JPH07270449A - Piezoelectric type acceleration sensor - Google Patents

Abstract

PURPOSE:To provide a piezoelectric type acceleration sensor by which a holding body for holding a lead is not pushed into the inside of a shield case during resin molding. CONSTITUTION:Each one end of roughly U-shaped leads 2 is connected to each of electrodes 1a on both sides facing the rear of a piezoelectric element 1. Each lead 2 is held by means of a holding body 3 and fixed. The holding body 3 is provided with a metal header 4 in close contact with it so as to cover the circumferential surface of the holding body 3. The bending part 2a of each lead 2 is made to oppositely face the end surface of a header 4. On the circumferential edge on the end side of the header 4, external jaw parts 4a are formed over its full circumference. A piezoelectric element 1 is inserted into the inside of the metal shield case 5 and the bending part 2a of the lead 2 are protruded to the outside and sealed by the header 4. The resin filled between the bending part 2a of the lead 2 and the end surface of the header 4 interfere with the bending part 2a, and the lead 2 and the header 4 can be prevented from being pushed into the inside of the shield case 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric acceleration sensor which detects the acceleration of shock or vibration by utilizing the piezoelectric effect of a piezoelectric element.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 9, a lead 10 is joined by soldering or the like to each electrode 1a on both sides of the back surface of a piezoelectric element 1 so as to be electrically connected thereto, and a bottomed cylindrical shape is formed. In the metallic shield case 5, only the lead 10 is projected outside from the opening of the shield case 5, and the piezoelectric element 1
Inside the shield case 5 and lead 1 to the opening.
The lid 11 with 0 inserted is attached and fixed to the shield case 5 by welding, soldering or the like to seal the lead 10.
There is a piezoelectric acceleration sensor in which the gap between the lid and the lid 11 is sealed with glass or resin and the piezoelectric element 1 is housed and fixed in the shield case 5.

With the above structure, when the piezoelectric acceleration sensor is mounted on the substrate 12, as shown in FIG.
Is bent at a substantially right angle and soldered to the substrate 12, and the shield case 5 is connected to the ground in order to connect the shield case 5 to the ground.
Are directly soldered to the substrate 12. However, when the lead 10 is connected to the electrode 1a of the piezoelectric element 1, the piezoelectric element 1
Since it is difficult to fix and position the piezoelectric element 1, the direction of the piezoelectric element 1 is not constant, or as shown in FIG.
The piezoelectric acceleration sensor itself is tilted when it is mounted in No. 2, and the detection direction varies. Therefore, the entire shield case 5 in which the output element and the ground terminal are joined to the lead 10 and the shield case 5 by a method such as soldering or laser welding, and only the output terminal and the ground terminal are projected to the outside to house the piezoelectric element 1 There has been proposed a piezoelectric acceleration sensor formed by resin molding.

[0004]

However, in the latter conventional configuration, since the resin injection pressure acts from the opening of the shield case 5 inward when the resin is molded, the lid 11 holding the lead 10 is held. Is pushed into the shield case 5 by its injection pressure, and the piezoelectric element 1 comes into contact with the shield case 5 or the lid 1
There is a problem that stress is applied to the glass or resin that seals 1 and the lid 11, and the glass or resin is cracked or damaged.

An object of the present invention is to solve the above problems and to provide a piezoelectric acceleration sensor in which a holding body for holding leads is not pushed into the inside of a shield case during resin molding. To do.

[0006]

In order to achieve the above-mentioned object, the invention according to claim 1 holds a piezoelectric element, a substantially U-shaped lead whose one end is connected to an electrode of the piezoelectric element, and the lead. And a holding body to be formed into a bottomed cylindrical shape having an opening,
A metal shield case in which the bending element and the other end of the substantially U-shaped lead are projected to the outside to house the piezoelectric element and the opening is sealed in the holder, and one end is the outer surface of the shield case. A grounding terminal joined to the shield case, and an output terminal having a lead projecting from the shield case joined to one end thereof, and at least the other end of the output terminal and the other end of the grounding terminal are projected to the outside. The case and the holding body are resin-molded.

According to a second aspect of the invention, in the first aspect of the invention, one end of the output terminal to which the lead is joined is divided into a plurality of divided pieces to form a divided piece, and the lead is inserted between the divided pieces. It is characterized in that the leads are sandwiched by the divided pieces. According to a third aspect of the present invention, in the first or second aspect of the invention, an opening portion of a shield case, which is provided in close contact with the periphery of the holding body so as to cover the peripheral surface of the holding body, and in which a piezoelectric element is incorporated, is provided. A metal header for sealing is provided, and the metal header is provided with an outer collar portion that comes into contact with the end surface of the peripheral edge of the opening of the shield case.

[0008]

According to the first aspect of the invention, the piezoelectric element, the substantially U-shaped lead whose one end is connected to the electrode of the piezoelectric element, the holding body for holding the lead, and the bottomed cylinder having the opening are provided. A metal shield case, which is formed in a substantially U shape, has a bent portion and the other end of the substantially U-shaped lead protruding to the outside to house a piezoelectric element and has an opening sealed in a holder, and one end of the shield case. A ground terminal joined to the outer surface of the shield case and an output terminal having a lead protruding from the shield case joined to one end are provided, and at least the other end of the output terminal and the other end of the ground terminal are connected to the outside. Since the shield case and the holder are made to protrude and resin-molded, the bent portion of the substantially U-shaped lead faces the opening surface of the shield case, and the resin to be molded forms the bent portion and the opening portion of the shield case. Holding to seal The bending portion of the lead interferes with the resin filled between the lead and the holder against the injection pressure of the resin that is filled between the lead and the inside of the shield case when the resin is molded. Therefore, it is possible to prevent the holder from being pushed into the shield case.

According to the second aspect of the present invention, one end of the output terminal to which the lead is joined is divided into a plurality of divided pieces to form divided pieces, and the leads are inserted between the divided pieces to form the leads by the divided pieces. Since the leads are sandwiched by the divided pieces, the positioning is easy when the output terminals are joined to the leads. According to the third aspect of the present invention, a metal header is provided around the holder so as to be in close contact with the holder so as to cover the peripheral surface of the holder and seals the opening of the shield case in which the piezoelectric element is incorporated. Since this metal header is provided with the outer collar portion that comes into contact with the end face of the peripheral edge of the opening of the shield case, when the resin is molded as described above, the resin that acts inward from the opening of the shield case is injected. With respect to the pressure, the lead and the holding body against the injection pressure of the resin that acts inward from the opening of the shield case by the outer collar portion that is brought into contact with the peripheral edge surface of the opening of the shield case. Can be prevented from being pushed into the shield case.

[0010]

【Example】

(Embodiment 1) An embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the piezoelectric element 1 is a long plate having electrodes 1a on both sides facing back, and both electrodes 1a are connected to one end of a substantially U-shaped lead 2, respectively. . A holding body 3 made of glass or resin is provided near the end portion of the lead 2 on the side connected to the piezoelectric element 1, and the holding body 3 holds the pair of leads 2 together.
Are held and fixed.

On the other hand, as shown in FIG. 2 and FIG. 3, a substantially cylindrical metal-made header 4 is provided in close contact with the holding body 3 so as to cover the circumferential surface of the holding body 3. There is. Here, the bent portion 2a of the lead 2 is opposed to the end surface of the header 4, and the protruding portion 2b protruding from the header 4 is bent in a stepwise manner. Further, an outer flange portion 4a is formed over the entire circumference at the peripheral edge on the end face side of the header 4.

The piezoelectric element 1 is inserted into the inside of a metal shield case 5 formed in a cylindrical shape having a bottom, and the bent portion 2a and the protruding portion 2b of the lead 2 are protruded to the outside so that the header 4 is formed. Is press-fitted and sealed in the opening of the shield case 5. That is, since the piezoelectric element 1 has a high impedance and is easily affected by noise, the shield case 5 shields the piezoelectric element 1 from external noise. Here, the outer collar portion 4a of the header 4
Protects the header 4 from being pushed into the shield case 5 more than necessary when the header 4 is press-fitted into the shield case 5 and comes into contact with the end surface of the peripheral edge of the opening of the shield case 5.

On both sides of the outer wall of the shield case 5, ground terminals 6 formed by bending a thin plate member into a substantially L shape are joined by laser welding and connected to each other. An output terminal 7 which is also formed of a thin plate-like member is joined and connected to the pair of leads 2 projecting from the same by laser welding. Further, the ends of the output terminal 7 and the ground terminal 6 which are not connected to the lead 2 and the shield case 5, respectively, are projected to the outside, and the shield case 5 and the header 4 are resin-molded to form a piezoelectric acceleration sensor. ing.

Next, the manufacturing process of the piezoelectric acceleration sensor will be briefly described with reference to FIGS. 5 and 6. First, a hoop-shaped thin metal plate is processed to connect the output terminal 7 and the ground terminal 6 in a strip shape. The terminal pieces 8 are formed, and the ends of the pair of ground terminals 6 are bent in the same direction at substantially right angles to form the joints 6a. Then, the sensor body A, in which the piezoelectric element 1 is housed in the shield case 5 and sealed by the header 4, is arranged so as to be sandwiched between the output terminal 7 and the ground terminal 6, and the leads are projected from the sensor body A. After laser-welding the projecting portion 2b of 2 and the output terminal 7, and the outer peripheral surface of the shield case 5 and the joint portion 6a of the earth terminal 6, the unnecessary portion of the terminal piece 8 is cut off and resin-molded. Thus, the piezoelectric acceleration sensor is formed.

According to the above configuration, when the sensor body A to which the ground terminal 6 and the output terminal 7 are connected is resin-molded, the injection pressure of the resin is the longitudinal direction of the sensor body A (see FIG. 1).
Even if the lead 2 is substantially U-shaped and the bent portion 2a of the lead 2 faces the end surface of the header 4, the bent portion 2a of the lead 2 also acts in the direction (arrow direction shown in (a)). Since the resin is filled between the end face of the header 4 and the end face of the header 4 and interferes with the bent portion 2a of the lead 2, it is possible to prevent the lead 2 and the header 4 from being pushed into the inside of the shield case 5. Further, since the header 4 is provided with the outer flange portion 4a that comes into contact with the peripheral edge surface of the opening of the shield case 5, it is possible to prevent the outer flange portion 4a from being pushed into the shield case 5. It is a thing.

(Embodiment 2) Another embodiment of the present invention will be described with reference to FIGS. Since the basic configuration of the piezoelectric acceleration sensor according to this embodiment is the same as that of the first embodiment, the common parts are designated by the same reference numerals, and the description thereof will be omitted. Only the characteristic parts will be described. .

In the piezoelectric acceleration sensor of this embodiment, one end of the output terminal 7 is raised along the shield case 5,
The leading end of the rising piece 9 is divided into three pieces 9a, 9b, 9c substantially evenly along the rising direction. Then, as shown in FIG. 7, the rising piece 9 of the output terminal 7 is formed into a substantially Y shape by bending the middle divided piece 9b toward the shield case 5 side (see FIGS. 7C and 8). ,
The projecting portion 2b of the lead 2 is inserted between the split pieces 9a and 9c at both ends and the bent middle split piece 9b to sandwich the lead 2 by the elastic force of the three split pieces 9a to 9c. .

According to the above construction, the lead 2 is connected to the output terminal 7.
When the protruding portion 2b of the output terminal 7 is joined by laser welding, the output terminal 7 and the lead 2 can be easily positioned, and the lead 2 is sandwiched by the divided pieces 9a to 9c of the output terminal 7. It does not move unnecessarily, the welding conditions by laser welding are stabilized, and the automation of the welding process is facilitated.

In Embodiments 1 and 2, the output terminal 7, the lead 2, the ground terminal 6 and the shield case 5 were joined by laser welding, but the present invention is not limited to this and other methods may be used. For example, they may be joined by soldering.

[0020]

According to the invention of claim 1, a piezoelectric element, a substantially U-shaped lead whose one end is connected to an electrode of the piezoelectric element, a holder for holding the lead, and a bottomed cylinder having an opening. A metal shield case, which is formed in a substantially U shape, has a bent portion and the other end of the substantially U-shaped lead protruding to the outside to house a piezoelectric element and has an opening sealed in a holder, and one end of the shield case. A ground terminal joined to the outer surface of the shield case and an output terminal having a lead protruding from the shield case joined to one end are provided, and at least the other end of the output terminal and the other end of the ground terminal are connected to the outside. Since the shield case and the holder are made to protrude and resin-molded, the bent portion of the substantially U-shaped lead faces the opening surface of the shield case, and the resin to be molded forms the bent portion and the opening portion of the shield case. Holder to be sealed The bending portion of the lead interferes with the resin filled between the lead and the holding body against the injection pressure of the resin that is filled between the lead and the inward direction from the opening of the shield case during resin molding. Therefore, there is an effect that the holder can be prevented from being pushed into the shield case.

According to a second aspect of the present invention, one end of the output terminal to which the lead is joined is divided into a plurality of divided pieces to form divided pieces, and the leads are inserted between the divided pieces so that the divided pieces hold the lead. Since the lead is sandwiched by the divided pieces, positioning when joining the output terminal to the lead is easy, and moreover, the joining conditions can be stabilized when joining by laser welding or soldering. This has the effect of facilitating automation of work.

According to a third aspect of the present invention, there is provided a metal header which is provided around the holder so as to cover the peripheral surface of the holder in close contact with the holder and seals the opening of the shield case in which the piezoelectric element is incorporated. Since this metal header is provided with an outer flange portion that comes into contact with the end surface of the peripheral edge of the opening of the shield case, when the resin is molded as described above, the resin acting inward from the opening of the shield case is used. With respect to the injection pressure, the outer collar that abuts the peripheral edge surface of the opening of the shield case holds the lead and the lead against the injection pressure of the resin that acts inward from the opening of the shield case during resin molding. This has the effect of preventing the body from being pushed into the shield case.

[Brief description of drawings]

1A and 1B show Example 1, in which FIG. 1A is a partially cutaway plan view of the whole, FIG. 1B is a side view, and FIG. 1C is a sectional front view taken along line XX of FIG. 1A. Is.

2A and 2B are views showing a header of the same, where FIG. 2A is a plan sectional view and FIG. 2B is a front view.

3A and 3B are views showing the header of the same, where FIG. 3A is a plan view, FIG. 3B is a front view, and FIG. 3C is a side view.

FIG. 4 is a view showing the above shield case, (a)
Is a plan sectional view, and (b) is a side view.

5A and 5B are diagrams showing a terminal piece in the above manufacturing process, FIG. 5A being a plan view and FIG. 5B being a side view.

6A and 6B are diagrams showing a terminal piece and a sensor body in the same manufacturing process as above, wherein FIG. 6A is a partially broken plan view, and FIG.
Is a front view and (c) is a side view.

7A and 7B show Example 2, where FIG. 7A is a partially cutaway plan view of the whole, FIG. 7B is a side view, and FIG. 7C is a sectional front view taken along line XX of FIG. 7A. Is.

FIG. 8 is an explanatory diagram explaining the same as above.

FIG. 9 is a plan sectional view showing a conventional example.

FIG. 10 is a diagram showing a board mounting state of the above, FIG.
Is a front view and (b) is a side view.

[Explanation of symbols]

 1 piezoelectric element 1a electrode 2 lead 2a bent portion 3 holder 4 header 5 shield case 6 ground terminal 7 output terminal

Front page continuation (72) Inventor Hiromi Nishimura 1048, Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (3)

[Claims] 1. A piezoelectric element, a substantially U-shaped lead whose one end is connected to an electrode of the piezoelectric element, a holding body for holding the lead, and a bottomed cylindrical shape having an opening. A metal shield case in which the bending element and the other end of the mold lead are projected to the outside to house the piezoelectric element and the opening is sealed in the holder, and one end is joined to the outer surface of the shield case. Ground terminal and an output terminal to which a lead protruding from the shield case is joined to one end portion, and at least the other end portion of the output terminal and the other end portion of the ground terminal are protruded to the outside and these shield case and A piezoelectric acceleration sensor, characterized in that the holding body is molded with resin. 2. An output terminal to which a lead is joined is divided into a plurality of parts to form a divided piece, the lead is inserted between the divided pieces, and the lead is sandwiched by the divided pieces. The piezoelectric acceleration sensor according to claim 1. 3. A metal header is provided around the holder so as to cover the peripheral surface of the holder in close contact with the holder and seals an opening of a shield case in which a piezoelectric element is provided. The piezoelectric acceleration sensor according to claim 1 or 2, wherein the header is provided with an outer collar portion that abuts an end surface of a peripheral edge of the opening of the shield case.