JPH04110977U - Acceleration sensor with self-diagnosis function - Google Patents

Abstract

(57) [Summary] [Purpose] Provide a self-diagnosis function that checks the sensor status based on the sensor output when the cantilever is vibrated using magnetic force or electrostatic force. [Structure] The cantilever 4 is provided with a vibration generating means 16 that applies vibrations due to magnetic force or electrostatic force, and the cantilever is vibrated periodically or when the power is turned on, and the sensor output corresponding to the vibration at this time and the sensor when the sensor is in normal operation are generated. Diagnose normal operation of the sensor by comparing with the output.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention uses magnetic force or electrostatic force to vibrate the cantilever, and the sensor is activated. This invention relates to an acceleration sensor that self-diagnoses whether the

0002

[Conventional technology]

Acceleration sensors with cantilevers may fail due to excessive impact or fatigue. It self-diagnoses whether or not the unit is malfunctioning each time it is used (every time the power is turned on), and the There is a need to improve reliability. Conventionally, cantilever bending was detected A wiring is provided on the cantilever for indirect self-diagnosis due to disconnection of this wiring, etc. was being carried out. For this reason, it is possible to diagnose whether the cantilever is correct or abnormal, but if the sensor is It is not possible to diagnose whether it is always working or not. Against this background, periodic or Acceleration sensor with self-diagnosis function that checks sensor function when power is turned on. is proposed.

0003

[Problem that the idea aims to solve]

However, as a self-diagnosis method, a shock is applied to the sensor itself using a solenoid. The shock applied to the sensor varies depending on the characteristics of the moving parts. In addition, it is difficult to miniaturize the moving parts, and it is difficult to diagnose sensor deterioration. There was a problem. The object of the present invention is to vibrate a cantilever using magnetic force or electrostatic force. Acceleration equipped with a self-diagnosis function that checks the sensor status based on the sensor output. An object of the present invention is to provide a degree sensor.

0004

[Means to solve the problem]

In order to achieve the above purpose, the acceleration sensor with self-diagnosis function of the present invention is Diagnose normal operation based on sensor output when forced vibration is applied to the cantilever In an acceleration sensor having a function, the cantilever is subjected to magnetic force or electrostatic force. The device is characterized in that it is provided with a vibration generating means for applying vibration according to the amount of vibration.

[Effect]

Apply magnetic or electrostatic force to the cantilever periodically or at power-on. When the sensor is vibrated, an electrical signal corresponding to the vibration is output from the sensor. This center The quality of the sensor can be determined by comparing the sensor output with the sensor output when the sensor is operating normally. make a judgment.

[0005]

【Example】

A first embodiment of the present invention will be described. Figure 1A shows the appearance of the acceleration sensor before the cover is sealed. It is shown. FIG. 1B shows the AA cross section of FIG. 1A after the cover is sealed. The metal stem 1 is made of a magnetic material such as permalloy. stem A protrusion 2 with a flat upper surface is formed in a part of the protrusion 1, and a stand is mounted on the upper surface of this protrusion 2. An acceleration sensor chip 5 having a cantilever 4 with a seat 3 interposed therebetween and a stem 1 A hybrid integrated circuit (HIC) substrate 6 is fixed to each surface by adhesive. Ru. The output is fixed by a hermetic seal 8a in close proximity to this HIC board 6. A pin 8 is arranged. The HIC substrate 6 is made of a ceramic base such as alumina. This ceramic board has amplifier circuits, temperature compensation circuits, sensitivity adjustment circuits, etc. Which processing section is provided? The processing section is connected to the output pin 8 by a wire 7, A signal is taken out from this output pin 8. Connect wire 7 using Al wire or Au wire. It is done by earboding. Pedestal 3 is made of silicon, glass, metal, etc. The portion where the cantilever 4 is located is open. In addition, 9 is made of metal A protective cover that is hermetically welded to stem 1.

[0006] The acceleration sensor chip 5 uses a silicon wafer and is manufactured using semiconductor manufacturing technology as shown in FIG. A cantilever 4 with a cantilevered structure shown in Fig. 4 causes stress and strain due to vibration of this cantilever Semiconductor strain gauge 1 placed at the location where strain occurs (at the base of the cantilever) 0 and an electric signal in response to vibration due to resistance value change of this semiconductor strain gauge 10 An IC section is created that performs electrical processing such as amplification, and the signal from this IC section is sent to the bond. It is sent to the HIC board 6 through the ring pad 11 and the wire 12. The cantilever 4 extends from the IC section side shown in FIG. 2B by anisotropic etching. A thin part 13 and a thick part 14 continuous to this thin part are formed, and the thick part at the tip of the thin part 13 is formed. The portion 14 constitutes a weight portion. On the surface of the weight part located on the pedestal side, A magnetic body 15 is formed (by vapor deposition, plating, or Adhesion of magnetic material). As shown in FIG. 3, the coil assembly 16 is a coil box with a through hole 17 in the center. A magnet wire 19 is wound around the bottle 18, and this wire 19 is attached to the bobbin 18. from the pad 21 wired to this terminal to the HIC board 6. Continued. As shown in FIG. 1B, this coil assy 16 extends over the protrusion 2 of the stem 1. The coil assembly 16 is attached by being inserted into the through hole 17 of the coil assembly 16. in this way By arranging the coil assembly 16, the magnetic flux is directed to the coil in the open part 3a of the pedestal 3. It can act on the magnetic body 15 of the bench lever.

[0007] Next, the operation of the acceleration sensor will be explained. Magnet Y of coil assembly 16 For example, pulsed electricity is applied to the wire 19. Then, the switch will turn on only during this power-on time. The protrusion 2 of the stem 1 acts as the iron core of the coil 19, and serves as the weight of the acceleration sensor chip 5. Attracts the magnetic body 15 provided in the portion 14. After that, the power to coil 19 is cut off. At this time, the cantilever 4 loses the electromagnetic action of the coil 19 and becomes free. The amplitude will be as if acceleration were applied from the outside. The application in this vibration state Process and diagnose the output signal of the speed sensor. This diagnostic method includes, for example, external The device stores an output signal similar to the above in the initial state, and combines this signal with the detected one. Diagnose whether the sensor is normal or not by comparing the detected signals. See you again The disconnection timing is configured to be performed periodically or when the power is turned on.

[0008] A second embodiment of the present invention will be described. Figure 4A shows the appearance of the acceleration sensor before the cover is sealed. It is shown. FIG. 4B shows the CC cross section of FIG. 4A after the cover is sealed. Note that the same reference numerals are given to the same members as in the first embodiment, and the explanation thereof will be omitted.

[0009] The cantilever 51 of the acceleration sensor chip 50 is located on the metal stem 1. For example, place a core 22 of permalloy or ferrite slightly on the surface side of the stem 1. Make it protrude and extend it to the extent that the coil assy 30 is fitted on the back side of the stem 1. It is fixed by a hermetic seal 31 in this state. As shown in FIGS. 5A and 5B, the acceleration sensor chip 50 is made of, for example, a permallo A cantilever 51 having a cantilever structure is provided by removing a part of the magnetic metal substrate 52 such as A, An insulating layer 53 is formed on the surface of this magnetic substrate by P-CVD or the like, and the upper surface of this insulating layer 53 is A thin film strain gauge 54 is constructed at the base of the cantilever by sputtering, vapor deposition, etc. This is what I did.

0010 As shown in FIG. 6, the coil assembly 30 includes a coil bobbin on a printed circuit board 32. 33 is fixed, and the coil bobbin 33 is placed on the stem 1 side. The coil bobbin 33 is fixed to the stem 1 by adhesive. And ma The net wire 34 is connected to the HIC board via a terminal 35 provided on the printed circuit board 32. Connected to plate 6. In this embodiment, a magnetic field is generated in the core by passing a current through the magnet wire 34. Therefore, the cantilever 4, which is a magnetic material, can be vibrated as in the first embodiment. can. Note that if the cantilever is configured so that force can be applied magnetically, the cantilever The base material of the chilever may be semiconductor, ceramic, or metal. Also a strain game The film can be made of a semiconductor, a thin film, a thick film, or the like.

[0011] A third embodiment of the present invention will be described. Figure 7A shows the appearance of the acceleration sensor chip and Figure 7B shows the appearance of an acceleration sensor with a fixed stopper equipped with a counter electrode. Ru. The acceleration sensor chip 60 includes a cantilever 4, a semiconductor strain gauge 10, and and an electrode 40, using the same semiconductor manufacturing technology as the first embodiment using a silicon wafer. made by. A semiconductor strain gauge 10 is wired to a pad 11, and this pad is connected to the HIC substrate 6 through a wire, and the electrode 40 connects the pad 41 to the HIC substrate 6 through a wire. It is connected to the HIC board 6 through it, and a voltage is applied during self-diagnosis. This cantilever A stopper 42 is arranged opposite the bar 4. The stopper 42 is shown in FIG. 8A and As shown in 8B, the etched surface 43, leaving both sides, is coated with vapor deposition, sputtering, etc. A metal electrode 44 (counter electrode) is formed, and a voltage is applied to the counter electrode 44 on the opposite side. A bonding pad 45 for applying the voltage is formed. Both sides of the stopper 42 As shown in FIG. The counter electrode 44 of the stopper 42 is placed at a certain distance from the electrode 40 of the cantilever 4. Set it up and confront it. In addition, 46 is a pedestal for fixing the acceleration sensor to the stem 1. It is.

0012 Next, the operation of the above embodiment will be explained. When the power is turned on, both electrodes 40 and 44 have the same polarity. When a voltage is applied, the cantilever 4 is separated from the opposing electrode due to electrostatic reaction force for the duration of the voltage application. It deflects in the direction of moving away (arrow a in Figure 8). On the other hand, with voltages of different polarity, electrostatic Attracted by gravity. If you stop applying voltage from this state, the cantilever 4 vibrates at its own resonant frequency. Change in the output of the strain gauge 10 due to this vibration By detecting this, it is possible to diagnose deterioration of the acceleration sensor. In this example, a semiconductor acceleration sensor was described, but the What type of acceleration sensor can be used if the structure has electrodes on each part facing the It can also be applied to sensors.

[0013]

[Effect of the idea]

As mentioned above, according to the present invention, the cantilever bead is formed by magnetism or static electricity. Since the force is applied to the sensor, there are fewer moving parts compared to applying impact to the sensor with a solenoid. Because there is no becomes possible.

[Brief explanation of drawings]

1 is an acceleration sensor showing a first embodiment of the present invention, FIG. 1A is an external view of the sensor, and FIG. 1B is a cross-sectional view taken along line AA in FIG. 1A.

FIG. 2 is an enlarged view of the acceleration sensor chip, with FIG. 2A being a plan view and FIG. 2B being a cross-sectional view taken along line BB in FIG. 2A.

FIG. 3 is a perspective view of the coil assembly.

4 is an acceleration sensor showing a second embodiment of the present invention, FIG. 4A is an external view of the sensor, and FIG. 4B is a sectional view taken along line CC in FIG. 4A.

5 is an enlarged view of the acceleration sensor chip, FIG. 5A is a plan view, and FIG. 5B is a cross-sectional view taken along line DD in FIG. 5A.

FIG. 6 is a perspective view of the coil assembly.

7 is an enlarged view of a chip constituting an acceleration sensor according to a third embodiment of the present invention, FIG. 7A is a plan view, and FIG. 7B is a plan view when a stopper is attached.

8 is a cross-sectional view of the chip shown in FIG. 7, and FIG. 8A is a cross-sectional view of the chip shown in FIG.
8B is a cross-sectional view taken along line FF.

[Explanation of symbols]

1 Metal stem 3 pedestal 4 Cantilever 5, 50, 60 acceleration sensor chip 6 HIC board 8 Output pin 10 Strain gauge 15 Magnetic material 16,30 Coil assy 40 electrode 42 Stopper 44 Counter electrode

Claims (1)

[Scope of utility model registration request] [Claim 1] An acceleration sensor having a function of diagnosing normal operation based on a sensor output when forced vibration is applied to a cantilever, comprising a vibration generating means for applying vibration to the cantilever by magnetic force or electrostatic force. An acceleration sensor having a self-diagnosis function.