Probe for inspection

Abstract

To reduce an error in capacity measurement.SOLUTION: A probe 1 for inspection includes: a coaxial switch 11 that selectively connects, to an LCR meter, one of a terminal Xc connected to a first electrode plate of a sensor chip forming a pressure sensitive capacity and a terminal Rc connected to a second electrode plate of a sensor chip forming a reference capacity among terminals provided on a diaphragm vacuum gage 200 and terminates the terminal which is not selected between the terminals Xc and Rc; and a coaxial switch 10 that selectively connects, to the LCR meter, one of a terminal Xd for pressure sensitive capacity and a terminal Rd for reference capacity when the terminals Xd and Rd connected to a third electrode plate provided on a diaphragm of the diaphragm vacuum gage 200 so as to face the first and second electrode plates use the diaphragm vacuum gage 200 independently provided with the pressure sensitive capacity and the reference capacity as an object to be measured.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a test probe used for capacitance testing in the testing process of a diaphragm vacuum gauge. [Background technology]

[0002] A capacitance detection type diaphragm vacuum gauge measures pressure by detecting the displacement of a diaphragm from a change in capacitance. Figure 7 is a cross-sectional view showing a schematic configuration of a main part of a sensor chip used in a diaphragm vacuum gauge. A recess is formed in the center of a base 101 of a sensor chip 100. A diaphragm 102 configured to be deformable according to pressure P is bonded to the surface of the base 101 on which the recess is formed. The recess of the base 101 forms a capacitance chamber 103 together with the diaphragm 102.

[0003] A fixed electrode plate 104 (first electrode plate) is formed on the surface of the base 101 facing the capacitance chamber 103, and a movable electrode plate 105 (third electrode plate) is formed on the surface of the diaphragm 102 facing the capacitance chamber 103 so as to face the fixed electrode plate 104. In this way, the fixed electrode plate 104 and the movable electrode plate 105 are arranged to face each other across a gap. When the diaphragm 102 is deflected by receiving pressure P, the distance between the movable electrode plate 105 and the fixed electrode plate 104 changes, and the electrostatic capacitance (pressure-sensitive capacitance) between the movable electrode plate 105 and the fixed electrode plate 104 changes. The pressure P received by the diaphragm 102 can be detected from the change in pressure-sensitive capacitance.

[0004] Furthermore, a fixed electrode plate 106 (second electrode plate) is formed on the surface of the base 101 on the capacitance chamber 103 side outside the fixed electrode plate 104. Even if the diaphragm 102 is bent by pressure P, the edge of the diaphragm 102 is hardly deformed, so that the electrostatic capacitance (reference capacitance) between the movable electrode plate 105 and the fixed electrode plate 106 at the edge of the diaphragm 102 is unlikely to change. The reference capacitance is provided to eliminate measurement errors due to temperature changes inside and outside the sensor, humidity changes inside the capacitance chamber 103, etc.

[0005] The housing of the diaphragm vacuum gauge that houses the sensor chip 100 is provided with terminals that are electrically connected to the electrode plates 104 to 106. For example, as shown in Fig. 8, some diaphragm vacuum gauges are provided with a total of three terminals: a positive terminal Xd connected to the movable electrode plate 105, a negative terminal Xc connected to the fixed electrode plate 104, and a negative terminal Rc connected to the fixed electrode plate 106. The appearance of the housing 107 of this product is shown in Fig. 9.

[0006] 10, another product is provided with a total of four terminals: two positive terminals Xd, Rd connected to movable electrode plate 105, a negative terminal Xc connected to fixed electrode plate 104, and a negative terminal Rc connected to fixed electrode plate 106. The appearance of housing 107 of this product is shown in FIG.

[0007] Conventionally, the manufacturing process of a diaphragm vacuum gauge includes a process for testing capacitance. In this testing process, a probe is placed on the terminals of the diaphragm vacuum gauge to measure two types of capacitance using an LCR meter: the capacitance between the movable electrode plate 105 and the fixed electrode plate 104, and the capacitance between the movable electrode plate 105 and the fixed electrode plate 106. The probes used in the testing process have a fixed terminal pitch on the probe side. However, there are some products in which the pitch between terminals Xd and Xc and the pitch between terminals Xd and Rc are different in the diaphragm vacuum gauges configured as shown in Figures 8 and 9, so there are cases in which the two types of capacitance cannot be measured with the same probe.

[0008] In addition, in the process of testing the capacitance between the movable electrode plate 105 and the fixed electrode plate 104, electric field lines E are generated throughout the entire movable electrode plate 105, which has a larger area, inside the sensor chip, as shown in Figures 12 and 13, and flow into the fixed electrode plate 104, which has a smaller area. The designer of the diaphragm vacuum gauge designs the capacitance using the area of ​​the fixed electrode plate 104, which has a smaller area. However, as shown in Figures 12 and 13, when the electric field lines E generated throughout the entire movable electrode plate 105 flow into the fixed electrode plate 104, the measured capacitance becomes a value obtained by adding parasitic capacitance to the capacitance between the movable electrode plate 105 and the fixed electrode plate 104, and an error occurs in the capacitance measurement. Such a measurement error also occurs when measuring the capacitance between the movable electrode plate 105 and the fixed electrode plate 106.

[0009] Conventionally, as a technology for reducing the influence of parasitic capacitance in a capacitance detection circuit, the technology disclosed in Patent Document 1 is known. However, although the technology disclosed in Patent Document 1 can reduce the parasitic capacitance between the electrode on the input side of the capacitance and ground, and the parasitic capacitance between the electrode on the output side of the capacitance and ground, it does not realize a technology for reducing the parasitic capacitance generated between the electrodes. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2013-160707 A Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention has been made to solve the above-mentioned problems, and has an object to provide an inspection probe that can reduce the parasitic capacitance that occurs between the electrode plates of a diaphragm vacuum gauge when measuring capacitance, thereby reducing errors in capacitance measurement. [Means for solving the problem]

[0012] The present invention provides a test probe for testing a pressure-sensitive capacitance and a reference capacitance of a diaphragm vacuum gauge having a sensor chip that forms a pressure-sensitive capacitance that changes in response to a displacement of a diaphragm due to pressure and a reference capacitance for correcting the pressure-sensitive capacitance, the test probe being configured to selectively connect one of terminals provided on the diaphragm vacuum gauge, a first terminal connected to a first electrode plate of the sensor chip that forms the pressure-sensitive capacitance, and a second terminal connected to a second electrode plate of the sensor chip that forms the reference capacitance, to an LCR meter, and terminate the terminal not selected from the first terminal and the second terminal. and a second switch configured to selectively connect the third terminal for the pressure sensitive capacitance and the third terminal for the reference capacitance to the LCR meter when a first diaphragm vacuum gauge provided in common for the pressure sensitive capacitance and the reference capacitance is to be measured, the third terminal being connected to a third electrode plate provided on the diaphragm facing the first and second electrode plates.

[0013] Moreover, one configuration example of the inspection probe of the present invention further includes a jig having a terminal corresponding to either one of the first diaphragm vacuum gauge and the second diaphragm vacuum gauge, and configured to be attachable to a tip of the inspection probe, the inspection probe further including a first connector for connection with the first terminal, a second connector for connection with the second terminal, a third connector for connection with the third terminal of the first diaphragm vacuum gauge or a third terminal for the pressure sensitive capacitance of the second diaphragm vacuum gauge, and a fourth connector for connection with the third terminal for the reference capacitance of the second diaphragm vacuum gauge, and the jig corresponding to the first diaphragm vacuum gauge includes a fourth terminal in contact with the first terminal, a fifth terminal in contact with the second terminal, a sixth terminal in contact with the third terminal, and a sixth terminal in contact with the fourth terminal and the first terminal. the jig corresponding to the second diaphragm vacuum gauge comprises a fourth terminal in contact with the first terminal, a fifth terminal in contact with the second terminal, a sixth terminal in contact with the third terminal for the pressure sensitive capacitor, a seventh terminal in contact with the third terminal for the reference capacitor, a fifth connector for connecting the fourth terminal and the first connector, a sixth connector for connecting the fifth terminal and the second connector, a seventh connector for connecting the sixth terminal and the third connector, and an eighth connector for connecting the seventh terminal and the fourth connector.

[0014] In one configuration example of the inspection probe of the present invention, the first switch is composed of a first terminating resistor having one end connected to ground, a second terminating resistor having one end connected to ground, a first common terminal connected to the LCR meter, a first contact terminal, and a second contact terminal, and the first common terminal is composed of a first switch selectively connected to either the first contact terminal or the second contact terminal, and a second common terminal, a third contact terminal, and a fourth contact terminal connected to the first connector. the third contact terminal is connected to a first contact terminal of the first switch, the fourth contact terminal is connected to the other end of the first termination resistor, the second common terminal is selectively connected to either the third contact terminal or the fourth contact terminal, and the third common terminal is connected to the second connector, and a fifth contact terminal and a sixth contact terminal, the fifth contact terminal is connected to the other end of the second termination resistor, and the sixth contact terminal is connected to the second contact terminal of the first switch. the second switch is composed of a fourth common terminal connected to the LCR meter, a seventh contact terminal and an eighth contact terminal, the seventh contact terminal is connected to the third connector, the eighth contact terminal is connected to the fourth connector, and the fourth common terminal is composed of a fourth switch configured to selectively connect to either the fifth contact terminal or the sixth contact terminal; the second switch is composed of a fourth common terminal connected to the LCR meter, a seventh contact terminal and an eighth contact terminal, the seventh contact terminal is connected to the third connector, the eighth contact terminal is connected to the fourth connector, and the fourth common terminal is composed of a fourth switch configured to selectively connect to either the fifth contact terminal or the sixth contact terminal. the first to third switches select the first, third and fifth contact terminals when testing the pressure sensitive capacitance, and select the second, fourth and sixth contact terminals when testing the reference capacitances of the first and second diaphragm vacuum gauges; and the fourth switch selects the seventh contact terminal when testing the pressure sensitive capacitance and the reference capacitance of the first diaphragm vacuum gauge, and selects the eighth contact terminal when testing the reference capacitance of the second diaphragm vacuum gauge. Effect of the Invention

[0015] According to the present invention, by providing a first switch and a second switch, it is possible to measure the pressure-sensitive capacitance and the reference capacitance by simply switching between the first and second switches without repositioning the test probe. In the present invention, by terminating the terminal that is not selected from the first and second terminals, it is possible to reduce the parasitic capacitance that occurs between the electrode plates of the diaphragm vacuum gauge during capacitance measurement, and thus to reduce errors in capacitance measurement. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a configuration of an inspection probe according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a configuration when the jig of the inspection probe according to the embodiment of the present invention is replaced. [Diagram 3] FIG. 3 is a diagram showing a state in which a coaxial switch of the inspection probe according to the embodiment of the present invention is switched. [Figure 4] FIG. 4 is a diagram showing a state in which a coaxial switch of the inspection probe according to the embodiment of the present invention is switched. [Diagram 5] FIG. 5 is a diagram for explaining the effect of this embodiment. [Figure 6] FIG. 6 is a diagram for explaining the effect of this embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing a schematic configuration of a main part of a sensor chip used in a diaphragm vacuum gauge. [Figure 8] FIG. 8 is a diagram showing an example of connection between the electrode plates and terminals of a diaphragm vacuum gauge. [Figure 9] FIG. 9 is a diagram showing the appearance of the housing of the diaphragm vacuum gauge of FIG. [Figure 10] FIG. 10 is a diagram showing another example of the connection between the electrode plate and the terminal of the diaphragm vacuum gauge. [Figure 11] FIG. 11 is a diagram showing the appearance of the housing of the diaphragm vacuum gauge of FIG. [Figure 12] FIG. 12 is a diagram for explaining the problem in the conventional technology. [Figure 13] FIG. 13 is a diagram for explaining the problem in the conventional technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of an inspection probe according to an embodiment of the present invention. The inspection probe 1 includes a coaxial switch 10 (second switch), a coaxial switch 11 (first switch), a housing 12 that houses the coaxial switches 10 and 11, and connectors 13-Xd, 13-Rd, 13-Xc, and 13-Rc provided at the tip of the housing 12 on the side of the diaphragm vacuum gauge 200 to be measured.

[0018] The coaxial switch 10 includes a switch SW1 (fourth switch) including a contact terminal T7 (seventh contact terminal) connected to a connector 13-Xd (third connector), a contact terminal T8 (eighth contact terminal) connected to a connector 13-Rd (fourth connector), and a common terminal TC4 (fourth common terminal) connected to shielded cables 3-Hcur and 3-Hpot for connection to an LCR meter (not shown). Either the contact terminal T7 or the contact terminal T8 is selectively connected to the common terminal TC4.

[0019] The coaxial switch 11 includes termination resistors R1 and R2 each having one end connected to ground, a common terminal TC1 (first common terminal) connected to shielded cables 3-Lcur and 3-Lpot for connection to an LCR meter, a switch SW2 (first switch) consisting of a first contact terminal T1 and a second contact terminal T2, either of which is selectively connected to the common terminal TC1, a common terminal TC2 (second common terminal) connected to a connector 13-Xc (first connector), a contact terminal T3 (third contact terminal) connected to the other end of the termination resistor R1, and a contact terminal T4 (third contact terminal) connected to the first contact terminal T1 of the switch SW2. the second contact terminal T2 of the switch SW2, and a switch SW3 (second switch) to which the common terminal TC2 and either the third contact terminal T3 or the fourth contact terminal T4 are selectively connected; a common terminal TC3 (third common terminal) connected to the connector 13-Rc (second connector), a contact terminal T5 (fifth contact terminal) connected to the second contact terminal T2 of the switch SW2, and a contact terminal T6 (sixth contact terminal) connected to the other end of the termination resistor R2; and a switch SW4 (third switch) to which the common terminal TC3 and either the fifth contact terminal T5 or the sixth contact terminal T6 are selectively connected.

[0020] The switches SW1 to SW4 may be made of electrically switchable elements such as relays or semiconductors, or may be manually switchable switches. The shielded cables 3-Hcur, 3-Hpot, 3-Lcur, and 3-Lpot are connected to the terminals Hcur, Hpot, Lcur, and Lpot of the LCR meter, respectively.

[0021] A jig 2 for connection to the diaphragm vacuum gauge 200 is attached to the tip of the housing 12 on the diaphragm vacuum gauge 200 side. The jig 2 includes a housing 20, connectors 21-Xd (seventh connector), 21-Rd (eighth connector), 21-Xc (fifth connector), and 21-Rc (sixth connector) provided on the surface of the housing 20 on the inspection probe 1 side, and terminals 22-Xd (sixth terminal), 22-Rd (seventh terminal), 22-Xc (fourth terminal), and 22-Rc (fifth terminal) provided on the surface of the housing 20 on the diaphragm vacuum gauge 200 side and connected to the connectors 21-Xd, 21-Rd, 21-Xc, and 21-Rc, respectively.

[0022] The jig 2 shown in Fig. 1 is for a diaphragm vacuum gauge 200 (second diaphragm vacuum gauge) in which four terminals Xd (third terminal for pressure-sensitive capacitance), Rd (third terminal for reference capacitance), Xc (first terminal), and Rc (second terminal) are provided on the housing as shown in Fig. 10 and Fig. 11. In the diaphragm vacuum gauge 200, the terminals connected to the movable electrode plate 105 are provided independently for the pressure-sensitive capacitance and the reference capacitance.

[0023] The jig 2 can be attached to the inspection probe 1 by fitting the connectors 21-Xd, 21-Rd, 21-Xc, and 21-Rc with the connectors 13-Xd, 13-Rd, 13-Xc, and 13-Rc of the inspection probe 1, respectively. The terminals 22-Xd, 22-Rd, 22-Xc, and 22-Rc of the jig 2 are arranged so as to face the terminals Xd, Rd, Xc, and Rc of the diaphragm vacuum gauge 200 when the jig 2 and the diaphragm vacuum gauge 200 are faced to each other.

[0024] On the other hand, in the case of a diaphragm vacuum gauge 200a (first diaphragm vacuum gauge) in which three terminals Xd (third terminal), Xc (first terminal), and Rc (second terminal) are provided on the housing as shown in Figures 8 and 9, the jig 2a shown in Figure 2 is used. In the diaphragm vacuum gauge 200a, the terminal Xd connected to the movable electrode plate 105 is shared by the pressure sensitive capacitor and the reference capacitor.

[0025] The jig 2a includes a housing 20, connectors 21-Xd (seventh connector), 21-Xc (fifth connector), and 21-Rc (sixth connector) provided on the surface of the housing 20 on the inspection probe 1 side, and terminals 22-Xd (sixth terminal), 22-Xc (fourth terminal), and 22-Rc (fifth terminal) provided on the surface of the housing 20 on the diaphragm vacuum gauge 200a side and connected to the connectors 21-Xd, 21-Xc, and 21-Rc, respectively.

[0026] The jig 2a can be attached to the inspection probe 1 by fitting the connectors 21-Xd, 21-Xc, and 21-Rc with the connectors 13-Xd, 13-Xc, and 13-Rc of the inspection probe 1, respectively. The terminals 22-Xd, 22-Xc, and 22-Rc of the jig 2a are arranged to face the terminals Xd, Xc, and Rc of the diaphragm vacuum gauge 200a when the jig 2a and the diaphragm vacuum gauge 200a are faced to each other. The configuration of the sensor chip used in the diaphragm vacuum gauges 200 and 200a is as shown in FIG.

[0027] As described above, in this embodiment, by changing the jig according to the type of diaphragm vacuum gauge to be measured, one inspection probe 1 can be used to accommodate multiple types of diaphragm vacuum gauges with different terminal arrangements.

[0028] Next, a capacitance inspection method using the inspection probe 1 of this embodiment will be described. An operator who inspects a diaphragm vacuum gauge brings the terminals at the tip of the jig 2 or jig 2a into contact with the terminals of the diaphragm vacuum gauge to be measured. As described above, in the case of the diaphragm vacuum gauge 200a having three terminals Xd, Xc, and Rc, the jig 2a is used, and the terminals 22-Xd, 22-Xc, and 22-Rc of the jig 2a are brought into contact with the terminals Xd, Xc, and Rc of the diaphragm vacuum gauge 200a. In addition, in the case of the diaphragm vacuum gauge 200 having four terminals Xd, Rd, Xc, and Rc, the jig 2 is used, and the terminals 22-Xd, 22-Rd, 22-Xc, and 22-Rc of the jig 2 are brought into contact with the terminals Xd, Rd, Xc, and Rc of the diaphragm vacuum gauge 200.

[0029] When inspecting the pressure-sensitive capacitance between terminals Xd and Xc of diaphragm vacuum gauge 200, 200a (the capacitance between movable electrode plate 105 and fixed electrode plate 104), an operator selects the seventh contact terminal T7 of switch SW1, the first contact terminal T1 of switch SW2, the fourth contact terminal T4 of switch SW3, and the sixth contact terminal T6 of switch SW4, as shown in Figures 1 and 2. In this case, terminals Hcur, Hpot of the LCR meter are connected to terminal Xd of diaphragm vacuum gauge 200, 200a via shielded cables 3-Hcur, 3-Hpot, switch SW1, connector 13-Xd of inspection probe 1, connector 21-Xd of fixture 2, 2a, and terminal 22-Xd of fixture 2, 2a.

[0030] Furthermore, the terminals Lcur and Lpot of the LCR meter are connected to the terminal Xc of the diaphragm vacuum gauge 200, 200a via the shielded cables 3-Lcur and 3-Lpot, the switches SW2 and SW3, the connector 13-Xc of the inspection probe 1, the connector 21-Xc of the fixtures 2 and 2a, and the terminal 22-Xc of the fixtures 2 and 2a. At this time, the terminal Rc of the diaphragm vacuum gauge 200, 200a is connected to the terminating resistor R2 via the terminal 22-Rc of the fixtures 2 and 2a, the connector 21-Rc of the fixtures 2 and 2a, the connector 13-Rc of the inspection probe 1, and the switch SW4, and is terminated. The LCR meter measures the pressure-sensitive capacitance between the terminals Xd and Xc by the well-known four-terminal method.

[0031] On the other hand, when inspecting the reference capacitance between terminals Rd and Rc of diaphragm vacuum gauge 200 (the capacitance between movable electrode plate 105 and fixed electrode plate 106), the operator selects the eighth contact terminal T8 of switch SW1, the second contact terminal T2 of switch SW2, the third contact terminal T3 of switch SW3, and the fifth contact terminal T5 of switch SW4, as shown in Fig. 3. In this case, terminals Hcur and Hpot of the LCR meter are connected to terminal Rd of diaphragm vacuum gauge 200 via shielded cables 3-Hcur and 3-Hpot, switch SW1, connector 13-Rd of inspection probe 1, connector 21-Rd of jig 2, and terminal 22-Rd of jig 2.

[0032] Furthermore, terminals Lcur, Lpot of the LCR meter are connected to terminal Rc of diaphragm vacuum gauge 200 via shielded cables 3-Lcur, 3-Lpot, switches SW2, SW4, connector 13-Rc of inspection probe 1, connector 21-Rc of jig 2, and terminal 22-Rc of jig 2. At this time, terminal Xc of diaphragm vacuum gauge 200 is connected to termination resistor R1 via terminal 22-Xc of jig 2, connector 21-Xc of jig 2, connector 13-Xc of inspection probe 1, and switch SW3, and is terminated. The LCR meter measures the reference capacitance between terminals Rd and Rc using the four-terminal method.

[0033] Furthermore, when inspecting the reference capacitance (the capacitance between the movable electrode plate 105 and the fixed electrode plate 106) between terminals Xd and Rc of the diaphragm vacuum gauge 200a, the operator selects the seventh contact terminal T7 of the switch SW1, the second contact terminal T2 of the switch SW2, the third contact terminal T3 of the switch SW3, and the fifth contact terminal T5 of the switch SW4, as shown in Fig. 4. In this case, the terminals Hcur and Hpot of the LCR meter are connected to the terminal Xd of the diaphragm vacuum gauge 200a via the shielded cables 3-Hcur and 3-Hpot, the switch SW1, the connector 13-Xd of the inspection probe 1, the connector 21-Xd of the jig 2a, and the terminal 22-Xd of the jig 2a.

[0034] Furthermore, the terminals Lcur and Lpot of the LCR meter are connected to the terminal Rc of the diaphragm vacuum gauge 200a via the shielded cables 3-Lcur and 3-Lpot, the switches SW2 and SW4, the connector 13-Rc of the inspection probe 1, the connector 21-Rc of the jig 2a, and the terminal 22-Rc of the jig 2a. At this time, the terminal Xc of the diaphragm vacuum gauge 200a is connected to the terminating resistor R1 via the terminal 22-Xc of the jig 2a, the connector 21-Xc of the jig 2a, the connector 13-Xc of the inspection probe 1, and the switch SW3, and is terminated. The LCR meter measures the reference capacitance between the terminals Xd and Rc by the four-terminal method.

[0035] As described above, if relays or semiconductors are used as the switches SW1 to SW4, the switches SW1 to SW4 can be electrically switched by a control signal. Moreover, the switches SW1 to SW4 may be switches that can be manually switched by an operator.

[0036] As described above, in this embodiment, the pressure-sensitive capacitance (capacitance between the movable electrode plate 105 and the fixed electrode plate 104) between terminals Xd and Xc and the reference capacitance (capacitance between the movable electrode plate 105 and the fixed electrode plate 106) between terminals Xd (or Rd) and Rc can be measured simply by switching the coaxial switches 10, 11 without repositioning the inspection probe 1.

[0037] 5 and 6, when measuring the capacitance between terminals Xd and Xc, the electric field lines E generated in the portion of movable electrode plate 105 facing fixed electrode plate 106 flow into fixed electrode plate 106. As a result, in this embodiment, the parasitic capacitance generated between movable electrode plate 105 and fixed electrode plate 106 is not added to the pressure-sensitive capacitance between movable electrode plate 105 and fixed electrode plate 104. Therefore, in this embodiment, the error in capacitance measurement can be reduced.

[0038] Similarly, in this embodiment, when measuring the capacitance between terminals Xd (or Rd) and Rc, terminal Xc is terminated, so that electric field lines E generated in a portion of movable electrode plate 105 facing fixed electrode plate 104 flow into fixed electrode plate 104. As a result, in this embodiment, the parasitic capacitance generated between movable electrode plate 105 and fixed electrode plate 104 is not added to the reference capacitance between movable electrode plate 105 and fixed electrode plate 106. [Industrial Applicability]

[0039] The present invention can be applied to a technique for testing the capacitance of a diaphragm vacuum gauge. [Explanation of symbols]

[0040] 1...inspection probe, 2, 2a...jig, 3-Hcur, 3-Hpot, 3-Lcur, 3-Lpot...shielded cable, 10, 11...coaxial switch, 12...housing, 13-Xd, 13-Rd, 13-Xc, 13-Rc, 21-Xd, 21-Rd, 21-Xc, 21-Rc...connectors, 22-Xd, 22-Rd, 22-Xc, 22-Rc, Xd, Rd, Xc, Rc...terminals, SW1 to SW4...switches, R1, R2...termination resistors.

Claims

1. 1. A test probe for testing a pressure-sensitive capacitance and a reference capacitance of a diaphragm vacuum gauge having a sensor chip that constitutes a pressure-sensitive capacitance that changes in response to a displacement of a diaphragm due to pressure and a reference capacitance for correcting the pressure-sensitive capacitance, comprising: a first switch configured to selectively connect one of terminals provided on the diaphragm vacuum gauge, a first terminal connected to a first electrode plate of the sensor chip forming the pressure sensitive capacitance, and a second terminal connected to a second electrode plate of the sensor chip forming the reference capacitance, to an LCR meter, and to terminate the terminal not selected from the first terminal and the second terminal; a third terminal connected to a third electrode plate provided on the diaphragm so as to face the first and second electrode plates, the third terminal being connected to the LCR meter when a first diaphragm vacuum gauge provided in common for the pressure sensitive capacitance and the reference capacitance is to be measured, and a second switch configured to selectively connect either the third terminal for the pressure sensitive capacitance or the third terminal for the reference capacitance to an LCR meter when a second diaphragm vacuum gauge provided independently for the pressure sensitive capacitance and the reference capacitance is to be measured.

2. 2. The inspection probe according to claim 1, a jig provided with a terminal corresponding to either one of the first diaphragm vacuum gauge and the second diaphragm vacuum gauge and configured to be attachable to a tip of an inspection probe; the inspection probe further comprises a first connector for connection with the first terminal, a second connector for connection with the second terminal, a third connector for connection with the third terminal of the first diaphragm vacuum gauge or a third terminal for the pressure sensitive capacitance of the second diaphragm vacuum gauge, and a fourth connector for connection with a third terminal for the reference capacitance of the second diaphragm vacuum gauge; the jig corresponding to the first diaphragm vacuum gauge includes a fourth terminal in contact with the first terminal, a fifth terminal in contact with the second terminal, a sixth terminal in contact with the third terminal, a fifth connector for connecting the fourth terminal and the first connector, a sixth connector for connecting the fifth terminal and the second connector, and a seventh connector for connecting the sixth terminal and the third connector; the jig corresponding to the second diaphragm vacuum gauge comprises a fourth terminal in contact with the first terminal, a fifth terminal in contact with the second terminal, a sixth terminal in contact with the third terminal for the pressure sensitive capacitor, a seventh terminal in contact with the third terminal for the reference capacitor, a fifth connector for connecting the fourth terminal and the first connector, a sixth connector for connecting the fifth terminal and the second connector, a seventh connector for connecting the sixth terminal and the third connector, and an eighth connector for connecting the seventh terminal and the fourth connector.

3. 3. The inspection probe according to claim 2, The first switch is a first termination resistor having one end connected to ground; a second termination resistor having one end connected to ground; a first switch including a first common terminal connected to the LCR meter, a first contact terminal, and a second contact terminal, the first common terminal being selectively connected to either the first contact terminal or the second contact terminal; a second switch including a second common terminal connected to the first connector, a third contact terminal, and a fourth contact terminal, the third contact terminal being connected to a first contact terminal of the first switch, the fourth contact terminal being connected to the other end of the first termination resistor, and the second common terminal being selectively connected to either the third contact terminal or the fourth contact terminal; a third switch including a third common terminal connected to the second connector, a fifth contact terminal, and a sixth contact terminal, the fifth contact terminal being connected to the other end of the second termination resistor, the sixth contact terminal being connected to a second contact terminal of the first switch, and the third common terminal being selectively connected to either the fifth contact terminal or the sixth contact terminal; The second switch is a fourth switch including a fourth common terminal connected to the LCR meter, a seventh contact terminal, and an eighth contact terminal, the seventh contact terminal being connected to the third connector, the eighth contact terminal being connected to the fourth connector, and the fourth common terminal being selectively connected to either the fifth contact terminal or the sixth contact terminal; the first to third switches select the first, third and fifth contact terminals when testing the pressure sensitive capacitance, and select the second, fourth and sixth contact terminals when testing the reference capacitances of the first and second diaphragm vacuum gauges; the fourth switch selects the seventh contact terminal when testing the pressure sensitive capacitance and the reference capacitance of the first diaphragm vacuum gauge, and selects the eighth contact terminal when testing the reference capacitance of the second diaphragm vacuum gauge.

Images