JPH0634454A - Piezoelectric vibrating sensor device and its manufacture - Google Patents

Abstract

PURPOSE:To improve productivity without deteriorating the measurement frequency characteristics of a sensor and reduce manufacturing cost by connecting a signal processing circuit to a cable with a connector and then forming the connector in one piece with a package. CONSTITUTION:A piezoelectric vibration sensor 20, a circuit substrate 30, and a connector 40 are housed inside a package which is constituted of a package base 10 and a package cap and a cable 50 is lead out of the connector 40 through the package. The package base 10 is a highly rigid pedestal and is provided with a fitting surface 11 which is closely adhered to an object to be measured and a fitting means 12 such as a screw hole. The package base 10 is provided with a connector housing part 13 which is formed in one piece on the surface at the opposite side of the fitting surface 11. The connector 40 is housed and fixed in the storage chamber 14 of the connector storage part 13, thus preventing abnormal resonance due to vibration of the object to be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibration sensor device, and more particularly to a piezoelectric vibration sensor device which enhances productivity and reduces manufacturing costs without impairing measurement frequency characteristics.

[0002]

2. Description of the Related Art Basically, a piezoelectric vibration sensor has one surface of a piezoelectric element, which is composed of a film-shaped piezoelectric material and electrode plates adhered to both surfaces thereof, rigidly attached to an object to be measured through an insulating sheet. The piezoelectric element is bonded to the pedestal, and the other surface of the piezoelectric element is bonded to a load body acting as an inertial mass via an insulating sheet. Such a piezoelectric vibration sensor needs to be mounted so that its pedestal vibrates in the same manner as the vibration of the measured object. If it has a peak resonance frequency, it means that the vibration of the measured object cannot be measured correctly.

On the other hand, the piezoelectric vibration sensor device has, in addition to the piezoelectric vibration sensor, a built-in signal processing circuit for processing the electric vibration generated by the piezoelectric vibration sensor and converting it into a desired electric signal.
When this device is attached to the object to be measured, it is necessary to connect a signal cable for transmitting the electric signal to another device such as a display device and a power cable as a power source of the device by some means.

[0004]

In the conventional piezoelectric vibration sensor device, there was a problem with the connecting means between the device and the cable as described above. That is, when a normal connector is used, this connector part has a peak resonance frequency (hereinafter referred to as "abnormal resonance"), which is so-called chattering, within the vibration frequency band to be measured, and the measured value is It becomes a disturbing noise source, and the measurable vibration frequency band is significantly narrowed. Conventionally, two means have been taken as means for avoiding such abnormal resonance. One of them is a method of using an extremely strong connector, whereby an abnormal resonance due to the connector is excluded outside the measurement frequency band. However, this method comes at an extra cost because such rigid connectors are expensive. The other means is a so-called direct connection method in which the conductor of the cable is directly connected to the substrate of the signal processing circuit incorporated in the piezoelectric vibration sensor device by soldering.
In this method, no abnormal resonance occurs because the connector is not used, but the process of soldering the cable to the board is often a manual process, which results in poor productivity, which is also expensive.

Therefore, an object of the present invention is to increase the productivity and reduce the manufacturing cost without damaging the measurement frequency characteristics of the sensor, regardless of the use of expensive connectors or the means of manual connection. A vibration sensor device and a manufacturing method thereof are provided.

[0006]

This problem is a piezoelectric vibration sensor device in which a piezoelectric vibration sensor using a piezoelectric body and a signal processing circuit are housed in a package. This can be solved by providing a piezoelectric vibration sensor device in which cables are connected by a connector, and the connected connector is integrated with the package. In the above piezoelectric vibration sensor device, it is preferable that one terminal of the connector is directly connected to the substrate of the signal processing circuit and the other terminal is connected to the cable. The piezoelectric vibration sensor device is manufactured by connecting one terminal of the connector connected to the signal processing circuit and the other terminal of the connector connected to the cable, and then integrally molding this connector with the package. can do.

As described above, in the piezoelectric vibration sensor device of the present invention, one terminal of the connector is connected to the signal processing circuit and the other terminal is connected to the cable. Then, the signal processing circuit and the cable are electrically coupled by connecting the both terminals. This connector is
Since the piezoelectric vibration sensor and the signal processing circuit are fixed in a package in which both terminals are connected and integrally formed, abnormal resonance does not occur in this portion.

Next, the present invention will be specifically described with reference to the drawings. FIG. 1 partially shows an embodiment of the piezoelectric vibration sensor device of the present invention. In FIG. 1, this piezoelectric vibration sensor device has a package composed of a package base 10 and a package cap (not shown). Inside the package, the piezoelectric vibration sensor 20,
The circuit board 30 and the connector 40 are housed, and the cable 50 is pulled out from the connector 40 through the package.

The package base 10 is a high-rigidity pedestal and has a mounting surface 11 that is densely mounted on an object to be measured (not shown) and a mounting means 12 such as a screw hole. The package base 10 has a connector housing 13 integrally formed on the surface opposite to the mounting surface 11. The connector housing portion 13 has a housing chamber 1 in which a connector 40 is housed and fixed.
4, the wall 15 around the storage chamber serves as a board fixing base, and the peripheral edge of the circuit board 30 is closely attached to the board fixing surface 16 of the board fixing base. . In addition, a cable groove 17 for passing the cable 50 through is provided in a part of the wall portion 15. The peripheral portion of the circuit board 30 is densely attached to the board fixing surface 16. The circuit board 30 is provided with an input terminal for inputting an electric signal generated by the piezoelectric vibration sensor 20, a signal processing circuit for converting the electric signal into an output signal, the output terminal, and a power supply terminal.

The piezoelectric vibration sensor 20 is densely attached to the circuit board 30. The piezoelectric vibration sensor 20 includes a sensor chip 21, a load body 22 and wiring. The sensor chip 21 is composed of a film-shaped piezoelectric material having film-shaped conductors provided as electrodes on both surfaces thereof, and a highly rigid non-conductive sheet laminated on both surfaces thereof. One of the non-conductive sheets is tightly attached to the circuit board 30. A metal load body 22 acting as an inertial mass is attached to the other non-conductive sheet.
The laminated body composed of the film-shaped piezoelectric body, the film-shaped conductor, the non-conductive sheet, and the load body 22 is formed in a shape that is line-symmetric with respect to the vibration sensing axis passing through the layered body. A lead wire is drawn out from the electrode of the sensor chip 21 and connected to an input terminal provided on the circuit board 30.

The output terminal provided on the circuit board 30 is connected to the circuit side terminal 41 of the connector 40. The output terminal and the circuit side terminal 41 can be connected via a lead wire, but it is preferable that they are directly connected. This is because abnormal resonance is further suppressed and the number of manufacturing steps is reduced. The other terminal of the connector 40 is connected to the conductor of the cable 50 and forms a cable terminal 42. The connector 40 is housed in the housing chamber 14 with both terminals electrically coupled, and is fixed so as not to cause abnormal resonance due to external vibration. Each terminal of the connector 40 may have any shape as long as it can maintain electrical stability and durability even when subjected to vibration. Usually, a pin-shaped or tongue-shaped terminal and a receptacle terminal biased so as to sandwich and press the terminal are used.

The cable 50 has conductors for signal output and power supply, and the conductors are respectively connected to the cable terminals 42 inside the package. The piezoelectric vibration sensor device has a package cap (not shown). The package cap is attached to the outer periphery of the wall portion 15, covers the piezoelectric vibration sensor 20 so as not to contact the piezoelectric vibration sensor 20, and is integrated with the package base 10 to form a package.

Next, the operation of this piezoelectric vibration sensor device will be described. The mounting surface 11 of the piezoelectric vibration sensor device is rigidly mounted on the object to be measured by the mounting means 12. When the measured object vibrates, this vibration is transmitted to the wall portion 15 of the package base, and from the board fixing surface 16 to the circuit board 30.
The sensor chip 21 is vibrated via the. At this time, the load body 22 acts as an inertial mass and resists vibration, so that the film-shaped piezoelectric body of the sensor chip 21 receives a pressure change with respect to a vibration component parallel to the vibration sensing axis of the piezoelectric vibration sensor 20, and the change occurs. Generates a corresponding voltage oscillation. The voltage oscillation generated here is input to the signal processing circuit from the input terminal of the circuit board 30 via the lead wire, undergoes electrical processing here, is converted into an output signal, and the circuit side terminal of the connector 40 is output from the output terminal. 41 and the cable terminal 42,
The signal is sent from the cable 50 to a signal processing device (not shown) such as a display device. At this time, since the entire connector 40 is housed and fixed in the housing chamber 14 inside the package, abnormal resonance does not occur due to vibration of the measured object.

Next, an embodiment of a method of manufacturing this piezoelectric vibration sensor device will be described. A cable with a terminal in which the cable terminal 42 is connected to the end of the cable 50 by soldering or the like in advance is prepared. On the other hand, an assembly is prepared in which the piezoelectric vibration sensor 20, the circuit board 30, and the circuit side terminal 41 of the connector are fixed in advance. Next, the circuit-side terminal 41 of this assembly is connected to the cable terminal 42 of the cable with the above terminal, the connected connector is housed and fixed in the housing chamber 14 of the package base, and the cable 50 is inserted into the cable groove 17. This is pulled out to the outside, and the peripheral portion of the circuit board 30 is adhered to the board fixing surface 16 using an epoxy resin adhesive or the like. Then, the package cap is attached to the assembly, and the manufacturing is completed.

Although what has been described above is the preferred embodiment of the piezoelectric vibration sensor device and the manufacturing method thereof according to the present invention, the present invention is not limited to the above-described modes and manufacturing methods.
For example, in another embodiment, the circuit board 30 has a pin or tongue conductor vertically attached thereto as the circuit side terminal 41. On the other hand, in the package base, a receptacle terminal is provided as a cable terminal 42 at a position to be engaged with the circuit-side terminal 41 so as to be embedded when the package base is molded. In this case, the circuit side terminal 4
When 1 is inserted into the receptacle terminal (cable terminal) 42 on the package base side, the assembly and the package base are joined at the same time when the connector is connected, and the connector is integrated with the package. Such an embodiment is preferable in that the manufacturing process can be easily automated. As another embodiment, after the connector 40 is stored, the storage chamber 14
The voids can be filled and sealed with epoxy resin or the like. This further strengthens the integration of the package and the connector, further reducing abnormal resonance and improving durability.

[0016]

EXAMPLES Next, examples of the present invention will be described in more detail. Example 1 A piezoelectric vibration sensor device as described with reference to FIG. 1 was produced. Membrane piezoelectric material with a thickness of 110 μm and 5 mm
Use a square polyvinylidene fluoride film, and apply 30
A sensor chip 21 was obtained by adhering a copper foil having a thickness of μ and a square of 5 mm and further adhering a glass epoxy resin plate having a thickness of 1.5 mm and a square of 5 mm to both surfaces thereof. Sensor chip 2
One of the glass epoxy resin surfaces of 1 is closely adhered to the circuit board 30 on which the signal processing circuit and the circuit side terminal 41 of the connector are provided in advance, and the lead wire is drawn from the copper foil to input the signal processing circuit input terminal. Connected to. A brass load element 22 was bonded to the other glass epoxy resin surface.
The terminal of the cable 50 is connected to the cable terminal 42 of the connector 40.
And the cable terminal 42 was connected to the circuit side terminal 41 provided on the circuit board 30. The connector 40 formed by this connection is housed and fixed in the housing chamber 14 provided in the package base 10, the cable 50 is pulled out from the cable groove 17, and at the same time, the peripheral portion of the circuit board 30 is packaged using an epoxy resin adhesive. Base 10
It was bonded to the substrate fixing surface 16. Finally, the package cap was attached to the package base 10 to complete the piezoelectric vibration sensor device of this embodiment.

(Comparative Example 1) A comparative example 1 was prepared in which the connector portion of the piezoelectric vibration sensor device was exposed to the outside and was not integrated with the package. (Comparative Example 2) A cable was directly connected to the circuit board of the piezoelectric vibration sensor device by soldering without using a connector, and the cable was directly exposed from the package.

Regarding Example 1 and Comparative Examples 1 and 2,
The measurable vibration frequency band was measured without being hindered by abnormal resonance. The results are shown in Table 1 as comparative values with the value of Comparative Example 2 being 1.0. Further, the number of manufacturing steps per product when manufacturing these was set to 1.0 in Comparative Example 2 and compared. The results are shown in Table 1.

[0019]

[Table 1]

From the above results, it is clear that the piezoelectric vibration sensor device of the present invention has a wide band vibration measurement capability and the number of manufacturing steps is reduced.

[0021]

The piezoelectric vibration sensor device of the present invention is a piezoelectric vibration sensor device in which a piezoelectric vibration sensor using a piezoelectric material and a signal processing circuit are housed in a package. Since the cables are connected by the connector and the connected connector is integrated with the package, it is possible to improve the productivity and reduce the manufacturing cost without impairing the measurement frequency characteristics of the piezoelectric vibration sensor device. There is an effect that you can.

[Brief description of drawings]

FIG. 1 is a schematic view showing a portion of a piezoelectric vibration sensor device of the present invention.

[Explanation of symbols]

10 ... Package base, 13 ... Connector housing, 20
... Piezoelectric vibration sensor, 30 ... Circuit board, 40 ... Connector, 41 ... Circuit side terminal, 42 ... Cable terminal, 50 ... Cable.

Claims (3)

[Claims] 1. A piezoelectric vibration sensor device in which a piezoelectric vibration sensor using a piezoelectric body and a signal processing circuit are housed in a package, wherein the signal processing circuit and a cable are connected by a connector. A piezoelectric vibration sensor device in which a connector is integrated with the package. 2. The piezoelectric vibration sensor device according to claim 1, wherein one terminal of the connector is directly connected to the substrate of the signal processing circuit, and the other terminal is connected to the cable. Piezoelectric vibration sensor device. 3. When manufacturing the piezoelectric vibration sensor device according to claim 1, one terminal of the connector is connected to a signal processing circuit, the other terminal is connected to a cable, and then both terminals are connected, A method of manufacturing a piezoelectric vibration sensor device, which is characterized by integrally molding this connector with a package.