JP2005315694A - Electronic component device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the capacity of a variable capacity structure at high speed, while suppressing deterioration of detection accuracy, even when a parasitic capacity is large to the capacity of the variable capacity structure. <P>SOLUTION: This device has a variable shape structure 1 displaced corresponding to a control signal or a physical quantity to be detected, and a structure displacement detection unit 2 for detecting the capacity showing displacement of the variable shape structure 1. The variable shape structure 1 is equipped with the variable capacity structure 10 whose capacity is changed corresponding to its displacement. The structure displacement detection unit 2 is equipped with an electric field generation part 20 for generating an electric field on the variable capacity structure 10, a guide signal generation part 22 for outputting a guide signal Sd which is a base for electric field generation to the electric field generation part 20, a capacity information extraction part 23 for extracting an information signal Si showing the capacity of the variable capacity structure 10 from a capacity signal Scap of the variable capacity structure 10, and an output adjusting part 24 for converting the information signal Si into a format capable of information processing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electronic component device including a MEMS (micro mechanical system) device typified by an optical switch or an acceleration sensor, and more particularly to a technique for detecting a minute capacitance generated in a MEMS structure.

  2. Description of the Related Art Conventionally, electronic component devices using MEMS (Micro Electro Mechanical Systems) structures formed by microfabrication techniques are known (see, for example, Non-Patent Document 1, Non-Patent Document 2, and Non-Patent Document 3). In such an electronic component device, a technique has been developed in which a target physical quantity is detected by detecting a capacitance generated in the MEMS structure, or self control is performed based on the detected physical quantity. For example, in an acceleration sensor, acceleration is detected by detecting a capacitance generated between a pair of electrodes manufactured by MEMS technology.

  FIG. 15 shows a configuration of a general electronic component device using the MEMS structure. The electronic component device includes a substrate 100, a movable member 101 made of a conductive material, a support column 102, a control electrode 103, a detection electrode 104, and a structure control device 105. When the electronic component device is an optical switch, the movable member 101 is a mirror. The support column 102 supports the movable member 101 so that the movable member 101 is spaced apart from the control electrode 103 and the detection electrode 104. The movable member 101 is set to a predetermined potential via the support column 102. When a control voltage is applied to the control electrode 103 by the structure control device 105, an electrostatic force is generated between the movable member 101 and the control electrode 103, and the movable member 101 is displaced by an amount corresponding to the electrostatic force. When the movable member 101 is displaced, the electrostatic capacitance Cs formed between the movable member 101 and the detection electrode 104 changes. The structure control device 105 detects the position of the movable member 101 by detecting the capacitance Cs, and controls the voltage applied to the control electrode 103. Thus, the position of the movable member 101 can be controlled.

  However, in the electronic component device shown in FIG. 15, since a parasitic capacitance Cp is generated between the detection electrode 104 and the ground potential, it is difficult to detect the capacitance Cs formed between the movable member 101 and the detection electrode 104. There was a problem. The reason is that the structure controller 105 detects a capacitance in which the capacitance Cs and the parasitic capacitance Cp are connected in parallel. The capacitance Cs is several tens of fF to several hundreds of fF, whereas the parasitic capacitance Cp is This is because it becomes several pF.

  There is a technique disclosed in Non-Patent Document 4 as a technique that makes it possible to detect a target capacitance even when a large parasitic capacitance occurs with respect to the capacitance to be detected (hereinafter referred to as a first conventional example). ). The present technology relates to a capacitive fingerprint sensor. The first conventional example will be described with reference to FIG. The capacitive fingerprint sensor shown in FIG. 16 acquires a fingerprint image by detecting a capacitance Cs formed between the detection electrode 201 and a human finger 203. In this capacitive fingerprint sensor, a compensation electrode 202 is disposed opposite the detection electrode 201. Since the compensation electrode 202 is controlled to have the same potential as the detection electrode 201 by feedback of the operational amplifier 205, parasitic capacitance generated in the detection electrode 201 is suppressed.

  Hereinafter, the operation of the sensor shown in FIG. 16 will be described. First, in the reset state, the potential Vr at one end of the first control switch 204 is set to V1, and the first control switch 204 is turned on. On the other hand, the second control switch 206 provided between the non-inverting input terminal and the output terminal of the operational amplifier 205 is also turned on, and the feedback loop of the operational amplifier 205 is closed. Since the potential of the inverting input terminal of the operational amplifier 205 is V1, the potential of the detection electrode 201 is also V1 due to the feedback loop. Next, the potential of the detection electrode 201 when the second control switch 206 is opened is set to V2. At this time, if the effective finger capacitance is Cf, the capacitance between the non-inverting input terminal and the output terminal of the operational amplifier 205 is Cspl, and the difference between the potentials V1 and V2 is ΔVr, the output voltage Vout of the operational amplifier 205 Becomes ΔV0 = (1 + Cf / Cspl) ΔVr, and a signal output corresponding to the finger capacitance Cs can be obtained.

  As another technique that makes it possible to detect a target capacitance even when a large parasitic capacitance occurs with respect to the capacitance to be detected, there is a technology disclosed in Patent Document 1 (hereinafter referred to as a second conventional example). Call). The present technology relates to a pressure sensor using a diaphragm. The second conventional example will be described with reference to FIG. In the pressure sensor shown in FIG. 17, the reference voltage Vh is supplied to the non-inverting input terminal of the operational amplifier 302 via the first control switch 303. A second control switch 304 is connected between the inverting input terminal and the output terminal of the operational amplifier 302, and a capacitance Cs is set between the sensor input terminal 301 and the non-inverting input terminal of the operational amplifier 302. The sensor S which has is connected. The parasitic capacitance Cp is formed at the connection between the sensor S and the non-inverting input terminal of the operational amplifier 302. The reference voltage Vh is, for example, a ground potential. As an example of the sensor S, there is a sensor that is processed so as to have a small area by a micromachine and that a capacitor Cs is formed between an opposing diaphragm and an electrode. The sensor S changes the capacitance Cs according to the displacement of the diaphragm caused by the change of the applied physical quantity.

  Hereinafter, the operation of the sensor shown in FIG. 17 will be described. The sequence for detecting the capacitance Cs includes an initialization cycle and a measurement cycle. During the initialization cycle, the first control switch 303 and the second control switch 304 are turned on, and the input voltage Vin is set to the reference voltage Vh (Vin = Vh). Thereby, the output voltage Vout is also set to be equal to the reference voltage Vh. On the other hand, during the measurement cycle, the first control switch 303 and the second control switch 304 are turned off, and the input voltage Vin is set to Vh + ΔV. When the first control switch 303 and the second control switch 304 are turned off to measure the capacitance Cs, the output voltage Vout of the operational amplifier 302 satisfies the following equation.

Vout = − (Rf1 / Ri1) (Vin−v ⁺ ) + V ⁺ = −Vin + 2v ⁺
... (1)
In equation (1), v ⁺ is the voltage at the non-inverting input terminal of the operational amplifier 302. In addition, the resistor Ri1 provided between the sensor input terminal 301 and the inverting input terminal of the operational amplifier 302 is equal to the resistor Rf1 provided between the inverting input terminal and the output terminal of the operational amplifier 302. (Rf1 = Ri1).
When the input voltage Vin is changed from Vh set in the initialization cycle to Vh + ΔV, the charge Q1 stored in the sensor capacitor Cs and the charge Q2 stored in the parasitic capacitor Cp are expressed by the following equations.
Q1 = (Vin−V ⁺ ) Cs = (Vh + ΔV−v ⁺ ) Cs (2)
Q2 = v ⁺ Cp (3)

Since the sensor capacitor Cs and the parasitic capacitor Cp are connected in series, the same charge amount is accumulated in Cs and Cp, and thus Q1 = Q2. Therefore, the following equation is established.
v ⁺ Cp = (Vh + ΔV−v ⁺ ) Cs (4)
As described above, when the reference voltage Vh is the ground potential (Vh = 0), the voltage v ⁺ of the non-inverting input terminal of the operational amplifier 302 is expressed by the following equation.
v ⁺ = ΔV · Cs / (Cs + Cp) (5)
If Expression (5) is substituted into Expression (1), the output voltage Vout of the operational amplifier 302 can be rewritten as follows.
Vout = −Vin + 2 · ΔV · Cs / (Cs + Cp) (6)

When the sensor S and the part other than the sensor in the circuit of FIG. 17 are formed on different chips and these chips are electrically connected, the parasitic capacitance Cp is about several pF to about 15 pF or more. The capacitance Cs of the sensor S is usually about 1 fF to several hundreds fF. Accordingly, since the parasitic capacitance Cp is larger than the capacitance Cs of the sensor S, Cs / (Cs + Cp) can be approximated by Cs / Cp. Therefore, the output voltage Vout of the operational amplifier 302 is expressed by the following equation.
Vout = −Vin + 2 · ΔV · Cs / Cp (7)
Expression (7) represents that the output voltage Vout of the operational amplifier 302 changes linearly according to the capacitance Cs of the sensor S.

  Thus, even when the parasitic capacitance Cp exists in the vicinity of the non-inverting input terminal of the operational amplifier 302, as long as the capacitance Cs of the sensor S is extremely smaller than the parasitic capacitance Cp, the operational amplifier 302 has a linear relationship with the capacitance Cs. A certain voltage Vout can be output. Furthermore, a sufficiently large output voltage Vout can be obtained by adjusting the gain (Rf1 / Ri1) of the operational amplifier 302 and the change amount ΔV of the input voltage Vin according to the capacitance Cs.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Special table 2001-510580 gazette “Optical Networking: MEMS Mirror Control”, ANALOG DEVICES, search September 18, 2002, Internet <http: // www. analog. com / productSelection / signal Chains / communications / comms_17. html> Madana Gopal (KVMadanagopal) and two others, "Real Time Software Control Of Spring Suspended Micro-Electro-Mechanical (MEM) Devices For Precision Optical Positioning Applications" , 2002 International Conference on Optical MEMS 2002, August 2002, p. 41-42 Hirao et al., “Examination of MEMS mirror high-speed drive circuit”, 2002 IEICE Communication Society Conference, p. 445, September 11, 2002 “500 dpi Capacitive-Type CMOS Fingerprint Sensor with Pixel-Level Adaptive Image Enhancement Scheme”, ISSC 2002 Papers (ISSCC2002 PAPERS), 2003 February, p. 352-353

  However, in the first conventional example shown in FIG. 16, it is necessary to set the potential of the detection electrode 201 to V1 by the first control switch 204 and to open the second control switch 206. There is a problem that it takes time to detect the capacitance Cs. Therefore, this first conventional example cannot be applied to feedback control of an optical switch that requires high-speed operation. Further, in the first conventional example, there is a problem that noise accompanying opening / closing of the second control switch 206 deteriorates the accuracy of capacitance detection.

  In the second conventional example shown in FIG. 17, as in the first conventional example, the step of setting the input voltage Vin to Vh by the first control switch 303 and the step of opening the second control switch 304 Therefore, there is a problem that it takes time to detect the capacitance Cs. Further, there is a problem that noise accompanying opening / closing of the second control switch 304 deteriorates the accuracy of capacitance detection. Further, in the case of the second conventional example, it is necessary to draw out a terminal connected to the input terminal 301 and a terminal connected to the non-inverting input of the operational amplifier 302 from the sensor S. However, when the optical switch is realized by the electronic component device shown in FIG. 15, the movable member 101 is normally set to the ground potential, and the terminal is drawn only from the detection electrode 104. For this reason, when the structure of the second conventional example is applied to an optical switch, there is a problem in that the number of process steps increases in order to newly extract a terminal, and the manufacturing cost increases.

  The present invention has been made to solve the above-described problems, and a variable shape structure that is displaced according to a control signal or a physical quantity to be detected, and a variable capacity structure that has a capacitance that varies according to the displacement of the variable shape structure. An object of the present invention is to detect a capacitance of a variable capacitance structure at high speed while suppressing deterioration in detection accuracy even when a parasitic capacitance is larger than a capacitance of the variable capacitance structure.

  The present invention relates to an electronic component device having a shape variable structure that is displaced according to an input control signal or a physical quantity to be detected, and a structure displacement detection unit that detects a capacitance representing the displacement of the shape variable structure. The variable shape structure includes a variable capacity structure whose capacity changes in accordance with the displacement, and the structural displacement detection unit includes an electric field generating unit that generates an electric field in the variable capacity structure, and a base for generating the electric field. An induction signal generating unit that outputs an induction signal to the electric field generation unit, and an information signal that represents the capacitance of the variable capacitance structure from the capacitance signal that is output from the output terminal of the variable capacitance structure by the generation of the electric field A capacity information extraction unit for extracting the information signal, and an output adjustment unit for converting the information signal into a format that can be processed, and the induction signal generation unit instructs the generation start of the electric field. An induction start signal generating unit for outputting a start signal; and an electric field induction unit for outputting the induction signal in response to the induction start signal, wherein the capacitance information extraction unit is a first potential comparison reference having a predetermined potential. A first potential comparison reference signal generation unit that generates a signal; a first potential comparison unit that amplifies a potential difference between the capacitance signal and the first potential comparison reference signal; and outputs the detection result as a detection signal; and the detection signal And a phase comparison unit that extracts a phase difference between the induction start signal as the information signal, and the output adjustment unit converts time information included in the pulse width of the information signal into an analog voltage. The circuit comprises a conversion circuit and an A / D conversion circuit that converts the analog voltage into a digital signal.

  In the electronic component device according to the aspect of the invention, the variable shape structure includes a variable capacitance structure whose capacitance changes according to the displacement, and the structural displacement detection unit generates an electric field in the variable capacitance structure. From the electric field generation unit, the induction signal generation unit that outputs the induction signal that is the basis of the electric field generation to the electric field generation unit, and the capacitance signal that is output from the output terminal of the capacitance variable structure by the generation of the electric field, A capacitance information extraction unit that extracts an information signal representing the capacitance of the capacitance variable structure; and an output adjustment unit that converts the information signal into a format that can be processed. The induction signal generation unit starts generation of the electric field. An induction start signal generating unit for outputting an induction start signal for instructing and an electric field induction unit for outputting the induction signal in response to the induction start signal. A first potential comparison reference signal generating unit for generating a first potential comparison reference signal; and a first potential comparison for amplifying a potential difference between the capacitance signal and the first potential comparison reference signal and outputting the amplified signal as a detection signal And a phase comparison unit that extracts a phase difference between the detection signal and the induction signal as the information signal, and the output adjustment unit converts the time information of the pulse width of the information signal into an analog voltage. It comprises a time-voltage conversion circuit for conversion and an A / D conversion circuit for converting the analog voltage into a digital signal.

In the configuration example of the electronic component device according to the present invention, the electric field induction unit includes an induction voltage generation circuit that outputs a predetermined voltage, a control terminal connected to an output terminal of the induction start signal generation unit, and an input terminal Is connected to the output terminal of the induction voltage generation circuit, the output terminal is connected to the input terminal of the electric field generation unit, and the control switch is closed according to the output of the induction start signal. .
In the configuration example of the electronic component device of the present invention, the capacitance information extraction unit further delays the induction start signal or the induction signal input from the induction signal generation unit to the phase comparison unit. And a delay unit for inputting to the phase comparison unit.
Further, in one configuration example of the electronic component device of the present invention, the delay unit includes a second potential comparison reference signal generation unit that generates a second potential comparison reference signal having a predetermined potential, and the induction signal generation unit. And a second potential comparison unit that outputs to the phase comparison unit a signal obtained by amplifying a potential difference between the input induction start signal or the induction signal and the second potential comparison reference signal.
Further, in one configuration example of the electronic component device according to the present invention, the variable capacity structure is composed of a movable member of the variable shape structure and a detection electrode disposed opposite to the movable member. is there.
Moreover, in one structural example of the electronic component device of the present invention, the electric field generating unit is composed of a capacitive element.
Further, in one configuration example of the electronic component device of the present invention, the variable capacitance structure is configured by a movable member of the variable shape structure and a first detection electrode disposed to face the movable member. The electric field generator is composed of a second detection electrode that is disposed to face the first detection electrode.
Moreover, in one configuration example of the electronic component device of the present invention, the variable shape structure is a micromirror that changes a light path.

  According to the present invention, since the induction signal is applied to the detection electrode through the electric field generator, the feedback control of the operational amplifier as in the conventional sensor is not required, and the step of applying the induction signal and the step of converting the information signal The capacity of the variable capacity structure can be detected at high speed only by two control steps, and the displacement of the variable shape structure can be detected at high speed. Further, if the potential of the first potential comparison reference signal is appropriately set, only the change due to the capacitance of the capacitance variable structure can be amplified and extracted from the capacitance signal, so that the capacitance of the capacitance variable structure is parasitic. Even when the capacitance is smaller than the capacitance, the capacitance of the variable capacitance structure can be detected. Further, since only one control switch for determining the capacitance is required to determine whether or not to apply the induction signal to the electric field generation unit, it is possible to suppress deterioration in detection accuracy. In addition, since the induction signal is applied to the detection electrode through the electric field generation unit and the capacitance signal is extracted from the detection electrode, only one output terminal of the capacitance variable structure is required. As a result, even when the present invention is applied to an optical switch, it is not necessary to take out a new terminal and the number of process steps is not increased.

  Moreover, since the minimum value of the pulse width of the information signal can be reduced by inputting the induction signal instead of the induction start signal to the phase comparison unit, the capacitance element used for the time-voltage conversion circuit of the output adjustment unit can be reduced. The capacitance value can be reduced, and the layout area of the time-voltage conversion circuit can be reduced.

  Further, by delaying the induction start signal or induction signal input from the induction signal generation unit to the phase comparison unit and then inputting the delay unit to the phase comparison unit in the capacitance information extraction unit, the pulse width of the information signal can be reduced. The minimum value can be reduced, and the layout area of the time-voltage conversion circuit of the output adjustment unit can be reduced.

  In addition, if the delay unit includes a second potential comparison reference signal generation unit and a second potential comparison unit, and the potential of the second potential comparison reference signal is set appropriately, the induction start signal or the induction signal is delayed. Then, it can be input to the phase comparator, and the minimum value of the pulse width of the information signal can be reduced. Further, the layout area of the delay unit can be reduced as compared with the case where the delay unit is configured by a multi-stage inverter circuit.

  In addition, since the second detection electrode is arranged opposite to the first detection electrode, it is possible to prevent the first detection electrode from generating a parasitic capacitance. The change in the capacitance signal can be increased, and the sensitivity of capacitance detection can be increased.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an electronic component device according to a first embodiment of the present invention.
The electronic component device includes a shape variable structure 1 that is displaced according to an input control signal or a physical quantity to be detected, and a structure displacement detection unit 2 that detects a capacitance representing the displacement of the shape variable structure 1. . An example of the electronic component device is an optical switch.

  The variable shape structure 1 includes a variable capacity structure 10 whose capacity changes according to the displacement. The structural displacement detection unit 2 includes an electric field generation unit 20 that generates an electric field in the variable capacitance structure 10 and a structural displacement detection circuit 21 that detects the capacitance of the variable capacitance structure 10. The structural displacement detection circuit 21 includes an induction signal generation unit 22 that outputs an induction signal Sd that is a base for generating an electric field to the electric field generation unit 20, and a connection between the output terminal of the variable capacitance structure 10 and the output terminal of the electric field generation unit 20. The capacity information extraction unit 23 that extracts the information signal Si representing the capacity of the variable capacity structure 10 from the capacity signal Scap obtained by the unit, and the output adjustment unit 24 that converts the information signal Si into an output signal So of a format that can process information. And have.

  A specific example of the variable shape structure 1 of the present embodiment is shown in FIG. The variable shape structure 1 includes a variable capacity structure 10, a substrate 11, a movable member 12 made of a conductive material, a control electrode 13 formed on the substrate 11, and the movable member 12 on the control electrode 13. It has the support | pillar 14 which supports the movable member 12 so that it may arrange | position apart. The variable capacitance structure 10 includes a movable member 12 and a detection electrode 15 formed on the substrate 11.

When the electronic component device is an optical switch, the movable member 12 is a mirror. The movable member 12 is set to a predetermined potential via the support column 14. When a control voltage is applied to the control electrode 13 by a drive circuit (not shown), an electrostatic force is generated between the movable member 12 and the control electrode 13, and the movable member 12 is displaced by an amount corresponding to the electrostatic force.
Specific examples of the variable capacitance structure 10 and the electric field generator 20 are shown in FIG. As described above, the variable capacitance structure 10 includes the movable member 12 and the detection electrode 15, and the electric field generation unit 20 includes the capacitive element Cstd.

  When the movable member 12 of the shape variable structure 1 is displaced, the capacitance Cs formed between the movable member 12 and the detection electrode 15 changes. The induction signal generation unit 22 of the structural displacement detection circuit 21 inputs the induction signal Sd to the input terminal of the capacitive element Cstd of the electric field generation unit 20. The capacitive element Cstd generates an electric field in the variable capacitance structure 10 by the input of the induction signal Sd. Due to the generation of this electric field, a capacitance signal Scap including information on the capacitance Cs of the capacitance variable structure 10 is output from the connection portion between the output terminal (detection electrode 15) of the capacitance variable structure 10 and the output terminal of the capacitance element Cstd. The The capacity information extraction unit 23 compares the capacity signal Scap with the induction start signal Ss generated by the induction signal generation unit 22 and extracts the information signal Si representing the capacity Cs of the variable capacity structure 10. The output adjustment unit 24 converts the information signal Si into an output signal So having a format that can be processed, and outputs the output signal So.

  FIG. 4 shows a specific example of the structural displacement detection circuit 21 of the structural displacement detection unit 2 of the electronic component device according to the present embodiment. The induction signal generation unit 22 includes an induction start signal generation unit 220 that outputs an induction start signal Ss that instructs the start of electric field generation, and an electric field induction unit 221 that outputs an induction signal Sd according to the induction start signal Ss. ing.

  The electric field induction unit 221 includes an induction voltage generation circuit 222 that outputs a predetermined voltage, and a control switch 223 that is closed according to the output of the induction start signal Ss from the induction start signal generation unit 220. A control terminal of the control switch 223 is connected to an output terminal of the induction start signal generation unit 220, an input terminal of the control switch 223 is connected to an output terminal of the induction voltage generation circuit 222, and an output terminal (induction signal generation unit) of the control switch 223. 22 output terminal) is connected to the input terminal of the electric field generator 20.

  As shown in FIG. 4, the capacitance information extraction unit 23 compares the potential comparison reference signal generation unit 230 that generates the potential comparison reference signal Svref with a predetermined potential, and the potential comparison that compares the capacitance signal Scap and the potential comparison reference signal Svref. 231 and a phase comparator 232 that compares the phase of the detection signal Se output from the potential comparator 231 and the phase of the induction start signal Ss output from the induction start signal generator 220.

The potential comparison unit 231 compares the capacitance signal Scap and the potential comparison reference signal Svref, and outputs a detection signal Se obtained by amplifying the potential difference between the capacitance signal Scap and the potential comparison reference signal Svref. A general reference voltage generation circuit may be used as the potential comparison reference signal generation unit 230, and a general differential amplifier circuit may be used as the potential comparison unit 231.
The phase comparison unit 232 compares the phases of the detection signal Se and the induction start signal Ss, and extracts the phase difference between the detection signal Se and the induction start signal Ss as the information signal Si. As a specific example of the phase comparison unit 232, a general exclusive OR circuit or the like may be used.

  As shown in FIG. 4, the output adjustment unit 24 processes the time-voltage conversion circuit 240 that converts the pulse width of the information signal Si into the analog voltage San, and the analog voltage San output from the time-voltage conversion circuit 240. And an A / D conversion circuit 241 for converting the digital signal into an easy digital signal.

  FIG. 5 is a diagram illustrating signal waveforms of respective units in the induction signal generation unit 22 according to the present embodiment. As shown in FIG. 5A, when the induction start signal Ss transitions from the low level to the high level, the control switch 223 of the electric field induction unit 221 is turned on. As a result, the voltage output from the induction voltage generation circuit 222 is applied to the electric field generation unit 20 as the induction signal Sd, and capacitance detection is started.

At this time, the induction signal Sd gradually rises as shown in FIG. 5B and settles to a constant induction potential (the output potential of the induction voltage generation circuit 222). This induced potential is set to an intermediate potential between the first common potential (for example, ground potential) and the second common potential (for example, power supply potential).
The capacitive element Cstd provided in the electric field generation unit 20 is set to a size that is approximately the same as the parasitic capacitance Cp generated in the detection electrode 15. Due to the electric field generated by applying the induction signal Sd, a charge corresponding to the displacement of the movable member 12 of the variable shape structure 1 is induced in the detection electrode 15 of the variable capacity structure 10. At this time, the capacitance signal Scap generated at the detection electrode 15 is obtained as an induction signal Sd by the capacitance (Cs + Cp) obtained by adding the capacitance Cs of the capacitance variable structure 10 and the parasitic capacitance Cp and the capacitance Cstd of the electric field generator 20. It becomes a divided potential. Therefore, the capacitance signal Scap decreases toward the first common potential side as the capacitance Cs of the capacitance variable structure 10 increases.

  FIG. 6 is a diagram illustrating signal waveforms of respective units in the induction signal generation unit 22 and the capacity information extraction unit 23. As shown in FIG. 6A, regarding the capacitance signal Scap, both the case where the capacitance Cs takes the minimum value and the case where the capacitance Cs takes the maximum value are shown. The potential comparison reference signal Svref of the present embodiment is set to a potential at which the slope of the capacitance signal Scap becomes small. More specifically, a potential slightly lower than the saturation potential of the capacitance signal Scap when the capacitance Cs takes the maximum value is preferable. This is because the detection sensitivity of the capacitor Cs can be increased when the potential comparison reference signal Svref is closer to the saturation potential.

  The potential comparison unit 231 of the capacitance information extraction unit 23 outputs a rectangular wave detection signal Se obtained by amplifying the potential difference between the capacitance signal Scap and the potential comparison reference signal Svref (FIG. 6B). Therefore, the change in the capacitance signal Scap due to the capacitance Cs is converted into a change in the time when the detection signal Se transitions (in the example of FIG. 6B, the time when the detection signal Se rises from the low level to the high level). The larger it is, the longer the time until the detection signal Se transitions.

  The phase comparison unit 232 performs exclusive OR processing between the detection signal Se and the induction start signal Ss shown in FIG. 6C, thereby extracting the phase difference between the detection signal Se and the induction start signal Ss as the information signal Si. can do. Thus, the change in the capacitance signal Scap due to the capacitance Cs is converted into the change in the pulse width twidth of the information signal Si. As shown in FIG. 6D, the pulse width twidth increases as the capacitance Cs increases.

  The time-voltage conversion circuit 240 of the output adjustment unit 24 converts the pulse width twidth of the information signal Si into an analog voltage San. As a specific example of the time-voltage conversion circuit 240, a capacitor element having a capacity value that is partially charged with the pulse width twidth of the information signal Si may be used. The A / D conversion circuit 241 converts the analog voltage San output from the time-voltage conversion circuit 240 into a digital signal and outputs it as an output signal So. In this way, an output signal So correlated with the capacitance Cs of the variable capacitance structure 10 is obtained.

  As described above, since the electronic component device according to the present embodiment applies the induction signal to the detection electrode 15 through the electric field generation unit 20, feedback control of an operational amplifier such as the sensor shown in FIGS. 16 and 17 is necessary. Instead, the capacitance Cs of the variable capacitance structure 10 can be detected at high speed only by two control steps of applying the induction signal and converting the information signal into a digital signal. Displacement can be detected at high speed. In the present embodiment, the potential comparison reference signal Svref is set to a potential at which the slope of the capacitance signal Scap becomes small, the potential comparison reference signal Svref is set as a threshold, and the change in the capacitance signal Scap due to the capacitance Cs is taken as a time change. Therefore, even when the capacitance Cs of the variable capacitance structure 10 is smaller than the parasitic capacitance Cp, the capacitance Cs can be detected.

Further, in the present embodiment, only one control switch 223 that determines whether or not to apply the induction signal Sd to the electric field generation unit 20 is necessary for the capacitance detection, so that deterioration in detection accuracy is suppressed. Can do. In the present embodiment, the capacity variable structure 10 may have one output terminal. As a result, even when the present embodiment is applied to an optical switch, there is no need to newly take out a terminal and the number of process steps is not increased.
5 and 6, each signal is transitioned from the first common potential (ground potential), but each signal may be transitioned from the second common potential (power supply potential).

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 7 is a block diagram showing a specific example of the structural displacement detection unit 2 in the electronic component device according to the second embodiment of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals. The electronic component device according to the present embodiment uses an induction signal generation unit 22a instead of the induction signal generation unit 22 of the first embodiment, and uses a capacity information extraction unit 23a instead of the capacity information extraction unit 23. Yes, the signal input from the induction signal generator 22a to the capacity information extractor 23a is different from the first embodiment.

  That is, the induction signal generation unit 22a outputs the induction signal Sd to the capacity information extraction unit 23a. The phase comparison unit 232a of the capacitance information extraction unit 23a compares the phases of the detection signal Se and the induction signal Sd output from the potential comparison unit 231, and sets the phase difference between the detection signal Se and the induction signal Sd as the information signal Si. Extract.

  FIG. 8 is a diagram illustrating signal waveforms of respective units in the induction signal generation unit 22a and the capacity information extraction unit 23a. As shown in FIG. 8A, the detection signal Se shows both the case where the capacitance Cs takes the minimum value and the case where the capacitance Cs takes the maximum value. A phase difference between the detection signal Se and the induction signal Sd is extracted as the information signal Si by performing an exclusive OR process on the detection signal Se and the induction signal Sd shown in FIG. (FIG. 8D). In FIG. 8C, Vth is a logical threshold value of the phase comparison unit 232a.

  As in the first embodiment, a change in the capacitance signal Scap due to the capacitance Cs of the variable capacitance structure 10 is converted into a change in the pulse width twidth of the information signal Si, and the pulse width twidth increases as the capacitance Cs increases. . Here, assuming that the pulse width twidth when the capacitance Cs takes the minimum value is tmin and the pulse width twidth when the capacitance Cs takes the maximum value is tmax, the change in the pulse width twidth when the capacitance Cs changes the maximum. The minute is a range obtained by subtracting tmin from the pulse width tmax as shown in FIG. For example, when the shape variable structure 1 is a micromirror, the pulse width twidth of the information signal Si changes from tmin to tmax or from tmax to tmin when the mirror is rotated by the maximum displacement amount allowable. The range information of the displacement of the body 1 represents the range. That is, a portion of the minimum value tmin in the pulse width twidth of the information signal Si is a period that does not include information on the displacement of the shape variable structure 1.

  When a capacitor is used in the time-voltage conversion circuit 240 of the output adjustment unit 24 as in the first embodiment and the information signal Si is converted into the analog voltage San by charging within the time of the pulse width twidth, If the minimum value tmin is large, it is necessary to increase the capacitance value of the capacitive element by the amount of time tmin, which increases the circuit layout area. Therefore, it is desirable to reduce the minimum value tmin of the pulse width of the information signal Si.

  Therefore, in the present embodiment, the phase difference between the detection signal Se and the induction signal Sd is extracted as the information signal Si. As shown in FIG. 8C, since the induction signal Sd rises in response to the output of the induction start signal Ss, the time when the phase comparison unit 232a reaches the logical threshold value Vth is later than the induction start signal Ss. Therefore, the minimum value tmin of the pulse width of the information signal Si can be reduced in the present embodiment compared to the first embodiment that uses the induction start signal Ss for comparison with the detection signal Se. The capacitance value of the capacitive element used in the time-voltage conversion circuit 240 of the adjustment unit 24 can be reduced, and the layout area of the time-voltage conversion circuit 240 can be reduced.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 9 is a block diagram showing a specific example of the structural displacement detection unit 2 in the electronic component device according to the third embodiment of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals. The electronic component device according to the present embodiment uses a capacity information extraction unit 23b instead of the capacity information extraction unit 23 according to the first embodiment.

  The delay unit 233 of the capacity information extraction unit 23b delays the induction start signal Ss output from the induction signal generation unit 22, and outputs the delayed signal as the phase comparison reference signal Spref. As a specific example of the delay unit 233, for example, a multistage inverter circuit may be used. The phase comparison unit 232b compares the phases of the detection signal Se output from the potential comparison unit 231 and the phase comparison reference signal Spref, and extracts the phase difference between the detection signal Se and the phase comparison reference signal Spref as the information signal Si. .

  In this embodiment, since the phase comparison reference signal Spref obtained by delaying the induction start signal Ss is compared with the detection signal Se, the minimum value tmin of the pulse width of the information signal Si can be reduced, so that the output adjustment unit The capacitance value of the capacitive element used in the 24 time-voltage conversion circuits 240 can be reduced, and the layout area of the time-voltage conversion circuit 240 can be reduced.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 10 is a block diagram showing a specific example of the structural displacement detection unit 2 in the electronic component device according to the fourth embodiment of the present invention. The same reference numerals are used for the same components as those in FIGS. Is attached. The electronic component device of the present embodiment uses an induction signal generation unit 22a instead of the induction signal generation unit 22 of the third embodiment, and uses a capacity information extraction unit 23c instead of the capacity information extraction unit 23b. Yes, the signal input from the induction signal generator 22a to the capacity information extractor 23c is different from that of the third embodiment.

  That is, the induction signal generation unit 22a outputs the induction signal Sd to the capacity information extraction unit 23c. The delay unit 233c of the capacity information extraction unit 23c delays the induction signal Sd and outputs the delayed signal as the phase comparison reference signal Spref. The phase comparison unit 232c extracts the phase difference between the detection signal Se and the phase comparison reference signal Spref as the information signal Si.

  In the present embodiment, in order to compare the phase comparison reference signal Spref obtained by delaying the induction signal Sd and the detection signal Se, the minimum value tmin of the pulse width of the information signal Si is further reduced as compared with the third embodiment. Since the size can be reduced, the layout area of the time-voltage conversion circuit 240 of the output adjustment unit 24 can be further reduced.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. FIG. 11 is a block diagram illustrating a configuration of a delay unit according to the fifth embodiment of this invention. The electronic component device according to the present embodiment uses a delay unit 233d instead of the delay unit 233c in the capacity information extraction unit 23c of the fourth embodiment. The delay unit 233d compares the second potential comparison reference signal generation unit 2330 that generates the second potential comparison reference signal Svref2 with a predetermined potential, and the second potential comparison signal Sd output from the induction signal generation unit 22a. The second potential comparator 2331 compares the reference signal Svref2. As a specific example of the second potential comparison reference signal generation unit 2330, a general reference potential generation circuit may be used. As a specific example of the second potential comparison unit 2331, a general differential amplifier circuit is used. That's fine.

  FIG. 12 is a diagram illustrating signal waveforms of respective units in the induction signal generation unit 22a and the capacity information extraction unit 23c of the present embodiment. The second potential comparison unit 2331 outputs a signal obtained by amplifying the potential difference between the second potential comparison reference signal Svref2 and the induction signal Sd shown in FIG. 12A as the phase comparison reference signal Spref (FIG. 12B). ). As described in the fourth embodiment, the phase comparison unit 232c of the capacitance information extraction unit 23c extracts the phase difference between the detection signal Se output from the potential comparison unit 231 and the phase comparison reference signal Spref as the information signal Si. (FIG. 12D).

In the present embodiment, by adjusting the potential of the second potential comparison reference signal Svref2, the transition timing of the phase comparison reference signal Spref can be adjusted, and as a result, the minimum value tmin of the pulse width of the information signal Si. Can be reduced. In the present embodiment, the delay unit 233d is composed of the second potential comparison reference signal generation unit 2330 and the second potential comparison unit 2331, so that the delay unit 233c is a multi-stage inverter as in the fourth embodiment. The layout area of the delay unit 233d can be reduced as compared with the case where the circuit is configured with a circuit.
In the present embodiment, the example applied to the fourth embodiment has been described. However, the delay unit 233d may be used instead of the delay unit 233 as applied to the third embodiment. .

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. The electronic component device of the present embodiment is different from the first to fifth embodiments in the configuration of the electric field generator. Specific examples of the variable capacitance structure 10 and the electric field generator 20a of the present embodiment are shown in FIG. Similar to the first to fifth embodiments, the variable capacitance structure 10 includes a movable member 12 and a detection electrode (hereinafter referred to as a first detection electrode) 15. The electric field generator 20 a is configured by a second detection electrode 25 disposed in the substrate 11 so as to face the first detection electrode 15.

  FIG. 14 is a diagram showing the connection relationship between the variable capacitance structure 10 and the electric field generator 20a and the capacitance generated in these. In the first to fifth embodiments, the output terminal (first detection electrode 15) of the variable capacitance structure 10 and the output terminal of the electric field generation unit 20 are connected. The second detection electrode 25 of the electric field generating unit 20a is arranged to face the first detection electrode 15 without connecting them.

  Similar to the first to fifth embodiments, the capacitance variable structure 10 has a capacitance Cs that changes due to the displacement of the movable member 12 of the variable shape structure 1 between the movable member 12 and the first detection electrode 15. Formed. On the other hand, a capacitance Cstd is generated between the first detection electrode 15 and the second detection electrode 25, and a parasitic capacitance Cp is generated between the second detection electrode 25 and the first common potential (ground potential). Will occur. In the present embodiment, by generating a capacitance Cstd between the first detection electrode 15 and the second detection electrode 25, a parasitic capacitance is generated between the first detection electrode 15 and the first common potential. Does not occur. In order to ensure the effect that the parasitic capacitance is not generated, it is preferable that the area of the second detection electrode 25 is the same as that of the first detection electrode 15 or larger than that of the first detection electrode 15. .

  The induction signal Sd is input from the structural displacement detection circuit 21 to the second detection electrode 25 of the electric field generating unit 20a, and the capacitance signal Scap output from the first detection electrode 15 is input to the structural displacement detection circuit 21. As the configuration of the structural displacement detection circuit 21, any one of the configurations described in the first to fifth embodiments may be used.

  In the present embodiment, by disposing the second detection electrode 25 so as to face the first detection electrode 15, it is possible to prevent the first detection electrode 15 from generating a parasitic capacitance. The change of the capacitance signal Scap due to the change of can be increased, and the sensitivity of the capacitance detection can be increased as compared with the first embodiment.

  The present invention can be applied to MEMS devices represented by optical switches and acceleration sensors.

It is a block diagram which shows the structure of the electronic component apparatus used as the 1st Embodiment of this invention. It is sectional drawing which shows the structure of the shape variable structure in the 1st Embodiment of this invention. It is a figure which shows the specific example of the capacity | capacitance variable structure in the 1st Embodiment of this invention, and an electric field generation | occurrence | production part. It is a block diagram which shows the specific example of the structural displacement detection circuit in the 1st Embodiment of this invention. It is a figure which shows the signal waveform of each part in the induction | guidance | derivation signal generation part of the 1st Embodiment of this invention. It is a figure which shows the signal waveform of each part in the induction | guidance | derivation signal production | generation part and capacity | capacitance information extraction part of the 1st Embodiment of this invention. It is a block diagram which shows the specific example of the structural displacement detection unit in the electronic component apparatus of the 2nd Embodiment of this invention. It is a figure which shows the signal waveform of each part in the induction | guidance | derivation signal production | generation part and capacity | capacitance information extraction part of the 2nd Embodiment of this invention. It is a block diagram which shows the specific example of the structural displacement detection unit in the electronic component apparatus of the 3rd Embodiment of this invention. It is a block diagram which shows the specific example of the structural displacement detection unit in the electronic component apparatus of the 4th Embodiment of this invention. It is a block diagram which shows the structure of the delay part of the capacity | capacitance information extraction part in the electronic component apparatus of the 5th Embodiment of this invention. It is a figure which shows the signal waveform of each part in the induction | guidance | derivation signal production | generation part and capacity | capacitance information extraction part of the 5th Embodiment of this invention. It is sectional drawing which shows the specific example of the capacity | capacitance variable structure and electric field generation | occurrence | production part in the 6th Embodiment of this invention. It is a figure which shows the connection relation of the capacity | capacitance variable structure and electric field generation | occurrence | production part in the 6th Embodiment of this invention, and the capacity | capacitance which arises in these. It is sectional drawing which shows the structure of the general electronic component apparatus which uses a MEMS structure. It is a block diagram which shows the structure of the capacitive fingerprint sensor of a 1st prior art example. It is a block diagram which shows the structure of the pressure sensor of a 2nd prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Variable shape structure, 2 ... Structural displacement detection unit, 10 ... Capacity variable structure, 11 ... Substrate, 12 ... Movable member, 13 ... Control electrode, 14 ... Support | pillar, 15 ... Detection electrode, 20 ... Electric field generation part, DESCRIPTION OF SYMBOLS 21 ... Structural displacement detection circuit 22, 22a ... Guidance signal generation part, 23, 23a, 23b, 23c ... Capacitance information extraction part, 24 ... Output adjustment part, 25 ... 2nd detection electrode, 220 ... Induction start signal generation part 221 ... Electric field induction unit, 222 ... Induction voltage generation circuit, 223 ... Control switch, 230 ... Potential comparison reference signal generation unit, 231 ... Potential comparison unit, 232, 232a, 232b, 232c ... Phase comparison unit, 233, 233c, 233d: delay unit, 240: time-voltage conversion circuit, 241: A / D conversion circuit.

Claims (9)

In an electronic component device having a shape variable structure that is displaced according to an input control signal or a physical quantity to be detected, and a structure displacement detection unit that detects a capacitance representing the displacement of the shape variable structure.
The shape variable structure includes a variable capacity structure whose capacity changes according to the displacement,
The structural displacement detection unit includes an electric field generation unit that generates an electric field in the variable capacitance structure, an induction signal generation unit that outputs an induction signal that is a basis of the electric field generation to the electric field generation unit, and generation of the electric field. A capacity information extraction unit that extracts an information signal representing the capacity of the variable capacity structure from a capacity signal output from the output terminal of the capacity variable structure, and an output adjustment that converts the information signal into a format that can be processed With
The induction signal generation unit includes an induction start signal generation unit that outputs an induction start signal that instructs generation start of the electric field, and an electric field induction unit that outputs the induction signal according to the induction start signal,
The capacitance information extraction unit amplifies a potential difference between a first potential comparison reference signal generation unit that generates a first potential comparison reference signal having a predetermined potential, and the capacitance signal and the first potential comparison reference signal. A first potential comparison unit that outputs as a detection signal, and a phase comparison unit that extracts a phase difference between the detection signal and the induction start signal as the information signal,
The output adjustment unit includes a time-voltage conversion circuit that converts time information included in the pulse width of the information signal into an analog voltage, and an A / D conversion circuit that converts the analog voltage into a digital signal. An electronic component device. In an electronic component device having a shape variable structure that is displaced according to an input control signal or a physical quantity to be detected, and a structure displacement detection unit that detects a capacitance representing the displacement of the shape variable structure.
The shape variable structure includes a variable capacity structure whose capacity changes according to the displacement,
The structural displacement detection unit includes an electric field generation unit that generates an electric field in the variable capacitance structure, an induction signal generation unit that outputs an induction signal that is a basis of the electric field generation to the electric field generation unit, and generation of the electric field. A capacity information extraction unit that extracts an information signal representing the capacity of the variable capacity structure from a capacity signal output from the output terminal of the capacity variable structure, and an output adjustment that converts the information signal into a format that can be processed With
The induction signal generation unit includes an induction start signal generation unit that outputs an induction start signal that instructs generation start of the electric field, and an electric field induction unit that outputs the induction signal according to the induction start signal,
The capacitance information extraction unit amplifies a potential difference between a first potential comparison reference signal generation unit that generates a first potential comparison reference signal having a predetermined potential, and the capacitance signal and the first potential comparison reference signal. A first potential comparison unit that outputs the detection signal as a detection signal, and a phase comparison unit that extracts a phase difference between the detection signal and the induction signal as the information signal,
The output adjustment unit includes a time-voltage conversion circuit that converts time information included in the pulse width of the information signal into an analog voltage, and an A / D conversion circuit that converts the analog voltage into a digital signal. An electronic component device. The electronic component device according to claim 1 or 2,
The electric field induction unit includes an induction voltage generation circuit that outputs a predetermined voltage, a control terminal connected to an output terminal of the induction start signal generation unit, an input terminal connected to an output terminal of the induction voltage generation circuit, and an output An electronic component device comprising: a control switch that is connected to an input terminal of the electric field generation unit and is closed in response to an output of the induction start signal. The electronic component device according to claim 1 or 2,
The capacitance information extraction unit further includes a delay unit that delays the induction start signal or the induction signal input from the induction signal generation unit to the phase comparison unit and inputs the delayed signal to the phase comparison unit. Electronic component device characterized. The electronic component device according to claim 4,
The delay unit includes a second potential comparison reference signal generation unit that generates a second potential comparison reference signal having a predetermined potential, the induction start signal or the induction signal input from the induction signal generation unit, and the first An electronic component device comprising: a second potential comparison unit that outputs a signal obtained by amplifying a potential difference with respect to two potential comparison reference signals to the phase comparison unit. The electronic component device according to any one of claims 1 to 5,
The capacitance variable structure is composed of a movable member of the variable shape structure and a detection electrode disposed opposite to the movable member. The electronic component device according to any one of claims 1 to 5,
The electric field generating unit is composed of a capacitive element. The electronic component device according to any one of claims 1 to 5,
The variable capacitance structure is composed of a movable member of the variable shape structure, and a first detection electrode installed opposite to the movable member,
The electronic part device is characterized in that the electric field generation unit includes a second detection electrode disposed to face the first detection electrode. The electronic component device according to any one of claims 1 to 8,
The electronic component device according to claim 1, wherein the variable shape structure is a micromirror that changes a light path.

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