JP2022176609A - Diaphragm gauge - Google Patents

Abstract

To reduce power consumption for heating to reduce the size of a sensor chip.SOLUTION: A diaphragm gauge comprises: a sensor chip in which the interval between first and second electrodes changes according to displacement of a diaphragm due to pressure of a medium to be measured; a signal generator 120 that selectively applies, to the second electrode, any one of a first sensor drive signal and a second sensor drive signal with a higher frequency than that of the first sensor drive signal; an amplifier 121 that converts current output from the first electrode into voltage; a capacity calculation unit 123 that calculates the value of the capacitance Cx between the first and second electrodes from an output signal from the amplifier 121; a pressure measuring unit that converts the capacitance into a measured pressure value; and a control unit that controls the signal generator 120 to apply the first sensor drive signal to the second electrode during pressure measurement and apply the second sensor drive signal to the second electrode during heating.SELECTED DRAWING: Figure 4

Description

The present invention relates to a diaphragm vacuum gauge.

Diaphragm gauges are used for pressure measurement in semiconductor process chambers. If the temperature of the semiconductor process gas is not appropriate, it liquefies or solidifies and adheres to the sensor chip of the diaphragm vacuum gauge, affecting measurement. Therefore, the diaphragm vacuum gauge has a self-heating function for preventing adhesion of liquefied or solidified process gas (see Patent Documents 1, 2, and 3).

However, since it is difficult to heat only the sensor chip, conventional diaphragm vacuum gauges having a self-heating function heat the entire pressure-receiving part including the sensor chip.
However, heating the entire pressure-receiving portion requires a large heater, resulting in a problem of increased power consumption. In addition, if a large heater is used, the temperature of nearby circuits rises even if the heater is insulated.

Although it is possible to install a heater in the sensor chip, it is necessary to reduce the size of the electrodes for pressure detection. Moreover, since it is necessary to attach the heater to the sensor chip and wire to the heater, there is a problem that the sensor chip becomes large.

JP 2010-117154 A JP 2009-243887 A JP 2019-7906 A

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. intended to provide

A diaphragm vacuum gauge (first embodiment) of the present invention has a first electrode formed on a pedestal, and a diaphragm arranged across a gap from the pedestal so as to face the first electrode. a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor driving signal. and a second sensor drive signal having a higher frequency than the first sensor drive signal, to the second electrode; a signal generator configured to selectively apply to the second electrode; an amplifier configured to convert and amplify the current output from a voltage, and configured to calculate the value of the capacitance between the first and second electrodes from the output signal of the amplifier a capacitance calculation unit; a pressure measurement unit configured to convert the capacitance into a measured pressure value; a controller configured to control the signal generator to apply two sensor drive signals to the second electrode.

In addition, the diaphragm vacuum gauge (second embodiment) of the present invention has a first electrode formed on a pedestal, and a diaphragm arranged across a gap from the pedestal so as to face the first electrode. a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor. A first signal generator configured to output a drive signal and a second signal generator configured to output a second sensor drive signal having a higher frequency than the first sensor drive signal. and an amplifier configured to convert the current output from the first electrode into a voltage and amplify it, provided between the first and second signal generators and the second electrode , a first switch configured to selectively connect either one of the output terminal of the first signal generator and the output terminal of the second signal generator to the second electrode; a second switch provided between the first electrode and the amplifier and configured to selectively connect either an input terminal of the amplifier or ground to the first electrode; a capacitance calculator configured to calculate a capacitance value between the first and second electrodes from an amplifier output signal; and a pressure configured to convert the capacitance into a measured pressure value. a measuring unit, and when measuring pressure, controlling the first switch to connect the output terminal of the first signal transmitter and the second electrode, and connecting the first electrode and the input terminal of the amplifier; while controlling the second switch to connect the output terminal of the second signal generator and the second electrode during heating, and controlling the first switch to connect the output terminal of the second signal generator and the second electrode. a control unit configured to control the second switch to connect one electrode to ground.

In addition, a diaphragm vacuum gauge (third embodiment) of the present invention has a first electrode formed on a pedestal, and a diaphragm arranged across a gap from the pedestal so as to face the first electrode. a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor. a first signal generator configured to apply either a drive signal or a second sensor drive signal having a higher frequency than the first sensor drive signal to the second electrode; a second signal generator configured to output a signal out of phase with the sensor drive signal of the second signal generator, and an amplifier configured to convert the current output from the first electrode into a voltage and amplify it a first synchronous detection section configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the amplifier; and the output signal of the second signal generator from the output signal of the amplifier. a second synchronous detection section configured to demodulate a signal synchronized with the output signal; and calculating the value of the series resistance of the first and second electrodes from the output signals of the first and second synchronous detection units, and calculating the value of the series resistance a temperature calculation unit configured to obtain the temperature of the sensor chip from the above; a pressure measurement unit configured to convert the capacitance into a measured pressure value; and the first sensor drive during pressure/temperature measurement a controller configured to control the first signal generator to apply a signal to the second electrode while applying the second sensor drive signal to the second electrode during heating; It is characterized by comprising

In addition, a diaphragm vacuum gauge (fourth embodiment) of the present invention has a first electrode formed on a base, and a diaphragm disposed with a gap from the base so as to face the first electrode. a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor. A first signal generator configured to output a drive signal and a second signal generator configured to output a second sensor drive signal having a higher frequency than the first sensor drive signal. and a third signal generator configured to output a signal out of phase with the first sensor drive signal; and a current output from the first electrode to be converted into voltage and amplified. and an amplifier provided between the first and second signal generators and the second electrode, the output terminal of the first signal generator and the output of the second signal generator a first switch configured to selectively connect one of the terminals to the second electrode; and a first switch provided between the first electrode and the amplifier to connect the first electrode. a second switch configured to selectively connect to one of an input terminal of said amplifier and ground; and demodulate a signal synchronized with said first sensor drive signal from an output signal of said amplifier. a second synchronous detection section configured to demodulate a signal synchronized with the output signal of the third signal generator from the output signal of the amplifier; 1, a capacitance calculator configured to calculate the value of the electrostatic capacitance between the first and second electrodes from the output signal of the second synchronous detector; and the first and second synchronous detectors. a temperature calculation unit configured to calculate the series resistance values of the first and second electrodes from the output signal of and obtain the temperature of the sensor chip from the series resistance values; Controlling the first switch so as to connect the output terminal of the first signal generator and the second electrode during pressure/temperature measurement with a pressure measuring unit configured to convert into a pressure value and controlling the second switch to connect the first electrode and the input terminal of the amplifier, while connecting the output terminal of the second signal generator and the second electrode during heating. and a control unit configured to control the first switch so as to connect the first electrode to ground and to control a second switch to connect the first electrode to ground. It is a sign.

Further, in one configuration example (third and fourth embodiments) of the diaphragm vacuum gauge of the present invention, the control unit outputs the second sensor drive signal based on the temperature of the sensor chip and the heating temperature set value. The amount of heat generated by the first and second electrodes is controlled by controlling any of the frequency of the second sensor drive signal, the amplitude of the second sensor drive signal, and the length of time to apply the second sensor drive signal. It is characterized by

A diaphragm vacuum gauge (fifth embodiment) of the present invention has a first electrode formed on a pedestal and a diaphragm disposed with a gap from the pedestal so as to face the first electrode. A second electrode formed, a third electrode formed on the pedestal outside the first electrode, and a third electrode formed on the diaphragm outside the second electrode so as to face the third electrode a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor. a first signal generator configured to apply a drive signal to the second electrode; the first sensor drive signal; and a second sensor drive signal having a higher frequency than the first sensor drive signal. a second signal generator configured to selectively apply one of the above to the fourth electrode; and configured to convert the current output from the first electrode into a voltage and amplify it. a second amplifier configured to convert the current output from the third electrode into a voltage and amplify it; and the output signal of the first amplifier to the second a subtractor configured to subtract an output signal of an amplifier; and a first synchronous detector configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the first amplifier. a second synchronous detection unit configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the subtractor; , a first capacitance calculator configured to calculate a value of a first electrostatic capacitance between the second electrodes; and the third and fourth electrodes from the output signal of the second synchronous detector. a second capacitance calculation unit configured to calculate a value of a second capacitance between; and a capacitance configured to correct the first capacitance by the second capacitance a correction unit; a pressure measurement unit configured to convert the corrected first capacitance into a measured pressure value; and applying the first sensor drive signal to the fourth electrode during pressure measurement. and a controller configured to control the second signal generator to apply the second sensor drive signal to the fourth electrode during heating.

In addition, a diaphragm vacuum gauge (sixth embodiment) of the present invention has a first electrode formed on a base, and a diaphragm arranged across a gap from the base so as to face the first electrode. A second electrode formed, a third electrode formed on the pedestal outside the first electrode, and a third electrode formed on the diaphragm outside the second electrode so as to face the third electrode a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor. a first signal generator configured to apply a drive signal to the second electrode; and a first sensor drive signal and a second sensor drive signal having a higher frequency than the first sensor drive signal. a second signal generator configured to selectively apply either one to the fourth electrode; and a second signal generator configured to output a signal out of phase with the first sensor drive signal. 3 signal generator, a first amplifier configured to convert the current output from the first electrode into a voltage and amplify it, and convert the current output from the third electrode into a voltage a subtractor configured to subtract the output signal of the second amplifier from the output signal of the first amplifier; a first synchronous detector configured to demodulate a signal synchronized with the first sensor drive signal from an output signal; and a signal synchronized with the first sensor drive signal demodulated from the output signal of the subtracter. and a third synchronous detection section configured to demodulate a signal synchronized with the output signal of the third signal generator from the output signal of the first amplifier. and a first capacitance calculator configured to calculate a value of a first electrostatic capacitance between the first and second electrodes from output signals of the first and third synchronous detection units. a second capacitance calculator configured to calculate a value of a second electrostatic capacitance between the third and fourth electrodes from the output signal of the second synchronous detector; a temperature calculation unit configured to calculate the series resistance values of the first and second electrodes from the output signal of the third synchronous detection unit and obtain the temperature of the sensor chip from the series resistance values; a capacitance correction unit configured to correct the first capacitance with the second capacitance; and a measured pressure by correcting the corrected first capacitance with the temperature of the sensor chip. configured to convert to a value a pressure measurement unit, and the second sensor so as to apply the first sensor drive signal to the fourth electrode during pressure/temperature measurement and to apply the second sensor drive signal to the fourth electrode during heating. and a controller configured to control the signal generator of

In addition, a diaphragm vacuum gauge (sixth embodiment) of the present invention has a first electrode formed on a base, and a diaphragm arranged across a gap from the base so as to face the first electrode. A second electrode formed, a third electrode formed on the pedestal outside the first electrode, and a third electrode formed on the diaphragm outside the second electrode so as to face the third electrode a sensor chip configured to change the distance between the first and second electrodes according to the displacement of the diaphragm due to the pressure of the medium to be measured; and a first sensor. a first signal generator configured to apply a drive signal to the second electrode; and a first sensor drive signal and a second sensor drive signal having a higher frequency than the first sensor drive signal. a second signal generator configured to selectively apply either one to the fourth electrode; and a second signal generator configured to output a signal out of phase with the first sensor drive signal. 3 signal generator, a first amplifier configured to convert the current output from the first electrode into a voltage and amplify it, and convert the current output from the third electrode into a voltage a subtractor configured to subtract the output signal of the second amplifier from the output signal of the first amplifier; a first synchronous detector configured to demodulate a signal synchronized with the first sensor drive signal from an output signal; and a signal synchronized with the first sensor drive signal demodulated from the output signal of the subtracter. and a third synchronous detection section configured to demodulate a signal synchronized with the output signal of the third signal generator from the output signal of the subtractor. , a first capacitance calculation unit configured to calculate a value of a first capacitance between the first and second electrodes from an output signal of the first synchronous detection unit; a second capacitance calculator configured to calculate a value of a second electrostatic capacitance between the third and fourth electrodes from the output signal of the third synchronous detector; a temperature calculation unit configured to calculate the series resistance values of the third and fourth electrodes from the output signal of the synchronous detection unit and to obtain the temperature of the sensor chip from the series resistance values; a capacitance correction unit configured to correct the first capacitance using the capacitance of 2, and a measured pressure value by correcting the corrected first capacitance according to the temperature of the sensor chip. A pressure gauge configured to convert and the second sensor drive signal is applied to the fourth electrode during pressure/temperature measurement, and the second sensor drive signal is applied to the fourth electrode during heating. and a controller configured to control the signal generator.

In one configuration example (fourth to sixth embodiments) of the diaphragm vacuum gauge of the present invention, the control unit outputs the second sensor drive signal based on the temperature of the sensor chip and the heating temperature set value. The amount of heat generated by the third and fourth electrodes is controlled by controlling any of the frequency of the second sensor drive signal, the amplitude of the second sensor drive signal, and the length of time to apply the second sensor drive signal. It is characterized by
In one configuration example (fourth to sixth embodiments) of the diaphragm vacuum gauge of the present invention, the second electrode and the fourth electrode are electrically connected to form a single electrode. It is characterized by

According to the present invention, by applying the first sensor drive signal to the second electrode of the sensor chip during pressure measurement and applying the second sensor drive signal to the second electrode of the sensor chip during heating, the pressure Since the sensor chip can be heated using the first and second electrodes for measurement, there is no need to heat the entire pressure-receiving part including the sensor chip. Electric power can be reduced more than before. Moreover, since attachment of the heater to the sensor chip and wiring to the heater are not required, the size of the sensor chip can be reduced compared to the case where the heater is attached to the sensor chip.

Further, in the present invention, by providing the first and second switches, the first sensor drive signal is applied to the second electrode of the sensor chip during pressure measurement, and the second sensor drive signal is applied to the sensor chip during heating. can be applied to the second electrode, and pressure measurement and heating can be performed in a time division manner using the first and second electrodes for pressure measurement.

Further, in the present invention, by providing the first and second signal generators, the first and second amplifiers, the first and second synchronous detection units, and the temperature calculation unit, the sensor can be detected without using a temperature sensor. The temperature of the chip can be measured, and pressure/temperature measurement and heating can be realized with one sensor chip.

Further, in the present invention, a temperature sensor can be used by providing first to third signal generators, amplifiers, first and second synchronous detectors, temperature calculators, and first and second switches. It is possible to measure the temperature of the sensor chip without a sensor chip, and it is possible to perform pressure/temperature and heating in a time-sharing manner with one sensor chip.

Further, in the present invention, first and second signal generators, first and second amplifiers, subtractors, first and second synchronous detection units, first and second capacitance calculation units, and capacitance correction units and a pressure measuring unit, the first sensor driving signal is applied to the second and fourth electrodes of the sensor chip during pressure measurement, and the second sensor driving signal is applied to the fourth electrode of the sensor chip during heating. By doing so, the first and second electrodes of the sensor chip are used to perform capacitance measurement for pressure measurement, and the third and fourth electrodes of the sensor chip are used to perform capacitance measurement and heating for capacitance correction. can be implemented, and pressure measurement, capacity correction, and heating can be realized with one sensor chip.

Further, in the present invention, first to third signal generators, first and second amplifiers, subtractors, first to third synchronous detection units, first and second capacitance calculators, and temperature calculators , a capacitance correction unit, and a pressure measurement unit are provided, a first sensor drive signal is applied to the second and fourth electrodes of the sensor chip during pressure/temperature measurement, and a second sensor drive signal is applied to the sensor chip during heating. By applying voltage to the fourth electrode, capacitance measurement and temperature measurement for pressure measurement are performed using the first and second electrodes of the sensor chip, and the third and fourth electrodes of the sensor chip are used. In this way, a single sensor chip can perform pressure measurement, temperature measurement, capacitance correction, and heating.

Further, in the present invention, first to third signal generators, first and second amplifiers, subtractors, first to third synchronous detection units, first and second capacitance calculators, and temperature calculators , a capacitance correction unit, and a pressure measurement unit are provided, a first sensor drive signal is applied to the second and fourth electrodes of the sensor chip during pressure/temperature measurement, and a second sensor drive signal is applied to the sensor chip during heating. By applying voltage to the fourth electrode, capacitance measurement for pressure measurement is performed using the first and second electrodes of the sensor chip, and capacitance correction is performed using the third and fourth electrodes of the sensor chip. Capacitance measurement, temperature measurement, and heating can be performed for this purpose, and pressure measurement, temperature measurement, capacitance correction, and heating can be realized with one sensor chip.

FIG. 1 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing the configuration of the main part of the sensor chip of the diaphragm vacuum gauge according to the first embodiment of the present invention. FIG. 3 is a flow chart for explaining the pressure measuring operation of the diaphragm vacuum gauge according to the first embodiment of the present invention. FIG. 4 is a block diagram showing the configuration of the capacitance detection section of the diaphragm vacuum gauge according to the first embodiment of the present invention. FIG. 5 is a flow chart for explaining the heating operation of the diaphragm vacuum gauge according to the first embodiment of the present invention. FIG. 6 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a second embodiment of the present invention. FIG. 7 is a block diagram showing the configuration of the capacitance detection section of the diaphragm vacuum gauge according to the second embodiment of the present invention. FIG. 8 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a third embodiment of the present invention. FIG. 9 is a flow chart for explaining the pressure/temperature measuring operation of the diaphragm vacuum gauge according to the third embodiment of the present invention. FIG. 10 is a block diagram showing the configuration of the capacitance/temperature detector of the diaphragm vacuum gauge according to the third embodiment of the present invention. FIG. 11 is a diagram showing the waveform of the amplifier output during pressure/temperature measurement of the diaphragm vacuum gauge according to the third embodiment of the present invention. FIG. 12 is a diagram showing the output waveform of the synchronous detection section during pressure/temperature measurement of the diaphragm vacuum gauge according to the third embodiment of the present invention. FIG. 13 is a diagram showing the output waveform of the synchronous detection section during pressure/temperature measurement of the diaphragm vacuum gauge according to the third embodiment of the present invention. FIG. 14 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a fourth embodiment of the present invention. FIG. 15 is a cross-sectional view showing the configuration of the main part of the sensor chip of the diaphragm vacuum gauge according to the fourth embodiment of the present invention. FIG. 16 is a flow chart for explaining the pressure measuring operation of the diaphragm vacuum gauge according to the fourth embodiment of the present invention. FIG. 17 is a block diagram showing the configuration of the capacitance detection section of the diaphragm vacuum gauge according to the fourth embodiment of the present invention. FIG. 18 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a fifth embodiment of the present invention. FIG. 19 is a flow chart for explaining the pressure/temperature measuring operation of the diaphragm vacuum gauge according to the fifth embodiment of the present invention. FIG. 20 is a block diagram showing the configuration of the capacitance/temperature detector of the diaphragm vacuum gauge according to the fifth embodiment of the present invention. FIG. 21 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a sixth embodiment of the present invention. FIG. 22 is a block diagram showing the configuration of the capacity/temperature detector of the diaphragm vacuum gauge according to the sixth embodiment of the present invention. FIG. 23 is a block diagram showing a configuration example of a computer that implements the circuit section of the diaphragm vacuum gauge according to the first to sixth embodiments of the present invention.

[First embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing the configuration of a main part of a sensor chip used in the diaphragm vacuum gauge.

A diaphragm vacuum gauge has a pressure-receiving part 10 whose capacitance changes according to the displacement of a diaphragm (diaphragm) caused by the pressure of a medium to be measured (for example, process gas), and the change in the capacitance of the pressure-receiving part 10 is converted into a measured pressure value. and a circuit unit 11 for conversion.

A recess is formed in the central portion of the pedestal 101 of the sensor chip 1 of the pressure receiving portion 10 . A diaphragm 102 is joined to the surface of the pedestal 101 on which the recess is formed, the diaphragm 102 being deformable according to the pressure P of the medium to be measured (for example, process gas). A recess in the pedestal 101 forms a reference vacuum chamber 104 together with the diaphragm 102 .

In the sensor chip 1, a fixed electrode 105 is formed on the surface of the base 101 on the side of the reference vacuum chamber 104, and a movable electrode 106 is formed on the surface of the diaphragm 102 on the side of the reference vacuum chamber 104 so as to face the fixed electrode 105. ing. Thus, the fixed electrode 105 and the movable electrode 106 are arranged to face each other across a gap. When the diaphragm 102 receives the pressure P of the medium to be measured and bends, the distance between the movable electrode 106 and the fixed electrode 105 changes, and the capacitance between the movable electrode 106 and the fixed electrode 105 changes. The pressure P of the medium to be measured applied to the diaphragm 102 can be detected from the change in capacitance. The diaphragm component 100 and the base 101 are made of an insulator such as sapphire.

The diaphragm vacuum gauge shown in FIG. and a sensor case 4 covering the housing 2 . The sensor case 4 is covered with a heat insulating material 6 .

A partition wall 7 is provided inside the housing 2 . The partition wall 7 is composed of a base plate 7a and a support plate 7b, and separates the internal space of the housing 2 into a first space 2a and a second space 2b. The support plate 7b has its outer periphery fixed to the housing 2 and supports the base plate 7a in a floating state within the internal space of the housing 2 . The sensor chip 1 is fixed on the second space 2b side of the base plate 7a. Further, the base plate 7a is formed with a pressure introduction hole 7c for introducing the pressure in the first space 2a to the diaphragm 102 of the sensor chip 1. As shown in FIG. The second space 2b communicates with the reference vacuum chamber 104 of the sensor chip 1 and is in a vacuum state.

The pressure introduction pipe 3 is connected to the first space 2a side of the housing 2 . A baffle 8 is provided between the pressure introducing pipe 3 and the housing 2 . The medium to be measured introduced from the pressure introduction pipe 3 hits the plate surface of the baffle 8 and flows into the first space 2 a of the housing 2 through the gap around the baffle 8 .

The circuit unit 11 of the diaphragm vacuum gauge includes a capacitance detection unit 12 that calculates the capacitance value between the movable electrode 106 and the fixed electrode 105, a pressure measurement unit 13 that converts the capacitance into a measured pressure value, and a control unit 14 for controlling a sensor drive signal applied by a signal generator, which will be described later.

FIG. 3 is a flow chart for explaining the pressure measuring operation of the diaphragm vacuum gauge of this embodiment, and FIG.
The capacitance detection unit 12 includes a signal generator 120 , an amplifier 121 including a capacitance Cf and an operational amplifier A<b>1 , a low-pass filter 122 and a capacitance calculation unit 123 . In FIG. 4, the capacitance between the movable electrode 106 and the fixed electrode 105 of the sensor chip 1 is represented by Cx. A series resistance component between the movable electrode 106 and the fixed electrode 105 is represented by Rx.

The signal generator 120 applies a sinusoidal sensor drive signal for pressure measurement to the second electrode (for example, the movable electrode 106) of the sensor chip 1 during pressure measurement (step S100 in FIG. 3).
The amplifier 121 converts the current output from the first electrode (for example, the fixed electrode 105) of the sensor chip 1 into a voltage, amplifies the voltage, and outputs a signal having an amplitude proportional to the capacitance Cx.

Low-pass filter 122 removes noise from the signal output from amplifier 121 . The capacitance calculator 123 calculates the value of the capacitance Cx from the amplitude of the signal that has passed through the low-pass filter 122 (step S101 in FIG. 3).
The pressure measurement unit 13 converts the change in the capacitance Cx calculated by the capacitance detection unit 12 into a measured pressure value MP and outputs it (step S102 in FIG. 3).

The capacity detection unit 12 and the pressure measurement unit 13 perform the processing of steps S100 to S102 at each measurement cycle until the pressure measurement operation is completed according to the user's instruction (YES in step S103 in FIG. 3).

FIG. 5 is a flowchart for explaining the heating operation of the diaphragm vacuum gauge of this embodiment. A series resistance Rx is present between the movable electrode 106 and the fixed electrode 105 of the sensor chip 1, as shown in FIG. This embodiment utilizes this series resistor Rx as a heater.

In this embodiment, the sensor drive signal for pressure measurement is E1sin(2πf1t), and the sensor drive signal for heating is E2sin(2πf2t). E1 and E2 are amplitudes, f1 and f2 are frequencies, and t is time. In the present embodiment, the frequency f2 of the sensor drive signal for heating is set higher than the frequency f1 of the sensor drive signal for pressure measurement (f2>f1) to increase the current flowing through the series resistor Rx, The electrode 106 and the fixed electrode 105 are heated.

The impedance Z of the equivalent circuit of the electric circuit of the sensor chip 1 is given by the following formula.
Z=Rx+1/(2πfCx) (1)

Assuming that the voltage applied between the movable electrode 106 and the fixed electrode 105 is E, the current I flowing between the movable electrode 106 and the fixed electrode 105 is given by equation (2), and the power consumption W of the resistor Rx is given by equation (3).
I=E/Z (2)
W=I ² ×Rx (3)

When the frequency f of the sensor driving signal is increased, the impedance Z is decreased and the current I is increased, so that the power consumption W can be increased. Specific examples are shown in Table 1.

As is clear from Table 1, by increasing the frequency of the sensor driving signal for heating, the movable electrode 106 and the fixed electrode 105 can be caused to generate heat.

Control unit 14 outputs signal CTL to signal generator 120 so that signal generator 120 generates sensor drive signal E2sin(2πf2t) for heating (step S200 in FIG. 5).

The signal generator 120 applies a sinusoidal sensor drive signal E2sin (2πf2t) of frequency f2 according to the control signal CTL from the control unit 14 to the second electrode (eg, the movable electrode 106) of the sensor chip 1 during heating. (step S201 in FIG. 5). Thus, the amount of heat generated can be controlled by controlling the signal generator 120 to generate the sensor drive signal E2sin(2πf2t).

The capacity detection unit 12 and the control unit 14 perform the processing of steps S200 and S201 in each heating cycle until the heating operation is completed according to the user's instruction (YES in step S202 in FIG. 5).

In this embodiment, pressure measurement and heating may be performed at different times, or pressure measurement and heating may be performed at the same time. Therefore, the sensor drive signal E1sin (2πf1t) for pressure measurement and the sensor drive signal E2sin (2πf2t) for heating are simultaneously output from the signal generator 120, and the sensor drive signals E1sin (2πf1t) and E2sin are output from the amplifier 121. It is also possible for the (2πf2t) frequency components to be output simultaneously.

The cutoff frequency of the low-pass filter 122 is set so as to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). Therefore, the frequency component of the sensor drive signal E2sin(2πf2t) is removed by the low-pass filter 122, and only the frequency of the sensor drive signal E1sin(2πf1t) passes through the low-pass filter 122. Therefore, the sensor drive signal E2sin(2πf2t) for heating is does not affect the detection of the capacitance Cx.

In this embodiment, since the sensor chip 1 can be heated by using the electrodes 105 and 106 for pressure measurement, there is no need to heat the entire pressure receiving portion, and a large heater is not required. Electric power can be reduced more than before. Moreover, since attachment of a heater to the sensor chip 1 and wiring to the heater are not required, the size of the sensor chip 1 can be reduced compared to the case where the heater is attached to the sensor chip 1 .

[Second embodiment]
Next, a second embodiment of the invention will be described. FIG. 6 is a block diagram showing the configuration of a diaphragm vacuum gauge according to a second embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals. Also in this embodiment, the configuration of the pressure receiving portion 10 is as described in the first embodiment. The circuit section 11a is composed of a capacity detection section 12a, a pressure measurement section 13, and a control section 14a.

FIG. 7 is a block diagram showing the configuration of the capacitance detector 12a of this embodiment. The capacitance detection unit 12a includes signal generators 120-1 and 120-2, an amplifier 121, a low-pass filter 122, a capacitance calculation unit 123, signal generators 120-1 and 120-2, and the second sensor chip 1. and a switch 125 provided between the first electrode (for example, the fixed electrode 105) of the sensor chip 1 and the input of the amplifier 121. be done.

The signal generator 120-1 outputs a sensor drive signal E1sin(2πf1t) for pressure measurement. The signal generator 120-2 outputs a sensor drive signal E2sin(2πf2t) for heating.

The control unit 14a of this embodiment switches and controls the switches 124 and 125 by the control signal SWCTL. The controller 14a causes the switches 124 and 125 to select the S side in FIG. 7 during pressure measurement. As a result, the switch 124 selects the output terminal of the signal generator 120-1, so that the output terminal of the signal generator 120-1 and the second electrode (for example, the movable electrode 106) of the sensor chip 1 are connected. Also, since the switch 125 selects the input terminal of the amplifier 121, the first electrode (for example, the fixed electrode 105) of the sensor chip 1 and the input terminal of the amplifier 121 are connected. With such switch control, the pressure measurement operation becomes the same as the operation described with reference to FIG. 3 of the first embodiment.

On the other hand, the controller 14a causes the switches 124 and 125 to select the T side in FIG. 7 during heating. As a result, the switch 124 selects the output terminal of the signal generator 120-2, so that the output terminal of the signal generator 120-2 and the second electrode (for example, the movable electrode 106) of the sensor chip 1 are connected. Also, since the switch 125 selects the ground, the first electrode (for example, the fixed electrode 105) of the sensor chip 1 and the ground are connected. By such switch control, the heating operation becomes the same as the operation described with reference to FIG. 5 of the first embodiment.

Thus, by switching the switches 124 and 125 between pressure measurement and heating, pressure measurement and heating can be performed in a time-sharing manner. In this embodiment, when it is difficult to change the sensor drive signal with one signal generator, the circuits connected to the electrodes 105 and 106 can be changed between when measuring pressure and when heating.

As in the first embodiment, the control unit 14a may control the amount of heat generation by changing the frequency f2 of the sensor drive signal E2sin (2πf2t) during heating, or may control the amount of heat generation by changing the amplitude E2. You may make it

Further, the control unit 14a may control the heat generation amount by changing the length of time for applying the sensor drive signal E2sin(2πf2t). In the first embodiment, the length of time during which the signal generator 120 outputs the sensor drive signal E2sin(2πf2t) is changed. Also in this embodiment, the length of time for which the signal generator 120-2 outputs the sensor drive signal E2sin(2πf2t) may be changed. In addition, in a configuration in which the signal generator 120-2 constantly outputs the sensor drive signal E2sin (2πf2t), the length of time during which the switches 124 and 125 select the T side may be changed.

[Third embodiment]
A third embodiment of the present invention will now be described. Embodiment 3 FIG. 8 is a block diagram showing the configuration of a diaphragm vacuum gauge according to the third embodiment of the present invention, and the same components as in FIGS. 1 and 6 are denoted by the same reference numerals. The diaphragm vacuum gauge of this embodiment includes a pressure receiving portion 10b and a circuit portion 11b.

The difference from the pressure receiving portion 10 of the first and second embodiments is that the temperature of the sensor chip 1 can be measured without installing the temperature sensor 9 in the pressure receiving portion 10b.
The circuit portion 11b includes a capacity/temperature detection portion 12b, a pressure measurement portion 13, and a control portion 14b.

FIG. 9 is a flow chart for explaining the pressure/temperature measuring operation of the diaphragm vacuum gauge of this embodiment, and FIG. 10 is a block diagram showing the configuration of the capacity/temperature detector 12b of this embodiment. The capacitance/temperature detector 12b includes a signal generator 120, an amplifier 121, differential input type low-pass filters 122b-1 and 122b-2, a capacitance calculator 123b, an amplifier 121 and a low-pass filter 122b-1. A switch 126 provided between, a switch 127 provided between the amplifier 121 and the low-pass filter 122b-2, a temperature calculator 128, and a sensor drive signal E1sin (2πf1t) whose frequency is the same and whose phase is 90 degrees. and a signal generator 129 that outputs a shifted signal E1sin (2πf1t+π/2).

As in the first embodiment, the signal generator 120 applies the sensor drive signal E1sin (2πf1t) to the second electrode (for example, the movable electrode 106) of the sensor chip 1 and the switch 126 during pressure/temperature measurement ( FIG. 9 step S300).
The signal generator 129 applies to the switch 127 a signal E1sin (2πf1t+π/2) whose phase is 90 degrees out of phase with the sensor drive signal E1sin (2πf1t) during pressure/temperature measurement (step S301 in FIG. 9).

The switch 126 and the low-pass filter 122b-1 constitute a synchronous detection section 130. FIG. The cutoff frequency of the low-pass filter 122b-1 is set so as to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). Synchronous detection section 130 demodulates a signal synchronized with sensor drive signal E1sin (2πf1t) from the output of amplifier 121 .

Specifically, when the sensor drive signal E1sin (2πf1t) output from the signal generator 120 during pressure/temperature measurement is positive, the switch 126 switches between the output terminal of the amplifier 121 and the non-inverting input terminal of the low-pass filter 122b-1. to connect. Also, the switch 126 connects the output terminal of the amplifier 121 and the inverting input terminal of the low-pass filter 122b-1 when the sensor drive signal E1sin (2πf1t) is negative. As a result, a signal synchronized with the sensor drive signal E1sin (2πf1t) can be demodulated from the output of the amplifier 121 .

On the other hand, the switch 127 and the low-pass filter 122b-2 constitute a synchronous detection section 131. FIG. The cutoff frequency of the low-pass filter 122b-2 is set so as to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). The synchronous detection unit 131 demodulates from the output of the amplifier 121 a signal synchronized with the sensor drive signal E1sin (2πf1t) and the signal E1sin (2πf1t+π/2) 90 degrees out of phase.

Specifically, when the signal E1sin (2πf1t+π/2) output from the signal generator 129 during pressure/temperature measurement is positive, the switch 127 switches between the output terminal of the amplifier 121 and the non-inverting input terminal of the low-pass filter 122b-2. to connect. Switch 127 connects the output terminal of amplifier 121 and the inverting input terminal of low-pass filter 122b-2 when signal E1sin (2πf1t+π/2) is negative. As a result, from the output of the amplifier 121, it is possible to demodulate a signal synchronized with the sensor drive signal E1sin (2πf1t) and the signal E1sin (2πf1t+π/2) 90 degrees out of phase.

FIG. 11 is a diagram showing the waveform of the output A of the amplifier 121 during pressure/temperature measurement. The output A of the amplifier 121 can be represented by the following formula.

FIG. 12 is a diagram showing the waveform of the output vc of the synchronous detection section 130 during pressure/temperature measurement. The output vc of the synchronous detection section 130 can be expressed by the following equation. This vc mainly depends on the capacitance Cx, but is also affected by the value of the series resistance Rx.

FIG. 13 is a diagram showing the waveform of the output vt of the synchronous detection section 131 during pressure/temperature measurement. The output vt of the synchronous detection section 131 can be expressed by the following equation. This vt depends on the value of the series resistance Rx, but is also affected by the value of the capacitance Cx.

When the following equation is calculated from the output vc of the synchronous detection section 130 and the output vt of the synchronous detection section 131, a value proportional to only the capacitance Cx is obtained.

Further, when the following equation is calculated from the output vc of the synchronous detection section 130 and the output vt of the synchronous detection section 131, a value proportional to only the series resistance Rx is obtained.

α and β in equations (7) and (8) are circuit constants Cf, f, and E1 that do not depend on the capacitance Cx and series resistance Rx.
The capacitance calculator 123b calculates the value of the electrostatic capacitance Cx from the output vc of the synchronous detector 130 and the output vt of the synchronous detector 131 using equation (7) (step S302 in FIG. 9). The operation of the pressure measuring unit 13 (step S303 in FIG. 9) is the same as in the first embodiment.

The temperature calculation unit 128 calculates the value of the series resistor Rx from the output vc of the synchronous detection unit 130 and the output vt of the synchronous detection unit 131 using equation (8) (step S304 in FIG. 9). Then, the temperature calculator 128 derives the temperature of the sensor chip 1 from the value of the series resistance Rx (step S305 in FIG. 9). The relationship between the series resistance Rx and the temperature is stored in the temperature calculator 128 in advance. The temperature calculation unit 128 may calculate the temperature from the value of the series resistance Rx using a preset formula, or obtain the temperature value corresponding to the value of the series resistance Rx from a preset table. good too.

The capacity/temperature detection unit 12b and the pressure measurement unit 13 perform the processing of steps S300 to S305 at each measurement cycle until the pressure measurement operation is completed according to the user's instruction (YES in step S306 in FIG. 9).

Since the processing flow of the heating operation of this embodiment is the same as that of the first embodiment, the reference numerals in FIG. 5 are used for explanation.
During heating, the control unit 14b of this embodiment outputs the control signal CTL to the signal generator 120 so that the signal generator 120 generates the frequency f2 of the sensor driving signal E2sin (2πf2t) for heating ( FIG. 5 step S200).

As in the first embodiment, during heating, the signal generator 120 outputs the sensor drive signal E2sin (2πf2t) of frequency f2 corresponding to the control signal CTL from the control unit 14b to the second electrode of the sensor chip 1 (for example, movable electrode 106) (step S201 in FIG. 5).

The capacity/temperature detection unit 12b and the control unit 14b perform the processing of steps S200 and S201 in each heating cycle until the heating operation is completed according to a user's instruction (YES in step S202 in FIG. 5).

Thus, in this embodiment, the temperature of the sensor chip 1 can be measured without using a temperature sensor, and one sensor chip 1 can realize pressure measurement, temperature measurement, and heating.
As in the first embodiment, in this embodiment, pressure/temperature measurement and heating may be performed at different times, or pressure/temperature measurement and heating may be performed at the same time.

The controller 14b may control the amount of heat generated by changing the amplitude E2 so that the temperature measured by the capacity/temperature detector 12b matches the heating temperature set value tsp. In addition, the control unit 14b changes the length of time for applying the sensor drive signal E2sin (2πf2t) so that the temperature measured by the capacitance/temperature detection unit 12b matches the heating temperature set value tsp, thereby increasing the amount of heat generated. may be controlled.

Note that the second embodiment may be applied to this embodiment. In this case, signal generators 120-1 and 120-2 are provided in place of the signal generator 120 of the capacitance/temperature detection unit 12b, and the signal generators 120-1 and 120-2 and the second sensor chip 1 A switch 124 may be inserted between the electrode (for example, movable electrode 106 ), and a switch 125 may be inserted between the first electrode (for example, fixed electrode 105 ) of sensor chip 1 and the input of amplifier 121 . The control section 14b may control the switches 124 and 125 in the same manner as the control section 14a of the second embodiment.

[Fourth embodiment]
A fourth embodiment of the present invention will now be described. Embodiment 4 FIG. 14 is a block diagram showing the configuration of a diaphragm vacuum gauge according to the fourth embodiment of the present invention, and the same components as in FIGS. 1, 6 and 8 are denoted by the same reference numerals. The diaphragm vacuum gauge of this embodiment includes a pressure receiving portion 10c and a circuit portion 11c.

FIG. 15 is a cross-sectional view showing the configuration of the main part of the sensor chip 1c of this embodiment. In the sensor chip 1c, a fixed electrode 107 is formed on the surface of the pedestal 101 outside the fixed electrode 105 on the reference vacuum chamber 104 side. A movable electrode 108 is formed on the surface of the diaphragm 102 on the side of the reference vacuum chamber 104 outside the movable electrode 106 so as to face the fixed electrode 107 . Other configurations of the sensor chip 1 c are the same as those of the sensor chip 1 .

A fixed electrode 107 and a movable electrode 108 are formed on the edge of the diaphragm 102 . Even if the diaphragm 102 receives the pressure P of the medium to be measured and bends, the edge of the diaphragm 102 hardly deforms, so the capacitance between the movable electrode 108 and the fixed electrode 107 hardly changes. This capacitance is provided to eliminate measurement errors due to temperature changes inside and outside the sensor, humidity changes in the reference vacuum chamber 104, and the like.

The circuit portion 11c is composed of a capacitance detection portion 12c, a pressure measurement portion 13, and a control portion 14c.
FIG. 16 is a flow chart for explaining the pressure measuring operation of the diaphragm vacuum gauge of this embodiment, and FIG. 17 is a block diagram showing the configuration of the capacitance detection section 12c.

Capacitance detector 12c is provided between signal generators 132 and 133, amplifiers 134 and 135, subtractor 136, differential input type low-pass filters 137 and 138, and amplifier 134 and low-pass filter 137. It is composed of a switch 139 , a switch 140 provided between the amplifier 135 and the low-pass filter 138 , a capacitance calculator 141 , a reference capacitance calculator 142 , and a capacitance corrector 143 . In FIG. 17, Cr represents the capacitance between the movable electrode 108 and the fixed electrode 107 of the sensor chip 1c. A series resistance component between the movable electrode 108 and the fixed electrode 107 is represented by Rr.

The signal generator 132 applies a sinusoidal sensor driving signal E1sin (2πf1t) for pressure measurement to the second electrode (for example, the movable electrode 106) of the sensor chip 1c and the switch 139 during pressure measurement. The signal generator 133 applies the sensor drive signal E1sin (2πf1t) to the fourth electrode (for example, the movable electrode 108) of the sensor chip 1c and the switch 140 during pressure measurement (step S400 in FIG. 16).

The amplifier 134 converts the current output from the first electrode (for example, the fixed electrode 105) of the sensor chip 1c into a voltage, amplifies the voltage, and outputs a signal having an amplitude proportional to the capacitance Cx. The amplifier 135 converts the current output from the third electrode (for example, the fixed electrode 107) of the sensor chip 1c into a voltage, amplifies the voltage, and outputs a signal having an amplitude proportional to the capacitance Cr.
Subtractor 136 subtracts output signal B of amplifier 135 from output signal A of amplifier 134 .

The switch 139 and the low-pass filter 137 constitute a synchronous detection section 144 . The cutoff frequency of the low-pass filter 137 is set so as to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). A synchronous detection unit 144 demodulates a signal synchronized with the sensor drive signal E1sin (2πf1t) from the output of the amplifier 134 .

Specifically, the switch 139 connects the output terminal of the amplifier 134 and the non-inverting input terminal of the low-pass filter 137 when the sensor drive signal E1sin (2πf1t) output from the signal generator 132 during pressure measurement is positive. . Switch 139 connects the output terminal of amplifier 134 and the inverting input terminal of low-pass filter 137 when sensor drive signal E1sin (2πf1t) is negative. As a result, a signal synchronized with the sensor driving signal E1sin (2πf1t) can be demodulated from the output of the amplifier 134 .

On the other hand, the switch 140 and the low-pass filter 138 constitute a synchronous detection section 145 . The low-pass filter 138 has a cutoff frequency set to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). A synchronous detection unit 145 demodulates a signal synchronized with the sensor drive signal E1sin (2πf1t) from the output of the subtractor 136 .

Specifically, the switch 140 connects the output terminal of the subtractor 136 and the non-inverting input terminal of the low-pass filter 138 when the sensor drive signal E1sin (2πf1t) output from the signal generator 133 during pressure measurement is positive. do. Switch 140 connects the output terminal of subtractor 136 and the inverting input terminal of low-pass filter 138 when sensor drive signal E1sin (2πf1t) is negative. As a result, a signal synchronized with the sensor drive signal E1sin (2πf1t) can be demodulated from the output of the subtractor 136 .

The capacitance calculator 141 calculates the value of the capacitance Cx from the amplitude of the output vc of the synchronous detector 144 (step S401 in FIG. 16).
The reference capacitance calculator 142 calculates the value of the electrostatic capacitance (reference capacitance) Cr from the amplitude of the output vr of the synchronous detector 145 (step S402 in FIG. 16).

The capacitance correction unit 143 calculates a value (Cx-Cr)/Cx obtained by correcting the capacitance Cx using the reference capacitance Cr (step S403 in FIG. 16).
The pressure measuring unit 13 converts the change in capacitance (Cx-Cr)/Cx calculated by the capacitance detecting unit 12c into a measured pressure value MP and outputs it (step S404 in FIG. 16).

The capacity detection unit 12c and the pressure measurement unit 13 perform the processing of steps S400 to S404 at each measurement cycle until the pressure measurement operation is completed according to the user's instruction (YES in step S405 in FIG. 16).

Since the processing flow of the heating operation of this embodiment is the same as that of the first embodiment, the reference numerals in FIG. 5 are used for explanation.
During heating, the control unit 14c of this embodiment outputs the control signal CTL to the signal generator 133 so that the signal generator 133 generates the sensor drive signal E2sin (2πf2t) for heating (step 5 in FIG. 5). S200).

During heating, the signal generator 133 applies the sensor drive signal E2sin (2πf2t) of frequency f2 corresponding to the control signal CTL from the control unit 14c to the fourth electrode (for example, the movable electrode 108) of the sensor chip 1c (Fig. 5 step S201).

The capacity detection unit 12c and the control unit 14c perform the processing of steps S200 and S201 in each heating cycle until the heating operation is completed according to the user's instruction (YES in step S202 in FIG. 5).

Thus, in this embodiment, the fixed electrode 105 and the movable electrode 106 of the sensor chip 1c are used to perform capacitance measurement for pressure measurement, and the fixed electrode 107 and the movable electrode 108 of the sensor chip 1c are used to perform capacitance correction. It is possible to implement the reference capacitance measurement and heating for the pressure measurement, the capacitance correction, and the heating with one sensor chip 1c.
As in the first embodiment, in this embodiment, the pressure measurement and the heating may be performed at different times, or the pressure measurement and the heating may be performed at the same time.

As in the first embodiment, the controller 14c may change the amplitude E2 of the sensor drive signal E2sin(2πf2t) to control the amount of heat generated. Further, the control unit 14c may change the length of time for applying the sensor drive signal E2sin (2πf2t) to control the amount of heat generated.

[Fifth embodiment]
A fifth embodiment of the present invention will now be described. FIG. 18 is a block diagram showing the configuration of a diaphragm vacuum gauge according to the fifth embodiment of the present invention, and the same components as those in FIGS. 1, 6, 8 and 14 are denoted by the same reference numerals. . The diaphragm vacuum gauge of this embodiment includes a pressure receiving portion 10d and a circuit portion 11d.

The difference from the pressure receiving portion 10c of the fourth embodiment is that the temperature of the sensor chip 1 can be measured without installing a temperature sensor in the pressure receiving portion 10d.
The circuit section 11d is composed of a capacity/temperature detection section 12d, a pressure measurement section 13d, and a control section 14d.

FIG. 19 is a flow chart for explaining the pressure/temperature measuring operation of the diaphragm vacuum gauge of this embodiment, and FIG. 20 is a block diagram showing the configuration of the capacity/temperature detector 12d of this embodiment. The capacitance/temperature detector 12d includes signal generators 132 and 133, amplifiers 134 and 135, a subtractor 136, low-pass filters 137 and 138, switches 139 and 140, a capacitance calculator 141d, and a reference capacitance calculator. 142, a capacitance correction unit 143, a signal generator 146, a differential input type low-pass filter 147, a switch 148 provided between the amplifier 134 and the low-pass filter 147, and a temperature calculation unit 149. be.

The signal generator 132 applies the sensor drive signal E1sin (2πf1t) to the second electrode (for example, the movable electrode 106) of the sensor chip 1c and the switch 139 during pressure/temperature measurement. The signal generator 133 applies the sensor driving signal E1sin (2πf1t) to the fourth electrode (for example, the movable electrode 108) of the sensor chip 1c and the switch 140 during pressure/temperature measurement (step S500 in FIG. 19).

The signal generator 146 applies to the switch 148 a signal E1sin (2πf1t+π/2) whose phase is 90 degrees out of phase with the sensor driving signal E1sin (2πf1t) during pressure/temperature measurement (step S501 in FIG. 19).

As in the fourth embodiment, the synchronous detector 144 demodulates the output of the amplifier 134 into a signal synchronized with the sensor drive signal E1sin(2πf1t). A synchronous detection unit 145 demodulates a signal synchronized with the sensor drive signal E1sin (2πf1t) from the output of the subtractor 136 .

The switch 148 and the low-pass filter 147 constitute a synchronous detection section 150 . The cutoff frequency of the low-pass filter 147 is set so as to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). Synchronous detection section 150 demodulates from the output of amplifier 134 a signal synchronized with sensor drive signal E1sin (2πf1t) and signal E1sin (2πf1t+π/2) 90 degrees out of phase.

Specifically, the switch 148 connects the output terminal of the amplifier 134 and the non-inverting input terminal of the low-pass filter 147 when the signal E1sin (2πf1t+π/2) output from the signal generator 146 during pressure/temperature measurement is positive. Connecting. Switch 148 connects the output terminal of amplifier 134 and the inverting input terminal of low-pass filter 147 when signal E1sin (2πf1t+π/2) is negative. As a result, it is possible to demodulate from the output of the amplifier 134 a signal synchronized with the signal E1sin (2πf1t+π/2) that is 90 degrees out of phase with the sensor drive signal E1sin (2πf1t).

The capacitance calculator 141d calculates the value of the electrostatic capacitance Cx from the output vc of the synchronous detector 144 and the output vt of the synchronous detector 150 using equation (7) (step S502 in FIG. 19).
The reference capacitance calculator 142 calculates the value of the electrostatic capacitance (reference capacitance) Cr from the amplitude of the output vr of the synchronous detector 145 (step S503 in FIG. 19).

The capacitance correction unit 143 calculates a value (Cx-Cr)/Cx obtained by correcting the capacitance Cx using the reference capacitance Cr (step S504 in FIG. 19).
As in the third embodiment, the temperature calculation unit 149 calculates the value of the series resistance Rx from the output vc of the synchronous detection unit 144 and the output vt of the synchronous detection unit 150 using equation (8) (step S505 in FIG. 19). ), the temperature of the sensor chip 1c is derived from the value of the series resistor Rx (step S506 in FIG. 19).

The pressure measurement unit 13d corrects the capacitance (Cx−Cr)/Cx calculated by the capacitance/temperature detection unit 12d by the temperature of the sensor chip 1c calculated by the capacitance/temperature detection unit 12d to obtain the measured pressure value MP , and output (step S507 in FIG. 19). A method of correcting the capacitance (Cx-Cr)/Cx by the temperature of the sensor chip 1c may be performed using, for example, the following equation.

In equation (9), Vo is the capacitance (Cx-Cr)/Cx calculated by the capacitance/temperature detection unit 12d, Vt is the temperature of the sensor chip 1c calculated by the capacitance/temperature detection unit 12d, and _aij is The correction factors, i,j, are the degrees of the polynomial.

The capacity/temperature detection unit 12d and the pressure measurement unit 13d perform the processing of steps S500 to S507 at each measurement cycle until the pressure measurement operation is completed according to the user's instruction (YES in step S508 in FIG. 19).

Since the processing flow of the heating operation of this embodiment is the same as that of the fourth embodiment, it will be explained using the reference numerals in FIG.
The control unit 14d of this embodiment outputs the sensor drive signal E2sin (2πf2t) for heating to the signal generator 133 so that the temperature measured by the capacitance/temperature detection unit 12d matches the predetermined heating temperature set value tsp. is generated to the signal generator 133 (step S200 in FIG. 5).

The signal generator 133 applies the sensor drive signal E2sin (2πf2t) of frequency f2 corresponding to the control signal CTL from the controller 14d to the fourth electrode (for example, the movable electrode 108) of the sensor chip 1c during heating (Fig. 5 step S201).

The capacity/temperature detection unit 12d and the control unit 14d perform the processes of steps S200 and S201 in each heating cycle until the heating operation is completed according to a user's instruction (YES in step S202 in FIG. 5).

Thus, in this embodiment, the fixed electrode 105 and the movable electrode 106 of the sensor chip 1c are used to perform capacitance measurement and temperature measurement for pressure measurement, and the fixed electrode 107 and the movable electrode 108 of the sensor chip 1c are Reference capacitance measurement and heating for capacitance correction can be performed using one sensor chip 1c, and pressure measurement, temperature measurement, capacitance correction, and heating can be realized.
As in the first embodiment, in this embodiment, pressure/temperature measurement and heating may be performed at different times, or pressure/temperature measurement and heating may be performed at the same time.

As in the first embodiment, the control unit 14d changes the amplitude E2 so that the temperature measured by the capacitance/temperature detection unit 12d matches the heating temperature set value tsp to control the amount of heat generated. good too. In addition, the control unit 14d changes the length of time for applying the sensor drive signal E2sin (2πf2t) so that the temperature measured by the capacitance/temperature detection unit 12d matches the heating temperature set value tsp, thereby increasing the amount of heat generated. may be controlled.

[Sixth embodiment]
A sixth embodiment of the present invention will now be described. FIG. 21 is a block diagram showing the construction of a diaphragm vacuum gauge according to the sixth embodiment of the present invention, and the same reference numerals are assigned to the same constructions as in FIGS. I have The diaphragm vacuum gauge of this embodiment includes a pressure receiving portion 10d and a circuit portion 11e. The configuration of the pressure receiving portion 10d is as described in the fifth embodiment.

The circuit section 11e includes a capacity/temperature detection section 12e, a pressure measurement section 13e, and a control section 14e.
FIG. 22 is a block diagram showing the configuration of the capacitance/temperature detection unit 12e of this embodiment. The capacitance/temperature detector 12e includes signal generators 132 and 133, amplifiers 134 and 135, a subtractor 136, low-pass filters 137 and 138, switches 139 and 140, a capacitance calculator 141, and a reference capacitance calculator. 142e, a capacitance correction unit 143, a signal generator 146e, a temperature calculation unit 149e, a differential input type low-pass filter 151, and a switch 152 provided between the subtractor 136 and the low-pass filter 151. be done.

Since the process flow of the pressure/temperature measurement operation of the diaphragm vacuum gauge of this embodiment is the same as that of the fifth embodiment, it will be described using the reference numerals in FIG.
The signal generator 132 applies the sensor drive signal E1sin (2πf1t) to the second electrode (for example, the movable electrode 106) of the sensor chip 1c and the switch 139 during pressure/temperature measurement. The signal generator 133 applies the sensor driving signal E1sin (2πf1t) to the fourth electrode (for example, the movable electrode 108) of the sensor chip 1c and the switch 140 during pressure/temperature measurement (step S500 in FIG. 19).

The signal generator 146e applies to the switch 152 a signal E1sin (2πf1t+π/2) whose phase is 90 degrees out of phase with the sensor drive signal E1sin (2πf1t) during pressure/temperature measurement (step S501 in FIG. 19).

As in the fourth embodiment, the synchronous detector 144 demodulates the output of the amplifier 134 into a signal synchronized with the sensor drive signal E1sin(2πf1t). A synchronous detection unit 145 demodulates a signal synchronized with the sensor drive signal E1sin (2πf1t) from the output of the subtractor 136 .

The switch 152 and the low-pass filter 151 constitute a synchronous detection section 153 . The cutoff frequency of the low-pass filter 151 is set so as to pass the sensor drive signal E1sin (2πf1t) and block the sensor drive signal E2sin (2πf2t). The synchronous detection unit 153 demodulates from the output of the subtractor 136 a signal synchronized with the sensor drive signal E1sin (2πf1t) and the signal E1sin (2πf1t+π/2) 90 degrees out of phase.

Specifically, the switch 152 connects the output terminal of the subtractor 136 and the non-inverting input terminal of the low-pass filter 151 when the signal E1sin (2πf1t+π/2) output from the signal generator 146e during pressure/temperature measurement is positive. to connect. Switch 152 connects the output terminal of subtractor 136 and the inverting input terminal of low-pass filter 151 when signal E1sin (2πf1t+π/2) is negative. As a result, from the output of the subtractor 136, it is possible to demodulate a signal synchronized with the sensor drive signal E1sin (2πf1t) and the signal E1sin (2πf1t+π/2) 90 degrees out of phase.

The capacitance calculator 141 calculates the value of the capacitance Cx from the amplitude of the output vc of the synchronous detector 144 (step S502 in FIG. 19).
The reference capacitance calculator 142e calculates the value of the electrostatic capacitance (reference capacitance) Cr from the output vr of the synchronous detector 145 and the output vt of the synchronous detector 153 (step S503 in FIG. 19). This reference capacitance Cr can be calculated by replacing Cx with Cr and vc with vr in Equation (7).

The capacitance correction unit 143 calculates a value (Cx-Cr)/Cx obtained by correcting the capacitance Cx using the reference capacitance Cr (step S504 in FIG. 19).
The temperature calculation unit 149e calculates the value of the series resistance Rr from the output vr of the synchronous detection unit 145 and the output vt of the synchronous detection unit 153 (step S505 in FIG. 19), and calculates the temperature of the sensor chip 1c from the value of the series resistance Rr. It is derived (step S506 in FIG. 19).

The series resistance Rr can be calculated by replacing Rx with Rr and vc with vr in Equation (8). The relationship between the series resistance Rr and the temperature is stored in advance in the temperature calculator 149e. The temperature calculator 149e may calculate the temperature from the value of the series resistance Rr by a preset formula, or obtain the temperature value corresponding to the value of the series resistance Rr from a preset table. good too.

The pressure measurement unit 13e corrects the capacitance (Cx−Cr)/Cx calculated by the capacitance/temperature detection unit 12e by the temperature of the sensor chip 1c calculated by the capacitance/temperature detection unit 12e to obtain the measured pressure value MP , and output (step S507 in FIG. 19).

The capacity/temperature detection unit 12e and the pressure measurement unit 13e perform the processing of steps S500 to S507 at each measurement cycle until the pressure measurement operation is completed according to the user's instruction (YES in step S508 in FIG. 19).
Since the heating operation of this embodiment is the same as that of the fifth embodiment, the explanation is omitted.

Thus, in this embodiment, the fixed electrode 105 and the movable electrode 106 of the sensor chip 1c are used to perform capacitance measurement for pressure measurement, and the fixed electrode 107 and the movable electrode 108 of the sensor chip 1c are used to perform capacitance correction. Reference capacitance measurement, temperature measurement, and heating can be performed for this purpose, and one sensor chip 1c can realize four of pressure measurement, temperature measurement, capacitance correction, and heating.
As in the first embodiment, in this embodiment, pressure/temperature measurement and heating may be performed at different times, or pressure/temperature measurement and heating may be performed at the same time.
The two movable electrodes (the second electrode 106 and the fourth electrode 108) installed on the diaphragm 102 of the sensor chip 1 described in the fourth to sixth embodiments are electrically connected to form a single electrode. It may be formed as a movable electrode.

The circuit units 11, 11a, 11b, 11c, 11d, and 11e described in the first to sixth embodiments control a computer having a CPU (Central Processing Unit), a storage device, and an interface, and these hardware resources. It can be realized by a program that A configuration example of this computer is shown in FIG.

The computer comprises a CPU 200 , a storage device 201 and an interface device (I/F) 202 . The I/F 202 is connected to the hardware of the capacitance detectors 12, 12a and 12c and the hardware of the capacitance/temperature detectors 12b, 12d and 12e. In such a computer, a program for implementing the method of the present invention is stored in storage device 201 . The CPU 200 executes the processes described in the first to sixth embodiments according to the programs stored in the storage device 201. FIG.

The present invention can be applied to a diaphragm vacuum gauge.

1, 1c... sensor chip, 10, 10b, 10c, 10d... pressure receiving part, 11, 11a, 11b, 11c, 11d, 11e... circuit part, 12, 12a, 12c... capacity detection part, 12b, 12d, 12e... capacity Temperature detection unit 13, 13d, 13e Pressure measurement unit 14, 14a, 14b, 14c, 14d, 14e Control unit 102 Diaphragm 105, 107 Fixed electrode 106, 108 Movable electrode 120, 120-1, 120-2, 129, 132, 133, 146, 146e... signal generator, 121, 134, 135... amplifier, 122, 122b-1, 122b-2, 137, 138, 147, 151... low-pass filter , 123, 123b, 141, 141d...capacity calculation section, 124 to 127, 139, 140, 148, 152...switch, 128, 149, 149e... temperature calculation section, 130, 131, 144, 145, 150, 153...synchronization Detector 136 Subtractor 142, 142e Reference capacitance calculator 143 Capacitance corrector.

Claims (10)

a first electrode formed on a pedestal; and a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode, a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a signal generator configured to selectively apply either a first sensor drive signal or a second sensor drive signal having a higher frequency than the first sensor drive signal to the second electrode; ,
an amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
a capacitance calculator configured to calculate the value of the capacitance between the first and second electrodes from the output signal of the amplifier;
a pressure measuring unit configured to convert the capacitance into a measured pressure value;
The signal generator is configured to apply the first sensor drive signal to the second electrode during pressure measurement and to apply the second sensor drive signal to the second electrode during heating. A diaphragm vacuum gauge, comprising: a control unit; a first electrode formed on a pedestal; and a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode, a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a first signal generator configured to output a first sensor drive signal;
a second signal generator configured to output a second sensor drive signal having a higher frequency than the first sensor drive signal;
an amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
provided between the first and second signal generators and the second electrode, one of the output terminal of the first signal generator and the output terminal of the second signal generator and the a first switch configured to selectively connect the second electrode;
a second switch provided between the first electrode and the amplifier and configured to selectively connect either an input terminal of the amplifier or ground to the first electrode;
a capacitance calculator configured to calculate the value of the capacitance between the first and second electrodes from the output signal of the amplifier;
a pressure measuring unit configured to convert the capacitance into a measured pressure value;
During pressure measurement, the first switch is controlled to connect the output terminal of the first signal transmitter and the second electrode, and the first electrode and the input terminal of the amplifier are connected. While controlling the second switch during heating, the first switch is controlled to connect the output terminal of the second signal generator and the second electrode during heating, and the first electrode and and a controller configured to control the second switch to connect to ground. a first electrode formed on a pedestal; and a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode, a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a first signal generator configured to apply to the second electrode either a first sensor drive signal or a second sensor drive signal having a higher frequency than the first sensor drive signal; ,
a second signal generator configured to output a signal out of phase with the first sensor drive signal;
an amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
a first synchronous detection section configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the amplifier;
a second synchronous detection unit configured to demodulate a signal synchronized with the output signal of the second signal generator from the output signal of the amplifier;
a capacitance calculation unit configured to calculate a capacitance value between the first and second electrodes from output signals of the first and second synchronous detection units;
A temperature configured to calculate the series resistance values of the first and second electrodes from the output signals of the first and second synchronous detection units, and obtain the temperature of the sensor chip from the series resistance values. a calculation unit;
a pressure measuring unit configured to convert the capacitance into a measured pressure value;
The first signal generator applies the first sensor drive signal to the second electrode during pressure/temperature measurement, and applies the second sensor drive signal to the second electrode during heating. and a control unit configured to control the diaphragm vacuum gauge. a first electrode formed on a pedestal; and a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode, a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a first signal generator configured to output a first sensor drive signal;
a second signal generator configured to output a second sensor drive signal having a higher frequency than the first sensor drive signal;
a third signal generator configured to output a signal out of phase with the first sensor drive signal;
an amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
provided between the first and second signal generators and the second electrode, one of the output terminal of the first signal generator and the output terminal of the second signal generator and the a first switch configured to selectively connect the second electrode;
a second switch interposed between the first electrode and the amplifier and configured to selectively connect the first electrode to one of an input terminal of the amplifier and ground;
a first synchronous detection section configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the amplifier;
a second synchronous detection unit configured to demodulate a signal synchronized with the output signal of the third signal generator from the output signal of the amplifier;
a capacitance calculation unit configured to calculate a capacitance value between the first and second electrodes from output signals of the first and second synchronous detection units;
A temperature configured to calculate the series resistance values of the first and second electrodes from the output signals of the first and second synchronous detection units, and obtain the temperature of the sensor chip from the series resistance values. a calculation unit;
a pressure measuring unit configured to convert the capacitance into a measured pressure value;
During pressure/temperature measurement, the first switch is controlled to connect the output terminal of the first signal generator and the second electrode, and the first electrode and the input terminal of the amplifier are connected. while controlling the second switch to connect the output terminal of the second signal generator and the second electrode during heating and controlling the first switch to connect the output terminal of the second signal generator and the second electrode; and a controller configured to control the second switch to connect the electrode to ground. The diaphragm vacuum gauge according to any one of claims 3 to 4,
The control unit controls the frequency of the second sensor drive signal, the amplitude of the second sensor drive signal, and the time to apply the second sensor drive signal based on the temperature of the sensor chip and the heating temperature set value. A diaphragm vacuum gauge characterized in that the heating values of said first and second electrodes are controlled by controlling either length of . a first electrode formed on a pedestal; a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode; a third electrode formed on the pedestal; and a fourth electrode formed on the diaphragm outside the second electrode so as to face the third electrode. a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a first signal generator configured to apply a first sensor drive signal to the second electrode;
a second sensor drive signal configured to selectively apply either one of the first sensor drive signal and a second sensor drive signal having a higher frequency than the first sensor drive signal to the fourth electrode; a signal generator;
a first amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
a second amplifier configured to convert the current output from the third electrode into a voltage and amplify it;
a subtractor configured to subtract the output signal of the second amplifier from the output signal of the first amplifier;
a first synchronous detector configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the first amplifier;
a second synchronous detection unit configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the subtractor;
a first capacitance calculator configured to calculate a value of a first electrostatic capacitance between the first and second electrodes from an output signal of the first synchronous detector;
a second capacitance calculator configured to calculate a value of a second electrostatic capacitance between the third and fourth electrodes from the output signal of the second synchronous detector;
a capacitance correction unit configured to correct the first capacitance with the second capacitance;
a pressure measuring unit configured to convert the corrected first capacitance into a measured pressure value;
The second signal generator is controlled such that the first sensor drive signal is applied to the fourth electrode during pressure measurement, and the second sensor drive signal is applied to the fourth electrode during heating. A diaphragm vacuum gauge, comprising: a controller configured as follows. a first electrode formed on a pedestal; a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode; a third electrode formed on the pedestal; and a fourth electrode formed on the diaphragm outside the second electrode so as to face the third electrode. a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a first signal generator configured to apply a first sensor drive signal to the second electrode;
A second signal configured to selectively apply either a first sensor drive signal or a second sensor drive signal having a higher frequency than the first sensor drive signal to the fourth electrode. a generator;
a third signal generator configured to output a signal out of phase with the first sensor drive signal;
a first amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
a second amplifier configured to convert the current output from the third electrode into a voltage and amplify it;
a subtractor configured to subtract the output signal of the second amplifier from the output signal of the first amplifier;
a first synchronous detector configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the first amplifier;
a second synchronous detection unit configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the subtractor;
a third synchronous detection section configured to demodulate a signal synchronized with the output signal of the third signal generator from the output signal of the first amplifier;
a first capacitance calculator configured to calculate a value of a first electrostatic capacitance between the first and second electrodes from output signals of the first and third synchronous detection units;
a second capacitance calculator configured to calculate a value of a second electrostatic capacitance between the third and fourth electrodes from the output signal of the second synchronous detector;
A temperature configured to calculate series resistance values of the first and second electrodes from output signals of the first and third synchronous detection units, and obtain a temperature of the sensor chip from the series resistance values. a calculation unit;
a capacitance correction unit configured to correct the first capacitance with the second capacitance;
a pressure measurement unit configured to correct the corrected first capacitance by the temperature of the sensor chip and convert it into a measured pressure value;
The second signal generator is configured to apply the first sensor drive signal to the fourth electrode during pressure/temperature measurement and to apply the second sensor drive signal to the fourth electrode during heating. a diaphragm vacuum gauge, comprising: a controller configured to control a vacuum gauge; a first electrode formed on a pedestal; a second electrode formed on a diaphragm arranged across a gap from the pedestal so as to face the first electrode; a third electrode formed on the pedestal; and a fourth electrode formed on the diaphragm outside the second electrode so as to face the third electrode. a sensor chip configured such that the interval between the first and second electrodes changes according to the displacement of the diaphragm;
a first signal generator configured to apply a first sensor drive signal to the second electrode;
A second signal configured to selectively apply either a first sensor drive signal or a second sensor drive signal having a higher frequency than the first sensor drive signal to the fourth electrode. a generator;
a third signal generator configured to output a signal out of phase with the first sensor drive signal;
a first amplifier configured to convert the current output from the first electrode into a voltage and amplify it;
a second amplifier configured to convert the current output from the third electrode into a voltage and amplify it;
a subtractor configured to subtract the output signal of the second amplifier from the output signal of the first amplifier;
a first synchronous detector configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the first amplifier;
a second synchronous detection unit configured to demodulate a signal synchronized with the first sensor drive signal from the output signal of the subtractor;
a third synchronous detection unit configured to demodulate a signal synchronized with the output signal of the third signal generator from the output signal of the subtractor;
a first capacitance calculator configured to calculate a value of a first electrostatic capacitance between the first and second electrodes from an output signal of the first synchronous detector;
a second capacitance calculator configured to calculate a value of a second electrostatic capacitance between the third and fourth electrodes from output signals of the second and third synchronous detectors;
A temperature configured to calculate the series resistance values of the third and fourth electrodes from the output signals of the second and third synchronous detection units, and obtain the temperature of the sensor chip from the series resistance values. a calculation unit;
a capacitance correction unit configured to correct the first capacitance with the second capacitance;
a pressure measurement unit configured to correct the corrected first capacitance by the temperature of the sensor chip and convert it into a measured pressure value;
The second signal generator is configured to apply the first sensor drive signal to the fourth electrode during pressure/temperature measurement and to apply the second sensor drive signal to the fourth electrode during heating. a diaphragm vacuum gauge, comprising: a control unit configured to control the vacuum gauge; The diaphragm vacuum gauge according to any one of claims 7 to 8,
The control unit controls the frequency of the second sensor drive signal, the amplitude of the second sensor drive signal, and the time to apply the second sensor drive signal based on the temperature of the sensor chip and the heating temperature set value. A diaphragm vacuum gauge characterized in that the amount of heat generated by the third and fourth electrodes is controlled by controlling any one of the lengths of . The diaphragm vacuum gauge according to any one of claims 6 to 9,
A diaphragm vacuum gauge, wherein the second electrode and the fourth electrode are electrically connected to form a single electrode.

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