Sensor for a physical quantity
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- DENSO CORP
- Filing Date
- 2015-06-11
- Publication Date
- 2026-07-23
AI Technical Summary
Existing physical quantity sensors that house both acceleration and angular velocity sensors in a common housing face issues with detection accuracy due to pressure fluctuations in the housing space, leading to incorrect processing when the detection environment changes.
The sensor includes a self-diagnosis unit that detects the detection environment of the angular velocity sensor by monitoring the vibration state of its vibrating element, allowing for self-diagnosis of abnormal conditions caused by pressure fluctuations.
This configuration ensures accurate detection by preventing incorrect processing by identifying and correcting abnormal detection environments in both sensors, maintaining reliable sensor performance.
Abstract
Description
CROSS-REFERENCE TO RELATED REGISTRATION
[0001] This application is based on Japanese patent application No. 2014-121690, which was filed on June 12, 2014, and the disclosure of which is incorporated herein by reference. TECHNICAL AREA
[0002] The invention relates to a sensor for a physical quantity comprising an accelerometer, provided with a detection section that outputs a sensor signal corresponding to an acceleration, and an angular velocity sensor, which has a detection section that outputs a sensor signal corresponding to an angular velocity, both of which are housed in a housing space of a common housing. TECHNICAL BACKGROUND
[0003] A sensor for a physical quantity, disclosed in related technology, comprises an accelerometer provided with a sensing section that outputs a sensor signal corresponding to an acceleration, and an angular velocity sensor provided with a sensing section that outputs a sensor signal corresponding to an angular velocity, both of which are housed in a housing space of a common housing (see, for example, patent literature 1).
[0004] The accelerometer is preferably in a resting state when no acceleration is applied. Therefore, it is preferred that the accelerometer detects acceleration under atmospheric pressure, where air damping (the resistance of the gas flow) is high. In contrast, the angular velocity sensor has an oscillation or vibration element and detects angular velocity while the vibration element oscillates or vibrates. It is therefore preferred that the angular velocity sensor detects angular velocity under reduced pressure or vacuum, where air damping is low, allowing the vibration element to vibrate easily.
[0005] In one case, where the accelerometer and the angular velocity sensor are housed within the same enclosure, the pressure in the enclosure is set to a vacuum, and the angular velocity sensor is installed directly within the enclosure. Meanwhile, the accelerometer is installed within the enclosure in a packed configuration, where a sensing section is hermetically sealed in an airtight chamber maintained at atmospheric pressure. PRINTED STATEMENT OF TECHNICAL PATENT LITERATURE
[0006] Patent Literature 1: JP2013-101132A BRIEF DESCRIPTION OF THE INVENTION
[0007] In the physical quantity sensor configured as described above, the pressure in the housing and the pressure in the airtight chamber fluctuate when a leak occurs in the airtight chamber of the accelerometer within the packing structure. Furthermore, the accelerometer outputs a sensor signal corresponding to an applied acceleration even when the pressure in the airtight chamber fluctuates. Similarly, the angular velocity sensor outputs a sensor signal corresponding to an applied angular velocity even when the pressure in the housing fluctuates. In short, when the sensing environment changes, acceleration and angular velocity are detected, and the sensing accuracy changes accordingly. However, the physical quantity sensor lacks the ability to "know" the sensing environment.Accordingly, in a case where different processing methods, such as vehicle driving control, are performed using a sensor signal output by the accelerometer and a sensor signal output by the angular velocity sensor, incorrect processing may possibly occur.
[0008] In view of the foregoing difficulties, one objective of the invention is to provide a sensor for a physical quantity that is capable of self-diagnosing a detection environment of an accelerometer and an angular velocity sensor.
[0009] In accordance with one aspect of the invention, the sensor for a physical quantity comprises an accelerometer provided with a sensing section that outputs a sensor signal corresponding to an acceleration; an angular velocity sensor provided with a sensing section having a vibration element that vibrates in a predetermined direction, wherein the sensing section outputs a sensor signal corresponding to an angular velocity from the sensing section; and a housing with a housing space that is pressurized or fixed to a predetermined pressure and accommodates the accelerometer and the angular velocity sensor in the housing space.At least one of the accelerometer and angular velocity sensor is of a packing structure in which a cap section is arranged in a sensor section on which the sensor section is formed, and the sensor section is hermetically sealed in an airtight chamber defined between the sensor section and the cap section.
[0010] The sensor for a physical quantity further includes a detection unit that outputs a detection signal corresponding to a vibration of the vibration element in the angular velocity sensor, and a self-diagnostic unit that self-diagnoses a detection environment of the angular velocity sensor on the basis of the detection signal output by the detection unit.
[0011] Thanks to the configuration described above, the angular velocity sensor's detection environment can be self-diagnosed by the self-diagnostic unit. For example, in the case of a sensor for a physical quantity where only the accelerometer is part of a packing structure and the pressure in the housing is set to a negative or vacuum pressure, the pressure in the housing (the angular velocity sensor's detection environment) fluctuates when a leak occurs in the airtight chamber of the accelerometer within the packing structure, in response to changes in the vibration state of the vibrating element. Therefore, based on the detection signal, it can be determined that the angular velocity sensor's detection environment is abnormal.When a leak occurs in the airtight chamber of the accelerometer within the packing structure, the sensing environment of the angular velocity sensor becomes abnormal. Therefore, it can be determined that the sensing environment of the accelerometer is also abnormal if the angular velocity sensor is abnormal. Consequently, in a case where different processing methods are performed using signals output by the accelerometer and the angular velocity sensor, the execution of incorrect processing can be restricted. BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing and other objectives, features, and advantages of the invention are more readily apparent from the following detailed description with reference to the accompanying drawings. The drawings show:
[0013] Fig. 1 a sectional view of a sensor for a physical quantity according to a first embodiment of the invention;
[0014] Fig. 2 a sectional view of a Fig. 1 shown accelerometer;
[0015] Fig. 3 a supervision of one in Fig. 2 sensor section shown;
[0016] Fig. 4. Supervision of one in Fig. 1 shown angular velocity sensor;
[0017] Fig. 5 a view corresponding to a section along line VV of Fig. 4;
[0018] Fig. Figure 6 shows a view of the circuit configurations of the angular velocity sensor and a circuit board, as shown in Fig. 1, shows;
[0019] Fig. 7 a view showing a relationship between pressure and impedance; and
[0020] Fig. 8 a view showing a relationship between a pressure in an enclosure when a leak occurs in an airtight chamber, and a ratio of a volume of the airtight chamber to a volume of the enclosure. DESCRIPTION OF EXAMPLES OF EXECUTION
[0021] Exemplary embodiments of the invention are described below with reference to the drawings. Furthermore, essentially identical parts and components are designated with the same reference numeral and are described in the following exemplary embodiments. (First embodiment)
[0022] A first embodiment of the invention is described below with reference to the drawings. As shown in Fig. As shown in 1, a sensor for a physical quantity includes a housing. 10 , and the case 10 a housing section or accommodation section 11 and a lid section12 on.
[0023] The housing section 11 It is formed by stacking several ceramic layers made of aluminum oxide or the like and is shaped like a box in which there is a storage or housing space. 15 by providing a first exempted section 13 in a surface 11a and by providing a second exempt section 14 in a ground area of the first excluded section 13 is defined. In the housing section 11 are internal connection ports 16a and 16b on inner wall surfaces (a wall surface of the first excluded section) 13 and a wall surface of the second excluded section 14 ) are provided, and external connection ports not shown are provided on outer wall surfaces. The internal connection ports 16a and16b and the external connection terminals are electrically connected as required by an internal layer wiring system (not shown) or the like, which is provided on the inside.
[0024] The lid section 12 consists of metal or the like and is attached to the surface 11a of the housing section 11 bonded or joined by welding or similar processes to form the housing space 15 to be hermetically sealed or sealed. In the present embodiment, the housing space 15 a negative pressure or vacuum pressure is set, or it is subjected to a negative pressure or vacuum pressure, for example 1 Pa.
[0025] An accelerometer 20 , an angular velocity sensor 30 and a circuit board 40 are in the housing space 15 of the case 10housed or included. More precisely, the circuit board. 40 on a floor area of the second excluded section 14 via an adhesive or bonding agent 51 arranged, and is the accelerometer 20 via an adhesive or bonding agent 52 onto the circuit board 40 Stacked. The circuit board 40 is electrically connected to the internal connection 16b via a bond or connecting wire 61 connected, and the accelerometer 20 is electrically connected to the circuit board 40 via a bond or connecting wire 62 tied together.
[0026] The angular velocity sensor 30 is on the floor area of the first excluded section 13 via an adhesive or bonding agent 53 arranged. Specifically, the angular velocity sensor 30an outer peripheral section or circumferential section 313 on, and is the outer peripheral section 313 to the adhesive 53 bonded. The angular velocity sensor 30 is electrically connected to the internal connection section 16a via a bond or connecting wire 63 tied together.
[0027] The accelerometer 20 It consists of a packed structure that is sealed at atmospheric pressure and installed in the housing in a packed state. The angular velocity sensor 30 is directly in the housing space 15 installed. Therefore, the accelerometer detects 20 an acceleration under atmospheric pressure, whereas the angular velocity sensor 30 an angular velocity under a vacuum or vacuum pressure is measured.
[0028] A configuration of the accelerometer 20, a configuration of the angular velocity sensor 30 and a configuration of the circuit board 40 are described below.
[0029] As in Fig. The accelerometer shown in section 2 is the accelerometer. 20 of a packaging structure including a sensor section 201 and a cap section 202 .
[0030] The sensor section 201 is using a SOI (Silicon on Insulator) substrate. 214 produced from a carrier substrate 211 , an insulating film 212 and a semiconductor layer 213 , which are stacked sequentially. The carrier substrate 211 and the semiconductor layer 213 are produced from a silicon substrate or the like, and the insulating film 212 is produced from an oxide film or the like.
[0031] As in Fig. 2 and Fig. Figure 3 shows the SOI substrate. 214 finely machined in a known manner, and is a capture section. 215 provided. More precisely, by providing a groove section. 216 for the semiconductor layer 213 a movable section 220 , a first fixed section 230 and a second fixed section 240 provided, each with a comb-shaped beam structure, and the three beam structures together form the capture section. 215 , which outputs a sensor signal corresponding to an acceleration.
[0032] An opening section 217 a rectangular shape is suitable for the insulating film 212 by removing a section corresponding to areas where the beam structures 220 , 230 and 240 are provided by sacrificial layer etching or the like.
[0033] The movable section 220 is arranged in such a way that it covers the opening section 217 crosses, and both ends of a weight section 221 in a longitudinal direction are integral or one-piece attached to anchor sections 223a and 223b over beam sections 222 added. The weight section 221 It is a rectangular shape. The anchor section 223a and 223b are on the carrier substrate 211 about the insulating film 212 at an opening edge section along the opening section 217 supported. Consequently, the weight section lies 221 and the beam sections 222 the opening section 217 opposite. The sensor section 201 from Fig. 2 corresponds to a sectional view along line II-II of Fig. 3.
[0034] Each beam section 222It comprises two parallel beams joined at both ends in a rectangular frame and has a spring function for movement or displacement in a direction orthogonal to a longitudinal direction of the two beams. More precisely, it forces movement when the beam segment 222 an acceleration including a component in one direction along the longitudinal direction of the weight section 221 learns the beam section 222 the weight section 221 to proceed in the longitudinal direction, and allows the weight section 221 Likewise, it returns to an original state when the acceleration disappears. Therefore, when an acceleration is applied, the weight section shifts. 221 , which is via the bar sections configured as above 222 to the supporting substrate 211 is joined in an offset or displacement direction of the beam section 222 .
[0035] The movable section 220 includes several movable electrodes 224 , which are integral or one-piece with the weight section 221 are provided to be positioned opposite each other from or from both side surfaces in a direction orthogonal to the longitudinal direction of the weight section. 221 to excel. In Fig. 3 are the four movable electrodes 224 provided so that they can be accessed from or from each of the left and right sides of the weight section. 221 protrude or protrude, and all of the movable electrodes 224 the opening section 217 are facing each other. The respective movable electrodes 224 are integral with the weight section 221 and the beam sections 222 provided. Therefore, when the beam sections 222 shift the movable electrodes 224in the longitudinal direction of the weight section 221 together with the weight section 221 move.
[0036] The first fixed section 230 and the second fixed section 240 are over the insulating film 212 along the opening edge section of the opening section 217 in opposite side sections where the anchor sections 223a and 223b are not supported, on or against the supporting substrate or carrier substrate 211 supported. In short, the first fixed section 230 and the second fixed section 240 with the movable section 220 arranged in between. In Fig. 3 is the first fixed section 230 on a left side on a plate surface in relation to the moving section 220 arranged, and is the second fixed section 240on a right-hand side of the plate surface in relation to the moving section 220 arranged. The first fixed section 230 and the second fixed section 240 are electrically independent of each other.
[0037] The first fixed section 230 and the second fixed section 240 Each has several first fixed electrodes 231 and several second fixed electrodes 241 , which are opposite and parallel to the side surfaces of the movable electrodes 224 are arranged at predetermined detection intervals, and a first wiring section 232 and a second wiring section 242 , both of which are on the carrier substrate 211 about the insulating film 212 are supported.
[0038] In Fig. 3 are the first four fixed electrodes 231 and the four second fixed electrodes 241provided and aligned like comb teeth to align with the spaces between the comb teeth of the movable electrodes 224 to intervene. The first fixed electrodes 231 and the second fixed electrodes 241 are located at the wiring sections. 232 and 242 supported like a cantilever and are therefore part of the opening section 217 Facing the above. The above describes the configuration of the sensor section. 201 described the present embodiment.
[0039] As in Fig. As shown in section 2, the cap section includes 202 an insulating film 252 , which is for a substrate made of silicon or the like 251 on a surface of the substrate 251 opposite the sensor section 201 is provided, and an insulating film 253 , which is responsible for the other area or surface of the substrate 251opposite the surface of the substrate 251 is provided.
[0040] In the cap section 202 is the insulating film 252 to the sensor section 201 (semiconductor layer) 213 ) bonded. In the present embodiment, the insulating film is 252 and the sensor section 201 (semiconductor layer) 213 ) by, for example, so-called direct bonding, through which the insulating film 252 and the semiconductor layer 213 bonded by activating the respective bonding areas or bonding surfaces.
[0041] A section of tooth 254 is also for the cap section 202 in one of the sensor sections 215 opposite section provided. An airtight chamber 255 is between the sensor section 201 and the cap section 202through a section of the tooth 254 The enclosed space is defined. The sensor or detection section 215 , which is for the sensor section 201 It is provided, is in the airtight chamber 255 hermetically sealed. In the present embodiment, the airtight chamber 255 is set to or subjected to atmospheric pressure. This means, in essence, that in the present embodiment, the acceleration sensor 20 of a housing or packaging structure in which the measuring or detection section 215 in the airtight chamber 255 , which is fixed at atmospheric pressure and is hermetically sealed.
[0042] In addition, there are several through holes. 256 (only one through hole) 256 is in Fig. 2 shown) provided to go through the cap section 202in one stacking direction of the cap section 202 and the sensor section 201 to penetrate or pass through. More precisely, the respective through-holes. 256 Provided for this purpose, predetermined parts of the anchor section 223b , of the first wiring section 232 and the second wiring section 242 to expose. An insulating film. 257 , which is made of TEOS (tetraethyl orthosilicate) or the like, is on a wall surface of each through-hole 256 deposited. A through-hole electrode 258 , which is made of AI or the like, is on the insulating film 257 provided and, if required, electrically connected to the armature section 223b , the first wiring section 232 or the second wiring section 242 Furthermore, it is electrically connected to the circuit board. 40connected contact surface section 259 on the insulating film 253 provided.
[0043] A protective film 260 is on the insulating film 253 , the through-hole electrode 258 and the contact surface section 259 provided. The protective film 260 is equipped with a contact hole 260a provided, over which the contact surface section 259 has been exposed.
[0044] The above describes the configuration of the accelerometer. 20 described. When acceleration is applied to the accelerometer configured as described above, the weight section shifts. 221 In response to acceleration, the capacitances between the moving electrodes vary or change. 224 and the first fixed electrodes 231 and between the movable electrodes 224and the second fixed electrodes 241 with such a shift. Therefore, a sensor signal corresponding to the acceleration (the capacitances) is generated by the accelerometer. 20 issued.
[0045] Below is a configuration of the angular velocity sensor. 30 described. As in Fig. As shown in section 4, the angular velocity sensor is included. 30 a sensor section 301 , which is produced using a substrate made from a piezoelectric material such as crystal and PZT (lead zirconate titanate) 310 is produced. The substrate 310 is finely machined in a known manner, and a groove section 311 is provided. The substrate 310 is through the groove section 311 into a part in which a vibrating element or vibration element is located 312is provided, and a part in which the outer peripheral section or outer circumferential section 313 It is provided, subdivided.
[0046] The vibrating element 312 includes a first drive blade 314 , a second drive blade 315 and a data collection sheet 316 , all of which are divided into a basic section 317 be held, and the base section 317 is located on the outer peripheral section 313 via a beam unit 318 attached. To be more precise, the vibrating element is 312 a so-called tuning fork according to the tripod principle, in which the first drive blade 314 , the second drive blade 315 and the data collection sheet 316 compared to the base section 317 protrude in the same direction, and the registration sheet 316 between the first drive blade 314and the second drive blade 315 is located.
[0047] The beam unit 318 limits the transmission of a stress that occurs at the outer peripheral section 313 is developed, on the vibrating element 312 by mitigating the stress. The beam unit 318 However, it can be omitted. In short, a basic section can 317 directly to the outer peripheral section 313 be joined.
[0048] As in Fig. 4 and Fig. As shown in section 5, the first drive blade is shown. 314 , the second drive blade 315 and the data collection sheet 316 shaped like rods with a rectangular cross-section and surfaces 314a , 315a and 316a and rear surfaces 314b , 315b and 316b each parallel to the plane directions of the substrate 310 as well as each side surface 314cand 314d , 315c and 315d , and 316c and 316d exhibit.
[0049] In the first drive blade 314 is a control or drive electrode 319a on the surface 314a A control or drive electrode is provided. 319b on the back surface 314b provided, and are common electrodes 319c and 319d on the side surfaces 314c or 314d provided. Likewise, the second drive blade is also included. 315 a control or drive electrode 320a on the surface 315a A control or drive electrode is provided. 320b on the back surface 315b provided, and are common electrodes 320c and 320d on the side surfaces 315c or 315d provided. Furthermore, the data collection sheet contains... 316a control or drive electrode 321a on the surface 316a A control or drive electrode is provided. 321b on the back surface 316b provided, and are common electrodes 321c and 321d on the side surfaces 316c or 316d provided.
[0050] In the present embodiment, the first drive blade forms 314 , the second drive blade 315 , the registration form 316 , the control electrodes 319a until 320b , the detection electrodes 321a and 321b and the common electrodes 319c until 321d together a recording section 322 .
[0051] As in Fig. As shown in section 4, this is the outer peripheral section. 313 with multiple contact connection sections 323 equipped with electrically connected control electrodes 319auntil 320b , the detection electrodes 321a and 321b and the common electrodes 319c until 321d connected via wiring layers not shown or the like, and furthermore electrically to the circuit board 40 are connected.
[0052] The above describes the configuration of the angular velocity sensor. 30 described. This point is that the recording section 322 in the angular velocity sensor 30 The angular velocity sensor in the present embodiment is not hermetically sealed in an airtight chamber. 30 as above, an angular velocity is recorded, while the first drive blade 314 and the second drive blade 315 in an alignment direction of the first drive blade 314 , of the second drive blade 315 and the data collection sheet 316(a right-left direction on a plate surface of Fig. 4) vibrate or oscillate.
[0053] If an angular velocity is measured within a plane of the sensor section 301 Once applied, a pair of Coriolis forces develops on the first drive blade. 314 and the second drive blade 315 periodically in opposite orientations in one direction along the forward direction of the first drive blade 314 and the second drive blade 315 with regard to the basic section 317 Therefore, moments induced by the Coriolis forces are distributed across the base section. 317 on the data collection sheet 316 transferred, and the data entry sheet begins. 316 in the direction of alignment of the first drive blade 314 , of the second drive blade 315 and the data collection sheet 316to vibrate (to bend). Finally, the data sheet will be completed. 316 Charges are generated according to the angular velocity. A sensor signal corresponding to the angular velocity (charges) is therefore generated by the angular velocity sensor. 30 issued.
[0054] If the angular velocity is not applied, moments from the first drive blade are 314 and the second drive blade 315 about the base section 317 to the data collection sheet 316 They are laid out in opposite directions and therefore cancel each other out. Therefore, the data sheet is located... 316 essentially at rest or in a state of rest.
[0055] Below is a circuit configuration of the circuit board. 40 described. As in Fig. As shown in Figure 6, the circuit board 40 an angular velocity sensor control circuit410 , which uses the angular velocity sensor 30 controls, and a self-diagnostic circuit 420 on. The circuit board 40 It also features an (not shown) acceleration sensor control circuit that controls the acceleration sensor 20 controls a (not shown) processing circuit that processes the respective sensor signals, and so on. In Fig. 6 is the data collection sheet 316 omitted.
[0056] The angular velocity sensor control circuit 410 a control circuit 411 , a charge amplifier 412 , a rectifier circuit 413 , a first reference voltage generation circuit 414 , a differential amplifier 415 and so on. The self-diagnostic circuit 420 features a low-pass filter 421 , a second reference voltage generation circuit 422 , an adder 423, a subtractor 424 , a window comparator 425 and so on.
[0057] The control circuit 411 It features an AGC (Audio Gain Control) circuit or circuit for automatic gain control and is equipped with the control electrodes. 319a and 319b of the first drive blade 314 and the control electrode 320b of the second drive blade 315 connected. The control circuit 411 applies a constant control signal to the control electrodes 319a , 319b and 320b on, after an amplification of the control signal based on a voltage signal that is generated by the charge amplifier 312 was supplied, and a differential signal 430 , which is achieved through the differential amplifier 415 The power supplied is now set. This means, in other words, that the control circuit is... 411sets a control signal to determine the vibration amplitude of the first drive blade. 314 and the second drive blade 315 to make it constant, and applies the set control signal to the control electrodes. 319a , 319b , and 320b to.
[0058] A pulsed control signal (carrier) at a predetermined frequency and amplitude is sent to the control electrodes. 319a and 319b of the first drive blade 314 Applied. A control signal (carrier) that is sent to the control electrode. 320b of the second drive blade 315 The applied signal is the control signal (carrier) that is sent to the control electrodes. 319a and 319b The signal is applied with a 180° phase shift. Consequently, the first drive blade vibrates. 314 and the second drive blade 315 in an alignment direction of the first drive blade 314 , of the second drive blade 315and the data collection sheet 316 .
[0059] The charge amplifier 412 is connected to the control electrode 320a of the second drive blade 315 connected, and also with the control circuit 411 and the rectifier circuit 413 connected. The charge amplifier 412 converts charges that are present at the control electrode 320a were generated by vibrations or oscillations of the second drive blade 315 converts it into a voltage signal and routes the voltage signal to the control circuit. 411 and the rectifier circuit 413 to.
[0060] Charges that are at the control electrode 320a of the second control sheet 315 The vibrations generated vary depending on the vibration state of the second drive blade. 315 This means, in effect, that charges with an ambient pressure (detection environment) surround the second drive blade. 315(vibrating element) 312 ) change.
[0061] The rectifier circuit 413 is with the differential amplifier 415 connected. The rectifier circuit 413 generates a DC signal voltage comparable to a vibration amplitude of the second drive blade. 315 from the voltage signal generated by the charge amplifier 412 was supplied, and directs the DC signal voltage into the differential amplifier. 415 a.
[0062] The first reference voltage generation circuit 414 is with the differential amplifier 415 connected and directs a first reference voltage into the differential amplifier 415 a.
[0063] The differential amplifier 415 is connected to the control circuit 411 , the low-pass filter 421 and the window comparator 425 connected. The differential amplifier 415 conducts the differential signal 430between the DC signal voltage produced by the rectifier circuit 413 was supplied, and the first reference voltage, which was generated by the first reference voltage generation circuit 414 was supplied to the control circuit 411 , the low-pass filter 421 and the window comparator 425 a.
[0064] As described above, this is because the second drive blade 315 Charges generated according to the detection environment, which is produced by the differential amplifier 415 output differential signal 430 also a signal corresponding to the detection environment. Therefore, in the present embodiment, the differential amplifier corresponds to 415 a detection unit, and the difference signal corresponds to 430 a detection signal.
[0065] The low-pass filter 421 has a large time constant and is connected to the adder 423 and the subtractor 424connected. When the differential signal is supplied 430 The low-pass filter generates 421 an output signal that gradually or slowly corresponds to the difference signal 430 follows, and directs the output signal to the adder. 423 and the subtractor 424 one. That means, so to speak, that the low-pass filter 421 Basically, an output signal with a difference signal. 430 comparable voltage is generated. However, if the differential signal 430 The low-pass filter generates a signal that fluctuates sharply or varies greatly. 421 an output signal that does not perfectly follow the difference signal, but rather the difference signal 430 with a slight delay. More precisely, a low-pass filter with a cutoff frequency on the order of 0.1 Hz or 0.01 Hz is called the low-pass filter. 421 used to absorb temperature fluctuations and deterioration over time.
[0066] The second reference voltage generation circuit 422 is with the adder 423 and the subtractor 424 connected. The second reference voltage generation circuit 422 generates a second reference voltage and directs the second reference voltage into the adder 423 and the subtractor 424 One. The second reference voltage defines a range of a determination or measurement threshold value in the window comparator. 425 .
[0067] The adder 423 is with the window comparator 425 connected and transmits an upper reference voltage 431 , which is a sum when the second reference voltage corresponds to an output of the low-pass filter 421 The window comparator adds the data. 425 a.
[0068] The subtractor 424 is with the window comparator 425 connected and transmits a lower limit reference voltage 432, which is a difference when the second reference voltage is from an output of the low-pass filter 421 The subtraction is performed in the window comparator. 425 a.
[0069] The window comparator 425 determines whether a voltage is generated by the differential signal 430 specified, falls within a normal voltage range defined by the upper reference voltage. 431 , which are caused by the adder 423 is defined, and the lower reference voltage 432 , which are processed by the subtractor 424 The window comparator is defined. 425 It provides a diagnostic detection signal or diagnostic detection signal Vout in accordance with a determination of whether a difference signal 430 The specified voltage falls within the normal voltage range. For example, if a voltage is affected by the differential signal 430The window comparator indicates that the voltage falls within the normal range. 425 The diagnostic detection signal Vout, which is a high-level voltage signal indicating normality, is used. If a voltage is detected by the differential signal... 430 The window comparator indicates that the voltage falls outside the normal voltage range. 425 the diagnostic detection signal Vout, which is a low-level signal that indicates abnormality.
[0070] The term “normality or being normal”, which is referred to herein, means that the first drive blade 324 and the second drive blade 315 vibrate as desired. The term “abnormality or being abnormal” referred to herein means that the first drive blade 314 and the second drive blade 315It does not vibrate as desired. In the present embodiment, the window comparator corresponds to... 425 a self-diagnostic unit. The common electrodes 319c until 320d are associated with mass potential.
[0071] The foregoing has described the configuration of the sensor for a physical quantity in the present embodiment. The following describes a self-diagnosis performed by the sensor for a physical quantity.
[0072] In the sensor configured as above for a physical quantity, a pressure (degree of vacuum) increases in the housing space. 15 on, if there is a leak in the airtight chamber 255 in the accelerometer 20 occurs. Therefore, as in Fig. As shown in Figure 7, the impedance at both the first drive blade 314 as well as the second drive blade 315 to, and vibrations of the first drive blade will occur.314 and the second drive blade 315 smaller. In other words, the first drive blade vibrates 314 and the second drive blade 315 no longer normal. Because of vibrations of the first drive blade. 314 and the second drive blade 315 As they become smaller, charges at the control electrode become smaller. 320a of the second drive blade 315 The generation process is also reduced.
[0073] Therefore, a variable in the charge amplifier 412 converted voltage signal, and therefore the one from the differential amplifier varies 415 output differential signal 430 In short, this is the detection environment of the vibrating element. 312 corresponding differential signal 430 through the differential amplifier 415 issued.
[0074] Subsequently, as described, the difference signal is 430 through the differential amplifier415 into the window comparator 425 It is conducted and determined whether the difference signal 430 within the normal voltage range. If it is determined that the differential signal 430 If the voltage falls outside the normal voltage range, it will be a voltage indicating an abnormality, which is then used as the diagnostic detection signal Vout by the window comparator. 425 This results in a fluctuation in pressure within the housing. 15 In short, a detection environment for the angular velocity sensor is captured. 30 self-diagnosed.
[0075] When a detection environment of the angular velocity sensor 30 When diagnosed as abnormal, a leak occurs at the airtight chamber. 255 in the accelerometer 20 Therefore, it can be self-diagnosed that a detection environment of the accelerometer is affected. 20 is also abnormal.
[0076] In the present embodiment, a ratio of a volume of the airtight chamber 255 in relation to the volume of the housing space 15 to 1.0 × 10 –7 or set higher. The ratio is set as above because, as in Fig. Figure 8 shows when the ratio of a volume of the airtight chamber 255 in relation to the volume of the housing space 15 to less than 1.0 × 10 –7 is determined to have a pressure in the housing space 15 even when there is a leak in the airtight chamber, it hardly fluctuates or varies. 255 occurs.
[0077] As described above, in the present embodiment vibration states of the first drive blade are 314 and the second drive blade 315 The differential signal corresponding to the vibration states is detected and becomes the signal that corresponds to the vibration states. 430 through the differential amplifier 415Output. That is to say, so to speak, when there is pressure in the housing space 15 in the event of a leak in the airtight chamber 255 The vibration states of the first drive blade fluctuate and vary. 314 and the second drive blade 315 Therefore, the difference signal 430 corresponding to a pressure in the housing space 15 through the differential amplifier 415 issued.
[0078] It is the window comparator 425 , which determines whether the difference signal 430 falls within the normal voltage range. Therefore, a detection environment for the angular velocity sensor is possible. 30 (pressure in the housing space) 15 ) can be self-diagnosed. If the angular velocity sensor's detection environment 40 When diagnosed as abnormal, a leak occurs at the airtight chamber. 255 in the accelerometer 20Therefore, a detection environment for the accelerometer can be used. 20 be diagnosed as abnormal. Therefore, in a case where different processing methods are performed using signals from the accelerometer, 20 and the angular velocity sensor 30 Issues will be issued, and the execution of incorrect processing will be restricted. (Other examples)
[0079] The invention is not limited to the embodiments mentioned above and can be amended and modified to various embodiments which are also within the scope and protection of the present disclosure.
[0080] For example, the preceding embodiment described a case in which the acceleration sensor 20 is housed or packed. However, the angular velocity sensor can be used instead.30 It must be enclosed or packed. In such a case, the enclosure space 15 fixed to atmospheric pressure, and is an airtight chamber in which the detection section 322 the angular velocity sensor 30 To seal, a vacuum pressure is set. Alternatively, both the accelerometer and the accelerometer can be used. 20 as well as the angular velocity sensor 30 be enclosed or packed. In such a case, the enclosure space 15 are either at atmospheric pressure or vacuum pressure.
[0081] In the respective embodiments described above, the angular velocity sensor can be 30 It could be a different type of tuning fork than the one that works on the tripod principle. For example, the angular velocity sensor could be used. 30 a so-called tuning fork according to the T-principle, in which the first drive blade 314 , the second drive blade315 and the data collection sheet 316 with the basic section 317 protrude on both sides in between. Furthermore, the angular velocity sensor 30 It could be a so-called H-type tuning fork or a standard tuning fork. This means, in other words, a configuration of the angular velocity sensor. 30 is not particularly limited, as long as an angular velocity is detected while the vibrating element is moving. 312 vibrates.
[0082] In the respective exemplary embodiments above, the acceleration sensor can 20 be of a piezoelectric type.
[0083] While the invention has been described with reference to exemplary embodiments thereof, it is understood that the invention is not limited to these exemplary embodiments and constructions. The invention is intended to cover various modifications and equivalent arrangements. Furthermore, in addition to the various combinations and configurations, other combinations and configurations, including more, fewer, or only a single element, also fall within the scope and protection of the invention.
Claims
[1] Sensor for a physical quantity, comprising: an accelerometer ( 20 ), which includes a recording section ( 215 ) is equipped with a sensor signal that outputs a signal corresponding to an acceleration; an angular velocity sensor ( 30 ), which includes a recording section ( 322 ) with a vibrating element ( 312 ) is equipped with a device that vibrates in a predetermined direction, with the detection section ( 322 ) outputs a sensor signal corresponding to an angular velocity from the detection section; and a case ( 10 ) with a housing space ( 15 ), which is pressurized to a predetermined pressure and accommodates the accelerometer and the angular velocity sensor in the housing space, wherein at least one of the accelerometer and angular velocity sensor is from a packing structure in which a cap section ( 202 ) in a sensor section ( 201 ) is arranged on which the sensor section is formed, and the sensor section is hermetically sealed in an airtight chamber ( 255 ) is sealed, which is defined between the sensor section and the cap section, further comprising: a recording unit ( 415 ), which contains a detection signal ( 430 ) outputs a signal corresponding to a vibration of the vibration element in the angular velocity sensor; and a self-diagnostic unit ( 425 ), which self-diagnoses a detection environment of the angular velocity sensor based on the detection signal output by the detection unit. [2] Sensor for a physical quantity according to claim 1, wherein a ratio of a volume of the airtight chamber to a volume of the housing space is 1.0 × 10 –7 or is set at a higher level. [3] Sensor for a physical quantity according to claim 1 or 2, wherein the accelerometer is of the packing structure and the airtight chamber is pressurized to atmospheric pressure and the housing space is pressurized to vacuum pressure. [4] Sensor for a physical quantity according to claim 1 or 2, wherein the angular velocity sensor is separated from the packaging structure and the airtight chamber is pressurized with a vacuum, and The housing space is pressurized with atmospheric pressure. [5] Sensor for a physical quantity according to claim 1 or 2, wherein the angular velocity sensor is separated from the packaging structure and the airtight chamber of the angular velocity sensor is pressurized with a vacuum, and The accelerometer is separated from the packaging structure and the airtight chamber of the accelerometer is pressurized to atmospheric pressure.