JP2015210158A - Current sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current sensor that can suppress reduction in detection accuracy.SOLUTION: A shielding member 60 having a ground potential is arranged between a first wire 51 electrically connecting a sensor chip 30 and a circuit chip 40 together and a detected-current path 90. In this arrangement, the first wire 51 and the detected-current path 90 are electrically isolated from each other, and a parasitic capacitance is not therefore formed between the first wire 51 and the detected-current path 90, which leads to reduction in the detection accuracy.

Description

  The present invention relates to a current sensor that is mounted on a detected current path and detects a current flowing through the detected current path.

  Conventionally, for example, in Patent Document 1, a sensor chip that outputs a sensor signal corresponding to a magnetic field and a circuit chip that performs a predetermined process on the sensor signal are mounted on a substrate, and the sensor chip and the circuit chip are wired. There has been proposed a current sensor that is electrically connected via a via. And this current sensor is arrange | positioned and used on the bus-bar as a to-be-detected electric current path | route.

  In such a current sensor, a current magnetic field generated according to the current flowing through the bus bar is applied to the sensor chip. A sensor signal is input from the sensor chip to the circuit chip via a wire, and a predetermined process is performed on the sensor signal by the circuit chip.

JP 2013-64663 A

  However, when the current sensor is disposed on the bus bar, a parasitic capacitance is formed between the wire and the bus bar that electrically connect the sensor chip and the circuit chip. For this reason, there is a problem that this parasitic capacitance becomes noise and the detection accuracy is lowered.

  An object of this invention is to provide the current sensor which can suppress that detection accuracy falls in view of the said point.

  In order to achieve the above object, according to the first aspect of the present invention, a sensor chip (30) that outputs a sensor signal corresponding to a magnetic field, a circuit chip (40) that performs predetermined processing on the sensor signal, and a sensor A first wire (51) for electrically connecting the chip and the circuit chip and a substrate (10) for mounting the sensor chip and the circuit chip are mounted on the detected current path (90) and the detected current The current sensor for detecting the current flowing through the path is characterized in that a shielding member (60) having a ground potential is disposed between the first wire and the detected current path.

  According to this, a shielding member having a ground potential is arranged between the first wire and the detected current path, and the first wire and the detected current path are separated in terms of potential. For this reason, a parasitic capacitance is not comprised between a 1st wire and a to-be-detected electric current path | route, and it can suppress that detection accuracy falls.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is sectional drawing when the current sensor in 1st Embodiment of this invention is attached to a bus-bar. It is sectional drawing when the current sensor in other embodiment of this invention is attached to a bus-bar. It is sectional drawing when the current sensor in other embodiment of this invention is attached to a bus-bar.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be described with the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described with reference to the drawings. Note that the current sensor of the present embodiment is attached to a bus bar as a detected current path connected to a vehicle-mounted battery or the like, and is used to detect a current flowing through the bus bar.

  As shown in FIG. 1, the current sensor includes a substrate 10 having one surface 10a and another surface 10b. In the present embodiment, the substrate 10 is a wiring substrate in which ceramic layers are laminated, and includes a through-hole electrode 11 in which an electrode 11b is embedded in a through-hole 11a, a surface layer wiring and an inner layer wiring (not shown), and the like. Yes.

  A bias magnet 20, a sensor chip 30, and a circuit chip 40 are mounted on one surface 10 a of the substrate 10.

  The bias magnet 20 applies a bias magnetic field to the sensor chip 30.

  The sensor chip 30 is mounted on the bias magnet 20 and outputs a sensor signal corresponding to the applied magnetic field. In the present embodiment, as the sensor chip 30, a known chip in which a magnetoresistive element whose resistance value changes according to a magnetic field is formed to constitute a bridge circuit is used.

  The circuit chip 40 includes various circuit elements such as a drive circuit that drives the sensor chip 30 and a processing circuit that performs predetermined processing on the sensor signal. The sensor chip 30 and the first wire 51 are electrically connected, and the electrode 11 b (substrate 10) and the second wire 52 are electrically connected.

  A shielding member 60 is disposed on the other surface 10 b of the substrate 10. The shielding member 60 is made of metal or the like, and is maintained at the ground potential by being electrically connected to the circuit chip 40 via the electrode 11b (substrate 10) and the second wire 52. In the present embodiment, the shielding member 60 is disposed on the other surface 10b of the substrate 10 so as to face the first and second wires 51 and 52 and a third wire 53 described later.

  The current sensor includes a lead 70 that is electrically connected to the circuit chip 40 via the third wire 53 and electrically connects the circuit chip 40 and an external circuit. And each member 10-60 is sealed by the mold resin 80 so that the part (outer lead part) on the opposite side to the board | substrate 10 side of the lead | read | reed 70 may be exposed, and it is mold IC.

  The above is the configuration of the current sensor in the present embodiment. And such a current sensor is mounted and used for the bus-bar 90 equivalent to the to-be-detected electric current path | route of this invention, as FIG. 1 shows. Specifically, the current sensor is mounted on the bus bar 90 so that the direction of the current flowing through the bus bar 90 (the left-right direction in FIG. 1) and the bias magnetic field generated by the bias magnet 20 are parallel. In other words, the current sensor is mounted on the bus bar 90 so that the current magnetic field generated by the detected current flowing in the bus bar 90 and the bias magnetic field generated by the bias magnet 20 are perpendicular to each other.

  Since the sensor magnetic field 30 is applied with the current magnetic field generated by the detected current and the bias magnetic field generated by the bias magnet 20, the sensor chip 30 outputs a sensor signal corresponding to the combined magnetic field of the current magnetic field and the bias magnetic field. . That is, since the bias magnetic field is constant, a sensor signal corresponding to the current magnetic field is output.

  The current sensor is mounted on the bus bar 90 so that the shielding member 60 and the bus bar 90 face each other. That is, the current sensor is mounted on the bus bar 90 so that the shielding member 60 is positioned between the first to third wires 51 to 53 and the bus bar 90. Thereby, since the shielding member 60 is set to the ground potential, the first to third wires 51 to 53 and the bus bar 90 are electrically separated. Therefore, it is possible to suppress the formation of parasitic capacitance between the first to third wires 51 to 53 and the bus bar 90.

  As described above, in the present embodiment, the shielding member 60 having the ground potential is disposed between the first wire 51 and the bus bar 90, and the first wire 51 and the bus bar 90 are divided in potential. Yes. For this reason, a parasitic capacitance is not comprised between the 1st wire 51 and the bus-bar 90, and it can suppress that detection accuracy falls.

  The shielding member 60 is also disposed between the second and third wires 52 and 53 and the bus bar 90. For this reason, no parasitic capacitance is formed between the second and third wires 52 and 53 and the bus bar 90, and it is possible to further suppress a decrease in detection accuracy.

(Other embodiments)
The present invention is not limited to the embodiment described above, and can be appropriately changed within the scope described in the claims.

  For example, in the first embodiment, as illustrated in FIG. 2, the shielding member 60 may be disposed only between the first wire 51 and the bus bar 90. That is, a sensor signal is input from the sensor chip 30 to the circuit chip 40 via the first wire 51. Since the sensor signal before being processed by the circuit chip 40 is a minute signal, the first wire 51 and the bus bar are processed. If a parasitic capacitance is formed between 90 and 90, the influence of noise increases. For this reason, it can suppress that detection accuracy falls by suppressing that a parasitic capacitance is formed between the 1st wire 51 and bus bar 90 at least.

  Moreover, in the said 1st Embodiment, as FIG. 3 shows, the bias magnet 20 may be arrange | positioned on the opposite side to the side in which the current sensor is provided among the bus bars 90.

DESCRIPTION OF SYMBOLS 10 Board | substrate 30 Sensor chip 40 Circuit chip 51 1st wire 90 Bus bar (current path to be detected)

Claims (3)

A sensor chip (30) for outputting a sensor signal corresponding to the magnetic field;
A circuit chip (40) for performing predetermined processing on the sensor signal;
A first wire (51) for electrically connecting the sensor chip and the circuit chip;
A substrate (10) on which the sensor chip and the circuit chip are mounted,
In the current sensor that is mounted on the detected current path (90) and detects the current flowing through the detected current path,
A current sensor, wherein a shielding member (60) having a ground potential is disposed between the first wire and the detected current path. The substrate is a wiring substrate;
A second wire (52) for electrically connecting the circuit chip and the wiring board;
The current sensor according to claim 1, wherein the shielding member is also disposed between the second wire and the detected current path. The current sensor according to claim 2, wherein the shielding member has a ground potential by being electrically connected to the circuit chip through the wiring board.

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