JPH11344504A - Acceleration sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acceleration sensor capable of preventing sensitivity characteristics of a sensor from deteriorating, without using lead lines for connecting a magnetic sensor with a circuit substrate for detecting acceleration. SOLUTION: In an acceleration sensor which comprises: a fixed portion 2 of square frame shape; a movable portion 3 movable in the vertical direction, both ends of which being fixed to the inside of the fixed portion 2; a permanent magnet 5 joined on the upper surface of the center of the movable portion 3; magnetic sensors 6, 7 which are disposed on the fixed portion 2 side so as to be opposed to the permanent magnet 5 with a clearance left therebetweeh, and formed of amorphous lines having a magnetic impedance effect such that an output voltage changes according to change in leakage magnetic field from the permanent magnet 5; and an acceleration detecting circuit substrate 9 for detecting an acceleration applied to the permanent magnet 5 according to change in output voltage from the magnetic sensors 6, 7, a sensor fixing substrate 8 is provided between the magnetic sensors 6, 7 and the acceleration detecting circuit substrate 9, to which the electric sensors 6, 7 are connected at each end by soldering via solder lands 10-13, and the acceleration detecting circuit substrate 9 is connected by soldering via through holes 14-17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor used for controlling industrial equipment and analyzing vibrations, and for detecting acceleration electromagnetically.

[0002]

2. Description of the Related Art Acceleration sensors for electromagnetically detecting acceleration have been used in fields such as vibration analysis of machine tools, robots and other devices, and impact analysis of automobiles. In such an acceleration sensor, a permanent magnet is attached to the tip of a cantilever made of a material that bends due to acceleration or to the center of the cantilever, and a magnetoresistive element is attached to a target position facing the permanent magnet via a gap. Alternatively, two magnetic sensors each composed of a Hall element are provided, and an acceleration calculation unit that calculates the acceleration by adding the outputs of these two magnetic sensors with opposite polarities is provided.
When acceleration is applied to the acceleration sensor from the outside, the flexible beam is displaced in the direction of the acceleration measured by the flexible beam, that is, in the vertical direction according to the magnitude of the acceleration. At this time, the output of both magnetoresistive elements changes due to the leakage magnetic field generated by the permanent magnet mounted on the flexible beam, and the differential output is input to the acceleration calculator to calculate the acceleration.

[0003]

However, in the prior art, in an acceleration sensor using a magnetoresistive element or a Hall element as a magnetic sensor, a change in output with respect to a change in a magnetic field is small (the sensitivity is low). Could not be measured. In addition, for such a magnetic sensor, a sensor using an amorphous wire having a magneto-impedance effect and having a sensitivity of about five orders of magnitude higher than that of the sensor has been proposed. However, this sensor deteriorates the characteristics such as sensitivity due to the lead wire for connecting the acceleration detection circuit board that detects the sensor signal from the amorphous wire, the detection signal fluctuates due to the vibration of the lead wire, There were problems such as disconnection. Therefore, the present invention prevents deterioration of the sensitivity characteristic of the sensor without using a lead wire for connecting the magnetic sensor and the circuit board for acceleration detection, and also realizes a high-level signal which does not cause signal fluctuation due to vibration of the lead wire. It is an object of the present invention to provide a sensitive acceleration sensor.

[0004]

According to a first aspect of the present invention, there is provided a movable part having at least one end fixed inside a fixed part and movable vertically. A permanent magnet joined to the top of the center of the
A magnetic sensor having a magnetic impedance effect in which an output voltage is changed by a change in a leakage magnetic field from the permanent magnet, the magnetic sensor being disposed to face the fixed portion through a gap with the permanent magnet, and provided in the fixed portion. And an acceleration detection circuit board that detects acceleration applied to the permanent magnet from a change in the output voltage of the magnetic sensor, wherein an acceleration detection circuit board is provided between the magnetic sensor and the acceleration detection circuit board. A solder land for connecting both ends of each of the magnetic sensors by soldering, a through hole for connecting the acceleration detection circuit board on the board end face or inside the board by soldering, the solder land and A sensor fixing substrate provided with a lead pattern for connecting a through hole is provided. According to a second aspect of the present invention, in the acceleration sensor according to the first aspect, the sensor fixing board and the acceleration detection circuit board are provided with positioning holes for positioning and fixing, respectively. . By the above-mentioned means, a sensor fixing board is provided between the magnetic sensor and the acceleration detecting circuit board, the ends of which are connected by soldering the amorphous wires constituting the magnetic sensor, and the sensor fixing board and the acceleration detecting circuit board are through-holeed. In this configuration, the lead wire for connecting the circuit board for acceleration detection from the amorphous wire becomes unnecessary, and as a result, the deterioration of the sensitivity characteristic of the sensor and the fluctuation of the signal due to the vibration of the lead wire are prevented.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an acceleration sensor according to a first embodiment of the present invention. FIG. 1A is a side sectional view of the acceleration sensor. FIG. 2B is a plan view of the sensor fixing board and the acceleration detection circuit board viewed from the line AA in FIG. FIG. 2 is an enlarged perspective view of the sensor fixing substrate according to the first embodiment of the present invention. In the drawing, 1 is an acceleration sensor, 2 is a square frame-shaped fixed portion, 3 is a movable portion formed of a leaf spring having both ends fixed inside the fixed portion 2, and 4 is a weight provided at the center of the movable portion 3. The weight body 5 is a permanent magnet made of a samarium cobalt magnet fixed to the vertical surface of the weight body 4 with an adhesive, and the permanent magnets 6 and 7 are provided on a sensor fixing substrate 8 to be described later through a predetermined gap with the permanent magnet 5. Amorphous wire (magnetic sensor) having a magneto-impedance effect, and is a FeCoSiB-based material having a diameter of 30 μm and a length of 1 mm. Reference numeral 9 denotes a circuit board for acceleration detection provided on a fixed portion and mounting electronic components (not shown). Here, two amorphous lines are arranged to obtain a differential. The configuration in which the present invention is different from the conventional one is as follows. A sensor fixing board 8 is provided between the amorphous wires 6 and 7 and the acceleration detecting circuit board 9. Solder lands 10, 1 for connecting both ends of the amorphous wires 6, 7 by soldering are provided on the inner surface of the sensor fixing substrate 8.
1, 12, 13 are provided, and the end surface of the sensor fixing substrate 8 is provided with:
Through holes 14, 15, 1 for connecting the sensor fixing board 8 and the acceleration detecting circuit board 9 by soldering
6 and 17 are provided. In addition, solder lands 10, 11, 12, 13 and through holes 14,
Leader patterns 18, 19, 20, and 21 for connecting 15, 16, 17 respectively are provided. Also,
As shown in FIG. 1B, the circuit board 9 for acceleration detection has through-holes 14, 15, 1
Solder lands 28, 29, 3 corresponding to positions 6 and 17
0 and 31 are provided. Next, the operation will be described. In the acceleration sensor 1, when an acceleration is applied, the movable portion 3 is bent and displaced in the direction of acceleration (up and down direction) according to the magnitude of the acceleration, and the permanent magnet 5 is displaced together with the weight 4 provided on the movable portion 3. I do. Accordingly, the output appearing at both ends of the amorphous wires 6 and 7 changes due to the leakage magnetic field from the permanent magnet 5. Such an acceleration sensor 1 includes an amorphous wire 6,
Reference numeral 7 denotes a configuration in which the sensor is soldered to the sensor fixing substrate 8 without using a lead wire and soldered to the acceleration detection circuit board via a through hole provided in the end face of the substrate. Also, the output change of the amorphous wires 6 and 7 can be detected with high sensitivity without causing the output fluctuation due to the vibration of the lead wire. FIG. 3 is a plan view of a sensor fixing substrate according to a second embodiment of the present invention. The difference from the first embodiment is that positioning holes 22 and 23 are provided on the sensor fixing substrate. Also, in the acceleration detection processing board, the positioning holes 2 on the sensor fixing board are used.
Positioning holes (not shown) are provided at positions corresponding to 2 and 23. Further, when soldering and fixing the sensor fixing board to the acceleration detecting circuit board, positioning can be facilitated by setting pins or the like in the positioning holes. FIG. 4 is a plan view of a sensor fixing substrate according to a third embodiment of the present invention. Through holes 24, 25, 2 for connecting the sensor fixing board 8 to the acceleration detecting circuit board 9
6 and 27 are provided, and the through hole 2 on the sensor fixing substrate 8 is provided.
Through holes (not shown) are provided inside the acceleration detecting circuit board 9 at positions corresponding to 4, 25, 26, and 27.
Through holes 24, 25, 26, on the sensor fixing substrate 8
For example, a conductive pin-like member (not shown) obtained by cutting a lead terminal of a resistor is placed on a through hole (not shown) of the circuit board 9 for acceleration detection and the sensor fixing substrate 8 side.
Soldering is performed on both sides of the acceleration detection circuit board 9. This pin (not shown) is used for both electrical connection / fixing and positioning. In the above three embodiments, the lead pattern is as thick as possible to reduce the impedance,
It is desirable to shorten it. Therefore, since the amorphous wire is connected to the circuit board for acceleration detection without using a lead wire, a highly sensitive acceleration which does not cause deterioration of characteristics such as sensitivity and does not cause signal fluctuation due to vibration of the lead wire. A sensor can be realized, and a highly reliable acceleration sensor free from disconnection of a lead wire due to vibration can be obtained. Here, it is naturally conceivable to use the amorphous wire directly soldered to the circuit board for acceleration detection. However, electronic circuit components and the like are usually mounted on the circuit base for acceleration detection, and if the amorphous wire and the permanent magnet are to be kept in the optimum gap, the electronic circuit components interfere with the movable part, the weight, and the permanent magnet. It is possible. Therefore, if the structure of the present invention is used, by arbitrarily changing the thickness of the sensor fixed substrate, the electronic components and the like on the acceleration detection processing substrate do not interfere with the movable portion, the weight, and the permanent magnet,
The optimum gap can be maintained. In addition, although a leaf spring was used for the movable part, a coil spring may be used. Further, a cantilever having one end fixed and the other end unrestricted may be used instead of the cantilever.

[0006]

As described above, according to the present invention, a structure in which an amorphous wire is soldered to a sensor fixing board, the sensor fixing board is soldered to a circuit board for acceleration detection, and no lead wire is used. Therefore, it is possible to realize a high-sensitivity acceleration sensor in which characteristics such as sensitivity are not deteriorated and a signal does not change due to vibration of a lead wire. In addition, reliability is improved because there is no fear of disconnection of the lead wire due to vibration. Further, by arbitrarily changing the thickness of the sensor fixing substrate, the components on the acceleration detecting substrate and the movable portion do not interfere with each other, and the optimum gap can be maintained, which leads to higher sensitivity of the acceleration sensor.

[Brief description of the drawings]

FIG. 1 is an acceleration sensor according to a first embodiment of the present invention, in which (a) is a side sectional view of the acceleration sensor. (B)
FIG. 3A is a plan view of the sensor fixing board and the acceleration detecting circuit board viewed from the line AA in FIG.

FIG. 2 is an enlarged perspective view of a sensor fixing substrate according to the first embodiment of the present invention.

FIG. 3 is an enlarged plan view of a sensor fixing substrate according to a second embodiment of the present invention.

FIG. 4 is an enlarged plan view of a sensor fixing substrate according to a third embodiment of the present invention.

[Explanation of symbols]

 1: Acceleration sensor 2: Fixed part 3: Movable part 4: Weight body 5: Permanent magnet 6, 7: Amorphous wire 8: Sensor fixed board 9: Acceleration detection circuit board 10, 11, 12, 13: Solder land 14 , 15, 16, 17: Through holes (board end face side) 18, 19, 20, 21: Pull-out patterns 22, 23: Positioning holes 24, 25, 26, 27: Through holes (board inside)

Claims (2)

[Claims] 1. A movable part having at least one end fixed inside a fixed part and movable in a vertical direction, a permanent magnet joined to an upper surface at the center of the movable part, and a gap between the permanent magnet and the permanent magnet. A magnetic sensor having a magneto-impedance effect in which the output voltage changes due to a change in a leakage magnetic field from the permanent magnet, which is provided on the fixed portion side, and an output voltage of the magnetic sensor provided in the fixed portion; An acceleration detection circuit board for detecting an acceleration applied to the permanent magnet from a change in the magnetic sensor, between the magnetic sensor and the acceleration detection circuit board, both ends of each of the magnetic sensors And a through hole for connecting the circuit board for acceleration detection on the end face of the board or inside the board by soldering. An acceleration sensor, comprising: a sensor fixing substrate provided with a through hole and a lead pattern for connecting the solder land and the through hole. 2. The acceleration sensor according to claim 1, wherein said sensor fixing board and said acceleration detecting circuit board are provided with positioning holes for positioning and fixing, respectively.