JPH03296665A - Current sensor - Google Patents

Abstract

PURPOSE:To miniaturize a sensor and to prevent the lowering of arrangement stability due to the displacement of the center of gravity by forming a substrate from a flexible material and curving at least one end edge thereof to reduce the protruding length of the substrate thereof in the plane direction thereof. CONSTITUTION:A flexible printed circuit board 40 is used as the substrate of a current sensor having a magnetoelectric converter element mounted thereon and one end part 40a thereof is curved upwardly to reduce the protruding length of the board in the plane direction thereof and the miniaturization of the plane shape of the board at the time of molding is achieved. Since a molding resin 45 is integrally and closely bonded to all of constitutional elements, there is possibility such that the insulating withstand voltage between the part on the primary side of the annular core 21 and coil 35 above a gap 23 and the part on the secondary side containing the element 37 thereof is lowered by the moisture in the resin and, therefore, the other end part 40b of the board 40 is folded back into gap 23 if necessary to increase a creepage distance to make it possible to secure withstand voltage without using a special insulating shield. Further, by arranging at least three or more lead terminals 43, 44, the arrangement stability of respective constitutional elements integrated by molding is enhanced.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to the improvement of a current sensor using a magnetoelectric conversion element such as a Hall element, and in particular to miniaturizing the overall shape of the current sensor including the core, and increasing the size of the current sensor on the motherboard. This invention relates to a current sensor with improved mechanical stability when installed upright.

(Prior technology) Facsimile, modem, NCU (Network
Control Units, etc. require elements and devices to detect the control status of the telephone line, that is, the presence or absence of line loop current and polarity reversal due to telephone on-footer, off-hook, or converter operation. A reed relay or photocoupler was inserted into the telephone line.

However, the minimum current value that can be detected by reed relays, photocouplers, etc. is relatively large, and the insertion impedance (resistance) is large (resulting in increased loss).

For this reason, current sensors (current detectors) using magnetoelectric conversion elements have been developed in recent years, and sensors with improved sensitivity and insertion loss have appeared.

As shown in FIGS. 3(a) and 3(b), such a current sensor uses a Hall element 5 as a magnetoelectric transducer and a part of an annular magnetic core 1 made of a magnetic material such as ferrite. The magnetic field of the core gap generated by energizing the coil 2 disposed in the narrow notched empty knee part 3 and wound around a part of the core 1 acts on the Hall element 5 to generate a current. It detects intensity and direction.

The Hall element 5 is mounted on a substrate 6 made of alumina or the like, and is positioned so that the Hall element 5 is placed in the gap 3 in an appropriate state. An insulating film 7 is inserted to cover this to ensure dielectric strength between the two.

On other parts of the alumina substrate 6, an operational amplifier 8, a resistor network (not shown), etc. are mounted and formed, and a large number of lead terminals 9 are fixed to one side of the substrate, and are connected to the wiring pattern on the substrate and the coil 2. It is connected to the extending lead wire 2a. The components of the current sensor including the upper part of the lead terminal are all integrated by a resin mold 1O, as shown in FIG. Each lead terminal 9 extends from the current sensor integrally fixed with the mold.
The lower end of the motherboard 11 is inserted and erected into a through hole 12 formed in the motherboard 11 and fixed with solder 13 .

Figure 5 is the same as Figure 3 above! a) This is a block schematic diagram of the current detector in [b], in which the value of the magnetic field detected by the Hall element 5 is converted to voltage and generated at the terminal of the Hall element, amplified by the amplifier 8, and then sent to the comparator. 15, the current is compared with a predetermined set value to determine the presence or absence of current and its polarity.

However, since the alumina substrate 6 is a flat plate with rigidity and at the same time requires a length to connect the necessary number of terminals 9 at a predetermined pitch, the alumina substrate 6 has to be enlarged and such a large-area substrate is required. A current sensor in which a core and the like are mounted on top and these are integrally molded becomes even larger.

In addition, as shown in Fig. 4, the parts corresponding to the heavy core and coil have a shape that greatly protrudes from the board, and the center of gravity is located at a high position, so that the connection between the lead terminal 9 and the through hole may be damaged due to vibration or impact. There is a risk of damage or the current sensor itself tilting in the direction of the arrow. As a result, there is a risk that the current sensor may be damaged or other components mounted on the motherboard may malfunction.

(Purpose of the Invention) The present invention has been made in view of the above, and in a current sensor in which a board on which a Hall element is mounted is positioned in a notch of an annular core, the current It is an object of the present invention to provide a current sensor that is capable of downsizing the current sensor by reducing the planar area of the substrate without deteriorating the characteristics of the sensor, and that prevents a decrease in installation stability due to deviation of the center of gravity.

(Summary of the Invention) In order to achieve the above object, the present invention comprises: a ring-shaped magnetic core with a gap formed by cutting out a part; a coil wound around an insulating bobbin fitted on one side of the core; A current sensor comprising a substrate on which an element is mounted, and the substrate is arranged so that the magnetoelectric transducer is located in a notch of the core, the substrate is made of a flexible material, and at least one edge of the flexible substrate is It is characterized by being curved to reduce the protrusion length in the planar direction.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 (al and (bl) are a perspective view and a front view showing the configuration of a current sensor according to one embodiment of the present invention.

This current sensor includes, for example, an annular core 21 made of a magnetic material with a rectangular cross section, a bobbin (not shown) made of an insulating material fitted around the upper side of the core 21, a coil 35 wound around the bobbin, and a gap 23. A flexible printed circuit board 40 that extends from the inside of the core including the inside of the core to the outside of the core 21 and has an upwardly curved outer end 40a, and a magnetoelectric conversion element 37 mounted on the surface of the flexible printed circuit board 4o located within the gap 23. , an operational amplifier 42 mounted on the surface of the curved end 40a of the flexible printed circuit board 40, and a plurality of lead terminals 43 extending downward from appropriate positions on the lower surface or side edge of the flexible printed circuit board,
It is comprised of an upper terminal 44 that is connected to a lead wire from the coil 35 near the core 21, and a mold resin 45 such as phenol resin that contains the above-mentioned components and molds them together.

The lower ends of the lead terminals 43 protrude downward from the dry resin 45 and are inserted and erected into through-hole indicators of a motherboard (not shown), and the upper ends are connected to the wiring pattern of the flexible printed circuit board 4o. Further, it is preferable to arrange at least three or more lead terminals 43, 44, etc. to improve the stability of setting of each component integrally fixed with the mold.

In the present invention, the flexible printed circuit board 40 is used, and one end 40a of the board 4o is curved upward to reduce the protrusion length of the board 4o in the planar direction, thereby reducing the planar shape when molded. The points are distinctive.

In addition, since the mold resin is closely integrated with all of the above-mentioned components, the primary side such as the bore portion located above the gap 23, the coil 35, etc., and the secondary side including the magnetoelectric conversion element 37 are connected to each other. There is also a possibility that the dielectric strength between the two may be reduced due to moisture contained in the resin. Therefore, if necessary, the other end 40b of the substrate 40 can be connected to the magnetoelectric transducer 3 as shown in the figure.
It is preferable that by folding it back toward the gap 23 at the top of 7, the withstand voltage can be ensured by increasing the creepage distance without using a special insulating sheet.

FIG. 2 shows a second embodiment of the present invention, in which a core 21 is fixed to the upper surface of a base 50 made of resin or the like, and a flexible substrate 40 similar to that described above is arranged from inside the gap 23 to the outside. The upper end of the lead terminal 43 inserted into the through hole 50a may be connected to the pattern of the substrate 40, and then integrated with a molded resin.
Alternatively, the inside may be sealed by covering the base 50 with a case (lid) made of resin, metal, or the like.

As described above, in the present invention, a flexible printed circuit board is used as a substrate for supporting the magnetoelectric transducer arranged in the gap of the core, and one end of the flexible printed circuit board extending outward from the gap is curved upward to form a flat surface. Since the directional protrusion length is reduced and each component is integrally molded or sealed with a case, the current sensor can be made smaller. Furthermore, since the current sensor is installed in the through-hole of the motherboard using three or more lead terminals protruding from the bottom surface of the board, the center of gravity can be lowered and problems such as damage caused by vibration or impact can be eliminated.

Furthermore, if the other inner end of the flexible printed circuit board is folded back to cover the magnetoelectric transducer as necessary, there is no need to insert a special insulating sheet into the gap 23, which simplifies the manufacturing process. be able to.

(Effects of the Invention) As described above, according to the present invention, in a current sensor in which a substrate on which a magnetoelectric conversion element is mounted within a notch of an annular core is positioned, there is no possibility that the mounted components will be adversely affected or the characteristics of the current sensor will be affected. It is possible to downsize the current sensor by reducing the planar area of the substrate without reducing the surface area of the substrate, and to prevent a decrease in installation stability due to deviation of the center of gravity.

[Brief explanation of the drawing]

1(a) and (b) are perspective views and front views showing the configuration of a current sensor as an embodiment of the present invention, FIG. 2 is an explanatory diagram of the configuration of another embodiment of the present invention, and FIG. 3 (a) and (b)
Figure 4 is a side view and bottom view of a conventional current sensor, Figure 4 is an explanatory diagram of a conventional current sensor integrated with a mold and mounted on a motherboard, and Figure 5 is a current detector in Figure 3(a) (bl). 21... Annular core 23... Gap 35... Coil 37... Magnetoelectric conversion element 40... Flexible printed circuit board 40a... One end of the board 40b... Others End 43.
44...Lead terminal 45...Mold resin 5
0...Base

Claims (1)

[Claims] (1) Consists of an annular magnetic core with a gap cut out, a coil wound around an insulating bobbin fitted on one side of the core, and a substrate on which a magnetoelectric transducer is mounted. In the current sensor in which the substrate is arranged such that the magnetoelectric transducer is located in the notch, the substrate is made of a flexible material, and at least one edge of the flexible substrate is curved to reduce the protrusion length in the planar direction. Characteristic current sensor.