JP2009042063A - Sensing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the frequency jump at the time of switching of a channel in fetching the frequency signals of a plurality of channels, which are respectively equipped with piezoelectric oscillators changed in natural frequency by adsorbing a sensing target, in a measuring part by time-sharing control. <P>SOLUTION: This sensing device is constituted so as to be equipped with a switching part, which is equipped with a plurality of oscillation circuits for respectively oscillating a plurality of the piezoelectric oscillators; a first contact provided at every oscillation circuit, in order to successively switch the respective oscillation circuits to connect them to the measuring part to connect the output terminal of the oscillation circuits to the measuring part and a second contact switching the output terminal of the oscillation circuits, with respect to the first contact to separate them from the measuring part; and the phase correcting circuit part which is connected to the second contact and shifts the phase of the frequency signals from the oscillation circuits, in order to suppress the disturbance of the waveforms of the frequency signals from the oscillation circuits at the time of switching of the switching part, to suppress the effect of a reflected wave. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is provided with a plurality of channels of piezoelectric vibrators whose natural frequency changes due to the adsorption of the sensing object, and these channels are sequentially switched and the frequency signal is taken into the measurement unit by time division to sense the sensing object associated with each channel. It is related with the sensing apparatus for doing.

In the fields of biotechnology, food, and environmental conservation, it is often necessary to accurately detect the presence or concentration of trace amounts of substances, and a sensing device using a quartz crystal is used as the method. A QCM (Quartz Crystal Microbalance) measurement method is known (Patent Document 1). This assay depositing a sensing substance, such as the dioxins on the surface of the crystal oscillator, which the natural frequency of the quartz resonator utilizing a property that varies depending on the deposition amount, 10 ^-12 High analytical accuracy on the order of g / ml. Therefore, this measurement method is remarkably low in cost, analysis time, and analysis accuracy compared to the official method (JIS) and ELISA method (enzyme-immobilized immunoassay method) using a high-resolution gas chromatograph mass spectrometer. It is advantageous.

  Recently, an antibody that chemically binds only a specific molecule has been actively developed, and an antibody that causes an antigen-antigen reaction to a specimen is previously adsorbed on the surface of a crystal resonator (specifically, the surface of an electrode). By forming it as a layer, it has become possible to analyze and analyze various fields.

  By the way, in the method of measuring contaminants in solution and antigens in blood using a quartz oscillator, it is necessary to wash the sensor part repeatedly and the antibody-antigen reaction may take a long time. Furthermore, since distribution data may be obtained by measuring a large number of specimens and statistical evaluation may be performed, an efficient method is desired. For these reasons, simultaneous measurements using a large number of quartz sensors are being studied. A technique using a large number of quartz sensors is described in Patent Document 1 and the like.

  FIG. 17 shows the sensing device 1 having an 8-channel configuration to which eight crystal resonators 11a to 11h are connected. In the figure, reference numerals 12a to 12h denote oscillation circuits of the crystal oscillators 11a to 11h, and a signal switching unit 14 including switch units 13a to 13o is provided at the subsequent stage of each of the oscillation circuits 12a to 12h. . A measurement main body unit 15 including a frequency measurement unit that measures the frequency is provided at the subsequent stage of the signal switching unit 14.

  The switch units 13a to 13o are controlled to be switched by a switching control unit (not shown). Specifically, each of the switch units 13a is connected so that each of the crystal resonators 11a to 11h is repeatedly connected to the measurement main body unit 15 one by one, that is, eight channels are connected one by one in order, for example. The control signals are output to .about.13o, and the frequency signals from the eight crystal resonators 11a to 11h (the frequencies from the eight oscillation circuits 12) are time-divided and output to the measurement main body 15. And in patent document 1, the measurement main-body part 15 will calculate the frequency of eight crystal oscillators 11a-11h in parallel based on the phase of each frequency signal, if it says roughly, and will be set to the calculated frequency. Based on this, the detection target substance is quantified and the presence or absence is determined.

  By the way, as shown in an evaluation test to be described later, immediately after switching the output to the measurement main body 15 from a predetermined oscillation circuit 12 to the next oscillation circuit 12, a phenomenon called a frequency jump in which the measured frequency rises temporarily is present. Arise. The reason for this is presumed from the following experimental examples and the like. If the contact on the side where the oscillation circuit is connected to the measurement unit in the switch unit is the ON contact, and the contact on the side where the oscillation circuit is disconnected from the measurement unit is the OFF contact, when the oscillation circuit is switched to the off contact, A reflected wave that totally reflects the output, that is, a reflected wave that is 180 ° out of phase is generated. For this reason, immediately after switching from the on-contact to the off-contact, it is considered that the waveform connection is disturbed due to the influence of the reflected wave. For this reason, when switching from the OFF contact to the ON contact while the waveform is distorted, the waveform of the frequency signal of the oscillation output directed to the measurement unit is distorted. Further, even after switching from the off contact to the on contact, the waveform connection is disturbed by the reflected wave as shown in FIG. 18, and thus the waveform at the time of switching from the on contact to the off contact and vice versa. It is presumed that a frequency jump occurs due to a disturbance of the waveform of the frequency signal input to the measurement unit as a result. For this reason, the sensitivity when adsorbed to the quartz resonator is degraded, and the frequency measurement accuracy is degraded.

  Therefore, conventionally, a stabilization time of a signal called a guard time in which the frequency is not measured is ensured until the frequency is stabilized after the channel is switched, and the measurement of the frequency is started after the guard time elapses.

  However, when the guard time is set to be long, the time for one slot of time division processing assigned to each channel is lengthened, and the frequency sampling interval is lengthened. In that case, it takes a long time to update the sampling value of the computer. For this reason, if the measurement time is lengthened, the measurement accuracy does not decrease, but if the same measurement time is measured, the frequency resolution decreases, and eventually the measurement accuracy also decreases.

In Patent Document 1, a terminal load is connected to an off contact in a sensing device having a similar configuration. This is because the oscillation frequency of the oscillation circuit is slightly shifted, and the oscillation circuit being measured is separated from the oscillation circuit that is disconnected. It is intended to prevent overlapping of the frequency spectrum and does not correct the phase. Therefore, the above problem cannot be solved.
Japanese Patent Laying-Open No. 2006-184260: FIG.

  The present invention has been made under the circumstances as described above, and takes in frequency measurement signals of a plurality of channels each having a piezoelectric vibrator that changes its natural frequency by adsorbing a sensing object to a measurement unit by time division control. In the meantime, it is an object of the present invention to provide a sensing device capable of detecting a sensing object with high accuracy while suppressing frequency jumps at the time of channel switching.

The sensing device of the present invention uses a piezoelectric vibrator in which an adsorption layer for adsorbing a sensing object is formed on the surface, and the natural frequency is changed by the adsorption of the sensing object. In a sensing device that senses a sensing object by a change,
A plurality of piezoelectric vibrators;
A plurality of oscillation circuits for oscillating each of the plurality of piezoelectric vibrators;
A first contact for connecting the output terminal of the oscillation circuit to the measurement unit and the first contact are provided for each oscillation circuit to sequentially connect the plurality of oscillation circuits to the measurement unit. A switching unit including a second contact that is switched from the measurement unit by switching the output end of the oscillation circuit;
A control unit that outputs a switching signal to the switching unit so that the frequency signal from the plurality of oscillation circuits is sequentially taken into the measurement unit by time division control;
A phase correction circuit unit that is connected to the second contact and that shifts the phase of the frequency signal from the oscillation circuit in order to suppress disturbance of the waveform of the frequency signal from the oscillation circuit when the switching unit is switched. It is characterized by.

  The phase correction circuit unit may be configured, for example, such that a phase shift of the frequency signal is in an absolute value range of 17 ° to 41 °, and the measurement unit is configured to output a switching signal, You may be comprised so that the frequency measured value after 1 millisecond or more may pass may be validated.

  According to the present invention, the phase correction circuit unit for shifting the phase of the frequency signal of the oscillation circuit is provided at the contact point on the side where the oscillation circuit is disconnected from the measurement unit for the switching contacts of the plurality of channels including the piezoelectric vibrator and the oscillation circuit. Therefore, as can be seen from the experimental results described later, the waveform disturbance when the oscillation circuit is connected to the measurement unit is suppressed, and the frequency jump is reduced. For this reason, even if the guard time, which is the signal stabilization time ensured after the channel switching, is short, the waveform disturbance can be suppressed, so that the sensing object can be measured with high accuracy.

  Embodiments of a sensing device according to the present invention will be described below. First, the overall structure of the sensing device will be briefly described. As shown in FIG. 1, the sensing device 2A includes a plurality of, for example, eight crystal sensors 2, an oscillation circuit unit 3 to which these crystal sensors 2 are detachably mounted, and a measuring instrument body connected to the oscillation circuit unit 3. 4 is provided. The oscillation circuit unit 3 includes an oscillation circuit E (E1 to E8) described later, a signal switching unit 32, and a switching control unit 33, and the measuring instrument main body 4 includes a measurement main unit 40 described later.

  As shown in FIGS. 1 and 2, the quartz sensor 2 includes a printed circuit board 21, for example, a printed circuit board 21. The printed circuit board 21 is overlaid with a rubber sheet 22 having a concave portion 23 provided on the surface thereof, and a rubber sheet. The protruding portion on the lower surface side of 22 is fitted into the opening 23 a of the printed circuit board 21. A crystal resonator 24, which is a piezoelectric resonator, is provided so as to close the concave portion 23. The lower surface side of the crystal resonator 24 faces an airtight space, and an injection port is formed in the space on the upper surface side of the crystal resonator 24. The sample solution injected from 25a is filled. In the figure, 25b is a confirmation port for confirming the presence or absence of the sample solution in the space. In the crystal unit 24, electrodes (not shown) are provided on both sides of a circular crystal piece, and these electrodes are a pair of printed wirings 27a, which are a pair of conductive paths provided on the substrate 21 via a conductive adhesive 26. 27b is electrically connected to each other. The upper electrode is provided with an adsorption layer for adsorbing the substance according to the substance to be measured in the sample solution.

  FIG. 3 is a block diagram of the sensing device. In this block diagram, the eight crystal sensors 2 attached to the oscillation circuit unit 3 are indicated by numbers F1 to F8 for convenience. The quartz sensor F (F1 to F8) is used as a sensing sensor that detects a change in its natural frequency by adsorbing a sensing object in the sample liquid to the electrode surface on the upper surface side of the quartz vibrator 24.

  The oscillation circuit unit 3 includes 8-channel oscillation circuits E1 to E8 for causing the quartz sensors F1 to F8 to oscillate, and the quartz sensors F1 to F8 are inserted into the insertion ports of the oscillation circuit unit 3 shown in FIG. As a result, terminal portions (not shown) provided in the insertion ports and the printed wirings 27a and 27b of the quartz sensors F1 to F8 are electrically connected to each other, and the quartz sensors F1 to F8 are electrically connected to the oscillation circuits 31. When connected, each crystal resonator 2 oscillates. Then, the electrical signals (frequency signals) of the crystal sensors F1 to F8 are output to the signal switching unit 32 at the subsequent stage of the oscillation circuits E1 to E8.

  The signal switching unit 32 includes switches SW1 to SW15, and switches SW1 to SW8 are provided in the subsequent stages of the oscillation circuits E1 to E8, respectively, but the structure of the signal switching unit 32 is shown in a simplified manner for convenience of illustration. The frames D2 to D3 in the subsequent stage of the oscillation circuits E3 to E8 are configured by connecting the switch SW and a phase correction termination circuit G to be described later in the same manner as in the dotted frame D1 in the subsequent stage of the oscillation circuits E1 and E2. ing. Just as SW9 is connected to the subsequent stage of SW1 and SW2, SW10 is connected to the subsequent stage of SW3 and SW4, SW11 is connected to the subsequent stage of SW5 and SW6, and SW12 is connected to the subsequent stage of SW7 and SW8. SW13 is connected to the subsequent stage of SW9 and SW10, SW14 is connected to the subsequent stage of SW11 and SW12, and SW15 is connected to the subsequent stage of SW14 and SW14 as shown in the figure.

  Each contact A of the switches SW1 to SW8 is an ON contact that is connected to the measurement main body 40 when the subsequent switches SW9 to SW12, switch SW13, and switch SW15 are switched. Further, a phase correction termination circuit G (G1 to G8) is connected to the subsequent stage of each contact B which is an OFF contact of the switches SW1 to SW8. The switches SW1 to SW15 are switched in response to a switching signal (control signal) from a switching control unit 33 described later.

  The phase correction termination circuits G1 to G8, which are phase correction circuit units, each include, for example, a capacitor, a resistor, an inductor, and the like. As described in the operation, each switch SW is switched, and each oscillation circuit E is connected to the measurement main body 40 from the phase correction termination circuit G corresponding to the oscillation circuit E. The phase of the frequency signal output from each oscillation circuit E to the phase correction termination circuit G is such that the disturbance of the waveform of the frequency signal output to the measurement main body 40 when connected to the measurement main body 40 is suppressed. Each phase correction termination circuit G is configured so as to advance, for example, 40 ° (deviation + 40 °) with respect to the phase of the frequency signal output to the measurement main body 40.

  The measurement main body 40 following the switch SW15 of the signal switching unit 32 includes an analog / digital (A / D) converter 41, a frequency measurement unit 42, a frequency calculation unit 43, and a display unit (not shown). The A / D converter 41 converts the frequency signal (analog signal) output in order from each oscillation circuit E into a digital signal.

A frequency measurement unit 42 is provided following the A / D converter 41. The frequency measurement unit 42 is configured by an FPGA, processes a digital signal from the A / D converter 41, and measures the frequency of the oscillation circuit E by a method described in, for example, 2006-184260. Various known methods can be employed for this frequency measurement method. The frequency measurement unit 42 is connected to the switching control unit 33 and sends a control signal to the switching control unit 33.

  Based on the control signal from the frequency measurement unit 42, the switching control unit 33 is connected to the oscillation circuits E1 to E8 one by one in sequence to the measurement main body 40, that is, the eight channels on the detection end side are connected one by one in order. A switching signal (control signal) is sent to each switch SW so that the oscillation circuit E other than the oscillation circuit of the channel connected to the measurement main body 40 is connected to the corresponding phase correction termination circuit G. Each switch SW is switched in order from, for example, the subsequent stage, that is, SW15, SW13 and 14, SW9 to SW12, and SW1 to 8 by this switching signal.

  Switching of each channel connected to the measurement main body 40 is performed at 12.5 nsec, for example, and the frequency measurement unit 42 receives frequency signals (frequency from eight oscillation circuits E1 to E8) from the eight crystal sensors F1 to F8. The frequency measurement unit 42 can obtain the frequencies of the eight crystal sensors F <b> 1 to F <b> 8 in parallel by time division. The channel switching time of 12.5 nsec corresponds to, for example, a shift of 41 ° to 42 ° of the frequency of the oscillation circuit E, and this channel switching time is much shorter than the guard time described later, It is set to be zero.

  A frequency calculation unit 43 including, for example, a CPU is provided after the frequency measurement unit 42, and the frequency calculation unit 43 calculates and obtains the frequency of each channel. The calculated frequency is displayed on the display unit.

  Next, the operation of the above-described sensing device 2A will be described. First, the oscillation circuit unit 3 and the measuring instrument main body 4 are connected, and the quartz sensors F1 to F8 are inserted into the oscillation circuit unit 3 to oscillate the crystal resonator 24, for example, in an empty state.

  Thereafter, for example, when the user presses a button (not shown) for starting the measurement provided in the measurement main unit 4, a control signal is output from the frequency measurement unit 42 to the switching control unit 33, and the oscillation circuits E1 to E8 are sequentially generated. Is connected to the measurement main body 40 by switching of the switches SW1 to SW15. The measurement main body 40 measures the frequency for each channel. At a certain time t1, the user injects, for example, pure water that does not include an object to be measured into each of the quartz sensors F1 to F8, the oscillation frequency of the crystal resonator 24 decreases, and the oscillation stabilizes. A sample solution containing a substance to be measured, such as dioxin, is injected into the quartz sensors F1 to F8. The substance to be measured is adsorbed on the adsorption layer provided on the excitation electrode of the crystal unit 24, and the oscillation frequency of the crystal unit 24 is lowered. FIG. 4 shows a graph of the frequency displayed on the display unit, and the user has obtained in advance from the difference q between the stable frequency between times t1 and t2 and the stable frequency after t2. Measure the dioxin concentration in each channel using a calibration curve.

  Assuming that the oscillation circuit E8 is being measured, the switch SW1 in the path of the oscillation circuit E1 is in the state shown in FIG. When the measurement of the oscillation circuit E8 is completed, the switching control unit 33 outputs a switching signal to each switch SW, each switch SW is switched as shown in FIG. 5B, and the connection of the oscillation circuit E8 is connected from the measurement main body unit 40. The phase correction termination circuit G8 is switched and the connection of the oscillation circuit E1 is switched from the phase correction termination circuit G1 to the measurement main body 40.

  As shown in FIG. 6, for example, when at least 1 msec, which is a predetermined time (guard time) that has been set in advance, has passed since the control signal is output from the frequency measurement unit 42 to the switching control unit 33, the frequency measurement unit 42 sets the frequency. Specifically, the frequency of the difference between the frequency from the oscillation circuit E1 and the frequency of the reference signal is measured, and the measured frequency is stored in the memory as time division data and displayed on the display unit.

  When the time division processing set in advance since the measurement of the frequency of the oscillation circuit E1 is started, that is, when the time of the slot assigned to each channel has elapsed, the contact of the switch SW9 is first switched based on the switching signal from the switching control unit 33. Then, the contact of the switch SW1 is switched from the A side to the B side, and then the contact of the switch SW2 is switched from the B side to the A side, and the oscillation circuit E2 is connected to the frequency measuring unit 42. Based on the output signal from the oscillation circuit E2, the frequency corresponding to the oscillation circuit E2 is measured.

  According to this embodiment, the phase of the frequency signal of the oscillation circuit E is shifted to the contact on the side where the oscillation circuit E is disconnected from the measurement main body 40 with respect to the switches SW1 to SW8 on the subsequent stage of the crystal sensor F and the oscillation circuit E. Since the phase correction termination circuit G is provided, when the oscillation circuit E is connected from the phase correction termination circuit G to the frequency measurement unit 42 by the signal switching unit 32, the frequency of the frequency correction termination circuit G is also shown as shown from the experimental results described later. Disturbance of the waveform can be suppressed. This is considered to be because the phase of the reflected wave is shifted from 180 ° due to the shift of the phase of the frequency signal, and the influence thereof is reduced. Therefore, it is possible to suppress the frequency jump immediately after switching the switch while shortening the guard time that is the stabilization time after the switch switching. As a result, highly accurate frequency measurement can be performed, the concentration of the substance to be measured in the sample solution can be measured with high accuracy, and the measurement time can be shortened.

  FIG. 7 shows the configuration of another sensing device. A circuit 55a and a circuit 56a are connected in parallel to the contact B of the switch SW1 of the sensing device 5, and phase correction is performed by these circuits 55a and 56a. A termination circuit unit 57a is configured. Similarly, a circuit 55b and a circuit 56b are connected in parallel to the contact B of the switch SW2, and these circuits 55b and 56b constitute a phase correction termination circuit unit 57b. Similarly to the phase correction termination circuit G, the phase correction termination circuit units 57a and 57b have a function of shifting the phase of the current flowing through the phase correction termination circuit units 57a and 57b with respect to the phase of the current flowing through the measurement main body unit 40. Each of the circuits 55a, 56a, 55b, and 56b is a circuit that includes, for example, a capacitor, a resistor, an inductor, and the like.

  FIG. 8 is a time chart of frequency measurement by the sensing device 5. A control signal output to the switch SW9 is shown as an output signal selection control signal, and a control signal output to the switches SW1 and SW2 is shown as a phase correction control signal. Each control signal is output from the switching control unit 33 corresponding to each other. When the output signal selection control signal having a value indicated by H in FIG. 8 is output to the switch SW9, the switch SW9 is connected to the contact C on the oscillation circuit E1 side, and the phase correction control of the value indicated by H in FIG. When the signal is output to the switches SW1 and SW2, the switch SW1 is connected to the contact A and the switch SW2 is connected to the contact B, respectively, and the oscillation circuit E1 is connected to the measurement main body 40 as shown in FIG. .

  When an output signal selection control signal having a value indicated by L in the figure is output to the switch SW9, the switch SW9 is connected to the contact D on the oscillation circuit E2 side, and the phase correction control signal having a value indicated by L in FIG. When output to SW1 and SW2, the switch SW1 is connected to the contact B and the switch SW2 is connected to the contact A, respectively, and the oscillation circuit E2 is connected to the measurement main body 40 as shown in FIG. Also in this sensing device 5, as shown in the time chart, the switching operation of each switch SW is performed from the output side, and the frequency is measured when the guard time elapses after the output signal selection control signal is output in each slot. Also in the sensing device 5 having such a configuration, occurrence of a frequency jump immediately after switching the oscillation circuit E can be suppressed when measuring the frequencies from the oscillation circuits E1 and E2.

(Evaluation Test 1-1)
In the conventional sensing device 1, a sample solution is put into each crystal sensor 11 to oscillate, and the oscillation circuit 12 connected to the measurement main body 15 is switched by the signal switching unit 14, and the frequency oscillated from each oscillation circuit 12a to 12d. Was measured. Although the frequency output from the oscillation circuits 12b to 12d was stable at 9167000 Hz, a frequency jump was observed for the frequency output from the oscillation circuit 12a as shown in FIG. In the graph, the frequencies detected from the oscillation circuits 12b to 12d are omitted for convenience.

(Evaluation Test 1-2)
Subsequently, each frequency output from the oscillation circuits 12a to 12d was measured using the sensing device 1 as in the evaluation test 1-1. However, during the frequency measurement, the switching to the measurement main body 15 by the signal switching unit 14 is not performed, and the frequencies of the oscillation circuits 12a to 12d are individually measured. FIG. 11 is a graph showing the frequency output from the oscillation circuit 12a. As shown in this graph, no frequency jump was measured. Although the display is omitted for convenience, the frequency output from the oscillation circuits 12b to 12c is the same as the frequency output from the oscillation circuit 12a, and no frequency jump was observed. From the results of the evaluation tests 1-1 and 1-2, it can be seen that a frequency jump is caused by switching the connection of each oscillation circuit 12 to the measurement main body 15.

(Evaluation Test 1-3)
FIGS. 12A and 12B are diagrams schematically showing the sensing device 1 for convenience, in which H1 oscillates in the crystal resonators 11a to 11d, H2 oscillates in the crystal resonators 11e to 11h, and I1 oscillates. In the circuits 12a to 12d, I2 corresponds to 12e to 12h, respectively. That is, the same measurement is performed for each of the four channels. A point J is a point between the oscillation circuit I1 and a subsequent switch, a point K is a point between the switch and a subsequent switch, and a point L is an off end of the switch. As shown in FIGS. 12A and 12B, each switch of the signal switching unit 14 was switched, and the phase of the current between the points JK and the phase of the current between the points JL were measured. The phase was measured after a predetermined time had elapsed since each switch was switched.

  FIG. 13A is a graph showing the frequency and phase between the points JK, and FIG. 13B is a graph showing the frequency and phase between the points JL. The vertical axis of each graph indicates the phase, and the horizontal axis indicates the frequency. The frequencies at the points P1 and P2 of each graph are 7.908 MHz and 9.182500 MHz, respectively. The phase of the frequency between JK corresponding to the point P1 is 85.963 °, the phase of the frequency between JL is 87.69 °, the phase of the frequency between the points JK corresponding to the point P2 is 71.271 °, JL The frequency phase between them was 72.218 °. Even if the phase is substantially the same at the same frequency, a frequency jump has occurred as shown in Evaluation Test 1-1. However, it is thought that frequency disturbance has occurred immediately after switching the switch.

(Evaluation test 2)
Similarly to the evaluation test 1-3, the phase of the current between the points MN and MO shown in FIG. 14 was measured in the case of measuring the frequencies of the oscillation circuits E1 and E2 by switching the switches SW for the sensing device 5. . As shown in FIG. 14, here, the point L is set between the switch SW1 and the phase correction termination circuit unit 57a.

  FIG. 15A is a graph showing the frequency and phase between points MN, and FIG. 16B is a graph showing the frequency and phase between points MO. The vertical axis and horizontal axis of each graph are shown in FIG. The phase and frequency are shown in the same manner as the graph. The frequencies at points P3 and P4 are 7.908 MHz and 9.18 MHz, respectively. At the point P3, the phase of the frequency between the points MN is 87.005 ° and the phase of the frequency between the MOs is 49.275 °. At the point P4, the phase of the frequency between the points MN is 71.389 ° and the frequency between the MOs The phase of is 30.773 °. Therefore, the phase difference was 41 ° to 42 °. At this time, the frequency output from the oscillation circuits E1 and E2 was measured as in the evaluation test 1-2, but no frequency jump was measured. Therefore, it can be seen that the frequency jump is reduced when the phase difference is provided in this way. The graph of FIG. 16 shows the time and current intensity when this evaluation test was performed, L1 is the current intensity between the points MN, L2 is the current intensity between the points MO, and L3 is for switching the switch SW9. Each of the pulses of the phase correction control signal is shown. The phase difference of 41 ° to 42 ° corresponds to a waveform shift of about 12.5 nsec in this evaluation test, and the rise time of the pulse of the phase correction control signal is about 12.4 nsec. The phase difference and the rise time were substantially the same.

(Evaluation tests 3-1 to 3-4)
In the sensing device 5, the phase correction circuit unit 57 a is adjusted to change the current phase shift between the points MN and MO shown in the evaluation test 2, and the frequency shift in the frequency measurement time after the guard time has elapsed. The average amount was measured. For tests 3-1 to 3-4, the length of the guard time was set to be longer in the order of test 3-1 <test 3-2 <test 3-3 <test 3-4.

  Table 1 below shows the results. As shown in this table, the average of the frequency shift amount suppressed by the magnitude of the phase shift varies, and the phase shift is -17 ° to -41 ° and 16 °. Especially when the angle is ˜39 °, the amount of frequency deviation is small, and it can be seen from evaluation test 3-4 that the amount of frequency deviation is suppressed to 0.03 Hz or less in the range of the phase deviation. From this result, it can be said that the phase shift is preferably in the range of 17 ° to 41 ° in absolute value.

1 is an overall configuration diagram of a sensing device according to an embodiment of the present invention. It is a vertical side view of the quartz sensor which comprises the said sensing device. It is a block diagram which shows the structure of the said sensing apparatus. It is a graph of the frequency and time at the time of measurement shown on the display part of the sensing device. It is the effect | action figure which showed a mode that the oscillation circuit connected to the said frequency measurement part switches. It is a time chart of the measurement in the said sensing apparatus. It is a block diagram of the sensing device of other composition. It is a time chart of the measurement in the said sensing apparatus. It is the effect | action figure which showed a mode that the oscillation circuit connected to the frequency measurement part of the said detection apparatus switched. It is the graph which showed the frequency measured by the conventional sensing apparatus. It is the graph which showed the frequency measured without performing switching of a switch in the conventional sensing device. It is explanatory drawing which showed the point which measures a phase in the conventional sensing apparatus. It is the graph which showed the phase measured in the conventional sensing apparatus. It is explanatory drawing which showed the point which measures a phase in the sensing apparatus of this invention. 4 is a graph showing a phase measured in the sensing device. It is the graph which showed the electric current intensity of each point which measured the phase in the sensing device. It is a block diagram of an example of the conventional sensing apparatus. It is explanatory drawing which showed the frequency output from the oscillation circuit in the said conventional sensing apparatus.

Explanation of symbols

2A Sensing device 2, F1 to F8 Crystal sensor 24 Crystal resonator E1 to E8 Oscillation circuit 32 Signal switching unit 33 Switching control unit G1 to G8 Phase correction termination circuit 40 Measurement body unit 42 Frequency measurement unit

Claims (3)

An adsorption layer for adsorbing the sensing object is formed on the surface, and a piezoelectric vibrator whose natural frequency changes due to the adsorption of the sensing object is used, and the sensing object is sensed by the change of the natural frequency of this piezoelectric vibrator. In the sensing device to
A plurality of piezoelectric vibrators;
A plurality of oscillation circuits for oscillating each of the plurality of piezoelectric vibrators;
A first contact for connecting the output terminal of the oscillation circuit to the measurement unit and the first contact are provided for each oscillation circuit to sequentially connect the plurality of oscillation circuits to the measurement unit. A switching unit including a second contact that is switched from the measurement unit by switching the output end of the oscillation circuit;
A control unit that outputs a switching signal to the switching unit so that the frequency signal from the plurality of oscillation circuits is sequentially taken into the measurement unit by time division control;
A phase correction circuit unit that is connected to the second contact and that shifts the phase of the frequency signal from the oscillation circuit in order to suppress disturbance of the waveform of the frequency signal from the oscillation circuit when the switching unit is switched. Sensing device characterized by.   2. The sensing device according to claim 1, wherein the phase correction circuit unit is configured such that a phase shift of the frequency signal is in an absolute value range of 17 ° to 41 °.   The sensing device according to claim 1, wherein the measurement unit is configured to validate a frequency measurement value after 1 millisecond or more has elapsed since the switching signal was output.

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