JP2015162432A - Discharge gap structure formed on base substrate, and electronic apparatus equipped with the base substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust a lower limit value of a discharge start voltage in a discharge gap structure without shortening a spacing distance between opposing electrodes.SOLUTION: An electronic apparatus includes a base substrate in which a discharge gap structure is formed. This discharge gap structure is constituted by including first to third electrodes. The first and second electrodes are arranged opposite to each other on one main surface of the base substrate. The third electrode is arranged on the other main surface of the base substrate and electrically connected to the first electrode. A spacing distance between the third electrode and the second electrode is less than that between the first electrode and the second electrode.

Description

  The present invention relates to a discharge gap structure formed on a substrate provided in an electronic device.

  When a lightning strike occurs in the vicinity of an electronic device such as a television device, an internal electrical circuit or the like may be destroyed due to the inflow of a lightning surge current. Therefore, a discharge gap structure is incorporated in a general electronic device as a surge absorber for protecting from lightning surge current.

  A conventional discharge gap structure is composed of a pair of discharge electrodes arranged opposite to each other as disclosed in Patent Document 1, for example. One end thereof is connected to an internal circuit of the electronic device, and the other end is grounded. When a lightning surge current flows into the electronic device and the potential difference between the discharge electrodes exceeds the discharge start voltage, discharge occurs between the discharge electrodes. This discharge allows the lightning surge current to flow to the ground potential, thereby protecting the electronic device from the lightning surge current. This discharge start voltage is usually adjusted by the interval between the discharge electrodes.

JP 2010-226925 A

  However, the minimum value of the distance between the discharge electrodes is limited by the safety standard (for example, JIS-C6065) of each country. Therefore, when the interval between the discharge electrodes is set according to the safety standard, the actual discharge start voltage cannot be made lower than the voltage threshold corresponding to the minimum value. Therefore, if the withstand voltage value of a circuit or element connected in parallel with the conventional discharge gap structure is lower than the voltage threshold value, they cannot be protected from lightning surge current and may be damaged or destroyed. Note that Patent Document 1 makes no mention of such a problem.

  The present invention has been made in view of such a situation, and a discharge gap structure capable of easily adjusting the lower limit value of the discharge start voltage without reducing the distance between the opposing electrodes, and the discharge gap structure. An object of the present invention is to provide an electronic device including a substrate to be formed.

  In order to achieve the above object, a discharge gap structure according to an aspect of the present invention includes a first electrode and a second electrode disposed opposite to each other on one main surface of a substrate, and a first electrode disposed on the other main surface of the substrate. Three electrodes, and the third electrode is electrically connected to the first electrode, and a spatial distance between the third electrode and the second electrode is less than a separation distance between the first electrode and the second electrode. A certain configuration (first configuration) is adopted.

  According to the first configuration, the third electrode is electrically connected to the first electrode. In addition, the spatial distance between the third electrode and the second electrode is less than the separation distance between the first electrode and the second electrode, but the third electrode and the second electrode are separated by the base. Therefore, when the potential difference between the first electrode and the second electrode exceeds a voltage threshold corresponding to the spatial distance between the third electrode and the second electrode, a discharge is generated between the first electrode and the second electrode. Therefore, the lower limit value of the discharge start voltage can be easily adjusted by setting the spatial distance between the third electrode and the second electrode without reducing the distance between the opposing first electrode and second electrode.

  In the discharge gap structure having the first configuration, the third electrode may have a configuration (second configuration) that is one of the conductor wire and the conductor pattern.

  According to this 2nd structure, a 3rd electrode can be arrange | positioned using a general purpose material and means. Accordingly, the discharge gap structure can be formed relatively easily without increasing the manufacturing cost.

  In the discharge gap structure having the first or second configuration, the third electrode may be configured to be electrically connected to the first electrode through a through hole formed in the base (third configuration).

  According to the third configuration, the third electrode can be electrically connected to the first electrode without going through a complicated wiring path.

  In the discharge gap structure having any one of the first to third configurations, the tip shape of the third electrode may be a round shape (fourth configuration).

  According to the fourth configuration, the fluctuation in the spatial distance between the third electrode and the second electrode due to the tip shape of the third electrode is reduced, and the discharge start voltage between the first electrode and the second electrode is further increased. Can be adjusted accurately.

  In order to achieve the above object, an electronic apparatus according to an aspect of the present invention has a configuration (fifth configuration) including a substrate on which the discharge gap structure having any one of the first to fourth configurations is formed. The

  According to the fifth configuration, in the discharge gap structure formed on the substrate, the spatial distance between the third electrode and the second electrode can be set without reducing the distance between the first electrode and the second electrode facing each other. Thus, the lower limit value of the discharge start voltage can be easily adjusted.

  According to the present invention, there is provided a discharge gap structure in which a lower limit value of a discharge start voltage can be easily adjusted without reducing a separation distance between opposing electrodes, and an electronic apparatus including a substrate on which the discharge gap structure is formed. be able to.

It is a figure which shows the example into which a lightning surge current flows in into a liquid crystal television. It is a circuit diagram of a liquid crystal television. It is a top view of the main structure of the surge absorber in a plan view when the printed circuit board is viewed from the normal direction of the mounting surface. It is sectional drawing of the main structures of the surge absorber which concerns on 1st Embodiment. It is a bottom view of the main structure of the surge absorber in a plan view of the printed circuit board viewed from the normal direction of the back surface. It is sectional drawing of the main structures of the surge absorber which concerns on 2nd Embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
<First Embodiment>

  When a lightning strike occurs in the vicinity of the liquid crystal television 100, a lightning surge current S may flow into the liquid crystal television 100. FIG. 1 is a diagram illustrating an example in which a lightning surge current flows into a liquid crystal television. As shown in FIG. 1, a lightning surge current Sa caused by a lightning strike flows into the liquid crystal television 100 through, for example, a power cord 108a. Alternatively, the lightning surge current Sb flows into the liquid crystal television 100 from the antenna 110 through the coaxial cable 111. Therefore, a surge absorber 101 (see FIG. 2 described later) is attached to the liquid crystal television 100 and connected in parallel with an internal circuit that protects against the lightning surge current S. The liquid crystal television 100 is an example of the electronic apparatus of the present invention.

  In the surge absorber 101, a voltage threshold (discharge start voltage described later) through which a high-voltage current flows is set lower than the withstand voltage of the internal circuit to be protected. Therefore, even if a lightning surge current S having a voltage value higher than the withstand voltage of the internal circuit flows into the liquid crystal television 100, the lightning surge current S flows through the surge absorber 101 without passing through the internal circuit. Therefore, the lightning surge current Sa flowing from the power cord 108 a is released to the ground of the antenna 110 through the coaxial cable 111. Further, the lightning surge current Sb flowing from the antenna 110 is discharged to the ground potential (for example, the ground of the outlet) through the power cord 108a.

  FIG. 2 is a circuit diagram of a liquid crystal television. As shown in FIG. 2, one end of the surge absorber 101 is connected between the rectifier circuit 102 and the primary side converter circuit 103, and the other end is connected to the ground potential line GND. The ground potential line GND is connected to the outer conductor 111 a of the coaxial cable 111 that connects the antenna 110 to the liquid crystal television 100. The external conductor 111a is electrically connected to the ground of the antenna 110 through a metal portion of a connector (not shown). The ground potential line GND is used as a reference potential line for the secondary side and secondary side circuit 105 of the transformer 104, for example. The secondary side circuit 105 includes various components that receive power supply from the secondary side of the transformer 104 via the rectifying element 106. For example, the secondary side circuit 105 includes a monitor unit, a tuner unit connected to the antenna 110, and the like. Note that the details of the secondary circuit 105 are out of the scope of the present invention, and thus the description thereof is omitted.

  The surge absorber 101 is connected in parallel with the Y capacitor 107. The Y capacitor 107 releases or reduces the common mode EMC noise current propagating in a wider range than the normal mode to the ground potential line GND. The withstand voltage of the Y capacitor 107 is, for example, less than 6 kV and is lower than the surge voltage (for example, 6 kV or more) indicated by the lightning surge current S. Therefore, the surge absorber 101 particularly protects the Y capacitor 107 from damage or destruction caused by the lightning surge current S.

  In FIG. 2, for example, even if a lightning surge current S flows from the AC power source 108, if the potential difference between both ends of the surge absorber 101 exceeds a voltage threshold (that is, a discharge start voltage described later), the lightning surge current S is converted into the surge absorber 101. To the ground potential line GND. The lightning surge current S is emitted through the outer conductor 111 a of the coaxial cable 111. In other words, even if the lightning surge current S flows into the liquid crystal television 100, it is emitted without passing through the components between the rectifier circuit 102 and the antenna 110 in FIG. Therefore, damage or destruction caused by the lightning surge current S in each component including the Y capacitor 107 can be prevented.

  Next, a specific configuration of the surge absorber 101 will be described. The surge absorber 101 includes the discharge gap structure 1. The discharge gap structure 1 is formed on a printed circuit board 2 built in the liquid crystal television 100. 3A to 3C are main structural diagrams of the discharge gap structure 1 in the surge absorber 101. FIG. FIG. 3A is a top view of the main structure of the surge absorber in a plan view of the printed circuit board viewed from the normal direction of the mounting surface. FIG. 3B is a cross-sectional view of the main structure of the surge absorber according to the first embodiment, showing a cross section taken along the single-dot chain line AA of FIG. 3A. FIG. 3C is a bottom view of the main structure of the surge absorber in a plan view of the printed circuit board viewed from the normal direction of the back surface. Of the two main surfaces of the printed circuit board 2, one main surface on which circuits and elements are mounted is defined as a mounting surface 2a. The other main surface (for example, a surface to which circuits and elements are soldered) is defined as a back surface 2b.

  As shown in FIGS. 3A to 3C, the discharge gap structure 1 includes a first discharge electrode 3, a second discharge electrode 4, and an induction electrode 5.

  The printed circuit board 2 is an example of the base body of the present invention. A through hole 2c is formed between both main surfaces 2a and 2b of the printed circuit board 2. The through hole 2c overlaps the first discharge electrode 3 and the induction electrode 5 in a plan view as viewed from the normal direction (z direction) of the mounting surface 2a or the back surface 2b.

  The first discharge electrode 3 and the second discharge electrode 4 are examples of the first electrode and the second electrode of the present invention, respectively, and are a pair of conductor patterns disposed opposite to each other on the back surface 2b of the printed circuit board 2. The distance D between them (that is, the spatial distance indicating the shortest distance between the first discharge electrode 3 and the second discharge electrode 4) is, for example, 6 mm. When the lightning surge current S flows through the surge absorber 101, discharge occurs between the first discharge electrode 3 and the second discharge electrode 4. The planar shapes of the first discharge electrode 3 and the second discharge electrode 4 are not particularly limited, but each preferably has at least one corner. Furthermore, it is more preferable that those angles are acute angles. As shown in FIGS. 3A to 3C, the first discharge electrode 3 and the second discharge electrode 4 are stabilized between the first discharge electrode 3 and the second discharge electrode 4 by causing the corner tips of the first discharge electrode 3 and the second discharge electrode 4 to face each other at the shortest distance. Discharge can be performed.

  The induction electrode 5 is an example of the third electrode of the present invention, and is disposed on the mounting surface 2a of the printed circuit board 2 using a wiring wire (conductor wire) bent into an L shape. If it carries out like this, the induction | dielectric electrode 5 can be arrange | positioned using a general purpose material and means. Therefore, the discharge gap structure 1 can be formed relatively easily without significantly increasing the manufacturing cost. The material of the induction electrode 5 is not particularly limited as long as it is a conductive member.

  The induction electrode 5 extends in the x direction from the through hole 2c toward the tip (that is, the corner) of the second discharge electrode 4. One end of the induction electrode 5 is inserted into the through hole 2 c, passes through the first discharge electrode 3, and is electrically connected to the first discharge electrode 3. In this way, the induction electrode 5 can be electrically connected to the first discharge electrode 3 without going through a complicated wiring path.

  Further, the tip of the other end of the dielectric electrode 5 faces the tip of the second discharge electrode 4 through the printed circuit board 2 as shown in FIG. 3B. The tip of the other end is round. In this way, the fluctuation of the spatial distance d caused by the tip shape of the dielectric electrode 5 is reduced, and the lower limit threshold value of the potential difference when the discharge is started between the first discharge electrode 3 and the second discharge electrode 4 is set. It can be adjusted more accurately. Hereinafter, this lower limit threshold is referred to as a discharge start voltage.

  The spatial distance d indicating the shortest distance between the induction electrode 5 and the second discharge electrode 4 is, for example, 2 to 3 mm, and is less than the separation distance D. Therefore, when a potential difference is generated between the first discharge electrode 3 and the second discharge electrode 4, the electric field generated between the second discharge electrode 4 and the dielectric electrode 5 is between the first discharge electrode 3 and the second discharge electrode 4. It becomes stronger than the electric field. In other words, the strength of the electric field near the tip of the second discharge electrode 4 is stronger than the discharge gap structure in which the induction electrode 5 is not disposed (that is, the structure in which only the first discharge electrode 3 and the second discharge electrode 4 are disposed). Become. Therefore, the discharge between the first discharge electrode 3 and the second discharge electrode 4 is started with a lower potential difference than the discharge gap structure in which the induction electrode 5 is not disposed. That is, the discharge start voltage of the discharge gap structure 1 can be lowered by the spatial distance d.

  Therefore, in the discharge gap structure 1 shown in FIGS. 3A to 3C, the potential difference between the first discharge electrode 3 and the second discharge electrode 4 is a voltage corresponding to the spatial distance d between the second discharge electrode 4 and the induction electrode 5. When the threshold value is exceeded, a discharge occurs between the first discharge electrode 3 and the second discharge electrode 4. Therefore, the lower limit of the discharge start voltage is set by setting the spatial distance d between the induction electrode 5 and the second discharge electrode 4 without reducing the distance D between the first discharge electrode 3 and the second discharge electrode 4 facing each other. The value can be adjusted easily.

  For example, there is nothing between the first discharge electrode 3 and the second discharge electrode 4 that prevents discharge such as air discharge and creeping discharge. Therefore, the separation distance D must comply with the safety standard defined in each country. For example, in JIS-C6065, when the effective value of the operating voltage is 200V, the internal contamination level is 2, the material group is II, and reinforced insulation is required, the minimum creepage distance is specified as 5.6 [mm]. ing. Therefore, under this condition, it is not permitted to set the separation distance D to less than 5.6 [mm]. Therefore, in order to satisfy the safety standard, the discharge start voltage between the first discharge electrode 3 and the second discharge electrode 4 cannot be set below the voltage threshold corresponding to 5.6 [mm]. Therefore, a surge absorber having a discharge gap structure in which the induction electrode 5 is not disposed cannot protect an element or circuit having a relatively low withstand voltage value, and in particular, it is difficult to protect the Y capacitor 107 from the lightning surge current S.

On the other hand, in the discharge gap structure 1 shown in FIGS. 3A to 3C, the induction electrode 5 and the second discharge electrode 4 are separated by the printed circuit board 2. Therefore, the setting of the spatial distance d does not need to follow safety standards and can be set arbitrarily. Furthermore, as described above, the discharge start voltage between the first discharge electrode 3 and the second discharge electrode 4 can be adjusted by the spatial distance d. Therefore, in the discharge gap structure 1 shown in FIGS. 3A to 3C, it is possible to protect an element or circuit having a relatively low withstand voltage value, and in particular, it is possible to protect the Y capacitor 107 from the lightning surge current S.
Second Embodiment

  Next, a second embodiment will be described. In the second embodiment, the induction electrode 5 is a conductor pattern formed on the mounting surface 2 a of the printed circuit board 2. The rest is the same as in the first embodiment. Hereinafter, a configuration different from the first embodiment will be described. Moreover, the same code | symbol is attached | subjected to the component similar to 1st Embodiment, and the description is abbreviate | omitted.

  FIG. 4 is a cross-sectional view of the main structure of the surge absorber according to the second embodiment. The induction electrode 5 is a conductor pattern formed on the mounting surface 2 a of the printed circuit board 2. The induction electrode 5 is electrically connected to the first discharge electrode 3 through a conductive path 2d formed in the through hole 2c. The conductive path 2d may be a conductor pattern formed on the inner wall of the through hole 2c, or may be a conductive material that fills the inside of the through hole 2c.

  In this way, the induction electrode 5 and the conductive path 2d can be disposed using general-purpose materials and means. Therefore, the discharge gap structure 1 can be formed relatively easily without significantly increasing the manufacturing cost.

  In addition, the induction electrode 5 extends from the through hole 2 c toward the tip end portion (that is, the corner) of the second discharge electrode 4. The tip of the dielectric electrode 5 faces the tip of the second discharge electrode 4 with the printed circuit board 2 interposed therebetween, and the planar shape of the tip is round. In this way, the fluctuation of the spatial distance d caused by the tip shape of the dielectric electrode 5 can be reduced, and the discharge start voltage between the first discharge electrode 3 and the second discharge electrode 4 can be adjusted more accurately.

  The embodiment of the present invention has been described above. Note that the above-described embodiment is an exemplification, and various modifications can be made to each component and combination of processes, and it will be understood by those skilled in the art that they are within the scope of the present invention.

  For example, in the first to second embodiments described above, the discharge gap structure 1 is formed on the general-purpose printed circuit board 2, but the scope of application of the present invention is not limited to this example. The substrate for forming the discharge gap structure 1 may be formed using an insulating material, and is particularly preferably formed using a high dielectric material. In this way, the electric field between the second discharge electrode 4 and the dielectric electrode 5 can be changed more greatly with respect to the adjustment amount of the spatial distance d. Therefore, the lower limit value of the discharge start voltage can be adjusted more easily and largely.

  In the first and second embodiments described above, the planar shape of the induction electrode 5 is linear in a plan view viewed from at least the z direction, but the scope of application of the present invention is not limited to this example. Any shape that can accurately set the spatial distance d between the second discharge electrodes 4 is acceptable. For example, the shape of the induction electrode 5 may be the same shape as that of the first discharge electrode 3, and the planar shape thereof may be a shape having an angle facing the second discharge electrode 4.

  In the first and second embodiments described above, the liquid crystal television 100 including the surge absorber 101 has been described as an example. However, the scope of application of the present invention is not limited to this example. The present invention can be applied to an electronic device including a base (a printed circuit board 2 or the like) on which a discharge gap structure 1 having induction electrodes 5 is formed.

DESCRIPTION OF SYMBOLS 100 LCD television 101 Surge absorber 102 Rectifier circuit 103 Primary side converter circuit 104 Transformer 105 Secondary side circuit 106 Rectifier element 107 Y capacitor 108 AC power supply 108a Power supply cord 110 Antenna 111 Coaxial cable 111a Outer conductor 1 Discharge gap structure 2 Printed circuit board 2a Mounting surface 2b Back surface 2c Through hole 2d Conductive path 3 First discharge electrode 4 Second discharge electrode 5 Induction electrode

Claims (5)

First and second electrodes disposed opposite to each other on one main surface of the substrate;
A third electrode disposed on the other main surface of the substrate;
With
The third electrode is electrically connected to the first electrode;
A discharge gap structure formed in the substrate, wherein a spatial distance between the third electrode and the second electrode is less than a separation distance between the first electrode and the second electrode.   The discharge gap structure formed on the base according to claim 1, wherein the third electrode is one of a conductor wire and a conductor pattern.   The discharge gap structure formed on the base according to claim 1 or 2, wherein the third electrode is electrically connected to the first electrode through a through hole formed in the base.   The discharge gap structure formed on the base according to any one of claims 1 to 3, wherein a tip shape of the third electrode is round.   An electronic device comprising a substrate on which the discharge gap structure according to any one of claims 1 to 4 is formed.

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