JP2011137824A - Mechanical quantity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a movable part from excessively displaced by an excessive mechanical quantity, concerning a mechanical quantity sensor that has the movable part displaced by application of a mechanical quantity, and detects the mechanical quantity by the amount of displacement of the movable part. <P>SOLUTION: The mechanical quantity includes an actuator 40 that applies acceleration to the movable part 31 in a direction opposite to the direction in which the movable part 31 is displaced by a mechanical quantity. The movable part 31 is configured as an angular velocity detection element which is driven to vibrate in one direction and which, when an angular velocity is applied, detects vibration by coriolis force applied in a direction perpendicular to the direction in which the angular velocity detection element is driven to vibrate. The actuator 40 applies acceleration to the movable part 31 in a direction opposite to the direction in which the movable part 31 is displaced by a mechanical quantity along the direction in which the angular velocity detection element is driven to vibrate. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mechanical quantity sensor having a movable part that is displaced by a mechanical quantity.

  Conventionally, as this type of mechanical quantity sensor, a sensor having a movable part that is displaced by application of a mechanical quantity and detecting an applied mechanical quantity according to the displacement of the movable part has been proposed. Specifically, acceleration sensors as described in Patent Document 1 and Patent Document 2 have been proposed.

  In such an acceleration sensor, the movable part is an acceleration detecting element that is displaced in the direction in which the acceleration is applied when acceleration as a mechanical quantity is applied. In general, a capacitance is formed between the movable portion and the fixed portion disposed opposite to the movable portion, and acceleration is detected based on the change in the capacitance between the movable portion and the fixed portion due to the displacement of the movable portion. Is to do.

JP 2003-21647 A JP 9-2111020 A

  However, in the mechanical quantity sensor as described above, when an excessive mechanical quantity such as an impact is applied from the outside, the movable part also causes an excessive displacement and collides with a part facing the movable part to move the movable part. The part may be damaged, or a sticking phenomenon may occur in which the movable part adheres to the other part.

  In particular, in this type of mechanical quantity sensor, in order to improve the sensor characteristics, a spring that supports the movable part is made soft in order to increase sensitivity. For this reason, the structural strength is reduced, and an excessive displacement of the movable portion is likely to occur, and the above-described problem of the excessive displacement of the movable portion is remarkable.

  The present invention has been made in view of the above problems, and has a movable part that is displaced by application of a mechanical quantity, and a mechanical quantity sensor that detects the mechanical quantity by the displacement amount of the movable part. The object is to prevent the movable part from being excessively displaced.

  In order to achieve the above object, the invention according to claim 1 is an actuator that applies acceleration to the movable part (31) in a direction opposite to a direction in which the movable part (31) is displaced by a mechanical quantity. The movable portion (31) is configured as an angular velocity detecting element that vibrates and detects by a Coriolis force applied in a direction orthogonal to the direction of the driving vibration when the driving vibration is applied in one direction and an angular velocity is applied. And applying an acceleration by the actuator (40) to the movable part (31) in a direction opposite to the direction in which the movable part (31) is displaced by the mechanical quantity along the direction of the drive vibration. , Feature.

  According to it, when the mechanical quantity applied to the movable part (31) is excessive, the displacement of the movable part (31) is excessive due to the excessive mechanical quantity, but so as to cancel this excessive displacement, Since acceleration is applied from the actuator (40) to the movable part (31), it is possible to prevent the movable part (31) from being excessively displaced by an excessive mechanical quantity.

  In the configuration in which the actuator (40) applies acceleration to the movable part (31) as in claim 1, the movable part (31) is driven and vibrated in one direction and an angular velocity is applied. In addition, when configured as an angular velocity detection element that detects and vibrates by a Coriolis force applied in a direction orthogonal to the direction of the drive vibration, the movable portion (31) is moved along the direction of the drive vibration by a mechanical quantity. The acceleration may be applied by the actuator (40) to the movable part (31) in the direction opposite to the direction of displacement.

  When the movable part (31) is configured as an angular velocity detecting element as in the invention described in claim 2, the movable part (31) is displaced by a mechanical quantity along the direction of application of the Coriolis force. You may make it apply the acceleration by an actuator (40) with respect to a movable part (31) in the direction opposite to a direction.

  Further, as in a third aspect of the invention, the mechanical quantity sensor having each of the above-described configurations is provided on the first fixed portion (32a) facing the movable portion (31) and the movable portion (31). A second fixed portion (32b) facing each other, and when applying a mechanical quantity, the movable portion (31) is displaced so as to approach one of both fixed portions (32a, 32b) and away from the other The differential capacitance between the capacitance between the movable portion (31) and the first fixed portion (32a) and the capacitance between the movable portion (31) and the second fixed portion (32b) is taken. Therefore, it is preferable to use it for a so-called differential type mechanical quantity sensor.

  Further, as in the invention described in claim 4, in each of the above-described configurations, the sensor chip (30) having the movable portion (31) may be disposed on the actuator (40). In this case, a reduction in size can be expected.

  Furthermore, in this case, an elastic adhesive member (60) is interposed between the movable part (31) and the actuator (40) arranged to overlap each other as in the invention described in claim 5. The movable part (31) is supported on the actuator (40) via the adhesive member (60), and the bonding wire (50) is electrically connected to the movable part (31). .

  In this case, the entire movable part (31) is moved by the elasticity of the adhesive member (60), and the bonding wire (50) is easily damaged. Even in such a case, the excessive displacement by the actuator (40) is caused. Due to this prevention effect, it is easy to suppress damage to the bonding wire (50).

  In addition to overlapping the movable part (31) on the actuator (40), the actuator (40) is arranged in a plane around the movable part (31) as in the invention described in claim 6. Also good.

  Further, as in the invention described in claim 7, each of the above-described configurations includes a circuit unit (20) electrically connected to the movable unit (31) and receiving a signal of the movable unit (31). If the circuit unit (20) drives the actuator (40) by the signal of the movable unit (31) input to the circuit unit (20), the circuit configuration can be reduced in size.

  Further, as in the inventions described in claims 8 and 9, in each of the above-described configurations, the actuator (40) includes a piezoelectric body that is displaced by a voltage signal, or an electrostatic drive driven by an electrostatic force. An electrically driven type can be adopted.

  In addition, the code | symbol in the bracket | parenthesis of each means described in the claim and this column is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

It is a figure which shows schematic structure of the acceleration sensor as a mechanical quantity sensor which concerns on 1st Embodiment of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing. FIG. 2 is an enlarged plan view of a sensor chip in the acceleration sensor shown in FIG. It is a circuit diagram which shows an example of the detection circuit in the acceleration sensor shown by FIG. It is a block diagram which shows the detection mechanism of the acceleration in 1st Embodiment, and the control mechanism of an actuator. It is explanatory drawing which shows an example of the non-servo type control method of the actuator in 1st Embodiment. It is a figure which shows schematic structure of the acceleration sensor as a mechanical quantity sensor which concerns on 2nd Embodiment of this invention, (a) is a schematic plan view, (b) is a schematic sectional drawing. It is a figure which shows schematic plan structure of the principal part in the acceleration sensor as a dynamic quantity sensor which concerns on 3rd Embodiment of this invention. It is a schematic plan view of an actuator and an actuator stage according to a third embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
FIG. 1 is a diagram showing a schematic configuration of an acceleration sensor 100 as a mechanical quantity sensor according to a first embodiment of the present invention, where (a) is a schematic plan view and (b) is a schematic cross-sectional view. FIG. 2 is an enlarged plan view for showing a more detailed configuration of the sensor chip 30 in the acceleration sensor 100 shown in FIG.

  Although this acceleration sensor 100 is not specifically limited, For example, it can apply to the acceleration sensor for vehicles, a gyro sensor, etc. for performing operation control, such as an airbag, ABS, VSC.

  As shown in FIG. 1, the acceleration sensor 100 generally includes a package 10, a circuit chip 20 supported on the package 10, an actuator 40 provided on the circuit chip 20, and the actuator 40. And a sensor chip 30 provided on the top.

  The package 10 accommodates the sensor chip 30, the actuator 40, and the circuit chip 20, and serves as a base for defining and forming the main body of the acceleration sensor 100, and for attaching the acceleration sensor 100 to an appropriate position of the measurement object. It is. The package 10 is not particularly limited but is made of ceramic, resin, or the like.

  In the example shown in FIG. 1, the package 10 is configured as a laminated substrate in which a plurality of ceramic layers such as alumina are laminated, and the wiring in the package 10 is not shown, but the surface of each ceramic layer and each ceramic layer are not shown. It is formed inside the through hole formed in the.

  And the acceleration sensor 100 and the exterior can be electrically connected through this wiring. A lid 11 is attached to the opening of the package 10 by welding or the like to seal the inside of the package 10.

  A circuit chip 20 as a circuit unit is mounted on the bottom surface of the package 10, and the circuit chip 20 and the package 10 are fixed via an adhesive (not shown) made of epoxy resin or the like.

  The circuit chip 20 is formed with a detection circuit (see FIG. 3 described later) for processing an output signal from the sensor chip 30. For example, the circuit chip 20 is formed by forming a MOS transistor element or the like on a semiconductor substrate such as a silicon substrate using a semiconductor process.

  A sensor chip 30 is mounted on the circuit chip 20 via an actuator 40 and an actuator stage 41. Here, the circuit chip 20, the actuator 40, the actuator stage 41, and the sensor chip 30 are bonded to each other through an adhesive made of an epoxy resin (not shown).

  The pads 34 (see FIG. 2) of the sensor chip 30, the pads 21 of the circuit chip 20, and the wiring not shown in the package 10 are electrically connected via bonding wires 50 such as gold and aluminum. Yes. Further, the pads 40 a of the actuator 40 and the circuit chip 20 are also electrically connected via the bonding wires 50.

  The sensor chip 30 is composed of, for example, an SOI (silicon-on-insulator) substrate obtained by bonding a first silicon substrate and a second silicon substrate via an oxide film, and is fixed to the movable electrode. A capacitive acceleration sensor chip that detects acceleration based on a change in capacitance with the electrode is configured. Since this capacitance type acceleration sensor chip is well known, the outline thereof will be described here.

  As shown in FIG. 2, the sensor chip 30 is formed with a beam structure 33 including a comb-like movable electrode 31 and fixed electrodes 32a and 32b facing each other, and an arrow X in FIG. When acceleration as a mechanical quantity is applied in the direction, the movable electrode 31 as the movable portion is displaced in the direction of the arrow X.

  Then, the capacitance signal between the electrodes 31, 32a, 32b changes based on the amount of displacement, and this capacitance signal is taken out from the bonding wire 50 to the circuit chip 20, and the voltage etc. Converted to a signal.

  The converted signal is transmitted from the bonding wire 50 to the package 10 and is output to the outside from the wiring provided in the package 10. Thus, in this embodiment, the acceleration applied in the arrow X direction is detected.

  In other words, in the sensor chip 30 of the present embodiment, the movable electrode 31 as the movable portion is configured as an acceleration detection element that is displaced in the direction in which the acceleration is applied when an acceleration as a mechanical quantity is applied. In other words, the movable portion 31 of the present embodiment is configured to be capable of being displaced in one direction and detecting acceleration as a mechanical quantity in the one direction.

  In particular, in the present embodiment, the first fixed electrode 32a as the first fixed portion facing the movable electrode 31 as the movable portion, and the second fixed portion as the second fixed portion facing the movable electrode 31. 2 fixed electrodes 32b. When the acceleration of the movable portion 31 in the direction of the arrow X is applied, the movable electrode 31 is displaced so as to approach one of the fixed electrodes 32a and 32b and away from the other.

  For this reason, the acceleration sensor 100 of the present embodiment performs a differential detection operation. This detection operation will be specifically described. In the present acceleration sensor 100, the side surfaces of the fixed electrodes 32a and 32b are respectively provided so as to face the side surfaces of the individual movable electrodes 31, and the respective opposing intervals of the side surfaces of the electrodes 31, 32a and 32b are provided. A detection interval for detecting the capacitance is formed.

  Here, the first capacitor CS1 is formed in the gap between the lower side surface in the drawing and the movable electrode 31 in the first fixed electrode 32a located on the left side in FIG. 2, while the first fixed electrode 32a is positioned on the right side. It is assumed that the second capacitor CS2 is formed in the interval between the upper side surface in the drawing and the movable electrode 31 in the second fixed electrode 32b.

  When acceleration is applied in the direction of arrow X in FIG. 2, the entire movable electrode 31 is integrally displaced in the direction of arrow X, and the capacitances CS1 and CS2 change according to the displacement of the movable electrode 31. To do.

  For example, consider the case in FIG. 1 where the movable electrode 31 is displaced downward along the arrow X direction. At this time, the distance between the first fixed electrode 32a and the movable electrode 31 is widened, while the distance between the second fixed electrode 32b and the movable electrode 31 is narrowed. Therefore, the first capacitor CS1 is reduced, the second capacitor CS2 is increased, and the detection sensitivity is improved by taking these differential capacitors (CS1-CS2).

  Thus, in the present embodiment, the acceleration in the arrow X direction is detected based on the change in the differential capacitance (CS1-CS2) by the movable electrode 31 and the fixed electrodes 32a and 32b. Specifically, a signal based on the differential capacitance (CS1-CS2) is output as an output signal from the acceleration sensor 100, and this signal is processed by the circuit chip 20 and finally output.

  FIG. 3 is a circuit diagram showing an example of a detection circuit 200 for detecting acceleration in the acceleration sensor 100. In this detection circuit 200, a switched capacitor circuit (SC circuit) 210 includes a capacitor 211 having a capacitance Cf, a switch 212, and a differential amplifier circuit 213. The input differential capacitance (CS1-CS2) is a voltage. Is supposed to be converted to

  In the present acceleration sensor 100, for example, the carrier wave 1 having the amplitude Vcc is input from the first fixed electrode 32a, and the carrier wave 2 having a phase shifted by 180 ° from the second fixed electrode 32b is input. The switch 212 of the circuit 210 is opened and closed at a predetermined timing. Then, the applied acceleration in the direction of the arrow X is output as a voltage value V0 as shown in Equation 1 below.

(Equation 1)
V0 = (CS1-CS2) .Vcc / Cf
As described above, the acceleration sensor 100 according to the present embodiment has a difference between the capacitance CS1 between the movable electrode 31 and the first fixed electrode 32a and the capacitance CS2 between the movable electrode 31 and the second fixed electrode 32b. The acceleration as the mechanical quantity is detected by taking the dynamic capacity (CS1-CS2).

  Here, in the acceleration sensor 100 of the present embodiment, the actuator 40 applies acceleration to the movable electrode 31 in a direction opposite to the direction in which the movable electrode 31 is displaced by acceleration. Specifically, the actuator 40 is moved along the arrow X direction when acceleration to be detected is applied to the movable electrode 31 in the downward direction along the arrow X direction in FIGS. The acceleration from the actuator 40 is applied upward.

  The actuator 40 is displaced by voltage application, and is made of a piezoelectric material such as PZT in this embodiment. Here, the actuator 40 expands and contracts by application of voltage from the circuit chip 20, and the actuator stage 41 on the actuator 40 moves in the direction of arrow X by this expansion and contraction.

  Here, since the sensor chip 30 is fixed to the actuator stage 41, the sensor chip 30, that is, the movable electrode 31 moves together with the actuator stage 41 in the direction of the arrow X by the actuator 40. In this way, the actuator 40 applies acceleration by the actuator 40 to the movable electrode 31 in the direction opposite to the acceleration to be detected.

  Here, each of the circuit chip 20, the actuator 40, the actuator stage 41, and the sensor chip 30 is bonded through an adhesive made of an epoxy resin (not shown), but the sensor is deformed by the above-described deformation of the actuator 40. The chip 30 can move. This can be achieved, for example, by adhering the actuator 40 to the actuator stage 41 above and below it, and the circuit chip 20 in a form in which part of the actuator 40 is adhered instead of the entire surface.

  It goes without saying that the operation of the actuator 40 made of such a piezoelectric body and the configuration for realizing it can be easily realized by using the principle of a piezoelectric body well known in the art.

  The actuator stage 41 is configured by a plate-like member made of electrically insulating ceramic or the like. The pad 40a of the actuator 40 is made of an aluminum vapor deposition film or the like, and as described above, the circuit chip 20 and the actuator 40 are electrically connected by performing wire bonding via the pad 40a. ing.

  The operation of the actuator 40 will be specifically described with reference to FIGS. FIG. 4 is a block diagram showing an acceleration detection mechanism and an actuator 40 control mechanism in the present embodiment.

  As shown in FIG. 4, the circuit chip 20 as a circuit unit includes the detection circuit 200 shown in FIG. 3 and an actuator control circuit 300 that controls the operation of the actuator 40. As described above, the detection circuit 200 converts the capacitance change (CS1-CS2) between the movable electrode 31 and the fixed electrodes 32a and 32b generated in the sensor chip 30 into a voltage and outputs it as a sensor output. is there.

  Also, as shown in FIG. 4, the sensor output, which is a signal obtained by converting the capacitance change (CS1-CS2) into a voltage value, is input to the actuator control circuit 300, and the control circuit 300 receives the input. A control signal is given to the actuator 40 in accordance with the sensor output.

  Thereby, when the acceleration applied to the movable electrode 31 is excessive, the acceleration applied to the movable electrode 31 can be reduced by driving the actuator 40 in the direction opposite to the arrow X direction of the movable electrode 31.

  In this case, in principle, it is ideal to drive the actuator 40 so that the displacement of the movable electrode 31 with respect to the input acceleration is zero. In this case, it is conceivable to adopt an operation method as a servo type acceleration sensor that is generally known from the past and whose control amount is equivalent to acceleration.

  However, in the case of this servo-type acceleration sensor, the spring supporting the movable electrode needs to be soft enough to follow a slight displacement of the movable electrode, that is, a minute acceleration. The structural strength of the support portion is weak against external impacts.

  In the present embodiment, it is sufficient that the acceleration that is the detection target can be suppressed to a level that does not cause a failure of the movable electrode 31 (such as a collision with the fixed electrodes 32a and 32b or sticking). It does not have to be equivalent to the acceleration to be detected as in the servo type. That is, in the present embodiment, the actuator 40 may be non-servo type control. This detail is shown in FIG.

  FIG. 5 is an explanatory diagram illustrating an example of a non-servo control method. The present embodiment is a capacitive acceleration sensor, which converts a capacitance change between the movable electrode 31 and the fixed electrodes 32a and 32b generated in the sensor chip 30 into a sensor output as a voltage and outputs it. In FIG. 5, the horizontal axis represents acceleration, and the vertical axis represents sensor output as a voltage value.

  Here, the “acceleration detection range” is an acceleration detection range detected by the displacement amount of the movable electrode 31 in the acceleration sensor 100. Specifically, the acceleration and the sensor output are in a range where the linearity is good, and the upper limit sensor output of the acceleration detection range is Vs. The “sensor output range” corresponding to the acceleration detection range is shown in FIG.

  In FIG. 5, the value indicated as “the upper limit value of the displacement amount” is a sensor output corresponding to the limit of the displacement amount of the movable electrode 31, that is, the acceleration value. Here, the limit of the amount of displacement of the movable electrode 31 is specifically the distance between the movable electrode 31 and each of the fixed electrodes 32a and 32b, and beyond that, the movable electrode 31 collides with the fixed electrodes 32a and 32b. Damage or cause sticking.

  In the present embodiment, as described above, in the circuit chip 20, the sensor output from the detection circuit 200 is input to the actuator control circuit 300, and this sensor output is within the acceleration detection range, that is, the acceleration detection range. The actuator 40 is not operated below the upper limit sensor output Vs.

  In the present embodiment, a threshold value (actuator drive threshold value) Va for driving the actuator is provided between the upper limit value Vs of the acceleration detection range and the upper limit value of the displacement amount. When the sensor output becomes equal to or greater than the actuator drive threshold value Va, the actuator 40 is operated by a signal from the actuator control circuit 300.

  The actuator 40 receives the voltage signal from the actuator control circuit 300 and applies acceleration to the movable electrode 31 in the direction opposite to the arrow X direction due to the acceleration to be detected by the movable electrode 31. The acceleration applied from the actuator 40 at this time is shown as “actuator driving acceleration” as shown in FIG. 5, and the magnitude thereof substantially corresponds to the sensor output.

  Further, when the sensor output (voltage signal) from the actuator control circuit 300 is received and the signal falls below the actuator stop threshold Va ′ shown in FIG. 5, the actuator control circuit 300 operates the actuator 40. I try to stop.

  Thus, in the present embodiment, the actuator 40 applies acceleration to the movable electrode 31 in a direction opposite to the displacement direction due to the acceleration to be detected by the movable electrode 31. Thereby, the actuator 40 is detected while suppressing the displacement amount of the movable electrode 31 when the acceleration detected by the displacement amount of the movable electrode 31 becomes equal to or greater than a predetermined value (actuator drive threshold Va in this example). The acceleration is suppressed below the predetermined value.

  As described above, in the present embodiment, the control by the non-servo type actuator 40 does not affect the detection. Rather, by performing signal processing such as FFT using a DSP (digital signal processor) or the like, it is possible to perform control such that the actuator 40 is driven only at a specific frequency such as the resonance frequency of the sensor structure or mounting structure. . Thereby, the movable electrode 31 can be protected without affecting the original acceleration detection.

  By the way, according to the present embodiment, in the acceleration sensor 100 that has the movable electrode 31 that is displaced by the application of acceleration as a mechanical quantity and detects the acceleration according to the displacement amount of the movable electrode 31, the acceleration of the movable electrode 31 is detected. An actuator 40 is provided that applies acceleration to the movable electrode 31 in a direction opposite to the direction of displacement due to.

  According to this, when the acceleration applied to the movable electrode 31 is excessive, the displacement of the movable electrode 31 is also excessive due to the excessive acceleration, but the movable electrode 31 is not affected by the excessive displacement. Since acceleration is applied from the actuator 40, it is possible to prevent the movable electrode 31 from being excessively displaced due to excessive acceleration, for example, external impact. As a result, damage or sticking of the movable electrode 31 can be prevented.

  In other words, in the present embodiment, when the acceleration detected by the displacement amount of the movable electrode 31 becomes equal to or greater than a predetermined value, the acceleration detected by suppressing the displacement amount of the movable electrode 31 is suppressed to less than the predetermined value. Since the actuator 40 is provided, it is possible to prevent the movable electrode 31 from being excessively displaced due to an excessive dynamic amount.

  In the present embodiment, as shown in FIG. 4, the circuit chip 20 is configured to include a detection circuit 200 that is electrically connected to the movable electrode 31 and receives a signal from the movable electrode 31. However, the circuit chip 20 further includes an actuator control circuit 300. The circuit chip 20 drives the actuator 40 by a signal from the movable electrode 31 input to the circuit chip 20.

  As a result, only one circuit chip 20 in the acceleration sensor 100 may be used, and the size can be reduced. However, the present embodiment is not limited to this, and the sensor output circuit section and the actuator control circuit section may be separate. That is, the detection circuit 200 and the actuator control circuit 300 shown in FIG. 4 may be separate circuit chips.

(Second Embodiment)
6A and 6B are diagrams showing a schematic configuration of the acceleration sensor 110 as a mechanical quantity sensor according to the second embodiment of the present invention. FIG. 6A is a schematic plan view of the acceleration sensor 110, and FIG. It is a schematic sectional drawing. The difference from the first embodiment will be mainly described.

  As shown in FIG. 6, also in the present embodiment, the sensor chip 30 having the movable electrode 31 is disposed on the actuator 40 in the same manner as in the first embodiment. Further, the actuator 40 acts in the same manner as described above, so that it is possible to prevent the movable electrode 31 from being excessively displaced due to excessive acceleration in this embodiment as well.

  Here, in the present embodiment, in addition to the configuration of the first embodiment, an adhesive member 60 having elasticity is interposed between the sensor chip 30, that is, the movable electrode 31 and the actuator 40. It is assumed that the actuator 40 is supported via the adhesive member 60.

  Specifically, the adhesive member 60 may employ a soft adhesive film such as that described in Patent Document 1, for example, a silicone resin. The actuator stage 41 and the sensor chip 30 are fixed by adhesion through the adhesive member 60.

  Also in the acceleration sensor 110 of the present embodiment, as in the first embodiment, the bonding wire 50 is electrically connected to the movable electrode 31 and the fixed electrodes 32a and 32b as the movable part via the pads 34. They are connected, and signals can be exchanged between the respective electrodes 31, 32 a, 32 b of the sensor chip 30 and the circuit chip 20 through the bonding wires 50.

  Here, when the method of adhering the lower part of the sensor chip 30 with the low elastic modulus adhesive member 60 as in the present embodiment is employed, as described in Patent Document 1, the sensor chip 30 is added. The thermal stress can be reduced by the low elastic adhesive member 60, and the temperature characteristics can be improved.

  However, since the adhesive member 60 has low elasticity, the strength of the adhesive chip 60 in the support structure of the sensor chip 30 is reduced, and the entire sensor chip 30 is likely to be excessively displaced when an excessive external impact is applied. There is a problem. When there is such a problem, the strength of the sensor body cannot be guaranteed, or excessive stress is applied to the bonding wire 50 due to excessive displacement of the sensor chip 30 and the product life is shortened. There is a risk that.

  In that respect, in the second embodiment, although the sensor chip 30 is configured to be supported by the adhesive member 60 such as a soft adhesive film, the actuator 40 can not only prevent the movable electrode 31 from being excessively displaced, The displacement of the entire sensor chip 30 can be suppressed.

  Therefore, deformation of the bonding wire 50 due to the displacement of the sensor chip 30 can also be suppressed, and protection including the bonding wire 50 is possible. As a result, failure due to disconnection of the bonding wire 50 can be prevented.

(Third embodiment)
FIG. 7 is a diagram showing a schematic plan configuration of a main part of an acceleration sensor as a mechanical quantity sensor according to the third embodiment of the present invention, and shows an arrangement configuration of the actuator 40 with respect to the sensor chip 30.

  In each of the embodiments described above, the movable electrode 31 as the movable portion is arranged so as to overlap the actuator 40. However, in the present embodiment, as shown in FIG. You may arrange.

  Specifically, also in FIG. 7, the actuators 40 are respectively arranged at both ends of the sensor chip 30 along the arrow X direction with the sensor chip 30 supported on the circuit chip 20 in FIG. 1. . These actuators 40 are displaced by a voltage signal, and the sensor chip 30 is pushed by the displacement, as in the above embodiments. Therefore, the actuator 40 can apply acceleration to the movable electrode 31.

  Thus, also in the present embodiment, the actuator 40 can apply acceleration to the movable electrode 31 in the direction opposite to the arrow X direction by the acceleration to be detected by the movable electrode 31, and an excessively large external It is possible to prevent the movable electrode 31 from being excessively displaced due to an impact or the like.

  In the example shown in FIG. 7, the actuator 40 is arranged at both ends of the sensor chip 30 along the arrow X direction. However, in FIG. 7, the actuator 40 is arranged only at one end side of the sensor chip 30. May be.

(Fourth embodiment)
FIG. 8 is a schematic plan view of the actuator 40 and the actuator stage 41 according to the third embodiment of the present invention. In each of the above embodiments, the actuator 40 is provided with a piezoelectric body that is displaced by a voltage signal, and acceleration is applied to the movable portion 31 by the displacement of the piezoelectric body. However, in this embodiment, the actuator 40 is Electrostatic drive type.

  Specifically, the actuator 40 according to the present embodiment is formed of a semiconductor chip similarly to the sensor chip 30, and can be created by using a semiconductor process for the semiconductor chip. As shown in FIG. 8, an actuator stage 41 supported by the semiconductor chip via a beam 42 as a spring portion is driven by a comb-shaped actuator 40.

  The actuator 40 is composed of two opposing comb electrodes, and the pads 43 corresponding to the comb electrodes are electrically connected to the circuit chip 20 via bonding wires or the like.

  A signal (voltage) is applied to the actuator 20 from the actuator control circuit 300, so that an electrostatic force acts between the two comb electrodes constituting the actuator 40. ing. The actuator stage 41 is displaced in the arrow X direction by the action of the beam 42 by the electrostatic force of the actuator 40.

  Therefore, in this embodiment, the sensor chip 30 is mounted on the actuator stage 41, and the actuator 40 is moved from the actuator 40 in a direction opposite to the direction of displacement due to acceleration to be detected by the movable electrode 31. By applying this acceleration, it is possible to obtain the same effects as those of the first embodiment.

(Other embodiments)
In each of the above embodiments, the movable part 31 is configured as an acceleration detection element. However, the movable part 31 provided in the sensor chip 30 may be any element that is displaced by application of a mechanical quantity. A generally known angular velocity detecting element may be used.

  The movable portion 31 as a general angular velocity detecting element is formed by a semiconductor process with respect to the sensor chip 30, and can be a beam structure having a comb-tooth structure. The detailed configuration of the movable portion 31 as the angular velocity detection element is different from the acceleration detection element shown in FIG.

  A general operation of the movable portion 31 as such an angular velocity detection element will be described. For example, in FIG. 1, when an angular velocity is applied when the movable portion 31 is driven to vibrate in the direction of the arrow X by the excitation mechanism, Coriolis force is generated in a direction perpendicular to the direction of the arrow X (left and right in FIG. The movable part 31 vibrates for detection. Then, the angular velocity can be detected by detecting the displacement of the movable portion 31 that vibrates as a change in capacitance.

  Here, the actuator 40 is provided under the sensor chip 30 via the actuator stage 41, for example, as in FIG. Then, the direction in which the movable part 31 is displaced by a mechanical quantity such as an external impact along the direction of the driving vibration, or the direction in which the movable part 31 is displaced by a mechanical quantity such as an external impact along the direction in which the Coriolis force is applied. The acceleration may be applied from the actuator 40 to the movable portion 31 in the direction opposite to the direction of displacement or in the opposite directions.

  Also in the case of this angular velocity detection element, the actuator 40 may be arranged in a plane with respect to the movable portion 31 as the angular velocity detection element as long as acceleration can be applied by the actuator 40. Further, in view of the properties of the angular velocity detection element, it is desirable that the actuator 40 preferably relaxes the impact force in the direction in which the Coriolis force is generated.

  In addition, the adoptable actuator 40 may be other than the piezoelectric body and the electrostatic drive type described above. For example, the actuator 40 can be a linear solenoid, a linear motor, or the like using a conventional electromagnetic force.

20 ... a circuit chip as a circuit part, 31 ... a movable electrode as a movable part,
32a ... 1st fixed electrode as 1st fixed part,
32b ... 2nd fixed electrode as 2nd fixed part, 40 ... Actuator,
60: Adhesive member.

Claims (9)

In a mechanical quantity sensor having a movable part (31) that is displaced by application of a mechanical quantity, and detecting the mechanical quantity in accordance with the displacement amount of the movable part (31),
An actuator (40) for applying acceleration to the movable part (31) in a direction opposite to a direction in which the movable part (31) is displaced by a mechanical quantity;
The movable portion (31) is configured as an angular velocity detection element that vibrates in a direction and detects and vibrates due to a Coriolis force applied in a direction orthogonal to the direction of the driving vibration when an angular velocity is applied. And
Applying acceleration by the actuator (40) to the movable part (31) in a direction opposite to the direction in which the movable part (31) is displaced by a mechanical quantity along the direction of the drive vibration. Characteristic mechanical quantity sensor. In a mechanical quantity sensor having a movable part (31) that is displaced by application of a mechanical quantity, and detecting the mechanical quantity in accordance with the displacement amount of the movable part (31),
An actuator (40) for applying acceleration to the movable part (31) in a direction opposite to a direction in which the movable part (31) is displaced by a mechanical quantity;
The movable portion (31) is configured as an angular velocity detection element that vibrates in a direction and detects and vibrates due to a Coriolis force applied in a direction orthogonal to the direction of the driving vibration when an angular velocity is applied. And
Applying acceleration by the actuator (40) to the movable part (31) in a direction opposite to the direction in which the movable part (31) is displaced by a mechanical quantity along the direction in which the Coriolis force is applied. Mechanical quantity sensor characterized by A first fixed portion (32a) facing the movable portion (31) and a second fixed portion (32b) facing the movable portion (31);
At the time of applying the mechanical quantity, the movable part (31) is displaced so as to approach one of the two fixed parts (32a, 32b) and away from the other,
A differential capacity between a capacity between the movable part (31) and the first fixed part (32a) and a capacity between the movable part (31) and the second fixed part (32b) The mechanical quantity sensor according to claim 1, wherein the mechanical quantity is detected by taking it.   The mechanical quantity sensor according to any one of claims 1 to 3, wherein the sensor chip (30) having the movable part (31) is arranged so as to overlap the actuator (40). . An elastic adhesive member (60) is interposed between the movable part (31) and the actuator (40), and the movable part (31) is interposed between the actuator (40) via the adhesive member (60). ) Is supported above,
The mechanical quantity sensor according to claim 4, wherein a bonding wire (50) is electrically connected to the movable part (31).   The mechanical quantity sensor according to any one of claims 1 to 3, wherein the actuator (40) is arranged in a plane around the movable portion (31). A circuit unit (20) that is electrically connected to the movable unit (31) and receives a signal from the movable unit (31);
The circuit unit (20) drives the actuator (40) by a signal of the movable unit (31) input to the circuit unit (20). The mechanical quantity sensor according to any one of the above.   The mechanical quantity sensor according to any one of claims 1 to 7, wherein the actuator (40) includes a piezoelectric body that is displaced by a voltage signal.   The mechanical quantity sensor according to any one of claims 1 to 7, wherein the actuator (40) is of an electrostatic drive type driven by an electrostatic force.

Images