JP2008224406A - Physical quantity sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem of a physical quantity sensor using a conventional bridge circuit wherein a part of the bridge circuit is set to have an opening end and hence the number of connecting terminals increases and size cannot be reduced. <P>SOLUTION: In the physical quantity sensor, a plurality of bridge circuits constituted using a plurality of piezoresistors disposed in a flexible portion of the sensor are constituted as a closed circuit without opening end. Each bridge circuit has a plurality of connecting terminals between the piezoresistors while one connecting terminal is shared and connected by each bridge circuit, and the number of connecting terminals can be reduced by applying the same potential. With this constitution, the size of this physical quantity sensor can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a physical quantity sensor having a bridge circuit. In particular, the present invention relates to a physical quantity sensor having a beam-shaped flexible portion between a weight portion and a fixed portion, and a plurality of detection elements mounted on the beam portion.

  Conventionally, a physical quantity sensor that electrically converts a physical change of a material itself according to an external force has been developed, and a product that applies the sensor has been developed and put on the market. These products are required to be reduced in weight, size, and cost while maintaining or improving performance. Therefore, the physical quantity sensor itself used as a part of the product is also required to be reduced.

  Many types of physical quantity sensors have been proposed. Among them, a semiconductor acceleration sensor that detects acceleration as a change in resistance value due to strain of gauge resistance is known.

In the semiconductor acceleration sensor, a gauge resistor as a detection element is provided on a beam-shaped flexible portion that connects the weight portion and the support portion. As the gauge resistance, a piezoresistive element or the like can be used. In many cases, a plurality of gauge resistors are provided, and when the support portion is formed in a frame shape and the weight portion is provided therein, there are many cases where four flexible portions are provided, and each of the four flexible portions is provided with a gauge resistance.
When detecting strain of the gauge resistance due to acceleration, each gauge resistance is bridge-connected, and a connection terminal to the outside is provided between the gauge resistances. When acceleration is applied to the semiconductor acceleration sensor, the weight part is displaced, and the flexible part bends according to the amount of displacement. As a result, the resistance of the gauge resistance changes, so the applied acceleration is detected from the connection terminal as an electrical signal. can do.

  Such a semiconductor acceleration sensor is required to have an equal balance between the values of each of the four gauge resistors to be bridge-connected, but when actually manufactured by a semiconductor manufacturing process, the internal stress and ambient temperature of the metal wiring Due to the difference in thermal stress due to the change, the resistance value of each gauge resistance varies. In order to suppress variation in each gauge resistance, it is known to newly provide a metal wiring pattern to make the resistance value of the gauge resistance uniform (for example, refer to Patent Document 1).

  The prior art disclosed in Patent Document 1 will be described with reference to FIG. FIG. 5 is a plan view illustrating the prior art shown in Patent Document 1 without departing from the gist thereof. In FIG. 5, 1 is a weight part, 2 is a support part, 3a is a first flexible part, 3b is a second flexible part, 3c is a third flexible part, 3d is a fourth flexible part, Reference numerals 4a to 4d, 5a to 5d, and 6a to 6d are piezoresistive elements, and 9a to 9r are connection terminals. These connection terminals are formed in a pad shape on the surface of the support portion 2. 8 and 81 are metal wirings.

In FIG. 5, the longitudinal direction of the first flexible part 3a and the third flexible part 3c is the X-axis direction, and the longitudinal direction of the second flexible part 3b and the fourth flexible part 3d is the Y-axis. The direction. A direction orthogonal to the X-axis direction and the Y-axis direction is taken as a Z-axis direction.
Each piezoresistive element provided in each flexible portion and each connection terminal are connected by a metal wiring 8. The metal wiring 81 is formed in the same manufacturing process as the metal wiring 8, and the metal of the first flexible part 3a and the third flexible part 3c, and the second flexible part 3b and the fourth flexible part 3d. The wiring pattern layout is formed to be symmetric.

In the prior art disclosed in Patent Document 1, a metal wiring 81 layout is newly provided on the surface of the physical quantity sensor, so that the metal wiring pattern layout on the beam-shaped flexible portion is symmetrical in the axial direction where the plane intersects planarly. Therefore, variations in gauge resistance due to internal stress of metal wiring and thermal stress due to changes in ambient temperature are suppressed.

JP 2003-92413 A (page 11, FIG. 2)

  The prior art disclosed in Patent Document 1 has a structure in which the metal wiring pattern layout is formed symmetrically, and the structure is such that the internal stress and the thermal stress due to changes in ambient temperature are substantially equal by newly providing the metal wiring 81. This has the advantage that the difference in internal stress and thermal stress due to changes in ambient temperature can be made uniform. However, as a result of studies by the inventors, it has been found that the conventional technique shown in Patent Document 1 cannot be used as a recent physical quantity sensor that has been miniaturized.

This will be described with reference to the drawings. FIG. 6 is an equivalent circuit diagram for explaining connection of each component of the plan view shown in FIG. Three bridge circuits corresponding to respective axes in the X, Y, and Z axis directions are shown. In order to detect the applied acceleration as an electrical signal from the connection terminal, it is necessary to use this bridge circuit.
In FIG. 6, 41 is a bridge circuit that detects a physical quantity in the X-axis direction, 51 is a bridge circuit that detects a physical quantity in the Y-axis direction, and 61 is a bridge circuit that detects a physical quantity in the Z-axis direction. The same numbers are assigned to the same configurations already described.

  As shown in FIG. 6, the bridge circuit 41 has an open end with connection terminals 9d and 9j and an open end with connection terminals 9e and 9k. The bridge circuit 51 has an open end with connection terminals 9f and 9l and an open end with connection terminals 9g and 9m. The bridge circuit 61 has an open end with connection terminals 9h and 9n and an open end with connection terminals 9i and 9o. That is, in the prior art disclosed in Patent Document 1, an open end always occurs in a part of the bridge circuit.

  In order to detect physical quantities using the bridge circuit shown in FIG. 6, connection terminals 9d and 9j, connection terminals 9e and 9k, connection terminals 9f and 9l, connection terminals 9g and 9m, connection terminals 9h and 9n, connection terminals 9i and 9o must have the same potential. Since each connection terminal has a pad shape as shown in FIG. 5, it must be connected to each other by wiring or the like outside the physical quantity sensor.

For this reason, the number of connection terminals provided in the support part 2 increases, and it becomes difficult to reduce the size of the physical quantity sensor. Further, in order to function as a physical quantity sensor, it is troublesome to connect the connection terminals externally, such as routing the wiring material.
Furthermore, since an electrical signal from the physical quantity sensor is used, it is often necessary to newly provide a circuit element such as a switch circuit or a resistor outside the physical quantity sensor in the operational environment of the sensor. For this reason, as a physical quantity sensor, it is desired to reduce its size, and a reduction in the number of wires is also desired for miniaturization of the environment including the sensor.
However, it is difficult to reduce the size and the number of wires in the prior art disclosed in Patent Document 1.

  The present invention has been made in order to solve the above-described problems, and is a physical quantity sensor that can measure the resistance values and temperature characteristics of a plurality of gauge resistors and can be reduced in size. Is to provide.

  In order to achieve the above object, the present invention adopts the following structure.

The movable part is composed of a weight part, a support part provided at a predetermined interval from the weight part, and a flexible part that connects the weight part and the support part. The movable part is provided to detect a physical quantity in a plurality of axial directions. A physical quantity sensor for detecting a physical quantity using a bridge circuit, wherein the detection means are connected to each other, and a plurality of bridge circuits corresponding to a plurality of axial directions are respectively formed.
The bridge circuit is a closed circuit having no open end when the detection means are connected to each other, and has a connection terminal at a connection portion between the detection means, and corresponds to one axial direction among a plurality of axial directions. One of the connection terminals of the bridge circuit and one of the connection terminals of the bridge circuit corresponding to the other axial direction are short-circuited or connected to a wiring that supplies the same potential.

  The connection terminal includes an input terminal, a common potential terminal, a first output terminal, and a second output terminal. The bridge circuit includes a first detection element between the input terminal and the first output terminal. The second detection means is provided between the input terminal and the second output terminal, the third detection means is provided between the common potential terminal and the second output terminal, and the common potential terminal and the first output terminal are provided. The fourth detection means is provided between the X direction, one direction parallel to one plane of the physical quantity sensor, the Y direction parallel to the one plane and perpendicular to the X direction, and the X direction and Y direction passing through the one plane. Are defined as the Z direction, the plurality of axial directions are the X axis direction, the Y axis direction, and the Z axis direction, respectively, and the first flexible portion detects the first detection in the X axis direction. And the second detection means are provided apart from each other, and the second flexible portion is a first detection means in the Y-axis direction and the Z-axis direction. The second detection means is provided separately from each other, and the third flexible portion is provided with the third detection means and the fourth detection means provided in the X-axis direction apart from each other, and the fourth flexible portion. Is characterized in that the third detection means and the fourth detection means in the Y-axis direction and the Z-axis direction are provided separately from each other.

  Each of the first to fourth detection means has a plurality of detection elements connected in series.

In the physical quantity sensor of the present invention, the number of terminals can be reduced by forming the bridge circuit as a closed circuit without an open end and forming connection terminals of the same potential in a plurality of bridge circuits as common terminals.
Since it has such a configuration, the physical quantity sensor of the present invention can easily calculate each resistance value of the detection means configuring the bridge closed circuit from the calculation. As a result, the circuit can be reduced in size and weight. In addition, there is an effect that the cost can be reduced as a physical quantity sensor.

  The best mode for carrying out the physical quantity sensor of the present invention will be described below in detail with reference to the drawings. In the embodiment of the present invention, the physical quantity sensor is exemplified by a case where it is formed by processing a solid such as a semiconductor substrate. The frame-shaped support portion is surrounded by the frame-shaped support portion, and has a weight portion on the inner side with a predetermined interval, and the weight portion and the support portion are connected by four beam-shaped flexible portions. The flexible part is a laminated film formed by laminating a plurality of films. This structure is referred to as a movable part because it is movable in response to acceleration. This flexible portion is provided with a piezoresistive element as detection means. The piezoresistive element is an element that can receive a physical quantity such as acceleration as a change in resistance value and detect the change in resistance value as an electric signal.

The piezoresistive elements are connected to each other to form a closed circuit bridge circuit without an open end. Three bridge circuits corresponding to the respective axial directions are configured so that the acceleration can be detected as components in the three directions of the X, Y, and Z axes.
A connection terminal which is one of the elements constituting the bridge circuit and a connection terminal which is one of the elements constituting the bridge circuit corresponding to another axial direction are connected to supply the same potential.

[Description of overall configuration: Figure, FIG. 2]
First, the overall configuration will be described with reference to FIGS. FIG. 1 is a plan view schematically showing a physical quantity sensor of the present invention. In FIG. 1, 1 is a weight part, 2 is a support part, 3a is a first flexible part, 3b is a second flexible part, 3c is a third flexible part, 3d is a fourth flexible part, Reference numerals 4a to 4d, 5a to 5d, and 6a to 6d are piezoresistive elements, 70 to 79 are connection terminals, and 8 is a metal wiring.

  For example, the weight part 1, the support part 2, and the flexible parts 3a to 3d have a laminated film structure in which a plurality of insulating layers are provided on a silicon semiconductor substrate. The insulating layer is not particularly limited, but can be composed of a silicon oxide film or a silicon nitride film. The flexible portions 3 a to 3 d are thinner than the weight portion 1 and the support portion 2 and have a flexible structure. The piezoresistive elements 4a to 4d, 5a to 5d, and 6a to 6d have a predetermined shape in a part of the insulating layers of the flexible portions 3a to 3d, and are formed using, for example, an ion implantation technique. The connection terminals 70 to 79 and the metal wiring 8 are formed on the insulating layer of the weight portion 1, the support portion 2, and the flexible portion 3 so as to connect the piezoresistive elements and form a bridge circuit. Although it does not specifically limit, it can comprise with aluminum, copper, and titanium, and you may laminate | stack a several different metal. Since the connection terminals 70 to 79 are also terminals that are connected to the outside, they have a pad shape.

  In FIG. 1, the longitudinal direction of the first flexible part 3a and the third flexible part 3c is the X-axis direction, and the longitudinal direction of the second flexible part 3b and the fourth flexible part 3d is the Y-axis. The direction. A direction orthogonal to the X-axis direction and the Y-axis direction is taken as a Z-axis direction.

In the example shown in FIG. 1, the piezoresistive elements 4a and 4b are provided in the first flexible part, and the piezoresistive elements 4c and 4d are provided in the third flexible part, and the piezoresistors 4a, 4b, 4c, A physical quantity in the X-axis direction is detected in 4d.
Further, the piezoresistive elements 5a and 5b are provided in the second flexible part, and the piezoresistive elements 5c and 5d are provided in the fourth flexible part, and the piezoresistors 5a, 5b, 5c and 5d are used in the Y-axis direction. The physical quantity of is detected.
Further, the piezoresistive elements 6a and 6b are provided in the second flexible portion so as to be separated from the piezoresistive elements 5a and 5b, and the piezoresistive elements 6c and 6d are separated from the piezoresistive elements 5c and 5d and are provided in the fourth flexible part. A physical quantity in the Z-axis direction is detected by the piezoresistors 6a, 6b, 6c, and 6d.

  FIG. 2 is a circuit diagram for explaining an equivalent circuit of the physical quantity sensor of the present invention. FIG. 2 shows three bridge circuits corresponding to the respective axes in the X, Y, and Z axis directions. 40 is a bridge circuit that detects a physical quantity in the X-axis direction, 50 is a bridge circuit that detects a physical quantity in the Y-axis direction, and 60 is a bridge circuit that detects a physical quantity in the Z-axis direction. Each bridge circuit is connected to the connection terminal 70 in common. The connection terminal 70 short-circuits a predetermined terminal of each bridge circuit as a common potential terminal. The connection terminal 70 is connected to a wiring for supplying the same potential and is applied with the same predetermined potential, which will be described in detail later.

The bridge circuit 40 for detecting the physical quantity in the X-axis direction includes piezoresistive elements 4a to 4d and connection terminals 70, 71, 74, and 75.
The connection terminal 71 is provided between the piezoresistive element 4a and the piezoresistive element 4b. The connection terminal 74 is provided between the piezoresistive element 4a and the piezoresistive element 4d. The connection terminal 75 is provided between the piezoresistive element 4b and the piezoresistive element 4c. The connection terminal 70 is provided between the piezoresistive element 4d and the piezoresistive element 4c.

The bridge circuit 50 for detecting a physical quantity in the Y-axis direction includes piezoresistive elements 5a to 5d and connection terminals 70, 72, 76, and 77.
The connection terminal 72 is provided between the piezoresistive element 5a and the piezoresistive element 5b. The connection terminal 76 is provided between the piezoresistive element 5a and the piezoresistive element 5d. The connection terminal 77 is provided between the piezoresistive element 5b and the piezoresistive element 5c. The connection terminal 70 is provided between the piezoresistive element 5d and the piezoresistive element 5c.

The bridge circuit 60 for detecting a physical quantity in the Z-axis direction includes piezoresistive elements 6a to 6d and connection terminals 70, 73, 78, and 79.
The connection terminal 73 is provided between the piezoresistive element 6a and the piezoresistive element 6b. The connection terminal 78 is provided between the piezoresistive element 6a and the piezoresistive element 6c. The connection terminal 79 is provided between the piezoresistive element 6b and the piezoresistive element 6d. The connection terminal 70 is provided between the piezoresistive element 6c and the piezoresistive element 6d.

  In the example shown in FIG. 1, each connection terminal is provided between the piezoresistive elements connected in series. Of course, the arrangement of the connection terminals 70 to 79 and each piezoresistive element can be freely selected according to the use of the physical quantity sensor of the present invention.

[Description of how to detect physical quantity: FIGS. 1 and 2]
Next, a state where a physical quantity applied to the physical quantity sensor of the present invention is obtained as an electric signal will be described. When an external force is applied to the physical quantity sensor of the present invention, the weight portion 1 is physically displaced according to the external force, and the flexible portion 3 bends accordingly, and the piezoresistive elements 4a to 4d, 5a to 5d, 6a to 6d. The resistance value of changes. The change in resistance value is detected by an external electronic device (not shown) connected via the connection terminals 70 to 79.
An example in which an external force is applied in a direction parallel to the X-axis direction will be described. When such an external force is applied, the weight portion 1 is tilted and the flexible portion 3 is bent accordingly. For example, at this time, it is assumed that the resistance value of the piezoresistive element 4a and the piezoresistive element 4c decreases, and the resistance value of the piezoresistive element 4b and piezoresistive element 4d increases. In this state, a current is passed between the connection terminal 71 and the connection terminal 70 in the bridge circuit 40 shown in FIG. Then, a voltage difference is generated between the connection terminal 74 and the connection terminal 75, and a current flows between the connection terminals. This current value is detected as a physical quantity.

  In the physical quantity applied to the physical quantity sensor of the present invention, even when an external force is applied in a direction parallel to the X-axis direction, the resistance value of the piezoresistive element 4a and the piezoresistive element 4c always decreases, and the piezoresistive element 4b and the piezoresistive element 4c. The resistance value of the resistance element 4d does not increase. It varies depending on the strength of the applied external force and the structure of the flexible part of the physical quantity sensor.

[Description of Calculation Method of Piezoresistance: FIG. 3]
Next, a method for obtaining the resistance value of each piezoresistive element by calculation will be described. In order to make the calculation formula easy to see, description will be made with reference to FIG. FIG. 3 is obtained by replacing the components of the bridge circuit shown in FIG. 2 with resistors. For example, taking the bridge circuit 40 as an example, the piezoresistive element 4a is R1, the piezoresistive element 4b is R2, the piezoresistive element 4c is R3, and the piezoresistive element 4d is R4. The connection terminal 71 is I, the connection terminal 74 is V1, the connection terminal 75 is V2, and the connection terminal 70 is GND (ground or 0 V). The combined resistance between the connection terminals is Ra between I and V1, Rb between I and V2, Rc between V2 and GND, Rd between V1 and GND, and V1 and V2. The interval is Re. Then, the following formulas (1) to (6) are established.

ARa = R1 (R2 + R3 + R4): Formula (1)
ARb = R2 (R1 + R3 + R4): Formula (2)
ARc = R3 (R1 + R2 + R4): Formula (3)
ARd = R4 (R1 + R2 + R3): Formula (4)
ARe = (R1 + R2) (R3 + R4): Formula (5)
A = R1 + R2 + R3 + R4: Formula (6)

Next, Equation (7) is calculated from Equation (1) and Equation (6).
A = R1 ² / (R1-Ra): Formula (7)

Next, Expression (8) is calculated from Expression (1), Expression (2), and Expression (5).
R2 = A * (Ra + Rb-Re) / 2R1: Formula (8)

Equation (5) is modified from the above equation to calculate equation (9).
R3 + R4 = (A × Re) / (R1 + R2)
= (A × Re) / (R1 + (A × (Ra + Rb−Re) / 2R1)): Formula (9)

By substituting Equation (7), Equation (8), and Equation (9) into Equation (6) and solving for R1, Equation (10) is obtained.
R1 = (4RaRe− (Ra−Rb + Re) ² ) / (2 (−Ra + Rb + Re))
: Formula (10)

Substituting R1 into equation (7) to obtain A, substituting R1 and A into equation (8) to obtain R2. By the same procedure, Formula (11) is obtained using Formula (3) and Formula (6).
A = A ′ = R3 ² / (R3-Rc): Formula (11)

Next, Formula (12) is obtained using Formula (3), Formula (4), and Formula (5).
R4 = A ′ × (Rc + Rd−Re) / 2R3: Formula (12)

Next, equation (5) is modified from the above equation to calculate equation (13).
R1 + R2 = (A ′ × Re) / (R3 + R4)
= (A ′ × Re) / (R3 + ((A ′ × (Rc + Rd−Re)) / 2R3)
: Formula (13)

Next, Expression (14) is obtained by substituting Expression (11), Expression (12), and Expression (13) into Expression (6) and solving for R3.
R3 = (4RcRe− (Rc−Rd + Re) ² ) / (2 (−Rc + Rd + Re))
: Formula (14)

  By substituting R3 into equation (11), A ′ is obtained, and R4 is obtained from equation (12). By the above calculation method, the resistance value of the piezoresistor between the connection terminals can be calculated.

[Description of different configuration: FIG. 4]
The physical quantity sensor of the present invention is not limited to the example shown in FIG. FIG. 4 is a plan view schematically showing the physical quantity sensor of the present invention and explains an example different from the example shown in FIG. The example shown in FIG. 4 is a view seen from the same direction as the example shown in FIG. Moreover, the same number is given to the same configuration already described, and the description is omitted.

In the example shown in FIG. 4, piezoresistive elements 6e-6h are newly added to the piezoresistive elements for detecting the physical quantity in the Z-axis direction in addition to the piezoresistive elements 6a-6d.
The piezoresistive element 6e and the piezoresistive element 6f are provided in the first flexible portion 3a apart from the piezoresistive element 4a and the piezoresistive element 4b. Similarly, the piezoresistive element 6g and the piezoresistive element 6h are provided apart from the piezoresistive element 4c and the piezoresistive element 4d in the third flexible portion 3c.

By adopting such a configuration, the four flexible portions of the first flexible portion 3a, the second flexible portion 3b, the third flexible portion 3c, and the fourth flexible portion 3d are respectively provided in the four flexible portions. Four piezoresistive elements can be provided, and the weight balance between the flexible portion in the X-axis direction and the flexible portion in the Y-axis direction can be made substantially equal.
In addition, since the number of piezoresistive elements that are detection means in the Z-axis direction increases, the displacement amount of the resistance value of the piezoresistive element with respect to the flexure of the flexible portion increases, so that the detected displacement amount in the Z-axis direction can be increased. Therefore, the sensitivity as a physical quantity sensor is improved.

  In the example shown in FIG. 4, an example is shown in which the weight balance of the flexible portion and the detected displacement amount in the Z-axis direction are increased. However, it can be changed according to the use state of the physical quantity sensor of the present invention. For example, when it is desired to increase the detected displacement amount in the X-axis direction, the number of piezoresistive elements corresponding to the axial direction may be increased.

  The same applies to the weight balance of the flexible portion. The piezoresistive element is formed with a shape in the flexible portion, and in order to obtain a predetermined resistance value, it is possible to inject a predetermined impurity by using an impurity injection technique applying a semiconductor device manufacturing process technique. At that time, the weight balance of each flexible portion can be made substantially equal by changing the amount of impurities to be implanted, the ion species, and the shape of the piezoresistive element.

  Moreover, since the weight balance of both the flexible parts can be changed also by changing the width and thickness of the flexible part in the X-axis direction and the flexible part in the Y-axis direction, the electronic device using the physical quantity sensor of the present invention. A physical quantity sensor can be configured by freely combining these in accordance with the number and shape of piezoresistive elements according to the requirements of the device or system.

  In the physical quantity sensor of the present invention, the connection terminal 70 of each bridge circuit is short-circuited and the GND potential is applied as the common potential terminal. However, of course, a predetermined potential necessary for measuring the resistance value may be applied. Needless to say. Further, the terminals corresponding to the connection terminals 70 of each bridge circuit may be independently connected to the GND potential or a constant potential. Further, for example, a constant voltage may be applied to the connection terminal 70, and the connection terminals 71, 72, 73 may be set to the GND potential. If it does so, the same value can be measured by the opposite sign to the above-mentioned detection example.

  The physical quantity sensor of the present invention can be used for sensors such as a pressure sensor and an acceleration sensor. In particular, since there are few connection terminals and it can respond to miniaturization, it is suitable for a sensor used in a miniaturized electronic device or system.

It is a top view for demonstrating the physical quantity sensor of this invention. It is an equivalent circuit diagram for demonstrating the physical quantity sensor of this invention. It is a circuit diagram for demonstrating calculation of the resistance value of each piezoresistive element which comprises the physical quantity sensor of this invention. It is a top view for demonstrating the different shape of the physical quantity sensor of this invention. It is a top view for demonstrating the prior art shown in patent document 1. FIG. It is an equivalent circuit diagram for demonstrating the prior art shown in patent document 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Weight part 2 Support part 3a 1st flexible part 3b 2nd flexible part 3c 3rd flexible part 3d 4th flexible part 4a, 4b Piezoresistive element 4c provided in a 1st flexible part 4d Piezoresistive elements 5a, 5b provided in the third flexible part Piezoresistive elements 5c, 5d provided in the second flexible part Piezoresistive elements 6a, 6b provided in the fourth flexible part Piezoresistive elements 6c, 6d Piezoresistive elements 6e, 6f provided in the fourth flexible part Piezoresistive elements 6g, 6h provided in the first flexible part Piezoresistive elements 70-79 connected in the third flexible part Terminal 8 Metal wiring

Claims (3)

A movable part is constituted by a weight part, a support part provided at a predetermined interval from the weight part, and a flexible part that connects the weight part and the support part, and the movable part is provided with a plurality of axial directions. A plurality of detection means for detecting the physical quantity of
In the physical quantity sensor that connects the detection means to each other, forms a plurality of bridge circuits corresponding to the plurality of axial directions, and detects a physical quantity using the bridge circuits,
The bridge circuit becomes a closed circuit without an open end by connecting the detection means to each other, and has a connection terminal at each connection portion of the detection means,
Whether one of the connection terminals of the bridge circuit corresponding to one axial direction of the plurality of axial directions is short-circuited with one of the connection terminals of the bridge circuit corresponding to another axial direction Or a physical quantity sensor connected to a wiring for supplying the same potential. The connection terminal includes an input terminal, a common potential terminal, a first output terminal, and a second output terminal.
The bridge circuit includes a first detection element between the input terminal and the first output terminal, and a second detection unit between the input terminal and the second output terminal. Providing a third detection means between a common potential terminal and the second output terminal, and providing a fourth detection means between the common potential terminal and the first output terminal;
One direction parallel to one plane of the physical quantity sensor is the X direction, a direction parallel to the one plane and perpendicular to the X direction is the Y direction, a direction passing through the one plane and perpendicular to the X direction and the Y direction is When the Z direction is defined, the plurality of axial directions are an X axis direction, a Y axis direction, and a Z axis direction, respectively.
The first flexible portion is provided by separating the first detection means and the second detection means in the X-axis direction from each other.
The second flexible portion is provided by separating the first detection means and the second detection means in the Y-axis direction and the Z-axis direction, respectively.
The third flexible portion is provided by separating the third detection means and the fourth detection means in the X-axis direction from each other.
The said 4th flexible part provides the said 3rd detection means and the said 4th detection means of the said Y-axis direction and the said Z-axis direction separately, respectively, The said 4th flexible part is characterized by the above-mentioned. Physical quantity sensor.   The physical quantity sensor according to claim 1, wherein each of the first to fourth detection units has a plurality of detection elements connected in series.

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