WO2016170743A1

WO2016170743A1 - Pressure sensor

Info

Publication number: WO2016170743A1
Application number: PCT/JP2016/001891
Authority: WO
Inventors: 大野　和幸
Original assignee: 株式会社デンソー
Priority date: 2015-04-22
Filing date: 2016-04-04
Publication date: 2016-10-27
Also published as: JP2016205989A

Abstract

This pressure sensor is provided with a sensing unit (10) that outputs a detection signal corresponding to pressure; an amplifying unit (30), which amplifies the detection signal at a predetermined amplification factor, and outputs the signal as a pressure signal; a determining unit (40); and a signal output unit (60). The determining unit (40) determines, on the basis of determining reference, whether the signal value of the pressure signal is a value of lower pressure with respect to a reference value at which a pressure detection range is halved. In the cases where the determining unit (40) determines that the signal value of the pressure signal is not a value of the lower pressure with respect to the reference value, the signal output unit (60) outputs a determination signal indicating that the signal value of the pressure signal is not a value of the lower pressure with respect to the reference value.

Description

Pressure sensor

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2015-87484 filed on April 22, 2015, the contents of which are incorporated herein by reference.

The present disclosure relates to a pressure sensor for measuring pressure.

Patent Document 1 proposes a pressure measuring device having a diaphragm in which a part of a sensor wafer is locally thinly formed. This pressure measuring device acquires the sensor output corresponding to the pressure value by electrically measuring the deformation amount of the diaphragm deformed by the pressure of the pressure medium.

JP 2011-191273 A

¡When the pressure of the pressure medium is small, the amount of deformation of the diaphragm is small. In this case, since the degree of non-linearity of the deformation of the diaphragm is small, the sensor output corresponding to the amount of deformation of the diaphragm changes almost linearly. However, as the pressure of the pressure medium increases, the degree of nonlinearity of the diaphragm deformation increases, and therefore the nonlinear component included in the sensor output corresponding to the amount of diaphragm deformation increases.

Therefore, it is conceivable to suppress nonlinear deformation in the diaphragm by adjusting the size and thickness of the diaphragm so that the nonlinear component included in the sensor output is within a certain range in the required pressure detection range. However, since the deformation of the diaphragm itself is very small on the low pressure side in the pressure detection range, it is necessary to amplify the sensor output by the amplifier circuit. Further, since the low-pressure side sensor output is amplified with an amplification factor that matches the upper limit value of the pressure detection range, the low-pressure side pressure cannot be detected with high accuracy. Furthermore, since the range of the amount of deformation of the diaphragm cannot be increased, the detectable pressure detection range is limited.

This disclosure is intended to provide a pressure sensor that can achieve both high accuracy of sensor output on the low pressure side in the pressure detection range and expansion of the pressure detection range.

In one embodiment of the present disclosure, the pressure sensor detects a pressure in the pressure detection range, outputs a detection signal corresponding to the pressure, and inputs the detection signal from the sensing unit, and the detection signal is input to a predetermined amplification factor. And an amplifying unit that amplifies and outputs as a pressure signal.

The pressure sensor receives a pressure signal from the amplifying unit and determines whether or not the signal value of the pressure signal is lower than the reference value with respect to the reference value that divides the pressure detection range into two. The determination part which determines according to is provided.

Further, the pressure sensor determines that the signal value of the pressure signal is not lower than the reference value when the determination unit determines that the signal value of the pressure signal is not lower than the reference value. A signal output unit for outputting a signal is provided.

According to this, since the pressure signal on the lower pressure side than the reference value in the pressure detection range is amplified by the amplification unit, the pressure on the low pressure side in the pressure detection range can be detected with high accuracy. In addition, since it is not necessary to limit the structure of the sensing unit for detecting pressure, the pressure detection range is not limited by the structure of the sensing unit. That is, the pressure detection range can be set wider than the conventional one. Therefore, it is possible to achieve both high accuracy of the signal value on the low pressure side in the pressure detection range and expansion of the pressure detection range.

It is the figure which showed the structure of the pressure sensor which concerns on 1st Embodiment. It is the figure which showed the whole circuit structure of the pressure sensor. It is the figure which showed the relationship between the pressure of a pressure medium, the signal value of a pressure signal, and a threshold value. It is the figure which showed the sensor output of the low voltage | pressure side and the sensor output of the high voltage | pressure side in a pressure detection range. It is the figure which showed the structure of the pressure sensor which concerns on 2nd Embodiment. It is the figure which showed the structure of the pressure sensor which concerns on 3rd Embodiment.

Embodiments will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
A first embodiment will be described with reference to the drawings. The pressure sensor according to the present embodiment detects the pressure of the pressure medium. As shown in FIG. 1, the pressure sensor includes a sensor chip 1 and a circuit chip 2.

The sensor chip 1 and the circuit chip 2 are electrically connected by a VS wire 3, a VP wire 4, and a VM wire 5. Each of the wires 3 to 5 is a bonding wire. A circuit constituting a pressure sensor is formed in the sensor chip 1 and the circuit chip 2.

Specifically, as illustrated in FIG. 2, the pressure sensor includes a sensing unit 10, a power supply unit 20, a first amplification unit 30, a determination unit 40, a storage unit 50, a signal output unit 60, a signal switching unit 70, and A second amplifying unit 80 is provided. The sensing unit 10 is formed on the sensor chip 1. On the other hand, the power supply unit 20, the first amplification unit 30, the determination unit 40, the storage unit 50, the signal output unit 60, the signal switching unit 70, and the second amplification unit 80 are formed in the circuit chip 2.

The sensor chip 1 and the circuit chip 2 are formed based on a semiconductor substrate such as a silicon substrate. That is, each component of the pressure sensor is formed on the sensor chip 1 and the circuit chip 2 by a semiconductor process. The sensor chip 1 and the circuit chip 2 are accommodated in a case (not shown).

The sensing unit 10 detects the pressure in the pressure detection range. The sensing unit 10 is formed, for example, in a diaphragm (not shown) in which a part of the sensor chip 1 is thinned. The pressure detection range is a preset range, for example, a range of 0 Pa to several MPa. The pressure detection range is adjusted by the thickness and size of the diaphragm. If the voltage range of the power supply is 0 V to 5 V, the pressure detection range is 0.5 V to 4.5 V, for example.

In addition, the sensing unit 10 includes a bridge circuit unit 11, a VS wiring 12, a VP wiring 13, and a VM wiring 14. The bridge circuit unit 11 includes a first resistor 11a, a second resistor 11b, a third resistor 11c, and a fourth resistor 11d whose resistance values change according to the application of pressure. The first resistor 11a and the second resistor 11b are connected in series, and the third resistor 11c and the fourth resistor 11d are connected in series. Each of the resistors 11a to 11d is a diffused resistor such as a P ++ type region or an N−− type region formed in the diaphragm of the sensor chip 1.

The VS wiring 12 is a wiring for applying an input voltage to the bridge circuit unit 11. A part of the VS wiring 12 is configured as the VS wire 3 described above.

One of the VP wirings 13 is connected to the first middle point 11e of the first resistor 11a and the second resistor 11b, and the other is connected to the first amplifying unit 30. A part of the VP wiring 13 is configured as the VP wire 4 described above.

One of the VM wirings 14 is connected to the second middle point 11f of the third resistor 11c and the fourth resistor 11d, and the other is connected to the first amplifying unit 30. A part of the negative electrode wiring is configured as the VM wire 5 described above.

The sensing unit 10 outputs a potential difference between the first voltage at the first middle point 11e and the second voltage at the second middle point 11f as a detection signal based on the input voltage applied to the bridge circuit unit 11. Since the signal value of the detection signal changes in accordance with the magnitude of the pressure applied to the diaphragm of the sensor chip 1, the first voltage corresponding to the magnitude of the pressure is applied to the VP wiring 13 and the second voltage is set to VM. Applied to the wiring 14.

The pressure detected by the diaphragm may be an absolute pressure or a differential pressure. The absolute pressure is detected by applying a vacuum pressure to one surface of the diaphragm and applying the pressure of the pressure medium to the other surface. The differential pressure is detected by the pressure applied to both sides of the diaphragm.

The power supply unit 20 is configured as a constant current source that generates a constant current. The power supply unit 20 supplies the constant current (i) to the bridge circuit unit 11 via the VS wiring 12. As a result, an input voltage is applied to the bridge circuit unit 11. The power supply unit 20 may be a constant current source or a constant voltage source.

The first amplifying unit 30 receives the detection signal from the sensing unit 10, amplifies the detection signal with a predetermined amplification factor, and outputs it as a pressure signal. Specifically, the first amplifying unit 30 is configured to receive the first voltage and the second voltage from the bridge circuit unit 11 and amplify the difference voltage between the first voltage and the second voltage with a predetermined amplification factor. This is a differential amplifier circuit unit. In the present embodiment, the first amplifying unit 30 multiplies the signal value of the pressure signal by A.

The determination unit 40 receives the pressure signal from the first amplifying unit 30, and determines whether the signal value of the pressure signal is lower than the reference value with respect to the reference value that divides the pressure detection range into two. Judge according to the criteria. Here, the criterion is a threshold value set in advance for the signal value of the pressure signal.

Also, “dividing the pressure detection range into two parts” is not limited to dividing the pressure detection range into two equal parts. For example, the case where the pressure detection range is divided into 1/3 and 2/3 is also included. In the present embodiment, the reference value for dividing the pressure detection range into two is the median value that bisects the pressure detection range. Thereby, the determination unit 40 determines whether the signal value of the pressure signal is a low-pressure side value or a high-pressure side value with reference to the reference value.

The determination unit 40 has a function of determining whether or not the VS wiring 12, the VP wiring 13, and the VM wiring 14 are disconnected. That is, the determination unit 40 determines whether the signal value of the pressure signal is a value indicating the disconnection of the VS wiring 12 according to the determination criterion. Similarly, the determination unit 40 determines whether the signal value of the pressure signal is a value indicating the disconnection of the VP wiring 13 or the VM wiring 14 according to the determination criterion.

The storage unit 50 is a storage unit in which determination criteria used for determination by the determination unit 40 are stored. In this embodiment, the determination criterion includes four threshold values of first to fourth threshold values set for the signal value of the pressure signal. These threshold values are the smallest value of the first threshold value, and are the larger values in the order of the second threshold value, the third threshold value, and the fourth threshold value.

The first threshold value is used to determine whether or not the VP wiring 13 is disconnected. The first threshold value and the second threshold value are used to determine whether the signal value of the pressure signal is a value on the low pressure side. The second threshold is a threshold corresponding to the signal value of the pressure signal that bisects the pressure detection range.

The second threshold value and the third threshold value are used for determining whether the signal value of the pressure signal is a value on the high pressure side. The third threshold value and the fourth threshold value are used for determining disconnection of the VS wiring 12. The fourth threshold value is used to determine disconnection of the VM wiring 14.

The storage unit 50 is a memory capable of writing and erasing data. That is, the criterion is stored in the storage unit 50 so as to be rewritable. Thereby, after manufacturing the product, it becomes possible to write the determination standard according to the situation and environment in which the pressure sensor is used, the measurement object, etc., and the versatility of the pressure sensor is improved.

The determination unit 40 performs determination using these determination criteria stored in the storage unit 50. The determination unit 40 outputs the determination result to the signal output unit 60 and the signal switching unit 70.

The signal output unit 60 generates and outputs a determination signal according to the determination result of the determination unit 40 when the determination unit 40 determines that the signal value of the pressure signal is not a value lower than the reference value. The determination signal is a signal indicating that the signal value of the pressure signal is not a value lower than the reference value. In the present embodiment, the determination signal is a signal indicating that the signal value of the pressure signal indicates the high voltage side, or a signal indicating disconnection of the wirings 12 to 14.

Specifically, the signal output unit 60 outputs a high-pressure signal indicating that the signal value of the pressure signal is a value on the high-pressure side with respect to the reference value as the determination signal. The signal output unit 60 outputs a VS disconnection signal indicating a disconnection of the VS wiring 12 as a determination signal. Further, the signal output unit 60 outputs a VP disconnection signal indicating disconnection of the VP wiring 13 as a determination signal, and outputs a VM disconnection signal indicating disconnection of the VM wiring 14 as a determination signal.

The high-voltage signal, the VS disconnection signal, the VP disconnection signal, and the VM disconnection signal that are determination signals are signals having different duty ratios, for example. These determination signals may be signals having a waveform such as a triangular wave, a sine wave, or a rectangular wave according to the determination result. Thus, the signal output unit 60 is a circuit that generates a plurality of determination signals according to the determination result.

The signal switching unit 70 switches the output path according to the determination result to the determination unit 40 so that one of the output of the first amplification unit 30 and the output of the signal output unit 60 is output to the external device. For this reason, the signal switching unit 70 includes a first switch 71 and a second switch 72. The first switch 71 connects the first amplification unit 30 and the second amplification unit 80. The second switch 72 connects the signal output unit 60 and the output terminal 90. Each of the

switches

71 and 72 is configured as a semiconductor switch, for example.

Specifically, when the determination unit 40 determines that the signal value of the pressure signal is lower than the reference value, the signal switching unit 70 turns on the first switch 71 and turns off the second switch 72. By doing so, the pressure signal can be output to the outside. On the other hand, when the determination unit 40 determines that the signal value of the pressure signal is not a value lower than the reference value, the signal switching unit 70 determines by turning off the first switch 71 and turning on the second switch 72. The signal can be output to the outside. As a result, either the pressure signal or the determination signal can be output from the pressure sensor to the outside.

The second amplifying unit 80 receives the pressure signal from the first amplifying unit 30, amplifies the pressure signal with a predetermined amplification factor, and outputs it as a sensor output. The second amplifying unit 80 is configured as a differential amplifier circuit unit, for example. The second amplifying unit 80 multiplies the signal value of the pressure signal by B. Therefore, the pressure sensor amplifies the pressure signal by two stages and outputs it as the sensor output.

The operation of the pressure sensor will be described. First, a description will be given of a normal state in which the wires 12 to 14 are not disconnected. When the pressure of the pressure medium is applied to the diaphragm of the sensor chip 1, a detection signal corresponding to the magnitude of the pressure is output from the sensing unit 10. The detection signal is multiplied by A by the first amplifying unit 30 and output as a pressure signal.

As shown in FIG. 3, the signal value of the pressure signal is in the range between the first threshold value and the third threshold value. Further, the signal value of the pressure signal changes almost linearly with respect to the pressure value. And it is determined by the determination part 40 whether the signal value of a pressure signal is a value of the low voltage | pressure side rather than a reference value. That is, it is determined whether or not the signal value of the pressure signal is included in the range from the first threshold value to the second threshold value. In FIG. 3, the pressure detection range is shown in a range of 0% to 100%.

When the signal value of the pressure signal is included in the range from the first threshold value to the second threshold value, the signal value of the pressure signal is a value on the lower pressure side than the reference value. In this case, the determination unit 40 turns on the first switch 71 and turns off the second switch 72. As a result, the pressure signal on the low pressure side is further multiplied by B by the second amplifying unit 80 and output as a sensor output. That is, as shown in FIG. 4, when the signal value of the pressure signal is a value on the low pressure side, a pressure signal that changes almost linearly according to the pressure value is output as the sensor output.

On the other hand, when the signal value of the pressure signal is larger than the second threshold value, that is, when the signal value of the pressure signal is included in the range from the second threshold value to the third threshold value, the signal value of the pressure signal is higher than the reference value. Is the value of In this case, the determination unit 40 turns off the first switch 71 and turns on the second switch 72. As a result, no pressure signal is output. Further, a high voltage signal is output as a determination signal from the signal output unit 60 according to the determination result of the determination unit 40. That is, as shown in FIG. 4, when the signal value of the pressure signal is a value on the high pressure side, a signal with a predetermined duty ratio is output as a sensor output.

Subsequently, the case where the wirings 12 to 14 are disconnected will be described. The disconnection of each of the wirings 12 to 14 has the highest possibility of disconnection of each of the wires 3 to 5, but there is also the possibility of disconnection of a portion formed in the sensor chip 1 or the circuit chip 2 of each of the wirings 12 to 14. .

As shown in FIG. 3, when the VS wiring 12 is disconnected, the determination unit 40 determines whether or not the signal value of the pressure signal is included in the range from the third threshold value to the fourth threshold value. When the signal value of the pressure signal is included in the range from the third threshold value to the fourth threshold value, the VS wiring 12 is disconnected.

Further, when the VP wiring 13 is disconnected, the determination unit 40 determines whether or not the signal value of the pressure signal is smaller than the first threshold value. When the signal value of the pressure signal is smaller than the first threshold value, the VP wiring 13 is disconnected.

Further, when the VM wiring 14 is disconnected, the determination unit 40 determines whether or not the signal value of the pressure signal is larger than the fourth threshold value. When the signal value of the pressure signal is larger than the fourth threshold value, the VM wiring 14 is disconnected.

In such a disconnection, the determination unit 40 turns off the first switch 71 and turns on the second switch 72. A determination signal is output from the signal output unit 60. A VS disconnection signal is output from the signal output unit 60 when the VP wiring 13 is disconnected, a VP disconnection signal is output from the signal output unit 60 when the VP wiring 13 is disconnected, and a signal output unit 60 when the VM wiring 14 is disconnected. A VM disconnection signal is output. These determination signals are set to different duty ratios. These determination signals are output to the outside as sensor outputs.

The sensor output output from the pressure sensor as described above is input to an external device that uses the pressure value for control. Then, the content of the sensor output is identified in the external device and used for control or the like.

As described above, in the present embodiment, since the pressure signal on the low pressure side than the reference value in the pressure detection range detectable by the sensing unit 10 is amplified by the first amplification unit 30, the low pressure side in the pressure detection range. The pressure can be detected with high accuracy. In the present embodiment, the pressure signal is also amplified by the second amplifying unit 80, so that the accuracy of the signal value of the pressure signal can be improved.

Further, when the signal value of the pressure signal is not a value lower than the reference value in the pressure detection range, a determination signal is generated. In other words, accuracy is not required for the pressure value on the high pressure side of the pressure detection range. For this reason, it is not necessary to restrict | limit the structure of the sensing part 10 so that the pressure value of a high voltage | pressure side can be detected with high precision. That is, since it is not necessary to match the accuracy of the pressure value on the low pressure side in the pressure detection range with the accuracy of the pressure value on the high pressure side, the pressure detection range can be set wider than in the past. Therefore, it is possible to achieve both high accuracy of the signal value on the low pressure side in the pressure detection range and expansion of the pressure detection range.

Further, in the present embodiment, when there is no disconnection in each of the wirings 12 to 14 and the signal value of the pressure signal is higher than the reference value, the high pressure side pressure is applied to the sensing unit 10. A high pressure signal is output from the pressure sensor. For this reason, high-precision sensor output is not required for the entire pressure detection range, and high-precision sensor output is required on the low-pressure side, while it is only necessary to detect whether or not pressure is applied on the high-pressure side of the pressure detection range. It can meet the needs of pressure measurement.

Specifically, in a system that uses a pressure sensor in a vehicle, for example, AT hydraulic pressure is measured. In this case, the pressure detection range is 0 to 1 MPa. The range in which pressure is actually detected with high accuracy is about 0 to 0.3 MPa. In such a system, it can be determined by a high-pressure signal that a high pressure is applied on the high-pressure side from 0.3 MPa. Therefore, the pressure sensor according to the present embodiment can function not only as pressure measurement but also as a pressure switch.

The first amplifying unit 30 corresponds to an “amplifying unit”. The VS wire 3 corresponds to an “input bonding wire”, the VP wire 4 corresponds to a “first bonding wire”, and the VM wire 5 corresponds to a “second bonding wire”.

VS wiring 12 corresponds to “input wiring”, VP wiring 13 corresponds to “first wiring”, and VM wiring 14 corresponds to “second wiring”. Further, the VS disconnection signal corresponds to the “input disconnection signal”, the VP disconnection signal corresponds to the “first disconnection signal”, and the VM disconnection signal corresponds to the “second disconnection signal”.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIG. 5, the signal output unit 60 is configured to generate and output each determination signal. That is, the signal output unit 60 includes a first signal output unit 61 that generates and outputs a high-voltage signal, a second signal output unit 62 that generates and outputs a VS disconnection signal, and a third signal output unit that generates and outputs a VP disconnection signal. 63, a fourth signal output unit 64 for generating and outputting a VM disconnection signal. Each signal output unit 61 to 64 always outputs a signal.

The signal switching unit 70 includes a third switch 73 corresponding to the first signal output unit 61, a fourth switch 74 corresponding to the second signal output unit 62, a fifth switch 75 corresponding to the third signal output unit 63, A sixth switch 76 corresponding to the fourth signal output unit 64 is provided.

According to such a configuration, the signal output unit 60 does not need to generate a determination signal according to the determination result of the determination unit 40, turns on any of the

switches

71 and 73 to 76 according to the determination result, and others. Can be turned off. As described above, the signal output unit 60 may be divided into a plurality of parts instead of one configuration.

(Third embodiment)
In the present embodiment, parts different from the first and second embodiments will be described. As shown in FIG. 6, the pressure sensor does not include the signal switching unit 70. Specifically, the signal output unit 60 is connected to output terminals 91 to 94 corresponding to each determination signal. And the signal output part 60 outputs a high voltage signal to the output terminal 91 according to the determination result of the determination part 40, outputs a VS disconnection signal to the output terminal 92, outputs a VP disconnection signal to the output terminal 93, VM A disconnection signal is output to the output terminal 94.

In such a configuration, the pressure signal is always output as the sensor output from the second amplifying unit 80, while the determination signal is output according to the determination result of the determination unit 40. Although the number of output terminals 90 to 94 increases, the signal switching unit 70 can be dispensed with. The external device identifies the signal input from the pressure sensor and uses it for control.

(Other embodiments)
The configuration of the pressure sensor shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and other configurations may be used. For example, each of the resistors 11a to 11d constituting the sensing unit 10 is not a diffused resistor, but may have another configuration in which the resistance value changes according to the pressure.

In each of the above embodiments, the second amplifying unit 80 is provided, but this is a configuration in which the pressure signal is further amplified to achieve high accuracy. Therefore, if the first amplifier 30 can sufficiently amplify the signal, the second amplifier 80 may not be provided in the pressure sensor.

In each of the above embodiments, the disconnection of each of the wirings 12 to 14 is detected, but this is an example of the configuration of the pressure sensor. Therefore, the pressure sensor may be configured without a disconnection detection function. In this case, the pressure sensor outputs a low pressure side pressure signal or a high pressure signal.

Further, the pressure sensor is not limited to the two-chip configuration of the sensor chip 1 and the circuit chip 2, and may be formed on one chip or may be formed on three chips. Since the wires 3 to 5 are unnecessary in the case of one chip, the determination unit 40 detects disconnection of the wirings 12 to 14 formed in one chip. On the other hand, in the case of three or more chips, since there is a high possibility of disconnection of the bonding wires connecting the chips, the disconnection of the bonding wires is detected.

In each of the above embodiments, the determination criterion is stored in the storage unit 50, but the determination criterion may be set in the determination unit 40. Further, the determination criteria stored in the storage unit 50 may not be rewritable. That is, the determination reference data may be fixed in the storage unit 50.

Claims

A sensing unit (10) for detecting a pressure in a pressure detection range and outputting a detection signal corresponding to the pressure;
An amplification unit (30) that receives the detection signal from the sensing unit (10), amplifies the detection signal at a predetermined amplification factor, and outputs the amplified signal as a pressure signal;
The pressure signal is input from the amplifying unit (30), and it is determined whether or not the signal value of the pressure signal is lower than the reference value with respect to a reference value for dividing the pressure detection range into two A determination unit (40) for determining according to a reference;
When it is determined by the determination unit (40) that the signal value of the pressure signal is not a value lower than the reference value, the signal value of the pressure signal is not a value lower than the reference value. A signal output unit (60) for outputting a determination signal indicating;
Equipped with pressure sensor.
When the determination unit (40) determines that the signal value of the pressure signal is lower than the reference value, the pressure signal can be output to the outside, while the determination unit (40) When it is determined that the signal value of the pressure signal is not a value lower than the reference value, a signal switching unit (70) is provided that switches an output path so that the determination signal can be output to the outside. Item 2. The pressure sensor according to Item 1.
The pressure sensor according to claim 1 or 2, wherein the signal output unit (60) outputs a high-pressure signal indicating that the signal value of the pressure signal is higher than the reference value as the determination signal.
The sensing unit (10)
A bridge circuit unit (11) configured by a first resistor (11a), a second resistor (11b), a third resistor (11c), and a fourth resistor (11d) whose resistance value changes according to the application of pressure; ,
A first wiring (13) connected to a first middle point (11e) of the first resistance (11a) and the second resistance (11b);
A second wiring (14) connected to a second middle point (11f) of the third resistor (11c) and the fourth resistor (11d);
The sensing unit (10) outputs a potential difference between the first wiring (13) and the second wiring (14) as the detection signal based on an input voltage applied to the bridge circuit unit (11).
The determination unit (40) determines whether the signal value of the pressure signal is a value indicating a disconnection of the first wiring (13) according to the determination criterion, while the signal value of the pressure signal is the value It is determined whether or not the value indicates a disconnection of the second wiring (14),
When the determination unit (40) determines that the first wiring (13) is disconnected, the signal output unit (60) indicates the disconnection of the first wiring (13) as the determination signal. When the determination unit (40) determines that the second wiring (14) is disconnected while outputting one disconnection signal, the second indicating the disconnection of the second wiring (14) as the determination signal. The pressure sensor according to claim 1, which outputs a disconnection signal.
The sensing unit (10) is formed on the sensor chip (1), and the amplification unit (30) is formed on the circuit chip (2).
Part of the first wiring and part of the second wiring electrically connect the sensing unit (10) of the sensor chip (1) and the amplification unit (30) of the circuit chip (2). Configured as a first bonding wire (4) and a second bonding wire (5),
The pressure sensor according to claim 4, wherein the determination unit (40) determines whether or not the first bonding wire (4) or the second bonding wire (5) is disconnected.
The sensing unit (10) includes a first resistor (11a), a second resistor (11b), a third resistor (11c), and a fourth resistor (11d) whose resistance values change according to the application of pressure. A bridge circuit section (11) and an input wiring (12) for applying an input voltage to the bridge circuit section (11), and outputting the detection signal based on the input voltage,
The determination unit (40) determines whether the signal value of the pressure signal is a value indicating disconnection of the input wiring (12) according to the determination criterion,
When the determination unit (40) determines that the input wiring (12) is disconnected, the signal output unit (60) indicates an input disconnection signal indicating the disconnection of the input wiring (12) as the determination signal. The pressure sensor according to any one of claims 1 to 5, wherein:
The sensing unit (10) is formed on the sensor chip (1), and the power supply unit (20) for generating the input voltage is formed on the circuit chip (2).
A part of the input wiring is configured as an input bonding wire (3) that electrically connects the sensing unit (10) of the sensor chip (1) and the power supply unit (20) of the circuit chip (2). Has been
The pressure sensor according to claim 6, wherein the determination unit (40) determines whether or not the input bonding wire (3) is disconnected.
A storage unit (50) for storing the determination criteria used for determination by the determination unit (40);
The pressure sensor according to any one of claims 1 to 7, wherein the determination unit (40) performs a determination using the determination criterion stored in the storage unit (50).
The pressure sensor according to claim 8, wherein the determination criterion is rewritably stored in the storage unit (50).