JP2582856Y2 - Acceleration sensor - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor which is mounted on a vehicle and detects acceleration of the vehicle for controlling a suspension system and controlling the operation of an airbag.

[0002]

2. Description of the Related Art As one type of acceleration sensor mounted on a vehicle, a sensor called a semiconductor type is becoming popular. As shown in FIG. 6, this semiconductor type acceleration sensor
A cantilever-shaped weight portion (pendulum portion) 52 is formed on a silicon substrate 51 by, for example, etching using an LSI technology, and a strain gauge of a piezoresistive element is formed at the base of the weight portion 52. Forming a sensor chip portion 55 serving as the center of the acceleration sensor by forming a portion 53 and simultaneously incorporating a signal processing circuit portion 54 such as an amplifier circuit on the same silicon substrate 51 as the weight portion 52. When an acceleration (deceleration) is applied to the weight 52, a strain is generated in the strain gauge 53.
It is based on extracting the change as an electric signal output (a similar technique is, for example, "Nikkei Mechanical", 19
September 2, 1991 (No. 357), published by Nikkei BP, P
32-33).

As shown in FIG. 7, the detection chip section 55 formed as a single chip is sealed in a case 57 filled with, for example, an insulating silicone oil 56 or the like as shown in FIG. And then
As shown in FIGS. 8 and 9, the printed circuit board 6 is mounted on a printed circuit board 60 together with other circuit components 59, 59.
0 is housed in the housing 61. Reference numeral 62 denotes a lid for sealing the housing 61. A connector 63 for connecting to an external device is fixed to the lid 62 in advance, and the connector 63 is connected to the printed circuit board 60 via a harness 64. It is connected.

The reason why the inside of the detection unit 58 is filled with the silicone oil 56 is that, in the event that an excessive input in the direction of the acceleration action is applied, the root portion of the weight 52 whose strength is weak. The silicone oil 56 serves as an oil damper that regulates the displacement of the weight 52 by viscous resistance.

As an alternative to the above structure, for example, as shown in FIG. 10, a harness 65 connected to a printed circuit board 60 is drawn out of a housing 66, and
In some cases, a connector 63 is connected to the terminal of the harness 65. In addition, 67 is a lid, and 68 is a grommet for sealing mounted in the hole 69.

[0006]

In the structure of the conventional acceleration sensor shown in FIG. 8, the printed board 60 and the harness 64, and the harness 64 and the terminal of the connector 63 must be connected by soldering. Not only does this increase the number of assembling steps, but also results in two soldering sites, which are not always sufficient in terms of connection reliability against disconnection and the like.

In the structure of the conventional acceleration sensor shown in FIG. 10, unlike the one shown in FIG. 8, the connector 63 is not fixed to the housing 66 and the connector 63 is connected to the printed circuit board via the harness 65. 60 is only connected by soldering.
3 has the advantage that the joining direction is not restricted, but at least one of the connecting portion between the printed circuit board 60 and the harness 65 and the connecting portion between the connector 63 and the harness 65 has the harness 65 connected to the housing. The connection work by soldering or the like cannot be performed until after the hole 66 is passed through the hole 69, and the assembling man-hour is increased due to a decrease in the assembling workability.
The same problem as that shown in FIG. 8 remains in connection reliability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems. An acceleration sensor which has improved assembly workability to reduce the number of assembly steps and cost and to improve connection reliability. The purpose is to provide a structure.

[0009]

According to the present invention, a detection chip portion for detecting acceleration and other circuit components attached to the detection chip portion are housed in a housing and sealed with a lid, and external equipment is provided. In the acceleration sensor having a connector for connection with the flexible printed circuit board, the detection chip section and the circuit component are mounted on a flexible printed circuit board, and the terminal section of the connector also serving as a lid is connected to the flexible printed circuit board in advance. Wherein the connector is fixed to a flexible printed circuit board, the flexible printed circuit board is accommodated in a housing, and the connector is fitted and fixed to the housing as a lid.

[0010]

According to this structure, by adopting the flexible printed circuit board, the connector is mounted on the flexible printed circuit board together with the detection chip portion and other circuit components, and the flexible printed circuit board is folded and housed in the housing. At the same time, the connector can be fitted and fixed to the housing as a lid. Therefore, the number of steps for connecting the connector and the number of connection portions can be reduced as compared with the related art.

[0011]

1A and 1B are views showing an embodiment of the present invention. In a rectangular housing 2 of an acceleration sensor 1, a resin base plate 3 and a lid are also used. A connector 9 is accommodated, and a single flexible printed circuit board 5 shared by the base plate 3 and the upper surface of the connector 9 is bonded and fixed with an adhesive 6 as shown in FIG. And the base plate 3 is a screw 4
And the inside of the housing 2 is completely sealed by a connector 9 also serving as a lid.

On a portion of the flexible printed circuit board 5 located on the base plate 3, a detection chip portion 7 for detecting acceleration, which is made into one chip, and circuit components 8, 8,... Of other peripheral circuits are mounted. On the other hand,
A terminal portion 10 of the connector 9 is connected to a portion of the flexible printed circuit board 5 located on the connector 9 by soldering.

As described above with reference to FIG. 6, the detection chip section 7 includes a cantilever-shaped weight section 52 and a piezoresistive element type strain gauge section (detection section) 53 at the base thereof. By forming the signal processing circuit section 54 such as an amplifier circuit on the common silicon substrate 51, the detection section serving as the center of the acceleration sensor 1 has a known structure in which the detection section is substantially made into one chip.

In a portion of the base plate 3 corresponding to the lower side of the detection chip portion 7, a circular hole 12 which is sufficiently larger than the detection chip portion 7 as shown in FIG. 1B and FIG. And the detection chip portion 7
Is also mounted on the flexible printed circuit board 5 on which
Four circular holes 13 are provided outside the detection chip 7 so as to overlap the holes 12 on the base plate 3 side.
Are formed. Therefore, the detection chip unit 7
Is supported only by the bridge portion 14 left by forming the hole 12 on the base plate 3 side and the four holes 13 on the flexible printed board 5 side, so that excessive acceleration input to the acceleration sensor 1 itself is performed. When applied, the acceleration input is buffered by the self-elastic deformation of the bridge portion 14 itself in the acceleration input direction.

Depending on the degree of the required buffer effect, it is possible to form the holes 12 only on the base plate 3 side and eliminate the plurality of holes 13 on the flexible printed circuit board 5 side, but the buffer effect is enhanced. Above, the hole 12 on the base plate 3 side and the hole 1 on the flexible printed circuit board 5 side
It is desirable that 3 and 3 coexist.

Here, an example of an assembling procedure of the acceleration sensor 1 will be described. As shown in FIG. 1B, a detection chip portion 7 and a circuit are mounted on a flat flexible printed circuit board 5 which is formed in advance in an expanded shape. After mounting necessary parts such as the parts 8, 8... Or the connector 9 and soldering them, the base plate 3 and the connector 9 are respectively bonded to the flexible printed circuit board 5 with the adhesive 6 as shown in FIG. Fix it. Then, the flexible printed circuit board 5 to which the base plate 3 and the connector 9 are fixed is folded in half from the center in the longitudinal direction, and the outer peripheral end face of the base plate 3 is connected to the inner peripheral surface of the housing 2 as shown in FIG. Insert it into the inside of the housing 2 from the opening end face side and fix it with screws 4
Finally, the connector 9 is fitted and fixed to the housing 2. By assembling according to such a procedure, the bent portion 15 of the flexible printed circuit board 5 functions as a cushioning material in the acceleration input direction by its own elastic force in addition to the bridge portion 14.

Therefore, according to the structure of the present embodiment, the connector 9 is mounted and fixed on the flexible printed circuit board 5 in advance together with the detection chip section 7 and other circuit components 8, 8,. Since it is not necessary to connect the printed circuit board and the connector using the harness, the assembling operability can be improved by that much, and the number of assembling steps can be reduced and the cost can be reduced. Moreover, by directly connecting the flexible printed circuit board 5 and the terminal portion 10 of the connector 9, only one connection position is required between them, and the connection reliability against disconnection and the like is improved.

Further, according to the structure of the above-described embodiment, for example, when the acceleration sensor 1 is mounted on a vehicle and an excessive input in an acceleration direction to be detected acts, the bent portion 15 of the flexible printed board 5 is elastically deformed. Excessive input is absorbed and mitigated by exhibiting a buffering effect.
Further, as shown in FIG. 3, the most important detection chip portion 7 as the acceleration sensor 1 is supported only by the four bridge portions 14 of the flexible printed circuit board 5, so that the bridge portions 14 It elastically deforms to absorb and reduce excessive input. As a result, the detection chip section 7 can be protected from excessive input, and deformation or breakage at the base of the weight section 52 (see FIG. 6) can be prevented.

FIGS. 4 and 5 show another embodiment of the present invention. In this embodiment, a housing 21 or 31, a flexible printed circuit board 22, a connector 23 also serving as a lid, and the like are provided. In the structure of the acceleration sensor 1 fixed to the mounting surface 25 on the vehicle body side by the housing 24, the housing 21 or 31 having the same external appearance in both FIGS.
In FIG. 4, the acceleration detection direction by the detection unit 58 including the detection chip unit 55 similar to that in FIG. 7 is set in the vertical direction (Z direction) after using the common flexible printed circuit board 22 and the connector 23. On the other hand, in FIG. 5, the acceleration detection direction by the detection unit 58 is changed to the horizontal direction (Y
Direction).

In any of the structures shown in FIGS. 4 and 5, the connector 23 is mounted on the flat flexible printed circuit board 22 together with the detection unit 58 and other circuit components 25, 25. After being connected to the flexible printed circuit board 22 by soldering, the base plate 27 is bonded and fixed to the flexible printed circuit board 22 on the back side of the detection unit 58. Then, the flexible printed circuit board 22 is bent and inserted into the housing 21 or 31, and finally the connector 23 also serving as a lid is fitted and fixed to the housing 21 or 31, whereby the inside of the housing 21 or 31 is sealed.

In this embodiment, the same operation and effects as those of the above-described first embodiment can be obtained. Thus, there is an advantage that the acceleration detection direction (direction of the detection unit) of the detection unit 58 can be arbitrarily set.

[0022]

As described above, according to the present invention, the detection chip portion and the circuit components attached to the detection chip portion are mounted on the flexible printed circuit board, and the terminal portion of the connector also serving as the cover is previously mounted on the flexible printed circuit board. The connector is fixed to the flexible printed circuit board by connecting, and the flexible printed circuit board is housed in the housing, and then the connector is fitted and fixed to the housing as a lid, so that the connector is mounted together with the detection chip and circuit components. It can be mounted on the flexible printed circuit board in advance, eliminating the need to connect the printed circuit board and the connector via a harness as in the past, thus improving assembly workability and reducing assembly man-hours and cost. Down, flexible printed circuit board and connector Connection reliability against breakage and the like by the connection part is only one location between the well has the effect of greatly improved.

[Brief description of the drawings]

1A and 1B are views showing an embodiment of the present invention, wherein FIG. 1A is a cross-sectional view of an acceleration sensor, and FIG. 1B is a development view of only the flexible printed circuit board of FIG.

FIG. 2 is a sectional view taken along line aa of FIG.

FIG. 3 is an enlarged perspective view of a main part of FIG.

FIG. 4 is a sectional view of an acceleration sensor according to another embodiment of the present invention.

FIG. 5 is a sectional view of an acceleration sensor showing another embodiment of the present invention.

FIG. 6 is an enlarged perspective view of a main part of a detection chip portion of a semiconductor type acceleration sensor.

FIG. 7 is a cross-sectional view of a detection unit configured to detect acceleration, which is configured around the detection chip unit shown in FIG. 6;

8 is a sectional view of a conventional acceleration sensor including the detection unit shown in FIG.

9 is an explanatory plan view of only the printed circuit board of the acceleration sensor shown in FIG. 8;

FIG. 10 is a sectional view showing another example of a conventional acceleration sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Acceleration sensor 2 ... Housing 5 ... Flexible printed circuit board 7 ... Detection chip part 8 ... Circuit component 9 ... Connector 10 ... Terminal part 12,13 ... Hole 14 ... Bridge part 21 ... Housing 22 ... Flexible printed circuit board 23 ... Connector 26 ... Terminal 31: Housing 58: Detection unit

Claims (1)

(57) [Scope of request for utility model registration] A detection chip for detecting acceleration and other circuit components attached to the detection chip are housed in a housing and sealed with a lid, and a connector for connection to an external device is provided. In the acceleration sensor, the connector is attached to the flexible printed circuit board by mounting the detection chip section and the circuit component on the flexible printed circuit board and connecting the terminal section of the connector also serving as a lid to the flexible printed circuit board in advance. An acceleration sensor, wherein: the flexible printed circuit board is accommodated in a housing, and the connector is fitted and fixed to the housing with the connector as a lid.