JPH0694757A - Current sensor - Google Patents

Abstract

PURPOSE:To reduce a size and to improve a dielectric strength by providing a magnetic detector and a current detecting coil on a board, and covering the detector with an insulating cap. CONSTITUTION:A board 7 of aluminum ceramics is used as a circuit board of a hybrid IC, and a current sensor is constituted on the board 7. A magnetic detector 6 is covered with an insulating cap 8 made of polyimide. A current detecting coil is so disposed on the board 7 that the detector 6 is disposed at a gap of cores 1a, 1b of the coil. Thus, the cores 1a, 1b for forming the gap are positioned separately from the surface of the board 7. Then, the entire sensor is resin-molded with resin 9. With the structure, a creepage distance from the gap of the cores 1a, 1b to a lead terminal of the detector 6 becomes a surface length of the cap 8, thereby obtaining a sufficient dielectric strength.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current sensor for detecting a current signal in an electrically insulated state from a current path to be measured.

[0002]

2. Description of the Related Art A current sensor for detecting a current signal in an insulated state from a current path to be measured obtains a predetermined withstand voltage from the current path to be measured, or a current signal detecting section affects the current path to be measured. Used to avoid. Such a current sensor is used, for example, in a circuit connected to a telephone line such as a telephone or a facsimile to detect whether or not the line is in use.

In the above current sensor, a core for inserting a core into a bobbin around which a coil is wound and a gap is provided in the core, and a current detecting coil, and a magnetic detecting element for detecting a magnetic flux passing through the gap of the core. It is configured by combining. An example thereof is shown in FIG. In FIG. 6, 7 is a substrate, 6 is a magnetic detection element provided on the substrate 7, and 1a and 1b are cores of a current detection coil provided so as to sandwich the substrate 7 and the magnetic detection element 6. An insulating synthetic resin sheet 10 is inserted between the core 1 a and the magnetic detecting element 6. This constitutes a current sensor, and the whole is resin-molded as shown by 9.

[0004]

However, in the conventional current sensor shown in FIG. 6, the magnetic fluxes generated by the cores 1a and 1b are perpendicular to the substrate 7, and the current detection coil is provided on the substrate 7. On the other hand, since it has to be arranged three-dimensionally, there is a drawback that the mounting structure is complicated and the size is increased as a whole. Further, the insulating sheet 10 is effective in increasing the withstand voltage between the core 1a and the magnetic detection element 6, but it is difficult to fix the insulating sheet 10,
When the insulating sheet 10 is displaced, the creepage distance as designed cannot be secured, and there is a risk that the withstand voltage is reduced.

Therefore, if the core of the current detecting coil is arranged on the substrate and the magnetic flux direction generated by the core is arranged parallel to the substrate, the above problem can be solved. However, since the gap portion of the core and the magnetic detecting element are close to each other, insulation In order to increase the withstand voltage without increasing the withstand voltage, the distance between the cores 1a and 1b and the magnetic detection element 6 must be wide enough as shown in FIG. The space in the direction becomes large. Further, there is also a problem that the current detection sensitivity is reduced as the magnetic flux density for the magnetic detection element 6 is reduced.

An object of the present invention is to provide a current sensor in which both a current detection coil and a magnetic detection element are arranged on a substrate and which is small and has a sufficient withstand voltage.

[0007]

A current sensor according to claim 1 of the present invention comprises a core partially having a gap, and a current detection coil comprising a coil wound around the core.
In a current sensor including a magnetic detection element for detecting a magnetic flux passing through the gap of the core, the magnetic detection element and the current detection coil are provided on a substrate, and the magnetic detection element is covered with an insulating cap. And

According to a second aspect of the present invention, there is provided a current sensor having a core partially having a gap, a current detection coil including a coil wound around the core, and a magnetic detection element for detecting a magnetic flux passing through the gap of the core. And a magnetic detection element and a current detection coil are provided on the substrate, and an insulating sheet is interposed between the cores of the magnetic detection element and the current detection coil.

[0009]

In the current sensor according to the first aspect of the present invention, the magnetic detection element and the current detection coil are both provided on the substrate,
The magnetic detecting element is covered with an insulating cap. Therefore, the creepage distance between the magnetic detection element and the core becomes long, and the withstand voltage is improved. Moreover, the insulating cap is not displaced between the magnetic detection element and the core, and it is possible to prevent a decrease in the dielectric strength voltage due to the displacement.

In the current sensor according to the second aspect of the invention, the magnetic detection element and the current detection coil are both arranged on the substrate, and the insulating sheet is interposed between the cores of the magnetic detection element and the current detection coil. There is. As a result, the creepage distance between the magnetic detection element and the core of the current detection coil is increased, and the withstand voltage is improved. Therefore, even if the gap between the magnetic detection element and the core is narrowed, a sufficient withstand voltage can be secured, and the overall size can be reduced.

[0011]

1 to 3 show the structure of a current sensor according to a first embodiment of the present invention.

FIG. 1 is a diagram showing the structure of a current detecting coil. This coil for current detection is, for example, a coil 4 wound around a bobbin 5 and two J-shaped cores 1a and 1b inserted into the bobbin 5. Reference numeral 2 is an external terminal of the coil 4.

FIG. 2 is a sectional view showing the structure of the entire current sensor. In FIG. 2, reference numeral 7 is a substrate such as alumina ceramics, and this current sensor is formed on a circuit board of a hybrid IC, for example. In the figure, 6 is a magnetic detection element, for example, a ferromagnetic magnetoresistive element is used. The magnetic detecting element 6 is covered with an insulating cap 8 made of, for example, polyimide. With respect to the magnetic detection element 6 covered with the insulating cap, the current detection coil is arranged on the substrate 7 so that the magnetic detection element is located in the gap portion of the core of the current detection coil shown in FIG. There is. When the current detection coil is arranged on the substrate 7,
The cores 1a and 1b forming the gap portion are located apart from the surface of the substrate 7. After that, the entire current sensor portion is resin-molded with, for example, a phenol resin as shown in 9.

With the above configuration, the core 1
The creepage distance from the gap part of a and 1b to the lead terminal of the magnetic detection element 6 becomes the surface length of the insulating cap 8, and a sufficient withstand voltage is secured.

Next, the structure of the current sensor according to the second embodiment is shown in FIGS. In FIG. 3, reference numeral 10 denotes an insulating sheet made of polyimide or the like, and the magnetic detecting element 6
And the cores 1a and 1b are interposed so as to cover the magnetic detection element 6. The other structure is similar to that shown in FIG. To obtain such a structure, for example, FIG.
As shown in FIG. 1, the insulating sheet 10 is arranged on the magnetic detection element 6 provided on the substrate 7, and the core 1 is further arranged on the insulating sheet 10.
By placing a and 1b and performing reflow soldering as it is, the insulating sheet 10 is softened by the high temperature atmosphere, and the insulating sheet 10 is weighted by the weight of the cores 1a and 1b.
3 is molded as shown in FIG. 3, and the current detection coil is soldered to the substrate 7 at the same time.

According to the second embodiment, the insulating sheet 10 floats from the substrate 7 even if the secondary side electrode exists immediately below the core as shown by 11 in FIG. , The creepage distance due to the insulating sheet 10 becomes sufficiently long,
A predetermined withstand voltage can be secured.

Next, the structure of the current sensor according to the third embodiment is shown in FIG. The difference from the embodiment shown in FIG. 3 is that the surface of the substrate 7 is covered with the insulating sheet 10.

In the current sensor having such a structure, the magnetic detection element 6 may be covered with a preformed insulating sheet, and then the current detection coil may be placed on the substrate 7. In addition, instead of using the insulatively molded insulating sheet, an adhesive is provided on the surface of the insulating sheet 10 on the side of the magnetic detecting element, and the insulating sheet 10 is attached along the outer surface of the magnetic detecting element 6. It may be molded.

In the first embodiment, the flange portion of the insulating cap 8 shown in FIG. 2 is floated from the surface of the substrate 7 and the core is placed on the flange portion of the cap as shown in FIG. By doing so, the positional relationship between the core and the magnetoresistive element can be optimized. Further, although the lead type magnetic detecting element is used in each of the embodiments, the present invention can be similarly applied to the case where the surface mounting type magnetic detecting element is used for surface mounting on the substrate. Regarding the configuration of the current detection coil, the coil may be wound directly on the core without using the bobbin.

[0020]

According to the present invention, since the magnetic detecting element and the current detecting coil are both arranged on the substrate, the dimension of the substrate in the thickness direction can be reduced, and the gap of the core can be narrowed to reduce the gap. Since the space between the magnetic detection elements can be narrowed, the dimension in the surface direction of the substrate can be reduced, and a small-sized current sensor having a high withstand voltage can be obtained.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of a current detection coil used in a current sensor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the current sensor according to the first embodiment.

FIG. 3 is a sectional view showing a configuration of a current sensor according to a second embodiment.

FIG. 4 is a schematic view showing a method of manufacturing the current sensor shown in FIG.

FIG. 5 is a sectional view showing a structure of a current sensor according to a third embodiment.

FIG. 6 is a cross-sectional view showing the structure of a conventional current sensor.

FIG. 7 is a diagram for explaining a drawback of the current sensor according to the related art.

[Explanation of symbols]

 1a, 1b-Core 2-External terminal 4-Coil 5-Bobbin 6-Magnetic detection element 7-Substrate 8-Insulating cap 9-Mold resin 10-Insulating sheet 11-2 Secondary electrode

Claims (2)

[Claims] 1. A current sensor comprising a core partially having a gap, a coil for current detection consisting of a coil wound around the core, and a magnetic detection element for detecting a magnetic flux passing through the gap of the core. A current sensor characterized in that a magnetic detection element and a current detection coil are provided on a substrate, and the magnetic detection element is covered with an insulating cap. 2. A current sensor comprising a core partially having a gap, a coil for current detection consisting of a coil wound around the core, and a magnetic detection element for detecting a magnetic flux passing through the gap of the core. A current sensor characterized in that a magnetic detection element and a current detection coil are provided on a substrate, and an insulating sheet is interposed between the cores of the magnetic detection element and the current detection coil.