JP2008164541A - Quartz type gas pressure gage, and vacuum unit using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quartz type gas pressure gage capable of eliminating data collection man-hours and a computing circuit for temperature calibration to reduce a cost, by controlling very efficiently a temperature of a tuning fork type quartz oscillator to be kept constant. <P>SOLUTION: This quartz type gas pressure gage 1 includes the tuning fork type quartz oscillator 30 having respectively two arm parts 32A, 32b of rectangular cross section, and a base part 34 for connecting the respective, and measures pressure of gas, based on a difference ΔZ between a natural resonance resistance Z<SB>0</SB>of the tuning fork type quartz oscillator and a measured resonance resistance Z. This pressure gage 1 has the first and second electrode patterns 70A, 70B formed insulatedly each other on surfaces of the two arm parts 32A, 32b of the tuning fork type quartz oscillator 30 and the base part 34, and a heating resistor pattern 72 formed on at least one of surfaces 32A3, 32B3 in the two arm parts 32A, 32b and the base part 34, and formed insulatedly each other from one or both of the first and second electrode patterns 70A, 70B formed on at least one of the surfaces 32A3, 32B3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a quartz gas pressure gauge and a vacuum apparatus using the same.

  2. Description of the Related Art Conventionally, there has been known a method of mainly measuring a pressure below atmospheric pressure using a tuning fork type crystal resonator (hereinafter also referred to as a resonator) (Patent Document 1). This is because the resonance resistance of the vibrator increases in proportion to the pressure in the molecular flow region and increases in proportion to the 1/2 power of the pressure in the viscous flow region. Is.

Since it is possible to measure in a wide pressure range from atmospheric pressure to 10 ⁻² to 10 ⁻³ Torr, it is recognized as an effective pressure measuring means.

In this measurement method using a vibrator, the vibrator is arranged in a space where pressure is to be measured, the vibrator is vibrated through an oscillation circuit, and the resonance resistance Z is obtained. The gas pressure is measured from the difference ΔZ (= Z−Z ₀ ) between the measured resonance resistance Z and the natural resonance resistance Z ₀ (value in high vacuum).

  In this measuring method, since the temperature of the vibrator during measurement is generally indefinite, there is a problem that a measurement error becomes large on the low pressure side and accurate pressure measurement cannot be performed.

The intrinsic resonance resistance Z0 changes only a few kΩ over a wide temperature range (−20 to + 60 ° C.). On the other hand, the difference ΔZ is about several kΩ in the region of 10 ⁻¹ to 10 ⁻² Torr, and about several tens of Ω in the region of 10 ⁻² to 10 ⁻³ Torr, and the difference ΔZ decreases as the pressure decreases. In other words, the change in the natural resonance resistance Z ₀ of the oscillator varies with the temperature can not be ignored. This is the measurement limit of the pressure range when measuring pressure using a vibrator.

The applicant of the present application measures the resonance frequency f of the tuning fork crystal resonator, obtains the temperature T of the tuning fork crystal resonator from the resonance frequency f, and obtains the natural resonance frequency (Z ₀ + Zt) and the resonance resistance Z at the temperature T. A method for measuring the pressure of gas from the difference ΔZ = Z− (Z ₀ + Zt) is proposed and patented (Patent Document 2).

  The above method has an effect of eliminating an error based on the temperature of the vibrator during measurement and measuring an accurate pressure.

However, since the pressure is calculated based on the correlation data between the resonance frequency f and the temperature T and the correlation between the temperature T and the natural resonance frequency (Z ₀ + Zt), data collection of correlation data for each crystal resonator is performed. There was a problem of increasing the cost by the number of man-hours and the arithmetic circuit.

  Here, unlike the above-described measuring method, a heat conduction type vacuum gauge (quartz type heat conduction type vacuum gauge) using a crystal temperature sensor is known (Patent Document 3).

However, this measurement principle is that when the vacuum chamber is depressurized, the gas density decreases and the amount of heat transferred from the heat source to the crystal temperature sensor (temperature-sensitive crystal resonator) decreases, resulting in the temperature of the crystal temperature sensor. Decreases and the oscillation frequency increases. Conversely, when the pressure in the vacuum chamber is increased, the gas density increases, the amount of heat transferred from the heat source to the quartz temperature sensor increases, and as a result, the temperature of the quartz temperature sensor rises and the oscillation frequency decreases. Thus, the amount of heat from the heat source is increased or decreased by the gas density depending on the pressure, and the pressure is measured based on the frequency change caused by the temperature change. Therefore, the heat source of this crystal unit is not for maintaining the crystal unit at a constant temperature, but is provided to give heat to the crystal unit as a measurement principle.
Japanese Utility Model Publication No. 64-38547 Japanese Patent Publication No. 7-97060 JP-A-1-31438

  The object of the present invention is to control the temperature of a tuning fork crystal unit very efficiently and uniformly, thereby eliminating the data collection man-hours and the arithmetic circuit for temperature calibration, and reducing the cost. It is to provide a meter and a vacuum apparatus using the meter.

One aspect of the present invention includes a tuning fork crystal resonator having two arm portions each having a rectangular cross section and a base portion having a rectangular cross section that connects the two arm portions, and a natural resonance resistance of the tuning fork crystal resonator. From the difference between the measured resonance resistance and the quartz gas pressure gauge that measures the gas pressure,
First and second electrode patterns formed on the surfaces of the two arm portions and the base portion of the tuning-fork type crystal resonator so as to be insulated from each other;
It is formed on at least one surface of the four surfaces of the two arm portions and the base portion, and is insulated from one or both of the first and second electrode patterns formed on the at least one surface. A heating resistor pattern formed by
Have
The tuning fork type crystal resonator is held at a constant temperature by the heating resistor pattern.

  According to one aspect of the present invention, on at least one surface of a tuning fork type crystal resonator, in addition to the first and second electrode patterns for transmitting the resonator, the temperature of the resonator is made constant. A heating resistor pattern is formed. For this reason, since the resonance resistance value of the crystal resonator having temperature dependence can be made substantially constant, it is not necessary to calibrate the gas pressure detected using this resonance resistance value from the atmosphere to high vacuum. . Therefore, the device can be manufactured at a low cost.

In one aspect of the present invention, a case main body forming a room communicating with the gas atmosphere;
An electrode connected to the tuning fork type crystal resonator;
The electrode is hermetically sealed and held, and the quartz crystal resonator connected to the electrode is disposed in the chamber, and is hermetically sealed and supported with respect to the case body, and
A filter member that surrounds the crystal resonator connected to the electrode together with the hermetic seal body to form a measurement chamber, and communicates with the measurement chamber and the gas atmosphere;
Further comprising
The electrodes may include first and second electrodes connected to the first and second electrode patterns, and third and fourth electrodes connected to the heating resistor patterns.

  The filter member is not always necessary, but the tuning fork type crystal resonator can be protected by providing the filter member.

Instead of the above structure, in one embodiment of the present invention,
A metal case body forming a chamber communicating with the gas atmosphere;
An electrode connected to the crystal unit;
A first seal body formed of an insulator for hermetically sealing and holding the electrode;
A cylindrical body made of metal, which is inserted into the case main body, and supports the first seal body in an airtight manner;
A second seal body that hermetically seals the metal cylinder and the case body;
A metal filter member that is held by the metal cylinder, surrounds the electrode and the quartz crystal resonator connected thereto, forms a measurement chamber, and communicates with the measurement chamber and the gas atmosphere;
Further comprising
The electrodes may include first and second electrodes connected to the first and second electrode patterns, and third and fourth electrodes connected to the heating resistor patterns.

  In particular, when the case main body and the cylinder are grounded and the case main body and the cylinder are electrically insulated by the second seal body, the following effects can be obtained.

  In a vacuum apparatus that generates plasma by supplying RF power in a chamber in which the case body is mounted, there is a possibility that the quartz crystal unit is adversely affected by RF noise. When the case main body and the cylinder electrically insulated by the second seal body are grounded, the filter member is also grounded. Therefore, even if RF noise is superimposed on the case main body, the RF noise is not generated in the cylinder and the filter member. Is not superimposed, the adverse effect of RF noise can be prevented.

  In one aspect of the present invention, the tuning fork type crystal resonator is a temperature-sensitive resonator in which an oscillation frequency changes linearly with respect to temperature. From the frequency measurement unit that measures the oscillation frequency, and the frequency measurement unit And a heater power control circuit for controlling the heater to a constant temperature based on the output of.

  In the temperature sensitive oscillator, the oscillation frequency changes linearly with respect to the temperature. Therefore, if the oscillation frequency of the crystal oscillator is measured by the frequency measuring means, the temperature of the crystal oscillator can be measured. Based on the measured temperature, the temperature of the crystal unit can be controlled to be substantially constant.

  Instead, in one aspect of the present invention, the heating resistor pattern is a PTC (Positive Temperature Coefficien) heating resistor pattern in which the resistance value suddenly increases with a temperature rise exceeding the Curie temperature. Can do.

  In this way, as long as the power supply is connected to the PTC heating resistor pattern heater, the heating resistor pattern with a positive temperature characteristic will suddenly increase in resistance value due to a temperature rise exceeding the Curie temperature, and the current will decrease and the amount of heat generation will decrease. On the other hand, the resistance value decreases as the temperature decreases, the current increases, and the amount of heat generation also increases, so that the crystal resonator can be self-controlled at a substantially constant temperature.

In one aspect of the present invention, a current-voltage converter that is connected to one end of the tuning fork crystal resonator and converts a current flowing through the tuning fork crystal resonator into a voltage;
An attenuator connected to the other end of the tuning fork crystal unit;
A first full-wave rectifier that rectifies current from the attenuator;
A comparator that compares a voltage from the first full-wave rectifier with a reference voltage;
A voltage controlled attenuator that further attenuates the output of the attenuator based on the output voltage of the comparator;
A second full-wave rectifier that rectifies the summed output of the voltage controlled attenuator and the current-voltage converter;
Can further be included.

Then, if the resonance resistance of the crystal resonator is Z, (1 / Z) is output as the output of the second full-wave rectifier, and the known resonance resistance Z ₀ of the crystal resonator and the measured resonance The pressure of the gas can be measured from the difference ΔZ (= Z−Z ₀ ) of the resistance Z.

In one aspect of the present invention, the tuning fork type crystal resonator has a resonance resistance that varies with temperature,
The PTC heating resistor pattern is set to a temperature in a positive temperature characteristic region where the resonance resistance increases as the temperature increases,
Another aspect of the present invention defines a vacuum apparatus in which the above-described quartz gas pressure gauge measures the pressure in a region where the atmosphere-vacuum is set.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not always.

1. 1. First embodiment 1.1. Structure of Pressure Gauge FIG. 1 is a cross-sectional view of a quartz gas pressure gauge according to the first embodiment of the present invention. In FIG. 1, the pressure gauge 1 has a case body 20 that forms a chamber 12 that communicates with a vacuum chamber 10. The tuning fork type crystal resonator 30 is connected to the electrode 40. The electrode 40 is hermetically sealed and held, and the quartz crystal resonator 30 connected to the electrode 40 is disposed in the chamber 12 to provide an airtight seal structure 50 that is hermetically sealed and supported with respect to the case body 20. It has been. Furthermore, a filter member 60 that is held by the hermetic seal structure 50 and surrounds the crystal resonator 30 connected to the electrode 40 to form the measurement chamber 62 and that allows the measurement chamber 62 and the vacuum chamber 10 to communicate with each other is provided. ing. A heater 70 is provided that is disposed on the atmosphere side of the hermetic seal body 50 and heats the crystal unit 30.

  The case body 20 is formed in a cylindrical shape, and the lower end flange 22 is fixed to the wall portion 14 of the vacuum chamber 10.

  The hermetic seal structure 50 is divided into, for example, a first seal body 52, a metal cylinder 54, and a second seal body 58. The first seal body 52 functions as an insulator that hermetically seals and holds the electrode 40 and electrically insulates the electrode 40. The cylindrical body 54 holds the first seal body 52 as an airtight seal therein. A threaded portion 56 is formed at the lower end of the cylindrical body 54 and is screwed into the filter member 60. The second seal body 58 is formed in a ring shape, and the cylinder is hermetically sealed in the case body 20 and held. The second seal body 58 also functions as an insulator that electrically insulates the case main body 20 and the cylindrical body 54 from each other when they are grounded.

  When RF plasma is generated in the vacuum chamber 10, the case body 20 and the cylinder body 54 are grounded, and the case body 20 and the cylinder body 54 are electrically connected using the second seal body 58 as an insulator. It is preferable to insulate. As a result, the filter member 60 is also grounded. This is because even if the RF noise is superimposed on the case body 20, it is possible to prevent the RF noise from being superimposed on the cylindrical body 54 and the filter member 60 that are electrically insulated from the case body 20. Thereby, the crystal unit 30 can be shielded from RF noise.

  Here, from the relationship of the hermetic seal, the thermal expansion coefficients of the case body 20 and the cylindrical body 54 that are metals and the thermal expansion coefficients of the first and second seal bodies 52 and 58 that are insulators are substantially equal. Is preferred. This is because the hermetic seal can be prevented from being damaged due to the difference in thermal expansion. In the present embodiment, the case main body 20 and the cylindrical body 54 are formed of Kovar metal, and the first and second seal bodies 52 and 58 are formed of Kovar glass (borosilicate glass), so that members that are in contact with each other are formed. The coefficient of thermal expansion of is made the same level. The lower flange 22 of the case body 20 can be formed of a different material, for example, a highly reliable stainless steel as a flange.

  The filter member 60 is formed of, for example, a SUS (stainless steel) sintered body in order to communicate the chamber 12 and the measurement chamber 62 and to protect the tuning fork type crystal resonator 30.

  In FIG. 1, the cylinder 54 may be deleted. In this case, the second seal body 58 is also unnecessary, and the first seal body (airtight seal body in a broad sense) 52 only needs to be supported by the case body 20. In this case, the filter member 60 may be supported by the case body 20 without being supported by the cylindrical body 54. The measurement chamber 62 is partitioned by the filter member 60 and the first seal body 52. This is because when no RF plasma is generated in the vacuum chamber 10, no countermeasure against RF noise is required. In this case, the filter member 60 may also be deleted, but providing the filter member 60 has an effect of protecting the tuning fork type crystal resonator 30.

1.2. Tuning Fork Type Crystal Resonator Structure As shown in FIG. 2, the tuning fork type crystal resonator 30 includes two arm portions 32A and 32B and a base portion 34 connecting one end of the two arm portions 32A and 32B. . The cross-sectional width W, the cross-sectional thickness t, and the length L of the two arm portions 32A and 32B are designed so that the pressure dependency of the resonance resistance Z is increased.

  FIG. 3 schematically shows a cross section of the two arms 32A and 32B of the tuning fork type crystal resonator 30 shown in FIG. As shown in FIG. 3, two arm portions 32A and 32B have first and second electrodes connected to the two first and second electrodes 40A and 40B of the electrodes 40 shown in FIG. Patterns 70A and 70B are formed.

  In FIG. 3, the first electrode pattern 70A is formed on the two surfaces of the arm portion 32A and on the first and third surfaces 32A1 and 32A3 having the width W opposite to each other. A second electrode pattern 70B is formed on the other two surfaces of the arm portion 32A and on the second and fourth surfaces 32A2 and 32A4 having the width t facing each other.

  On the other hand, the second electrode pattern 70B is formed on the two surfaces of the arm portion 32B and on the first and third surfaces 32B1 and 32B13 having the width W facing each other. A first electrode pattern 70A is formed on the other two surfaces of the arm portion 32B and on the second and fourth surfaces 32B2 and 32B4 having a width t opposite to each other.

  However, FIG. 3 schematically shows the connection between the first and second electrode patterns 70A and 70B and the electrodes 40A and 40B. Actually, as shown in FIGS. 4 and 5, the two arms 32A are used. , 32B, one or both of the first and second electrode patterns 70A, 70B are formed in different regions insulated from each other.

  FIG. 4 is a front view of the tuning fork type crystal resonator 30 viewed from the surface having the first surfaces 32A1 and 32B1 of the two arm portions 32A and 32B. In FIG. 4, the first and second electrode patterns 70 </ b> A and 70 </ b> B are distinguished from each other as hatching regions in opposite directions. The first and second electrode patterns 70A and 70B are patterned so as to be as symmetrical as possible with respect to the longitudinal center line of the tuning fork type crystal resonator 30. Although the pattern shape is different on the other three surfaces (second to fourth surfaces) other than the first surfaces 32A1 and 32B1, either one of the first and second electrode pattern surfaces 70A and 70B or Both are formed, and the first and second electrode patterns 70A and 70B are successively formed on the first to fourth surfaces. As a result, the first and second electrode patterns 70A and 70B become patterns that are continuous on the first to fourth surfaces, and are connected to the electrodes 40A and 40B at any one point.

  FIG. 5 is a back view of the tuning-fork type crystal resonator 30 as viewed from the surface having the third surfaces 32A3 and 32B3 of the two arm portions 32A and 32B. In FIG. 5, the first electrode pattern 70A is formed on the third surface 32A3 of the arm portion 32A, and the second electrode pattern 70B is formed on the third surface 32B3 of the arm portion 32B. On the third surfaces 32A3 and 32B3, in addition to the first and second electrode patterns 70A and 70, a heating resistor pattern 72 is provided in a region indicated by different cross hatching insulated from the patterns 70A and 70B. Is formed.

  The heating resistor pattern 72 is a continuous pattern on the third surfaces 32A3 and 32B3 of the two arm portions 32A and 32B, and has electrode portions 72A and 72B at both ends of the pattern formed on the base 34. The heating resistor pattern 72 is formed on the third surfaces 32A3 and 32B3 of the two arm portions 32A and 32B so as to have substantially the same area. In the present embodiment, the heating resistor pattern 72 is formed on the third surfaces 32A and 32B, but it may be formed on other surfaces, or two or more of the first to fourth surfaces. The heating resistor pattern 72 may be formed on the surface.

  The first and second electrode patterns 70A and 70 and the heating resistor pattern 72 can be formed on the tuning fork type crystal resonator 30 by photolithography. The first and second electrode patterns 70A and 70B can be formed of, for example, chromium (Cr), and the heating resistor pattern 72 can be formed of, for example, chromium (Cr) or platinum (Pt). The material is not limited to these. The heating resistor pattern 72 may have a two-layer structure, the first layer may be a chromium heating pattern, and the second layer may be covered with platinum (Pt) or the like having high corrosion resistance.

  In addition, as a pattern formed in 3rd surface 32A3, 32B3 with respect to 1st surface 32A1, 32B1 of FIG. 4, it can also be made into FIG. 6 or FIG. 6 and 7 are rear views of the tuning fork type crystal resonator 30 as seen from the surface having the third surfaces 32A3 and 32B3 of the two arm portions 32A and 32B.

  6 and 7, unlike FIG. 5, first and second electrode patterns 70A and 70B are formed on the respective surfaces of the third surfaces 32A3 and 32B3. In FIG. 6, unlike FIG. 5, the first and second electrode patterns 70 </ b> A and 70 </ b> B are formed at the extreme end of the base portion 34. , 72B. In FIG. 7, the electrodes 72 </ b> A and 72 </ b> B of the heating resistor pattern 72 are arranged at the extreme end of the base 34. However, one electrode 72B of the heating resistor pattern 72 cannot be continuously formed with the heating resistor pattern 72 by the second electrode pattern 70B. In this case, another electrode 72C continuously formed on the heating resistor pattern 72 can be provided, and the electrodes 72B and 72C can be wired by other wiring means other than the pattern.

1.3. FIG. 8 is a block diagram of the measuring unit 200 of the crystal type gas pressure gauge 1. In FIG. 8, the heating resistor pattern 72 is illustrated as a separate body from the tuning fork type crystal resonator 30, but is actually integrated as shown in FIG.

  In FIG. 8, a current-voltage converter 210 that is connected to one end of the crystal resonator 30 and converts a current flowing through the crystal resonator 30 into a voltage, and an attenuator connected to the other end of the pressure measuring unit 100, for example, 1/10. The attenuator 220, the first full-wave rectifier 230 that rectifies the current from the 1/10 attenuator 220, the voltage from the first full-wave rectifier 230, and the reference voltage from the reference voltage source 240 are compared. Comparator 250, voltage-controlled attenuator 260 that further attenuates the output of 1/10 attenuator 220 based on the output voltage of comparator 250, and the summed output of voltage-controlled attenuator 260 and current-voltage converter 210 are rectified. A second full-wave rectifier 270. In FIG. 8, in order to digitally display the pressure, an analog / digital (A / D) converter 280 connected to the second full-wave rectifier 270, and a CPU 290 that controls display of the display unit 300 based on the output thereof. Have Instead, the A / D converter 280, the CPU 290, and the display unit 300 may be deleted, and an analog meter may be connected to the second full-wave rectifier 270.

  In FIG. 8, frequency measuring means for measuring the oscillation frequency of the crystal unit 30, for example, a frequency counter 320, and a heater power control circuit 330 for controlling the power supplied to the heating resistor pattern 72 based on the output are further provided. Yes.

  Here, the relationship between the oscillation frequency of the crystal unit 30 and the temperature is as shown in FIG. 9, and the oscillation frequency f of the crystal unit 30 has a linear correlation with the actual temperature T. In this way, the crystal resonator 30 whose oscillation frequency changes linearly with respect to temperature is referred to as a temperature-sensitive resonator. Such a temperature sensitive oscillator can be formed depending on the cut angle of the crystal.

  The output of the 1/10 attenuator 220 in FIG. 8 is a rectangular wave output correlated with the oscillation frequency f of the crystal resonator 30. Therefore, the frequency counter 320 can detect the oscillation frequency f of the crystal unit 30 by counting the output frequency of the 1/10 attenuator 220. If the crystal unit 30 is a temperature-sensitive unit having the characteristics shown in FIG. 9, the temperature T of the crystal unit 30 can be obtained from the detected oscillation frequency f.

  The heater power control circuit 330 shown in FIG. 8 reduces the supply power based on the characteristics shown in FIG. 9 according to the output of the frequency counter 320 if the measured temperature T is higher than the temperature to be controlled. If the temperature is higher than the temperature to be controlled, the supply power is increased to control the heating resistor pattern 72 to the temperature to be controlled. In this way, pressure measurement can be performed while keeping the temperature of the crystal unit 30 constant. For example, when the set temperature of the crystal unit 30 is 45 ° C., the crystal unit 30 is heated to 45 ° C. ± 0.0 by heating with the heating resistor pattern 72 directly attached to the crystal unit 30 as shown in FIG. The temperature could be controlled with extremely high accuracy of 03 ° C. The set temperature of the crystal unit 30 may be room temperature, for example, 25 ° C., but the ambient temperature is controlled by controlling the temperature of the crystal unit 30 to a temperature, for example, 45 ° C. higher than the room temperature. The impact of changes is less.

Here, when the crystal resonator 30 is driven by the heating resistor pattern 72 controlled to one point temperature as described above, a value (1 / Z) reflecting the resonance resistance Z of the crystal resonator 30 is the second total. Obtained as the output of the wave rectifier 270. The difference ΔZ (= Z−Z ₀ ) between the measured resonance resistance Z of the crystal unit 30 and the intrinsic shared resistance Z ₀ of the crystal unit 30 corresponds to the gas pressure depending on the gas viscosity (concentration). To do. Therefore, the gas pressure can be measured with high accuracy from the natural resonance frequency Z ₀ at the set temperature of the crystal unit 30 and the resonance resistance of the crystal unit 30 measured at a constant temperature.

In the crystal type gas pressure gauge of the present embodiment, a heater (heating element resistance pattern) is directly installed on the temperature sensitive oscillator, and the resonance frequency of the crystal oscillator to be measured is constant at the reference temperature. The heater power is controlled so that Then, maintaining the temperature of the crystal unit constant by the heater power control, in which lost errors due to temperature of the natural resonance resistance Z ₀ of the crystal oscillator. Since the heater is directly installed in the crystal resonator, the heater power for holding the resonator at 45 ° C. may be as small as 200 μW or less. Since the temperature of the vibrator can be detected from the resonance frequency of the vibrator, it can be controlled with high accuracy of 45 ° C. ± 0.03 ° C. or less. This temperature accuracy corresponds to ± 1.5 × 10 ⁻⁵ Torr in terms of pressure.

In the configuration of FIG. 8, the arithmetic circuit and the D / A converter shown in FIGS. 7 and 8 of Patent Document 2 can be deleted. In FIG. 8, only the heating resistor pattern 72 and the heater power control circuit 330 shown in FIG. 5 are added as compared to FIGS. 3 and 5 of Patent Document 2. In addition, it is not necessary to collect correlation characteristic data between the specific resonance resistance (Z ₀ ) and temperature (T) of each vibrator. Therefore, the cost can be significantly reduced as compared with the configuration of Patent Document 2.

  In addition, the pressure gauge 1 according to the present embodiment can be combined with sensors having different pressure detection principles to form a composite vacuum gauge with an expanded measurement pressure range. Examples of other vacuum gauges combined with the quartz gas pressure gauge 1 include an ionization vacuum gauge and a Penning vacuum gauge using Penning discharge.

  For example, in an ionization vacuum gauge, a filament for emitting electrons becomes hot. On the other hand, in the Penning vacuum gauge, self-heating occurs in a high pressure region. Further, in any vacuum gauge, the temperature of the crystal unit 30 reaches 40 to 50 ° C. due to the heat generation described above.

  When the crystal resonator 30 is used in combination with other sensors as described above, the heating resistor pattern 72 may be controlled to an environmental temperature at that time, for example, 45 ° C.

2. Second Embodiment FIG. 10 is a block diagram of a crystal type pressure gauge according to a second embodiment of the present invention. In the pressure gauge 400 shown in FIG. 10, members having the same functions as those in FIG. 8 are given the same reference numerals as those in FIG. 8, and detailed descriptions thereof are omitted.

  The pressure gauge 400 shown in FIG. 10 is different from the pressure gauge 1 shown in FIG. 8 in that the resistance value suddenly increases due to a temperature rise exceeding the Curie temperature instead of the heating resistor pattern 72 of the first embodiment. This is that a PTC (positive temperature characteristic) heating resistor pattern 410 formed of a resistor is provided. That is, the cross hatching region shown in FIG. 5 is not the heating resistor pattern 72 but the PTC heating resistor pattern 410. In FIG. 10, the PTC heating resistor pattern 410 is illustrated as a separate body from the tuning fork type crystal resonator 30, but is actually integrated as shown in FIG. 5.

  Unlike the case shown in FIG. 8, only the power source 420 is connected to the two terminals of the PTC heating resistor pattern 410 as shown in FIG. That is, it is not necessary to control the temperature of the PTC heating resistor pattern 410 from the outside. This is because, due to self-control of the PTC heating resistor pattern 410 itself, when the temperature rises above the Curie temperature, the resistance value of the PTC heating resistor pattern 410 increases rapidly to suppress the current, and thus the heating temperature decreases. On the other hand, when the temperature drops, the resistance value of the PTC heating resistor pattern 410 decreases, the current increases, and the heating temperature increases.

  Such a PTC heating resistor pattern 410 can also be formed on the third surfaces 32A3 and 32B3 shown in FIG. 5, for example, using a photolithography technique.

  Here, the accuracy of controlling the PTC heating resistor pattern 410 to a constant temperature, for example, 45 ° C. is about 45 ° C. ± 1 ° C.

  In addition, although embodiment of this invention was described, it can be understood easily by those skilled in the art that many modifications which do not deviate substantially from the invention specific matter and effect of this invention are possible. Accordingly, all such modifications are included in the scope of the present invention. For example, a different term described at least once together with a broader or synonymous term in this specification or the drawings can be replaced with the broader or synonymous term in any part of the present specification or the drawings.

Since the pressure gauge of the present invention can hold the crystal resonator at a constant temperature with a heater, measurement in a wide pressure range from atmospheric pressure to 10 ⁻² to 10 ⁻³ Torr is possible. It can be used for pressure measurement in a gas path that changes in For this reason, it is most suitable as a pressure gauge of a vacuum apparatus provided with a chamber whose pressure changes in the atmosphere-vacuum. In addition, for example, it can be used as a sensor that determines the opening / closing timing of a gate valve that is opened in the atmosphere and closed in a vacuum, or as a sensor that determines the control timing of a cryopump. At the time of use, as described above, it may be configured as a composite sensor with another sensor that does not use a crystal resonator.

  Further, the crystal resonator used in the present invention is limited to the temperature-sensitive resonator having the characteristics shown in FIG. 9 in the first embodiment. However, if the temperature measurement is not required as in the second embodiment, the crystal resonator is used. Not only a temperature oscillator but also a non-temperature-sensitive oscillator may be used. A non-temperature-sensitive vibrator is a type in which the change in oscillation frequency with respect to temperature is not a straight line but a curve, and the temperature cannot be uniquely determined by the oscillation frequency.

It is sectional drawing of the crystal-type gas pressure gauge which concerns on 1st Embodiment of this invention. FIG. 2 is a schematic perspective view of a tuning-fork type water-use vibrator used in the pressure gauge of FIG. 1. It is explanatory drawing which shows typically the 1st, 2nd electrode pattern formed in a tuning fork type crystal resonator. It is a figure which shows an example of the 1st, 2nd electrode pattern formed in the 1st surface of a tuning fork type crystal resonator. It is a figure which shows an example of the 1st, 2nd electrode pattern and heating resistor pattern which are formed in the 3rd surface of a tuning fork type crystal resonator. It is a figure which shows another example of the 1st, 2nd electrode pattern and heating resistor pattern which are formed in the 3rd surface of a tuning fork type crystal resonator. It is a figure which shows another example of the 1st, 2nd electrode pattern and heating resistor pattern which are formed in the 3rd surface of a tuning fork type crystal resonator. It is a whole block diagram of a 1st embodiment. It is a characteristic view which shows the relationship of the oscillating frequency-temperature of a temperature sensitive vibrator. It is a whole block diagram of 2nd Embodiment.

Explanation of symbols

1,400 Pressure gauge, 10 Vacuum chamber, 12 rooms, 14 Wall part, 20 Case body, 22 Flange, 30 Quartz vibrator, 40 Electrode, 50 Airtight seal body, 52 First seal body, 54 Tube body, 56 Screw part , 58 Second seal body, 60 filter member, 70A
First electrode pattern, 70B Second electrode pattern, 72 Heating resistor pattern, 72A, 72B electrode, 87 amplifier, 88 Peltier element, 210 Current-voltage converter, 220 Attenuator (1/10 attenuator), 230 First 1 full wave rectifier, 240 reference voltage source, 250 comparator, 260 voltage controlled attenuator, 270 second full wave rectifier, 280 analog / digital (A / D) converter, 290 CPU, 300 display, 320 frequency Counter, 330 Heater power control circuit, 410 PTC heating resistor pattern, 420 Power supply

Claims (6)

Each including a tuning fork crystal resonator having two arms each having a rectangular cross section and a base having a rectangular cross section connecting the two arms, and the resonance resonance resistance and the measured resonance resistance of the tuning fork crystal resonator In the quartz gas pressure gauge that measures the gas pressure from the difference between
First and second electrode patterns formed on the surfaces of the two arm portions and the base portion of the tuning-fork type crystal resonator so as to be insulated from each other;
It is formed on at least one surface of the four surfaces of the two arm portions and the base portion, and is insulated from one or both of the first and second electrode patterns formed on the at least one surface. A heating resistor pattern formed by
Have
A quartz-type gas pressure gauge, wherein the tuning-fork type quartz vibrator is held at a constant temperature by the heating resistor pattern. In claim 1,
A case main body forming a room communicating with the gas atmosphere;
An electrode connected to the tuning fork type crystal resonator;
The electrode is hermetically sealed and held, and the quartz crystal resonator connected to the electrode is disposed in the chamber, and is hermetically sealed and supported with respect to the case body, and
A filter member that surrounds the crystal resonator connected to the electrode together with the hermetic seal body to form a measurement chamber, and communicates with the measurement chamber and the gas atmosphere;
Further comprising
The electrode includes first and second electrodes connected to the first and second electrode patterns, and third and fourth electrodes connected to the heating resistor pattern. Crystal type gas pressure gauge. In claim 1,
A metal case body forming a chamber communicating with the gas atmosphere;
An electrode connected to the crystal unit;
A first seal body formed of an insulator for hermetically sealing and holding the electrode;
A cylindrical body made of metal, which is inserted into the case main body, and supports the first seal body in an airtight manner;
A second seal body that hermetically seals the metal cylinder and the case body;
A metal filter member that is held by the metal cylinder, surrounds the electrode and the quartz crystal resonator connected thereto, forms a measurement chamber, and communicates with the measurement chamber and the gas atmosphere;
Further comprising
The electrode includes first and second electrodes connected to the first and second electrode patterns, and third and fourth electrodes connected to the heating resistor pattern. Crystal type gas pressure gauge. In any one of Claims 1 thru | or 3,
The tuning fork type crystal resonator is a temperature-sensitive resonator whose oscillation frequency changes linearly with respect to temperature,
Frequency measuring means for measuring the oscillation frequency;
A heater power control circuit for controlling the heater to a constant temperature based on an output from the frequency measuring means;
A crystal type gas pressure gauge further comprising: In any one of Claims 1 thru | or 4,
A current-voltage converter connected to one end of the tuning-fork crystal resonator and converting a current flowing through the tuning-fork crystal resonator into a voltage;
An attenuator connected to the other end of the tuning fork crystal unit;
A first full-wave rectifier that rectifies current from the attenuator;
A comparator that compares a voltage from the first full-wave rectifier with a reference voltage;
A voltage controlled attenuator that further attenuates the output of the attenuator based on the output voltage of the comparator;
A second full-wave rectifier that rectifies the summed output of the voltage controlled attenuator and the current-voltage converter;
A crystal type gas pressure gauge further comprising:   6. A vacuum apparatus, wherein the quartz gas pressure gauge according to claim 1 measures a pressure in a region set to atmosphere-vacuum.

Images