film, the resistance of the voltage non-linear resistor rapidly increases. Then, the current flows through the trigger discharge electrode film. As a result, electrons are emitted into the minute discharge gap, and a creeping discharge as a trigger discharge occurs. Next, the surface discharge changes to a glow discharge due to the priming effect of electrons. Then, the glow discharge shifts to the main discharge gap, and shifts to the main discharge arc discharge to absorb the surge. On the other hand, when a voltage less than the clamp voltage is applied, the resistance value of the voltage non-linear resistor remains high,
No current flows through the trigger discharge electrode film, and thus no creeping discharge occurs.

As described above, when the applied voltage value is less than the clamp voltage, no current flows through the trigger discharge electrode film. However, when the clamp voltage is reached, a large current flows at once, so that the main discharge gap is surely reduced. And the main discharge is started. Since the variation of this clamp voltage is extremely small,
By appropriately adjusting the clamp voltage of the voltage non-linear resistor, a voltage value (hereinafter, referred to as a “main discharge start voltage”) that shifts to the main discharge gap can be set stably. In addition,
Since the voltage non-linear resistor itself has a surge absorbing effect,
Even before the main discharge is started, the surge is absorbed by the voltage non-linear resistor having the excellent surge responsiveness forming the trigger discharge electrode film.

When an overvoltage equal to or higher than the rated voltage of the discharge type surge absorbing element with a security mechanism is continuously applied by an overvoltage test assuming a contact accident with a power line or such a situation, the minute discharge is prevented. The discharge continues in the gap and the main discharge gap, and a continuous overcurrent flows through the discharge. The continuous discharge of the overcurrent causes the trigger discharge electrode film to generate heat, and the insulating substrate is broken by thermal strain. As a result, air flows into the discharge gas in the discharge space, the discharge disappears, and the overcurrent is cut off.
Burnout of the discharge type surge absorbing element with a security mechanism can be prevented.

[0020] Legs project from opposite side edges of the rear surface of the insulating substrate, or external terminals projecting toward the rear surface of the insulating substrate are fixed to opposite side edges of the insulating substrate. Accordingly, when mounted on a circuit board or the like, the center portion of the insulating substrate is supported in a floating state by the legs or the external terminals. Therefore, not only is the crushing of the insulating substrate extremely easy, but also the crushed portion is depressed downward and the current path is completely cut off, so that the overcurrent can be reliably cut off.

When the current flows through the trigger discharge electrode film, the portion of the insulating substrate at which the temperature is highest is substantially the center of the trigger discharge electrode film and is substantially perpendicular to the direction of current flow. Distributed on the line. Therefore, when an overvoltage equal to or higher than the rated voltage of the discharge type surge absorbing element with a security mechanism is continuously applied, and the overcurrent due to the overvoltage continuously flows through the trigger discharge electrode film, the distribution of the high temperature is reduced. Along the line, a plurality of cracks are generated in a direction substantially perpendicular to the direction of the current flow. Therefore, the front and back surfaces of the insulating substrate are airtightly covered with an upper lid member and a lower lid member, respectively, and a through groove substantially parallel to the direction of current flow of the trigger discharge electrode film is formed in the insulating substrate by the trigger discharge electrode film and the main groove. When formed on both sides of the discharge electrode film, a part of the insulating substrate surrounded by the cracks and the through grooves falls into the lower cover member below. As a result, the path of the current is cut off, and the discharge surely disappears.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment. As shown in FIG. 1 and FIG. 2 which is a cross-sectional view taken along line AA of FIG. 1, the first discharge type surge absorbing element 2 with a security mechanism according to the first embodiment has a thickness of 0.4 to 1.0 mm. A first insulating substrate 4 made of ceramic or the like;
A cover member 8 covering the surface 6 of the base member;
A pair of trigger discharge electrode films 12 and 12 formed with a micro-discharge gap 10 of 0 μm therebetween and a width of 0.2 to
It has a pair of main discharge electrode films 16, 16 formed with a 10 mm main discharge gap 14 therebetween.

The trigger discharge electrode films 12, 12 are made of Zn.
It is formed by a voltage non-linear resistor such as O, SiC, TiO ₂ , and Fe ₂ O ₃ . Further, the main discharge electrode film 16,
16 is Mo, LaB ₆ , MoSi ₂ , TiO _2, etc.
It is formed of a conductive material having sputter resistance. The trigger discharge electrode films 12, 12 and the main discharge electrode films 16, 1
6 are electrically connected to each other.

At the tips of the trigger discharge electrode films 12, 12, sputter-resistant conductive protective films 18, 18 made of Mo, LaB ₆ , MoSi ₂ , TiO _{2 and the} like are formed. And the trigger discharge electrode film 1
Insulation deterioration of the minute discharge gap 10 due to the sputtering of 2, 12 is prevented, and the life characteristics are improved. Further, the surfaces of the trigger discharge electrode films 12 are coated with insulating films 20 made of non-crystallized glass or the like in order to prevent creeping discharge at the exposed portions.

The left and right edges of the back surface 22 of the first insulating substrate 4 protrude in a direction substantially perpendicular to the back surface 22 and are substantially perpendicular to the direction of conduction of the trigger discharge electrode films 12. The legs 24, 24 extending in the direction are formed integrally with the first insulating substrate 4.

From the surface 6 of the first insulating substrate 4 to the leg 2
Ag / Pd or N
A pair of first external terminal thin films 28, 28 made of i or the like are formed on the first external terminal thin films 28, 28.
Are electrically connected to the main discharge electrode films 16, 16.

The lid member 8 is made of an insulating material such as glass or ceramic.
It has a height of about mm. The side surface 30 and the surface 6 of the first insulating substrate 4 are sealed with a sealing material 32 made of low melting point glass or the like.
As a result, an airtight discharge space 34 having a height corresponding to the height of the side surface 30 is formed between the surface 6 of the first insulating substrate 4 and the cover member 8. The discharge space 34 is filled with a discharge gas mainly composed of a single or a mixture of rare gases such as He, Ne, Ar, and Xe. Instead of using the lid member 8 having the side surface 30 as described above, a flat lid member is used, and a spacer or the like is arranged between the lid member 8 and the first insulating substrate 4 to form the discharge space 34. May be.

When the overcurrent continuously flows through the trigger discharge electrode films 12, the first discharge type surge absorbing device 2 with the security mechanism, the trigger discharge electrode film 12, which is caused by the overcurrent, flows. 12, the first insulating substrate 4
Are configured to fracture by thermal strain. Specifically, the thickness of the first insulating substrate 4 and the thickness of the first insulating substrate 4 are considered in consideration of the resistance value of the voltage non-linear resistors forming the trigger discharge electrode films 12 and 12 during discharge and the amount of heat generated based on the amount of current. This is realized by appropriately selecting the material and the like (that is, adjusting the easiness of cracking of the insulating substrate 4).

The first external terminal thin films 28, 2 having the above-described first discharge type surge absorbing element 2 with a security mechanism mounted on a printed circuit board or the like of an electronic device are mounted.
When a surge equal to or higher than the clamp voltage of the voltage non-linear resistors constituting the trigger discharge electrode films 12, 12 is applied from outside via the trigger 8, the resistance value of the voltage non-linear resistors rapidly decreases, and the trigger discharge occurs. A large current flows through the electrode films 12 at a stretch. As a result, electrons are emitted to the minute discharge gap 10 to generate a creeping discharge as a trigger discharge, and the creeping discharge shifts to a glow discharge by a priming effect of the electrons. Then, the glow discharge is immediately applied to the main discharge gap 1.
4 and the arc shifts to the main discharge to absorb the surge. Note that even before the main discharge starts, the voltage non-linear resistor itself having excellent responsiveness and constituting the trigger discharge electrode films 12, 12 absorbs the surge.
Responsiveness to surge is improved.

When an overvoltage equal to or higher than the rated voltage of the first discharge type surge absorbing element 2 with a security mechanism is continuously applied by an overvoltage test assuming a contact accident with a power line or such a situation, Micro discharge gap 10 and main discharge gap 1
4, the discharge continues, and a continuous overcurrent flows through the discharge. In the case of such a short-circuit state, the trigger discharge electrode film 1 is caused by the continuous overcurrent.
2 and 12 generate heat, and the first insulating substrate 4 is broken by thermal strain. As a result, air flows into the discharge gas in the discharge space 32 to extinguish the discharge and cut off the overcurrent.

Since the legs 24 are formed on the back surface 22 of the first insulating substrate 4 as described above, the back surface of the first insulating substrate 4 may be mounted on a circuit board or the like. 2
2 does not adhere to the surface of the circuit board,
4, 24, the vicinity of the center of the first insulating substrate 4 is supported so as to float from the circuit board.
Is easily broken. Further, since the crushed portion is depressed downward, the current path is cut off, and the overcurrent can be more reliably cut off.

Next, a second embodiment according to the present invention will be described with reference to FIG. 3 and FIG. 4 which is a sectional view taken along the line BB of FIG. The second discharge-type surge absorbing element 40 with a security mechanism according to the present embodiment includes a second insulating substrate 42 made of ceramic or the like having a thickness of 0.4 to 1.0 mm, and a surface of the second insulating substrate 42. A cover member 8 covering the surface 44, a pair of trigger discharge electrode films 12, 12 formed on the surface 44 with the fine discharge gap 10 therebetween, and a pair of trigger discharge electrode films 12, also formed with the main discharge gap 14 formed therebetween. And a pair of main discharge electrode films 16. Conductive protective films 18, 18 are formed on the tips of the trigger discharge electrode films 12, 12, and the surfaces thereof are covered with insulating films 20, 20. Further, the trigger discharge electrode films 12, 12 and the main discharge electrode films 16, 16 are electrically connected to each other.

On the left end face 46 and the right end face 48 of the second insulating substrate 42, respectively, the back surface 5 of the second insulating substrate 42
External terminals 52, 52 protruding to the 0 side are fixedly provided.
The external terminals 52, 52 are formed of a conductive material such as Ag / Pd, and are also formed of Ag / Pd or the like.
External terminal connection thin films 54, 54 that are applied from the surface 44 of the insulating substrate 42 to the left end surface 46 or the right end surface 48.
Are electrically connected to the main discharge electrode films 16 and 16 via. This second discharge type surge absorbing element 4 with a security mechanism
0 is mounted on a circuit board or the like by fixing and connecting the external terminals 52, 52 on the surface of the circuit board or the like.

The second discharge type surge absorbing element 40 with a security mechanism also functions in the same manner as the first discharge type surge absorbing element 2 with a security mechanism. That is, when a surge equal to or higher than the clamp voltage of the voltage non-linear resistors constituting the trigger discharge electrode films 12, 12 is applied from the outside via the external terminals 52, 52, the resistance of the voltage non-linear resistors rapidly increases. ,
A large current flows through the trigger discharge electrode films 12, 12 at a stretch. As a result, electrons are emitted to the minute discharge gap 10 to generate a creeping discharge as a trigger discharge.
The transition to glow discharge occurs due to the priming effect of electrons. The glow discharge is immediately transferred to the main discharge gap 14, and shifts to the main discharge arc discharge to absorb the surge. Further, even before the main discharge starts, the voltage non-linear resistors constituting the trigger discharge electrode films 12, 12 absorb the surge.

When an overvoltage equal to or higher than the rated voltage of the second discharge-type surge absorbing element 40 with a security mechanism is continuously applied, the trigger electrode film 12, 12 generates heat, and the second insulating substrate 42 is broken by thermal strain. As a result, air flows into the discharge gas in the discharge space 34 to extinguish the discharge and cut off the overcurrent.

As described above, the external terminals 52, 52 fixed to the left end face 46 and the right end face 48 of the second insulating substrate 42 are provided.
Accordingly, the back surface 50 of the second insulating substrate 42 does not adhere to the surface of the circuit board, and the vicinity of the center of the second insulating substrate 42 is supported in a floating state from the circuit board. Is easily broken. Further, since the crushed portion is depressed downward, the current path is cut off, and the overcurrent can be more reliably cut off.

Next, a third embodiment according to the present invention will be described with reference to FIG. 5 and FIG. 6 which is a cross-sectional view taken along the line CC of FIG. The third discharge type surge absorbing element 60 with a security mechanism according to the present embodiment includes a third insulating substrate 62 made of ceramic or the like having a thickness of 0.4 to 1.0 mm, and a surface of the third insulating substrate 62. An upper lid member 66 that covers the second insulating substrate 62, a lower lid member 70 that covers the back surface 68 of the third insulating substrate 62, and a front surface 64 of the third insulating substrate 62 that are formed with a minute discharge gap 10 therebetween. A pair of trigger discharge electrode films 12, 12
And a pair of main discharge electrode films 16, 16 formed on the surface 64 with the main discharge gap 14 therebetween.
Conductive protective films 18, 18 are formed on the tips of the trigger discharge electrode films 12, 12, and the surfaces thereof are covered with insulating films 20, 20. Further, the trigger discharge electrode films 12, 12 and the main discharge electrode films 16, 16 are electrically connected to each other.

The third insulating substrate 62 has two through-grooves 72, 72 substantially parallel to the direction of conduction of the trigger discharge electrode films 12, 12, and the trigger discharge electrode films 12, 12, and the main discharge electrode film 16, , 16 are formed near both sides thereof. The surface 6 of the third insulating substrate 62
4 to the back surface 68, the second external terminal thin film 74,
74 is formed.

The upper lid member 66 and the lower lid member 70 have the same configuration as the above-mentioned lid member 8, and the upper lid member 66
Of the third insulating substrate 6 with the sealing material 32 interposed therebetween.
2 is fixed to the surface 64 of the third insulating substrate 6.
An airtight upper discharge space 78 is formed between the upper surface 64 and the upper lid member 66. Similarly, the lower lid member 70
Of the third insulating substrate 6 with the sealing material 32 interposed therebetween.
By fixing the third insulating substrate 6 to the back surface 68 of the second
An airtight lower discharge space 82 is formed between the lower surface 68 and the lower lid member 70. A discharge gas is sealed in the upper discharge space 78 and the lower discharge space 82. Note that the upper discharge space 78 and the lower discharge space 82 are separated from each other by the through groove 7.
They are communicated via 2 and 72.

While mounted on a printed circuit board or the like of an electronic device, the trigger discharge electrode film 12 is externally applied to the third discharge type surge absorbing element 60 with a security mechanism via the second external terminal thin films 74, 74. When a surge equal to or higher than the clamp voltage of the voltage non-linear resistors constituting the non-linear resistors is applied, the resistance value of the non-linear resistors rapidly decreases, and a large current flows through the trigger discharge electrode films 12, 12 at a stretch. . as a result,
Electrons are emitted into the minute discharge gap 10 to generate a creeping discharge as a trigger discharge, and the creeping discharge shifts to a glow discharge due to the priming effect of the electrons. The glow discharge is immediately transferred to the main discharge gap 14, and shifts to the main discharge arc discharge to absorb the surge. Also,
Even before the main discharge starts, the voltage non-linear resistors forming the trigger discharge electrode films 12, 12 absorb the surge.

When an overvoltage equal to or higher than the rated voltage of the third discharge-type surge absorbing element 60 with a security mechanism is continuously applied, the trigger discharge electrode film 12, 12 generates heat. in this case,
The portion of the third insulating substrate 62 where the temperature is the highest is a substantially central portion of the trigger discharge electrode films 12 and is distributed on a line substantially orthogonal to the direction of current flow. As a result, a plurality of cracks 84 are generated in the third insulating substrate 62 along the distribution line of the high temperature as shown in FIG. Then, a part of the third insulating substrate 62 surrounded by the cracks 84, 84 and the through grooves 72, 72 falls into the lower lid member 70. Thereby, the trigger discharge electrode film 1
The current path between the main discharge electrodes 2 and 12 and between the main discharge electrode films 16 and 16 is cut off, the discharge disappears, and as a result, the overcurrent is cut off.

[0042]

As described above, the discharge type surge absorbing element with a security mechanism according to the present invention comprises an insulating substrate, a cover member covering the insulating substrate, and a trigger discharge formed on the surface of the insulating substrate. Since the structure is made up of the electrode film and the main discharge electrode film, the outer shape can be flattened. as a result,
The use of the discharge type surge absorbing element with a security mechanism can be expanded, for example, it can be accommodated in a small device having a small space for accommodating parts, and the use value thereof can be increased.

Since the trigger discharge electrode film is composed of the voltage non-linear resistor, the starting voltage of the main discharge can be defined by the clamp voltage of the voltage non-linear resistor. That is, when a surge equal to or higher than the clamp voltage is applied, the main discharge is immediately started and the main discharge is reliably started, so that the start voltage of the main discharge can be set stably based on the clamp voltage. Further, even before the main discharge starts, the voltage non-linear resistor itself having excellent responsiveness itself absorbs the surge, so that the responsiveness to surge is improved.

The structure of the insulating substrate is configured to be broken by heat generation of the trigger discharge electrode film due to continuous overcurrent application, so that the rating of the discharge type surge absorbing element with a safety mechanism can be evaluated by a contact accident with a power line or various overvoltage tests. When an overvoltage equal to or higher than the voltage is continuously applied, the trigger discharge electrode film generates heat due to an overcurrent due to the overvoltage, and the insulating substrate is broken. As a result, air flows into the discharge gas in the discharge space, which causes the discharge to disappear and cuts off the overcurrent, thereby preventing the discharge type surge absorbing element with the security mechanism from being extinguished.

The leg portions may be formed so as to protrude at opposite side edges on the back surface of the insulating substrate, or external terminals protruding toward the back surface side of the insulating substrate may be fixed to both opposing end surfaces of the insulating substrate. With this configuration, when the discharge type surge absorbing element with a security mechanism according to the present invention is mounted on a circuit board or the like, the center part of the insulating substrate can be supported in a floating state by the legs or the external terminals. The crushing of the substrate becomes extremely easy. Further, since the crushed portion is depressed downward and the current path is completely cut off, the overcurrent can be reliably cut off.

The front and back surfaces of the insulating substrate are air-tightly covered with an upper lid member and a lower lid member, respectively, and a through groove substantially parallel to the direction of conduction of the trigger discharge electrode film is formed in the trigger substrate. By forming on both sides of the main discharge electrode film, an overvoltage exceeding the rated voltage of the discharge type surge absorbing element with a security mechanism according to the present invention is continuously applied, and an overcurrent due to the overvoltage is applied to the trigger discharge electrode film. In the case of continuous flow, a plurality of cracks are generated in a direction substantially perpendicular to the direction of conduction of the trigger discharge electrode film, and a part of the insulating substrate surrounded by the cracks and the through-groove is a lower cover member. Fall into. As a result, the current path is completely cut off, so that the overcurrent can be reliably cut off.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of a discharge type surge absorbing element with a security mechanism according to the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an exploded perspective view showing a second embodiment of the discharge type surge absorbing element with a security mechanism according to the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is an exploded perspective view showing a third embodiment of the discharge type surge absorbing element with a security mechanism according to the present invention.

FIG. 6 is a sectional view taken along the line CC of FIG. 5;

FIG. 7 is a perspective view of a main part of the third embodiment.

FIG. 8 is a schematic perspective view of a conventional surge absorbing element.

FIG. 9 is a schematic sectional view of a conventional surge absorbing element.

[Explanation of symbols]

 2 First discharge type surge absorbing element with security mechanism 4 First insulating substrate 6 Surface of first insulating substrate 8 Lid member 10 Micro discharge gap 12 Trigger discharge electrode film 14 Main discharge gap 16 Main discharge electrode film 22 First Back surface of insulating substrate of 24 legs 34 discharge space 40 second discharge type surge absorbing element with security mechanism 42 second insulating substrate 44 front surface of second insulating substrate 46 left end surface of second insulating substrate 48 second Right end surface of insulating substrate 50 Back surface of second insulating substrate 52 External terminal 60 Third discharge-type surge absorbing element with security mechanism 62 Third insulating substrate 64 Front surface of third insulating substrate 66 Upper lid member 68 Third Back surface of insulating substrate 70 Lower lid member 72 Through groove 78 Upper discharge space 82 Lower discharge space

Claims (3)

(57) [Scope of request for utility model registration] An insulating substrate, a lid member that hermetically covers a surface of the insulating substrate, forms a discharge space filled with a discharge gas between the insulating substrate, and a voltage non-linear resistor; A pair of trigger discharge electrode films formed on the surface of the insulating substrate so as to face each other with a minute discharge gap therebetween, and a pair of trigger discharge electrode films formed on the surface of the insulating substrate so as to face each other with a main discharge gap therebetween, A pair of main discharge electrode films electrically connected to the electrode film and a pair of main discharge electrode films opposed to each other on a back surface of the insulating substrate;
When a continuous overcurrent flows through the trigger discharge electrode film, heat is generated in the trigger discharge electrode film due to the application of the overcurrent, so that the insulation is generated. The substrate breaks, and the insulated substrate in the torn part falls down.
Characterized by being configured to death, with safety mechanism discharge surge absorbing element. 2. An insulating substrate, a lid member hermetically covering a surface of the insulating substrate, forming a discharge space filled with a discharge gas between the insulating substrate and the surface, and a voltage non-linear resistor, A pair of trigger discharge electrode films formed on the surface of the insulating substrate so as to face each other with a minute discharge gap therebetween, and a pair of trigger discharge electrode films formed on the surface of the insulating substrate so as to face each other with a main discharge gap therebetween, A pair of main discharge electrode films electrically connected to the electrode film ;
When the side end face is electrically connected to the main discharge electrode film,
An outer end that is fixedly protruded from the back side of the insulating substrate.
It and a child, if the overcurrent continuous to the trigger discharge electrode film flows, heat generated by the trigger discharge electrode film due to energization of the overcurrent, the insulating substrate is砕裂and disrupted
A discharge type surge absorbing element with a security mechanism, wherein a part of the insulating substrate is depressed downward . 3. An insulating substrate, an upper lid member hermetically covering a surface of the insulating substrate and forming an upper discharge space filled with a discharge gas between the insulating substrate and the upper surface of the insulating substrate. A lower lid member forming a lower discharge space filled with a discharge gas between the lower cover member and the back surface; and a voltage non-linear resistor, and covered so as to face the surface of the insulating substrate with a minute discharge gap therebetween. A pair of trigger discharge electrode films to be formed and a pair of main discharge electrode films formed so as to face the surface of the insulating substrate with a main discharge gap therebetween and electrically connected to the trigger discharge electrode film. possess the door, also on both sides of the trigger discharge electrode film and the main discharge electrode film in the insulating substrate, it forms a through groove pairs of substantially parallel and current direction of the trigger discharge electrode film, the trigger discharge When a continuous overcurrent flows through the electrode film Then, the heat generated in the trigger discharge electrode film due to the application of the overcurrent causes the trigger on the insulating substrate to be discharged .
In the direction substantially perpendicular to the direction of conduction of the
A crack is formed, and the part surrounded by the crack and the through groove is cut off.
A discharge type surge absorbing element with a security mechanism, wherein the edge substrate is configured to fall into a lower lid member .