JP2789952B2 - Magnetic sensor module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor module for detecting rotation of a rotating body using a magnetic sensing element.

[0002]

2. Description of the Related Art FIG. 6 shows a general structure of a magnetic sensor module for detecting a rotation speed and a rotation angle of a magnetic body such as a gear as a detection object. FIG. 5 shows a general schematic configuration of the magnetic detection unit 3 of the magnetic sensor module. In the figure, magnetoresistive elements MR1 and MR2 are used as magnetic sensing elements,
1, MR2 is fixed to the front side of the magnet 1 so as to face the gear 2. The magnetoresistive elements MR1 and MR2 are connected in series, one end of which is connected to the DC power supply, the other end is connected to the ground, and the magnetoresistive elements MR1 and MR2 are connected.
The detection unit output terminal 21 is drawn out from the series connection unit 2.

When the peaks and valleys of the gear 2 face the magnetoresistive elements MR1 and MR2 due to the rotation of the gear 2 and the like, the intensity of the bias magnetic field of the magnet 1 passing through the magnetoresistive elements MR1 and MR2 changes. Each magnetoresistive element MR1,
When the resistance of MR2 changes, each of the magnetoresistive elements MR1, MR
2 and the differential output _{Vout of the} generated voltage is extracted from the detection unit output terminal 21 as a sine wave analog waveform.

[0004] The magnetic detector 3 having the above-described operation is
The magnetoresistive elements MR1 and MR2 are arranged and fixed on the surface side of the magnet 1. The magnetic detecting section 3 is housed in a holder 10 and is housed in one end of a module case 17, and is connected to the holder 10. A circuit board 8 on which a signal processing circuit 20 is formed is fixed at an appropriate position with a screw 9 at an appropriate position. The lead wire 11 is long and wired between the holder 10 and the circuit board 8. After the holder 10, the circuit board 8, and the lead wires 11 are housed at predetermined positions in the module case 17, the sealing resin is sealed and the whole is integrally fixed. The connector 6 is provided on the module case 17 at a position different from the position where the holder 10 and the circuit board 8 are fixed.

As described above, the sine wave analog waveform signal V output from the detection section output terminal 21 of the magnetic detection section 3 is used.
_out is shaped into a digital waveform by the signal processing circuit 20 on the circuit board 8 and output from the connector 6 as a signal that can be input to the microcomputer.

[0006]

However, in this type of magnetic sensor module, a holder 10 for accommodating the magnetic detecting section 3 and a circuit board 8 for forming the signal processing circuit 20 are separately provided and mounted on a module case 17. Therefore, the workability of assembling is poor, and the necessity of assembling and fixing parts such as the screw 9 is also required, so that the material cost is increased, so that the manufacturing cost is increased and the product cost is also expensive.

Further, since the holder 10 and the circuit board 8 are disposed and fixed at separate positions, the magnetic sensor module becomes large, and a long lead wire 11 is provided between the holder 10 and the circuit board 8. Since the wires are routed, induction noise is apt to be mixed in the wires, which may cause a malfunction, and the lead wire 11 is broken by vibration or the like.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to eliminate malfunctions due to breakage of lead wires and mixing of induction noise, to facilitate work, and to reduce the size and cost. It is to provide a magnetic sensor module.

[0009]

The present invention is configured as follows to achieve the above object. That is, the magnetic sensor module of the present invention includes a holder for holding a magnetic detection unit including a magnet for applying a bias magnetic field and a magnetic detection element for detecting a magnetic change using the bias magnetic field, and a surface of the holder. A conductor pattern is formed on the conductor pattern, a circuit element for processing an output signal of the magnetic sensing element is mounted on the conductor pattern, and a signal processing circuit is formed on the holder surface using the holder itself as a substrate. .

[0010]

In the present invention having the above structure, a conductor pattern having the holder itself as a substrate is formed on the surface of the holder for holding the magnetic detecting section, various circuit elements are mounted thereon, and a signal processing circuit is formed. A sensor module is configured.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the configuration of one embodiment of a magnetic sensor module according to the present invention. In the same figure, the magnetism detecting unit 3 has magnets 1 and 1 as in the prior art.
It is composed of a pair of magnetoresistive elements MR1 and MR2, and has the same circuit configuration. As shown, the holder 10 has a flat plate 30
A housing 31 is integrally mounted and fixed to one end of the housing 31, and a side surface of the housing 31 is opened to accommodate the magnet 1. A mounting hole 29 for the magnetoresistive elements MR1 and MR2 is provided in an upper part of the housing 31. The conductor pattern 18 is formed of a copper layer or the like from the mounting hole 29 in which the magnetoresistive elements MR1 and MR2 are mounted to the surface side of the housing 31 and the flat plate 30.
The conductor pattern 18 is plated with gold. Circuit elements such as the custom IC 16, the inductance 7, the bypass capacitor 12, and the coupling capacitor 13 are mounted on the conductor pattern 18 on the flat plate 30 by soldering or the like. This conductor pattern 18 and various circuit elements 7, 1
2, 13, and 16 form a signal processing circuit 20 as shown in FIG. A connector 6 for extracting an output signal from the signal processing circuit 20 is provided on the bottom of the holder 10, that is, on the bottom of the flat plate 30.

The main part of the signal processing circuit 20 is a constant voltage section 25,
It comprises a custom IC 16 in which an amplifying section 26, a comparing section 27 and a pulse output section 28 are integrated. The amplifier 26 amplifies the output voltage V _out having the analog waveform as shown in FIG. The comparing unit 27 compares the voltage signal applied from the amplifying unit 26 with a predetermined reference voltage to shape the waveform into a rectangle. The pulse output unit 28 outputs a digital signal having the rectangular pulse waveform as shown in FIG. 4 to the outside. The signal processing circuit 20 includes the custom IC
In addition to 16, an inductance 7, a bypass capacitor 12, and a coupling capacitor 13 are connected.
The inductance 7 and the bypass capacitor 12 are a constant voltage part 25
The coupling capacitor 13 is connected between the magnetic detection unit 3 and the amplification unit 26 and between the amplification unit 26 and the comparison unit 27 to prevent high frequency noise.
The DC component is cut off, and only the AC voltage of the magnetic detection signal is extracted and applied to the comparison unit 27. Thus, the signal processing circuit 20
Then, the detection signal of the analog waveform from the magnetic detection unit 3 is converted into a digital signal that can be input to the microcomputer, and is output from the connector 6 to the outside.

As described above, the conductor pattern 18 is formed on the outer surface of the holder 10 accommodating the magnetic detection unit 3 and the various circuit elements 7, 12, 13, 16 are mounted in the module case 17. Then, the magnetic sensor module is completed by being integrally fixed by enclosing the encapsulating resin.

In the present embodiment, as described above, the conductor pattern 18 as the signal processing circuit 20 is formed on the outer surface of the holder 10 holding the magnetic detection unit 3, and various circuit elements 7, 12, 13,
Since 16 is mounted and the connector 6 is attached to the bottom of the holder 10, all components and circuits are mounted using the holder 10 as a support, so that the size is very small.

Therefore, it is not necessary to manufacture the circuit board 8 separately from the holder 10 and install it in the module case 17 and screw it into the module case 17 as in the prior art. Become. In addition, since there is no need for a built-in fixing part such as a screw, the material cost is reduced, and an inexpensive magnetic sensor module can be provided.

Further, conventionally, lead wires 11 are routed between the holder 10 and the circuit board 8, but in the present embodiment, the signal processing circuit 20 is formed with the conductor pattern 18 using the holder 10 itself as a substrate. This eliminates the need for the long lead wire 11, prevents the introduction of induced noise, and increases the reliability of magnetic detection. At the same time, there is no danger of breaking the lead wire 11 due to vibration or the like.

The present invention is not limited to the above embodiment, but can take various embodiments. For example, in this embodiment, a magnetoresistive element was used as the magnetic sensing element.
A hall element may be used.

Although the present embodiment has been described with reference to the example of rotation detection, the present invention can also be applied to linear movement detection, a magnetic card reader, and the like. Further, the conductor pattern 18 formed on the outer surface of the holder 10 is formed of copper, but may be formed of another conductor metal such as nickel.

[0019]

According to the magnetic sensor module of the present invention, the magnetic detecting portion is housed in the holder, and the holder itself is used as a substrate to form a signal processing circuit. In addition, since the mounting and fixing work is not required, the workability is improved and an inexpensive magnetic sensor module can be provided.

Further, since a long lead wire as in the prior art is not required, the incorporation of induced noise can be prevented, and the reliability of magnetic detection can be improved. There is no danger of breakage of the lead wire due to vibration or the like.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a magnetic sensor module according to the present invention.

FIG. 2 is a block diagram showing a signal processing circuit according to the embodiment.

FIG. 3 is a waveform diagram of an output signal from a magnetic detection unit.

FIG. 4 is a waveform diagram of an output signal from a pulse output unit of the signal processing circuit.

FIG. 5 is a conceptual diagram showing the principle of detection of gear rotation by a magnetic detection unit.

FIG. 6 is a sectional view showing the structure of a conventional magnetic sensor module.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnet MR1, MR2 Magnetoresistive element (magnetic sensing element) 3 Magnetic sensing part 7, 12, 13, 16 Circuit element 10 Holder 18 Conductor pattern 20 Signal processing circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-156391 (JP, A) JP-A-62-220882 (JP, A) JP-A-61-129164 (JP, U) (58) Survey Field (Int.Cl. ⁶ , DB name) G01D 5/245 G01R 33/09

Claims (1)

(57) [Claims] A magnet for applying a bias magnetic field;
A magnetic detection element for detecting a magnetic change using the bias magnetic field; and a holder for holding a magnetic detection unit. A conductor pattern is formed on a surface of the holder, and an output of the magnetic detection element is formed on the conductor pattern. A magnetic sensor module in which a circuit element for processing a signal is mounted, and a signal processing circuit is formed on a surface of the holder using the holder itself as a substrate.