JP3528834B2 - 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, and more particularly to an acceleration sensor suitable for automobiles.

[0002]

2. Description of the Related Art As a conventional device, for example, Japanese Patent Publication No. 4-5
There is an acceleration sensor formed by laminating glass or silicon as described in Japanese Patent No. 5267 and Japanese Unexamined Patent Publication No. 3-134570.

[0003]

In the conventional acceleration sensor, the detected acceleration direction is perpendicular to the mounting surface of the acceleration sensor, and since it uses the metal stem and the metal cover, it has a large weight. This has caused various restrictions in mounting the system equipped with this acceleration sensor. For example, in an airbag system, the control unit of the airbag system is usually mounted in the horizontal direction of the vehicle, but the detection direction of acceleration to be detected is the front-back direction of the vehicle. As described above, the direction of acceleration detected by the acceleration sensor is perpendicular to the mounting surface of the control unit, so there is a mounting problem in applications such as airbags.
Also, because the acceleration sensor itself is heavy, it easily resonates mechanically (mechanical resonance causes errors in acceleration detection), and to reduce this effect, it is firmly fixed to the side of the control unit case with screws. Had to do. In other words, the above-mentioned conventional technique does not consider the ease of mounting when the acceleration sensor is applied to an application such as an airbag.

An object of the present invention is to detect the direction of acceleration in the print mode.
Another object of the present invention is to provide an acceleration sensor that is parallel to the printed circuit board and can be surface-mounted on the printed circuit board .

[0005]

[Means for Solving the Problems] The above object is to respond to acceleration.
A mass part that displaces and a beam part that supports the mass part
And an information of the acceleration detection element
To generate an electric signal in response to the acceleration
A circuit, the acceleration detecting element, and the electronic circuit are installed.
And the acceleration detection element bonded to the substrate
And an airtight sealing body that hermetically seals the electronic circuit inside and
And a cover that is electrically connected to the electronic circuit,
The airtight seal from the substrate surface inside the airtight seal
A first conductor extending on the surface of the substrate outside the body.
Body pattern and the cover surface outside the hermetic seal
A second conductor pattern provided on the first conductor pattern,
Solder the conductor pattern and the second conductor pattern.
It is fixed to the printed board and the acceleration detection element
Acceleration parallel to the lint plate is detected and measured according to the acceleration.
Output an electric signal to the printed board through the solder
It is achieved by an acceleration sensor .

[0006]

[0007]

[Function] Even if the acceleration detection element is arranged inside the acceleration sensor so that the acceleration direction detected by the acceleration sensor is parallel to the mounting surface of the acceleration sensor and is mounted on the board surface of the control unit, the detected acceleration direction is horizontal to the board. It is easy to implement because it is oriented. Further, by sealing the acceleration detecting element airtightly by the substrate on which the acceleration detecting element is arranged and the cover arranged opposite to the substrate, the metal system is omitted and the weight is reduced, such as a printed board. Resonance can be prevented even if it is fixed to a material having low mechanical rigidity.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An acceleration sensor according to a first embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a sectional view of an acceleration sensor according to the first embodiment. The acceleration sensor includes an acceleration detection element 102 that detects acceleration in the horizontal direction of the ceramic substrate 109, and an electronic circuit 10 that outputs an electric signal corresponding to the acceleration from information of the acceleration detection element 102.
3 is arranged and the ceramic cover 101 is adhered to the ceramic substrate 109 to hermetically seal the acceleration detection element 102 and the electronic circuit 103. Wiring between the electronic circuit 103 and the outside was performed by the conductor patterns 104 and 106 printed on the ceramic substrate 109.
In addition, the conductor patterns 104 and 106 are printed boards 108.
It is also used as a solder pad for fixing and wiring, and as shown in FIG. 1, it can be fixed and wired to the printed board 108 of the control unit section in the airbag system by the solder 105, 107.

Next, an example of the acceleration detecting element formed by laminating glass or silicon will be described with reference to FIG. FIG. 2 is a sectional structure of the acceleration detecting element. The present acceleration detecting element is composed of glass plates 204, 208 and a silicon plate 206, and a movable electrode 202 supported by a beam 210 and moving according to acceleration is arranged on the central silicon plate 206. Further, the fixed electrodes 201, 2 are provided on the upper and lower glass plates 204, 208 so as to face the movable electrode 202.
09 are arranged, and fixed electrodes 201, 209 and movable electrode 202 are pads 203, 207, 205, respectively.
It is connected to and can be electrically connected to the outside. The movable electrode 202 is a mass having a weight function, and displaces the beam 210 according to acceleration. Therefore, when the acceleration in the detected acceleration direction acts on the present acceleration detection element, the movable electrode 202 moves in the detected acceleration direction. When the movable electrode 202 moves in the detected acceleration direction, the capacitance between the movable electrode 202 and the fixed electrode 201 and the movable electrode 2
02 and the fixed electrode 209 change in capacitance. That is, an output according to the acceleration is obtained by detecting the change in the electrostatic capacitance.

Next, a mounting structure type A of the acceleration detecting element according to the first embodiment of the present invention will be described with reference to FIG.
The acceleration detecting element 102 used in FIG. 3 is the acceleration detecting element described in FIG. First, the acceleration detection element 1
02 is fixed to the ceramic substrate 109 by increasing the length of the acceleration detecting element 102 in the stacking direction in order to obtain parallelism and adhesive strength of the acceleration detecting element 102.
The area of the adhesion surface with 9 was increased, and adhesion was performed using silicon rubber 504. In addition, the surface of the beam 210 farthest from the bonded portion is selected as the bonded surface to reduce the influence of the stress acting from the ceramic substrate 109 on the acceleration detecting element 102. Next, the wiring from the acceleration detection element 102 is connected to the gold wires 501, 50 from the pads 203, 205, 207.
2, 503 was wire-bonded.

Next, a mounting structure type B of the acceleration detecting element according to the first embodiment of the present invention will be described with reference to FIG.
First, the structure of the acceleration detecting element shown in FIG. 4 will be described.
This acceleration detecting element is composed of silicon plates 802, 805, 80.
8 and glass plates 803 and 806, and a movable electrode 81 that moves in response to acceleration is provided on the central silicon plate 805.
0 and a beam 809 supporting the movable electrode 810 are arranged. In addition, the movable electrodes 8 are formed on the glass layers 803 and 806.
Fixed electrodes 811 and 812 are arranged so as to face 10. Therefore, when acceleration acts on the present acceleration detection element, the movable electrode 810 moves, and the movable electrode 810 and the fixed electrode 811 move.
The electrostatic capacitance between them and the electrostatic capacitance between the movable electrode 810 and the fixed electrode 812 change. An output according to the acceleration can be obtained by detecting the change in the electrostatic capacitance. Also,
Wiring from the fixed electrodes 811 and 812 to the outside is provided with pads 801 and 807 via silicon plates 802 and 808, respectively.
The wiring from the movable electrode 810 to the outside is connected to the outside by the pad 804. Further, the fixing to the ceramic substrate 109 was performed by using silicone rubber 813 as in the first embodiment. At this time, as in the first embodiment, the adhesive strength is increased by increasing the length of the acceleration detecting element in the stacking direction and expanding the adhesive area, and the ceramic substrate 1 is selected by selecting the adhesive surface where the beam 809 is farthest from the adhesive portion.
From 09, the effect of stress acting on the acceleration detecting element was reduced. Further, the wiring from the acceleration detecting element is the pad 801,
It was performed by wire-bonding a gold wire to 804 and 807.

Next, a mounting structure type C of the acceleration detecting element according to the first embodiment of the present invention will be described with reference to FIG.
The acceleration detecting element in this mounting method is almost the same as that shown in FIG.

Pads 801, 804, 807 of the silicon plates 802, 805, 808 are provided below the acceleration detecting element as shown in the figure, and solder balls 814, 815, 8 are provided.
This is a method of adhering and fixing to the ceramic substrate 109 via 16. In this case, electrical connection with a conductor pattern (not shown in the figure) formed on the ceramic substrate 109 is achieved without a wire bonding operation for a gold wire or the like.

Next, a mounting structure type D of the acceleration detecting element according to the first embodiment of the present invention will be described with reference to FIG.
This mounting structure is the same as the mounting method of the acceleration detecting element shown in FIG. 3 and the structure and fixing method of the detecting element 102, but the wiring method is partially changed. That is, from the pads 203, 205, 207 to the gold wires 501, 502, 50
3 is a mounting method in which 3 is directly connected to an integrated circuit 604 in which electronic circuits are integrated by wire bonding.

Next, a mounting structure type E of the acceleration detecting element according to the first embodiment of the present invention will be described with reference to FIG.
The acceleration detecting element used in FIG. 7 is the acceleration detecting element described in FIG. First, the acceleration detection element is fixed to the ceramic substrate 109 by bonding the acceleration detection element 102 to the ceramic substrate 907 with silicon rubber 906,
Conductor patterns 904, 9 applied to the ceramic substrate 907
08 to the ceramic substrate 109 solder 905, 909
Through the ceramic substrate 907 to the ceramic substrate 109
Fixed to. Further, the wiring from the detection degree detection element 102 to the ceramic substrate 109 is connected to the pads 203, 205, 207.
From the gold wires 901, 902, 903 to the conductor pattern 9
No. 04 was wire-bonded to the ceramic substrate 109 with solder 905 from the conductor pattern 904. The conductor pattern 904 and the solder 90
It goes without saying that there are three 5 each.

Next, a mounting structure type F of the acceleration detecting element according to the first embodiment of the present invention will be described with reference to FIG.
The acceleration detecting element used in FIG. 8 is the acceleration detecting element 102 described in FIG. In this mounting method, a vertical member 1005 is provided on the ceramic substrate 109.
The acceleration detecting element 102 is adhered to 05 by a silicone rubber 1004, and the pads 203, 205, 2 are used for wiring.
It was achieved by wiring the gold wires 1001, 1002, 1003 from 07 to the vertical member 1005. In this mounting method, the vertical member 1005 is provided on the ceramic substrate 109 to improve the vertical accuracy of attachment of the acceleration detection element 102.

Next, an acceleration sensor according to a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a sectional view of the acceleration sensor according to the second embodiment. This acceleration sensor is an electronic circuit 1 that outputs an electric signal according to the acceleration from the information of the acceleration detection element 1103 and the acceleration detection element 1103 that detects the acceleration in the detected acceleration direction on the ceramic substrate 1101.
By arranging 104 and adhering the ceramic cover 1102 to the ceramic substrate 1101, the acceleration detecting element 1
103 and the electronic circuit 1104 are hermetically sealed. Wiring between the electronic circuit 1104 and the outside was performed by a conductor pattern 1105 printed on the ceramic substrate 1101. Further, the conductor pattern 1105 and the conductor pattern 1107 of the ceramic cover 1102 are the printed circuit board 1
It is also used as a solder pad for fixing to 08, and as shown in FIG. 9, it can be fixed to the printed board 108 by solder 1106 and 1108.

Next, an acceleration sensor according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 10 shows the third
10 is a perspective view of an acceleration sensor according to the embodiment of FIG.
FIG. 9 is a sectional view taken along line AA ′ in FIG. This acceleration sensor includes an acceleration detection element 1301 for detecting acceleration in the detected acceleration direction on the ceramic substrate 1207, and an electronic circuit 130 for outputting an electric signal corresponding to the acceleration from the information of the acceleration detection element 1301.
2 is arranged and the ceramic cover 1201 is adhered to the ceramic substrate 1207 to obtain the acceleration detection element 130.
1 and the electronic circuit 1302 are hermetically sealed.
The acceleration sensor is mounted on the ceramic substrate 120.
It can be attached to a control unit such as an air bag by using the attachment holes 1202 and 1203 arranged in 7.

Further, the leads 1204, 1205, 120
6 is attached to the ceramic substrate 1207 to facilitate wiring with an external device. This embodiment is an effective method when the control unit of the airbag system is mounted in the gravity direction.

Next, an acceleration sensor according to a fourth embodiment of the present invention will be described with reference to FIG. FIG. 12 is a sectional view of the acceleration sensor according to the fourth embodiment. This acceleration sensor is an electronic circuit 1 that outputs an electric signal corresponding to the acceleration from the information of the acceleration detection element 1402 and the acceleration detection element 1402 that detects the acceleration in the detected acceleration direction on the ceramic substrate 1405.
By disposing 403 and adhering the metal cover 1401 to the ceramic substrate 1405, the acceleration detecting element 1402
The electronic circuit 1403 is hermetically sealed. Further, the acceleration sensor is attached to the control unit of the airbag system by attaching holes 1404 and 1406 arranged in the metal cover 1401. This embodiment is also an effective method when the control unit itself is mounted on the vehicle so that it is oriented in the direction of gravity of the earth.

Next, an acceleration sensor according to a fifth embodiment of the present invention will be described with reference to FIG. FIG. 13 is a sectional view of the acceleration sensor according to the fifth embodiment. This acceleration sensor is an electronic circuit 1 that outputs an electric signal corresponding to the acceleration from the information of the acceleration detection element 1502 and the acceleration detection element 1502 that detect the acceleration in the detected acceleration direction on the ceramic substrate 1509.
503 is arranged and the ceramic cover 1501 is adhered to the ceramic substrate 1509 to obtain the acceleration detection element 1
502 and electronic circuit 1503 are hermetically sealed. The acceleration sensor is mounted on the ceramic substrate 1
By using the conductor patterns 1504 and 1506 applied to the printed wiring board 509, the printed circuit board 150 is soldered by the solder 1505 and 1507.
It can be fixed to 8. The conductor patterns 1504 and 1506 can also be used as wiring means from the electronic circuit 1503 to the printed board 1508. In the acceleration sensor of this embodiment, the mounting surface of the acceleration sensor and the detected acceleration direction are vertical. Therefore, it is effective as an acceleration sensor that can be surface-mounted on the system for mounting the control unit of the airbag system in the direction of gravity or for a system other than the airbag, such as a system for controlling the vibration of the vehicle.

Next, a three-axis acceleration sensor according to the present invention will be described with reference to FIG. This triaxial acceleration sensor has a ceramic substrate 1604, acceleration detecting elements 1601, 1602, and
The 1603 is arranged so that the detected acceleration directions are orthogonal to each other. Although not shown in this figure, an electronic circuit and a ceramic cover are attached to this triaxial acceleration sensor. That is, the acceleration detection elements 1601, 160
2, 1603 detect the acceleration of each of the three orthogonal axes, and the electronic circuit detects each acceleration detection element 160.
By converting the information from 1, 1602, 1603 into an electric signal, the triaxial acceleration is detected. The acceleration detecting elements are bonded and fixed to the ceramic substrate 1604 and electrically connected by the method described above.

Next, an air bag system using the acceleration sensor of the present invention will be described with reference to FIGS. FIG. 15 is a sectional view of a control unit of an airbag system using this acceleration sensor, and FIG. 16 is a configuration of the airbag system. The airbag system is composed of a case 1701 accommodating the airbag 1701, an acceleration sensor 1703, and a printed board 1704 on which an electronic circuit 1702 is mounted. In this airbag system, the acceleration sensor 17
03 is surface-mounted on the printed board 1704. Further, the fixed position of the acceleration sensor 1703 is arranged near the fixed part of the printed circuit board, and the printed circuit board 17
The effect of 04 resonance is reduced.

The schematic structure of the airbag system will be described with reference to FIG. This airbag system calculates the size of a collision from the outputs of an acceleration sensor 1801 and an acceleration sensor 1801 that detect the collision acceleration of a vehicle, and determines whether or not the airbag is deployed.
02, a drive circuit 1803 for amplifying the output of the microcomputer 1802 and driving the airbag. Although the capacitance type acceleration sensor is described in the present embodiment, it is also applicable to a strain gauge type or a piezoelectric type acceleration sensor. For example, considering a strain gauge type acceleration sensor in FIG. 2, the movable electrode 202 functions only as a weight, and the strain gauge formed on the beam 210 detects acceleration to apply the above-described mounting method in almost the same manner. It is possible.

[0025]

According to the present invention, the direction of detected acceleration is pre-set.
It is possible to configure an acceleration sensor that is parallel to the printed circuit board and can be surface-mounted on the printed board .

[Brief description of drawings]

FIG. 1 is a sectional view of an acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a sectional structural view of an example of an acceleration detecting element applied to the present invention.

FIG. 3 is a mounting structure type A of the acceleration detecting element according to the first embodiment of the present invention.

FIG. 4 is a mounting structure type B of the acceleration detection element according to the first embodiment of the present invention.

FIG. 5 is a mounting structure type C of the acceleration detecting element according to the first embodiment of the present invention.

FIG. 6 is a mounting structure type D of the acceleration detecting element according to the first embodiment of the present invention.

FIG. 7 is a mounting structure type E of the acceleration detecting element according to the first embodiment of the present invention.

FIG. 8 is a mounting structure type F of the acceleration detecting element according to the first embodiment of the present invention.

FIG. 9 is a sectional view of an acceleration sensor according to a second embodiment of the present invention.

FIG. 10 is a perspective view of an acceleration sensor according to a third embodiment of the present invention.

11 is a cross-sectional view taken along the line AA ′ in FIG.

FIG. 12 is a sectional view of an acceleration sensor according to a fourth embodiment of the present invention.

FIG. 13 is a sectional view of an acceleration sensor according to a fifth embodiment of the present invention.

FIG. 14 is a diagram showing a triaxial acceleration sensor according to the present invention.

FIG. 15 is a sectional view of a control unit of an airbag system using the acceleration sensor of the present invention.

FIG. 16 is a configuration diagram of an airbag system.

[Explanation of symbols]

101, 1102, 1201, 1501 ... Ceramic cover, 102, 302, 1103, 1301, 140
2, 1502, 1601, 1602, 1603 ... Acceleration detecting element, 103, 303, 1104, 1302, 14
03, 1503, 1702 ... Electronic circuit, 104, 10
6,904,908,1105,1107,1504
1506 ... Conductor pattern, 105, 107, 905, 9
09, 1106, 1108, 1505, 1507 ... Solder, 1
08,404,1508,1704 ... Printed board, 10
9,305,907,1101,1207,1405
1509, 1604 ... Ceramic substrate, 201, 209, 8
11, 812 ... Fixed electrode, 202, 810 ... Movable electrode, 2
03, 205, 207, 801, 804, 807 ... Pad, 204, 208, 803, 806 ... Glass plate, 20
6,802,805,808 ... Silicon plate, 210,8
09 ... Beam, 304, 307, 1202, 1203
1404, 1406 ... Mounting hole, 306 ... Metal stem,
401, 1701 ... Case, 402, 406 ... Screw, 40
3, 1703 ... Acceleration sensor, 405 ... Lead wire, 50
1,502,503,601,602,603,90
1,902,903,1001,1002,1003 ...
Gold wire, 504, 813, 906, 1004 ... Silicon rubber, 604 ... Integrated circuit, 814, 815, 816 ... Solder ball, 1005 ... Vertical member, 1204, 1205, 1
206 ... Lead, 1401 ... Metal cover, 1802 ... Microcomputer, 1803 ... Drive circuit.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-312006 (JP, A) JP-A-5-340963 (JP, A) JP-A-5-288768 (JP, A) Actual Kaihei 5- 87569 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01P 15/125 G01P 15/08

Claims (3)

(57) [Claims] 1. A mass part that displaces in response to acceleration and the mass.
An acceleration detection element having a beam section that supports the section, an electronic circuit that inputs information of the acceleration detection element and generates an electric signal according to the acceleration, the acceleration detection element, and the electronic circuit are installed. Board
And a cover forming an airtight sealing body which is adhered to the substrate and hermetically seals the acceleration detection element and the electronic circuit inside.
Chromatography and the electronic circuitry and is electrically connected to, among the hermetic seal body
The substrate outside the hermetically sealed body from the substrate surface on the side
A first conductor pattern provided extending to the surface , and a first conductor pattern provided on the cover surface outside the hermetically sealed body.
Two conductor patterns, and the first conductor pattern and the second conductor pattern
It is fixed to the printed board by soldering, and
Detects the acceleration parallel to the printed board,
Degree of electrical signal via the solder to the printed board
Accelerometer that outputs to . 2. The acceleration sensor according to claim 1, wherein the substrate and the cover are made of a ceramic material. 3. A claim 1 or 2, the acceleration sensor, wherein the acceleration detecting element is a capacitive or strain gauge type or piezoelectric type.