JPS61245218A - Pressure controller - Google Patents

Abstract

PURPOSE:To attain the optional pressure control according to the absolute pressure and the gauge pressure by operating a control mode selecting means to supply the output of a conversion means or the output of the 1st pressure detecting means. CONSTITUTION:A pressure controller is provided with a pressure sensor 2 within a sealed container 1, an atmospheric pressure detecting sensor 3, a switch circuit 5 which switches the control mode by the mode selection signal MS supplied from a pressure control mode selection switch 6 via a mode selection circuit 7, a control circuit 27 which controls the actions of each part of a pressure control mechanism 28 by the signal Vc obtained by comparing the detection signal Vs and the voltage Va set by a pressure setting switch 24, etc. Thus the selection is carried out between the pressure control based on the vacuum detected by the sensor 2 and the gauge pressure control based on the atmospheric pressure with operation of the switch 6. This attains the optional pressure control.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a pressure controller that controls gas pressure within, for example, a closed container.

``Prior Art'' As is well known, a semiconductor pressure sensor has four P-type detection resistors formed on a diaphragm made of, for example, n-type silicon by diffusion or ion implantation technology, and these detection resistors are bridge-connected. The detection voltage corresponding to the pressure to be measured is obtained. There are two types of semiconductor pressure sensors of this type: absolute pressure sensors and gauge pressure (relative pressure) sensors. In other words, a depression is formed on the back side of the diaphragm by etching, and by bonding this diaphragm to a plate-shaped base in a vacuum, the depression becomes a vacuum chamber, thereby forming a vacuum-based absolute pressure sensor. be done. On the other hand, by forming an atmospheric pressure introduction hole in the base and introducing atmospheric pressure into the recess of the diaphragm, the gauge pressure type detects the pressure inside the recess, that is, the relative pressure based on the ever-changing atmospheric pressure. A pressure sensor is configured.

"Problems to be Solved by the Invention" Conventionally, pressure controllers for controlling the gas pressure in a closed container have not been supplied with dedicated pressure controllers that are compatible with the above-mentioned absolute pressure type pressure sensor and gauge pressure type pressure sensor. Ta. Therefore, different types of pressure sensors must be installed depending on whether pressure control is required based on absolute pressure or pressure control based on gauge pressure. Since dedicated pressure controllers must be installed for each type of pressure sensor, the combination of these pressure sensors and pressure controllers is complicated. Furthermore, for example, when changing from pressure control based on absolute pressure to pressure control based on gauge pressure, there is also the complexity of having to replace the pressure sensor and pressure controller.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a pressure controller that can arbitrarily select between pressure control based on absolute pressure and pressure control based on gauge pressure.

"Means for Solving the Problems" The present invention includes a first pressure detection means inside the sealed container that detects pressure based on vacuum, and a first pressure detection means outside the sealed container that detects atmospheric pressure based on vacuum. a second pressure detection means; a conversion means for removing and outputting a common component between the output of the first pressure detection means and the output of the second pressure detection means; control mode selection means for selectively selecting either a first control mode for controlling pressure and a second control mode for controlling pressure in the closed container based on atmospheric pressure; a switching means that switches and outputs either the output of the converting means or the output of the first pressure detecting means based on the output; a pressure adjustment mechanism that pressurizes gas into and discharges gas into and out of the closed container; The method further comprises: a setting means for setting a desired pressure in the closed container; and a control means for controlling the pressure adjustment mechanism so that the output of the switching means corresponds to the output of the setting means. It is a feature.

"Operation" By operating the control mode selection means, either the output of the conversion means or the output of the first pressure detection means is supplied to the control means, so that the pressure in the closed container is controlled based on the vacuum. A first control mode in which the pressure inside the closed container is controlled based on atmospheric pressure and a second control mode in which the pressure inside the closed container is controlled can be arbitrarily selected.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, 1 is a sealed container in which air is sealed, 2 is a pressure sensor for detecting the pressure inside the container that outputs a detection signal Sa corresponding to the pressure of the air inside the sealed container 1, and 3 is a pressure sensor outside the sealed container l. This is a pressure sensor for detecting atmospheric pressure that outputs a detection signal sb corresponding to atmospheric pressure. These pressure sensors 2 and 3 are both constituted by vacuum-based absolute pressure type semiconductor pressure sensors, and are each supplied with a sensor drive power source (constant voltage Vr or constant current Ir) from a sensor drive circuit 4. Reference numeral 5 denotes a pressure control mode switching circuit, which is selected by a pressure control mode selection switch 6 and is switched to a mode selection circuit 7.
A state in which the detection signal Sa supplied from the pressure sensor 2 is directly output as the detection signal Sc based on the mode selection signal MS supplied via the It switches to one of the states in which a signal obtained by removing the in-phase component from the supplied detection signal sb is output as the detection signal SC. Here, the pressure sensor 2.3 and the pressure control mode switching circuit 5 have a circuit configuration as shown in FIG. Second
In the figure, the pressure sensor 2 includes a bridge circuit 2A formed by bridge-connecting gauge resistors lOa to 10d formed on a diaphragm, a constant current circuit 2B that supplies a constant current to the bridge circuit 2A, and an output of the bridge circuit 2A. It is comprised of a differential amplifier 2G that removes and amplifies the common mode component from the signals obtained from the terminals 11a and itb, respectively. The constant current circuit 2B includes an operational amplifier (hereinafter referred to as an OP amplifier) 12 to which a constant voltage Vr is supplied, and a transistor I3.
and resistance 14. It consists of 15. Further, the differential amplifier 2c includes OP amplifiers 16, 17, and 18, a semi-fixed resistor R3 for gain adjustment, and resistors R1 to R9. On the other hand, like the pressure sensor 2 described above, the pressure sensor 3 includes a bridge circuit 3A, a constant current circuit 3B, and a differential amplifier 3C. Furthermore, the pressure control mode switching circuit 5 includes a differential amplifier (same configuration as the differential amplifiers 2G and 3G) 5C that removes common-mode components from the detection signals Sa and sb supplied from the pressure sensors 2 and 3, respectively, and the mode selection circuit described above. It is composed of analog switches 19 and 20 that are switched based on the signal MS, and when the mode selection signal MS is at "H" level, the analog switch 1 is switched.
9 is in the on state, the analog switch 20 is in the off state, and the detection signal Sa supplied from the pressure sensor 2 is directly output as the detection signal Sc, and the mode selection signal MS is in the "L" state.
” level, the analog switch 20 is in the on state, the analog switch I9 is in the off state, and the differential amplifier 5C
The output signal is outputted as the detection signal Sc. The detection signal Sc output from the pressure control mode switching circuit 5 is amplified by the amplifier circuit 22 and supplied to one input terminal of the comparison circuit 23 as the detection voltage Vs.

The set value set in the pressure setting switch 24 is supplied to the other input terminal of the comparison circuit 23 as a set voltage Va via a pressure setting circuit 25 and a set pressure voltage generation circuit 26. The comparison circuit 23 compares the detected voltage Vs with respect to the set voltage Va, and sends the comparison signal Vc to the control circuit 2.
Supply to 7. The control circuit 27 controls the operation of each part of the pressure adjustment mechanism 28, which will be described later, based on the comparison signal Vc, that is, the press-in and discharge operations of air into the closed container l, and these press-in and discharge operations are performed by the display drive circuit. 3
0 on the display 31. The pressure adjustment mechanism 28 includes a high-pressure cylinder 33 filled with compressed air of approximately IO atmospheric pressure, and pressurizes the compressed air supplied from the high-pressure cylinder 33 into a closed container l, while supplying the compressed air in the closed container 1 to the container l. A press-in/discharge mechanism 34 that discharges the air to the outside, a leak valve 35 that is opened when finely adjusting the pressure inside the closed container l and discharges compressed air to the outside of the container in small amounts, and a leak valve 35 that sucks the air inside the closed container l. A rotary pump 36 that discharges the water to the outside
Under the control of the control circuit 27, these are a press-in/discharge mechanism drive circuit 37 and a leak valve drive circuit 3.
8 and a rotary pump drive circuit 39, respectively.

In the above configuration, when the pressure control mode selection switch 6 is operated to select the absolute pressure control mode in which the pressure in the closed container l is controlled based on absolute pressure, the mode selection circuit 7 selects an "H" level mode. Signal MS is supplied to pressure control mode switching circuit 5. As a result, the analog switch I9 in the pressure control mode switching circuit 5 is turned on, the analog switch 20 is turned off, and the detection signal Sa supplied from the pressure sensor 2 is directly supplied to the amplifier circuit 22 as the detection signal Sc. Next, the detection signal Sc is amplified by the amplifier circuit 22 and sent to the comparison circuit 23 as the detection voltage Vs.
The comparison circuit 23 compares the detected voltage VS with the set voltage Va, and the comparison signal Vc is supplied to the control circuit 27. Then, the control circuit 27 controls the operation of each part of the pressure adjustment mechanism 28 based on this comparison signal Vc. That is, pressure sensor 2
The operation of pressurizing and discharging air into and out of the closed container 1 is controlled so that the pressure inside the closed container 1 based on the vacuum detected by 1 matches the pressure set in the pressure setting switch 24. Thereby, the pressure inside the closed container I is controlled based on the vacuum.

Next, when the pressure control mode selection switch 6 is operated to select the gauge pressure control mode in which the pressure inside the closed container 1 is controlled based on atmospheric pressure, the mode selection circuit 7 outputs "L".
The level mode selection signal MS is supplied to the pressure control mode switching circuit 5, the analog switch 20 is turned on, the analog switch 19 is turned off, and the output signal of the differential amplifier 5C, that is, the detection of each of the pressure sensors 2 and 3. Signal Sa
, Sb from which the in-phase component is removed is supplied to the amplifier circuit 22 as a detection signal SC. Thereafter, the pressure inside the closed container 1 is controlled in the same manner based on the atmospheric pressure. In addition, when actually controlling the pressure above the atmospheric pressure, after performing rough pressure control with the press-in/discharge mechanism 34, the leak valve 35
Make fine adjustments. Conversely, when controlling below atmospheric pressure,
The rotary pump 36 is operated to perform vacuuming, and the leak valve 35 is used to perform fine adjustment.

According to the embodiment described above, a pressure controller with the same configuration and an absolute pressure type pressure sensor are used in both cases where pressure control based on absolute pressure is required and pressure control based on gauge pressure is required. 2.3, it eliminates the complexity of combining different types of pressure sensors and pressure controllers as in the past, and also allows pressure control to be changed from pressure control based on absolute pressure to pressure control based on gauge pressure, for example. Even when changing to the pressure control mode selection switch 6, it is only necessary to operate the pressure control mode selection switch 6, and there is no need to replace the pressure sensor or pressure controller as in the conventional case.

In the embodiment described above, a differential amplifier is used as the conversion means for removing the common-mode component, but the present invention is not limited to this, and a differential transformer or the like may be used.

"Effects of the Invention" As explained above, according to the present invention, the first pressure detection means for detecting the pressure based on the vacuum inside the closed container;
a second pressure detection means for detecting atmospheric pressure based on the vacuum outside the sealed container; and a common component between the output of the first pressure detection means and the output of the second pressure detection means is removed. A conversion means for outputting the output, a first control mode in which the pressure in the closed container is controlled with vacuum as a reference, and a second control mode in which the pressure in the closed container is controlled in reference to atmospheric pressure. a control mode selection means for selecting one; a switching means for switching and outputting either the output of the conversion means or the output of the first pressure detection means based on the output of the control mode selection means; and the airtight container. a pressure adjustment mechanism for pressurizing and discharging gas into and out of the container; a setting means for setting a desired pressure within the closed container; and a control means for controlling the pressure adjustment mechanism,
- An effect can be obtained in which pressure control based on absolute pressure and pressure control based on gauge pressure can be arbitrarily selected simply by operating the control mode selection means.

[Brief explanation of the drawing]

FIG. 2 is a circuit diagram showing a partial circuit configuration of an embodiment of the present invention. 1... Sealed container, 2... Pressure sensor for detecting pressure inside the container (first pressure detection means), 3...
...Pressure sensor for atmospheric pressure detection (second pressure detection means)
, 5... Pressure control mode switching circuit, 5C...
... Differential amplifier (conversion means), 6 ... Pressure control mode selection switch (control mode selection means), 19.
20... Analog switch (switching means), 23
. . . Comparison circuit, 24 . . . Pressure setting switch (setting means), 27 . . . Control circuit, 28.
...Pressure adjustment mechanism.

Claims (1)

[Claims] A pressure controller that controls the pressure inside the closed container, comprising: a) a first pressure detection means for detecting a pressure based on the vacuum inside the closed container; and b) a vacuum outside the closed container. c) a conversion means for removing and outputting a common component between the output of the first pressure detection means and the output of the second pressure detection means; and d) selecting either a first control mode in which the pressure in the closed container is controlled based on vacuum, and a second control mode in which the pressure in the closed container is controlled based on atmospheric pressure. e) a switching means for switching and outputting either the output of the conversion means or the output of the first pressure detection means based on the output of the control mode selection means; f) a pressure adjustment mechanism for pressurizing gas into and out of the sealed container; g) setting means for setting a desired pressure in the sealed container; and h) an output of the switching means is the same as an output of the setting means. A pressure controller comprising: control means for controlling the pressure adjustment mechanism so that the pressure adjustment mechanism reaches a corresponding value.