JP3428610B2 - Micro gap type surge absorber - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surge absorber having a function of absorbing a surge voltage applied to electronic equipment for communication equipment such as telephones, facsimiles, telephone exchanges, and modems. About. More specifically, an element having a micro gap is sealed in a glass tube or the like together with an inert gas or the like (herm
The present invention relates to a discharge-type surge absorber that has been subjected to etic sealing. 2. Description of the Related Art Conventionally, as a microgap type surge absorber, as shown in FIG. 3 , the surface of a cylindrical ceramic body 3a made of insulating ceramics such as mullite is formed of a metal, a metal oxide, or a metal. The element 3 is formed by being covered with a conductive film 3b of nitride, metal carbide, or the like, and a microgap of one or two or more filaments having a width of 10 to 1000 μm in a circumferential direction is formed on a peripheral surface of the element 3. The conductive film 3b is electrically divided into a plurality of parts by forming 3c with laser light or the like, and a pair of cap electrodes 9, 9 having a pair of lead wires 4, 4 are fitted to both ends of the element 3. A surge absorber 1 enclosed in a glass tube 2 with a part of these lead wires 4 and 4 is known. In this surge absorber 1, N ₂ , Ar, H
Gases such as e, CO ₂ , CO, and SF ₆ are filled. on the other hand,
As a micro-gap surge absorber, a micro-gap element 3 having a pair of cap electrodes fitted at both ends as shown in FIG. 4 is sandwiched between a pair of sealing electrodes 7 with lead wires 8. A surge absorber 5 sealed in a glass tube 6 is also known. [0003] These microgap type surge absorbers 1 or 5 are connected to an electronic device in a power supply circuit in parallel or as a ground circuit. Normally, no current flows through the surge absorber 1 or 5 due to the presence of the microgap 3c. However, when a surge voltage is applied to the surge absorber 1 or 5 due to a surge entering the power supply circuit, the microgap 3c A glow discharge is generated between the cap electrodes 9, which then becomes a creeping discharge along the conductive film 3b. If the surge continues, an arc discharge occurs between the pair of cap electrodes 9, 9 accompanied by generation of ions. As a result,
The current caused by the surge voltage is the surge absorber 1 or 5
Since the flow only flows and does not flow to the electronic device, the electronic device is protected from surge. However, in the micro-gap surge absorber 1 or 5, when a surge voltage is applied to the surge absorber 1 or 5 and an arc discharge occurs between the pair of cap electrodes 9, one of the cap electrodes 9 or 9 is used. 9
Then, metal ions of the electrode material are generated, and the ions contaminate the micro gap 3c. When this surge voltage is repeatedly applied to the surge absorber 1 or 5, the micro-gap 3c is filled with the metal by the metal ions, so that the divided conductive film 3b conducts, and the surge absorber 1 or 5 has its original function. Unable to fulfill
Les there was. [0005] In order to solve this problem, the present applicant has provided a pair of annular arc discharge absorbing electrodes spaced apart from and surrounding the conductive coating in the radial direction of the ceramic body, A patent application has been filed for a surge absorber in which the pair of arc discharge absorbing electrodes face each other and are electrically connected to a pair of sealing electrodes, respectively (Japanese Patent Laid-Open No. 6-310).
251). The annular arc discharge absorbing electrode is incorporated separately from the cap electrode so as to accommodate the cap electrode, or is formed integrally with the cap electrode by making the peripheral edge of the cap electrode larger in diameter than the cap electrode. In the surge absorber configured as described above, since arc discharge is performed between a pair of electrodes for absorbing arc discharge floating from the conductive film, fatigue or deterioration of the micro gap, the conductive film and the cap electrode is reduced, and the surge is reduced. The life characteristics can be improved. However, in the conventional improved surge absorber described above, the outer diameter of the arc discharge absorbing electrode must be formed larger than the outer diameter of the ceramic body. However, there was a problem that the size became large. In addition, it is necessary to incorporate the arc discharge absorbing electrode as an independent component or to process the cap electrode into a special shape. An object of the present invention is to provide a micro-gap surge absorber that is small in size and can improve surge life characteristics. Another object of the present invention is to provide a microgap surge absorber that requires a small number of parts and does not require special processing for the cap electrode. Means for Solving the Problems The invention according to claim 1 is:
As shown in FIG. 1 , housed inside a container 32 that maintains insulation
The element 73 is a ceramic body 74 and this ceramic
Conductive film 16 formed on the surface of
Mike formed circumferentially on the peripheral surface of the ceramic element body 74
And a pair of main discharge ports at both ends of the element 73.
Micro-gap type circuit provided with electrodes 17, 17
It is an improvement of the diabsorber. Its characteristic structure is
Mix element 74 is applied to a pair of main discharge electrodes 17, 17.
The first and second element bodies 74a, 74a contacting each other and having the same outer diameter.
4b and the first and second element bodies 74a and 74b
The diameter is smaller than the outer diameter of the first and second element bodies 74a, 74b
A small diameter element 74c, and the small diameter element 74c is
4a or the second element 74b.
Is formed separately from the first and second element bodies 74a and 74b,
The micro gap 18 is formed on the peripheral surface of the small diameter element 74c.
The ceramic body 74 has a small diameter body 74c
As a result, the pair of main discharge electrodes 17,
17 and an optical shield between the micro gap 18.
Where the stepped portion 74d is formed. In the micro-gap surge absorber according to the first aspect,
The metal ions generated at the main discharge electrode 17 adhere to the optical shield 14b and do not adhere to the micro gap 18 blocked by the shield 14b. Does not conduct. [0008] In the present invention, the above-mentioned effect is obtained by disposing the optical shield 14b between the main discharge electrode 17 and the micro gap 18 due to the straightness of metal ions. That is, the metal ions generated at one of the pair of main discharge electrodes 17 and 17 travel toward the counter electrode. At this time, if the shield 14b is not present, the micro gap 18 which is the counter electrode closest to the main discharge electrode 17 is used. And is discharged to the periphery to be reduced to metal.
However, if the shield 14b is present, the inertia of the shield 14b collides with the shield 14b and is reduced to metal by the shield 14b, so that the micro gap 18 is not stained. Next, a first embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the surge absorber 71 is a micro-gap discharge surge absorber, and is configured by housing an element 73 inside a container 32 that maintains insulation. Element 73 has a ceramic body 74, a conductive film 16 formed on the surface of the ceramic body 74, and a micro-gap 18 formed in the circumferential direction on the peripheral surface of the ceramic body 74. [0010] The container for maintaining insulation of the present invention includes a glass tube or an insulating ceramic tube, a container using a metal tube as a part of the glass tube or the insulating ceramic tube,
Alternatively, it is a container using glass or an insulating ceramic material for a part of a metal tube. The glass tube is made of lead glass, barium glass, soda glass, borosilicate glass or the like. The ceramic body 74 is formed of alumina, mullite, corundum mullite, or the like, and has a pair of cap electrodes.
First and second element bodies 74 each fitted with poles 17, 17
a, 74b and the outer diameter of the first and second element bodies 74a, 74b
And a smaller element 74c. First and second element
The body 74a has the same outer diameter. The first element 74a
The second element 74b is formed integrally with the small diameter element 74c.
Are formed separately. First element 74a and small diameter element 74c
A conductive film 16 is integrally formed on the surface of the second element.
The conductive film 16 is formed solely on the surface of the body 74b.
You. Small relative to the outer diameter of the first and second element bodies 74a, 74b.
The ratio of the outer diameter of the diabody 74c is in the range of 0.2 to 0.9.
Is preferred. The micro gap 18 is the small diameter element body described above.
74c is formed on the peripheral surface. The shape of the ceramic body 74 is a cylinder, an elliptical column, a rectangular parallelepiped, a cube, a truncated cone, a triangular prism, and other prisms other than the small diameter body and the small diameter body .
Triangular truncated pyramids, other truncated pyramids, or those obtained by deforming these can be used. The first and second element bodies 74a,
Small-diameter element relative to total length of 74b and small-diameter element 74c
The length ratio of 74c may be in the range of 0.2 to 0.9
preferable. First element 74a, small diameter element 74c and second element
Body 74b is alumina, mullite, corundum mullite
Etc., and Ti, Ni, T
a, W, TiN, TiC, SnO ₂ , BaAl alloy, etc.
Each of the conductive films 16 is formed. Also in the container 32
Are the first element 74a, the small diameter element 74c, and the second element 74b
And the first element 74a, the small diameter element 74c and
The conductive film 16 of the second element 74b is electrically connected in this order.
Continued. Note that the small diameter element is not the first element but the second element.
Body and may be integrally formed and the first body, a small diameter body
And the second element may be formed separately. Further
The lamic body 74 has a small diameter body 74c.
Steps 14b are formed in the ceramic body 74,
The stepped portion 74 d is formed by a pair of cap electrodes 17, 17.
It becomes an optical shield between the micro gap 18.
The film 16 is formed by spraying, sputtering, vapor deposition, printing, ion plating, plating, CV
It is formed on the surface of the ceramic body 74 by a thin film forming method such as the D method. The cap electrode 17 is formed of SUS (stainless steel), Ni, Mo, Ta, or the like. Microgap 18 laser processing method, the conductive film 16 of the small-diameter element 74c by micromachining method or a printing method such as etching
Are formed on the small diameter element body 74c so as to divide. In the laser method, a width of 10 to 2000 μm is formed based on the depth of focus of the laser beam and the thickness of the conductive film 16. Both ends of the container 32 are provided with a pair of sealing electrodes 39, 3
9 sealed. Container 32 contains molecular oxygen
No gas is sealed, and the element 73 is connected to the pair of sealing electrodes 3.
It is fixed by being pinched by the components 9, 39. Also
The pair of sealing electrodes 39, 39 are paired with the pair of cap electrodes 17,
17 and electrically connected to the conductive film 16 via
A pair of lead wires 4 is provided on the outer surfaces of the sealing electrodes 39, 39.
1, 41 are welded by brazing material such as solder
Welded by contact method. The sealing electrode 39 is a dumet wire,
It is formed by a slag lead or the like. Further sealed in container 12
The gas used is a gas that does not contain molecular oxygen, such as H
e, Ne, Ar, Xe, N 2, CO 2, SF 6 and C ₃ F ₈
Can be suitably used. In the micro-gap type surge absorber configured as described above, a voltage caused by the surge is applied to the pair of cap electrodes 17, 17 via the pair of lead wires 41 , 41.
Glow discharge starts at the micro gap 18 without delay, and the glow discharge extends to the pair of cap electrodes 17 and 17 in the form of creeping discharge, and arc discharge occurs between the pair of cap electrodes 17 and 17. Is formed. At this time, the micro gap 18 is located at the stepped portion from the arc discharge path.
Even if metal ions are scattered from the cap electrode 17 due to the arc discharge, the metal ions do not adhere to the micro gap 18 and the stepped portion 7
Attach to 4d and discharge to become metal. As a result, it is possible to prevent the discharge voltage of the surge absorber 71 from being lowered and the insulation resistance from being deteriorated due to the metal filling the micro gap 18. Compare the ceramic body 74
Of a first element 74a and a small diameter element 74c having a simple shape
Object and a second element 74b having a simple shape.
Therefore, the number of man-hours for manufacturing the ceramic body 74 can be slightly increased.
No. [0013] Figure 2 shows a second embodiment of the present invention.
2 , the same reference numerals as those in FIG. 1 indicate the same parts. This embodiment is configured the same as the first embodiment except that a pair of cap electrodes are not fitted to the first and second bodies 74a and 74b of the ceramic body 74. The small diameter element may be formed integrally with the second element instead of the first element, or the first element, the small element and the second element may be formed separately. . In the micro-gap surge absorber configured as described above, since the pair of cap electrodes is not fitted to both ends of the ceramic body 74, the number of manufacturing steps of the surge absorber 91 can be reduced as compared with the surge absorber of the first embodiment. . Next, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in <Embodiment 1> FIG. 1, the first constituting the ceramic body 74
The element body 74a and the small diameter element 74c are integrally formed, and the second element 74b is separately manufactured. First and second element bodies 74
a and 74b are formed in the same shape and have an outer diameter of 1.7, respectively.
mm and a length of 1.5 mm. The small diameter element 74c is formed in a cylindrical shape having an outer diameter of 1 mm and a length of 2 mm. First element 74a, small diameter element 74c, and second element 7
4b is formed of corundum mullite. The surfaces of the first element 74a and the small diameter element 74c are integrally formed with SnO.
_{The second} conductive film 16 is formed, and the SnO ₂ conductive film 16 is formed alone on the surface of the second element body 74b. In addition, the first element 7 is placed in a glass tube 32 made of lead glass.
4a, the small diameter element 74c, and the second element 74b are accommodated in this order, and are fixed by being sandwiched between a pair of sealing electrodes 39, 39. The first element 74a, the small element 74c, and the second element 74b are electrically connected in series in this order . The surge absorber 71 manufactured as described above was used as Example 1 . <Embodiment 2 > As shown in FIG. 2 , first and second ceramic bodies 74 are formed.
Body 74a, except that the cap electrodes are not fitted to 74b, configured similarly to the first embodiment. The surge absorber 91 manufactured in this manner was used as Example 2 . Comparative Example 1 As shown in FIG. 3 , a ceramic body 3a is formed in a cylindrical shape having an outer diameter of 1.7 mm and an overall length of 5.5 mm without a small diameter portion, and one ceramic body 3a is provided at the center in the longitudinal direction. Of the glass tube 2 without using a pair of sealing electrodes.
Is configured in the same manner as in the first embodiment except that is sealed . The surge absorber 1 manufactured as described above was used as Comparative Example 1. <Comparative Example 2> As shown in Fig. 4 , the ceramic body 3a is formed in a cylindrical shape having an outer diameter of 1 mm and a total length of 3 mm without a small diameter portion, and one micro gap 3c is formed at the center in the longitudinal direction. Except for this, the configuration is the same as that of the first embodiment. The surge absorber 5 manufactured in this manner was used as Comparative Example 2. [0017] <Comparative Test and Evaluation> Example 1, Example 2, examine a DC breakdown voltage and the surge life characteristic of the surge absorber of Comparative Example 1 and Comparative Example 2, the results are shown in Table 1. The surge life characteristic is determined by repeatedly applying an (8 × 20) μsec-100 A impulse current and checking whether or not the resistance value has decreased every 1000 times of application of the impulse current.
The presence or absence of insulation resistance deterioration was determined. [Table 1] [0019] As is apparent from Table 1, Example 1, performed
The DC discharge start voltage of the surge absorbers of Example 2 , Comparative Example 1 and Comparative Example 2 showed the same value. With respect to the surge life characteristics, the resistance value even surge absorber applied to 5000 times of the impulse current of Example 1 and Example 2 did not decrease, the surge absorber of Comparative Example 1 and Comparative Example 2 1000 When the resistance was measured after the application of the impulse current, the resistance was found to be low. Therefore, it was found that towards the surge absorber of Example 1 and Example 2 surge life characteristics than the surge absorber of Comparative Example 1 and Comparative Example 2 was significantly improved. As described above, according to the present invention, the cell
The lamic body contacts the pair of main discharge electrodes
Between the first and second element bodies and the first and second element bodies
Small diameter which is smaller than the outer diameter of the first and second element bodies
And a small-diameter element, either a first element or a second element.
Integrated with one of them or separately from the first and second bodies
To form a microgap on the peripheral surface of the small diameter element,
The ceramic body has a small diameter body,
Light between a pair of main discharge electrodes and a micro gap in a phosphor
Since the stepped portion serving as a mechanical shield is formed, metal ions generated at the main discharge electrode adhere to the optical shield, and do not adhere to the micro gap shielded by the shield. As a result, since the plurality of conductive films divided by the micro gap do not conduct, the surge life characteristic of the surge absorber can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a central longitudinal sectional view of a surge absorber according to Embodiment 1 of the present invention. FIG. 2 is a central longitudinal sectional view of a surge absorber according to Embodiment 2 of the present invention. FIG. 3 is a central longitudinal sectional view of a surge absorber of Comparative Example 1 . FIG. 4 is a central longitudinal sectional view of a surge absorber of Comparative Example 1 . [Description of Signs] 7 1,91 Surge absorber 7 4d Stepped portion (shield) 17 Cap electrode (main discharge electrode) 18 Micro gap 39 Sealing electrode (main discharge electrode)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01T 4/10-4/12

Claims (1)

(57) [Claims] [Claim 1] It is housed inside a container (32) which maintains insulation.
Element (73) is a ceramic body (74)
A conductive film (16) formed on the surface of the element body (74);
Microphone formed circumferentially on the peripheral surface of the lamic body (74)
A gap (18), and a pair of elements at both ends of the element (73).
Micro gaps with main discharge electrodes (17, 17, 39, 39)
In the pump-type surge absorber, the ceramic body (74) is provided with the pair of main discharge electrodes (17,
17, 39, 39) and the first and second
Between the two elementary bodies (74a, 74b) and the first and second elementary bodies (74a, 74b)
Outside diameter of the first and second element bodies (74a, 74b)
A smaller element body (74c), wherein the small element body (74c) is either the first element body (74a) or the second element.
One of the body (74b) or the first and
The micro gap (18) is formed separately from the second element body (74a, 74b), and is formed on the peripheral surface of the small diameter element body (74c).
Is formed, and the ceramic body (74) has the small diameter body (74c).
By this, the pair of main discharges is applied to the ceramic body (74).
Between the electrode (17, 17, 39, 39) and the micro gap (18)
A micro-gap surge absorber , wherein a stepped portion (74d) serving as an optical shield is formed .