JP5217045B2 - Pressure sensor - Google Patents

Description

  The present invention relates to a pressure sensor that outputs an output value corresponding to a detected value of a pressure receiving unit that detects pressure.

  In this type of pressure sensor, the output value corresponding to the detected pressure can be adjusted according to the aging of the sensor itself, the use conditions, and the like. As a method for adjusting the detected value and the output value, there is a conventional method in which a trimmer composed of a semi-fixed resistor, a trimmable resistor, or the like is provided, and a constant bias is applied between the detected value and the output value. It has been adopted.

Here, in the adjustment method using such a trimmer, the user has to perform adjustment manually and is complicated. For this reason, in recent years, there has been known one having an auto zero adjustment function for automatically adjusting a bias value so that an output value in a vacuum state is automatically adjusted to 0 (for example, Patent Document 1).
JP 60-138619 A

  However, depending on the user's equipment, the vacuum state cannot be realized, and there is a disadvantage that the auto zero adjustment function cannot be fully utilized.

  In view of the above circumstances, an object of the present invention is to provide a pressure sensor that can optimally adjust a detection value and an output value by a user's selection.

A pressure sensor according to a first aspect of the present invention is a pressure sensor capable of adjusting a correspondence relationship between a detected value of a pressure receiving unit that detects pressure and an output value corresponding to the detected value, and the pressure receiving unit is placed in a predetermined pressure state. In this case, a first mode for executing a process for matching the output value with a predetermined reference output value is switched to a second mode for allowing the output value for the detected value to be adjusted by a user operation. A switching unit, and an operation unit that performs an operation for selecting a first mode and a second mode that are switched by the switching unit. The second mode that is switched by the switching unit includes : It is allowed to adjust the output value with respect to the detected value when placed in a pressure state different from the pressure state by a user operation .

  According to the pressure sensor of the first aspect of the invention, the first mode in which the process of matching the detected value of the pressure receiving portion with a predetermined reference output value is executed, and the output value is allowed to be adjusted by a user operation. The second mode can be switched. Therefore, the user can select the first mode and the second mode according to the use state of his / her facilities and environment, and the second mode even in the use state where the first mode cannot be executed by the pressure sensor. Can be selected and used. On the other hand, when the first mode can be used, the user can select the first mode and easily match the detected value of the pressure receiving unit with the reference output value. Thus, according to the pressure sensor of the present invention, the detection value and the output value can be optimally adjusted by the user's selection.

The pressure sensor of the second invention, in the pressure sensor of the first invention, comprising a setting means for setting a pre-Symbol reference output value, by operating the said setting means from the user, the reference output is the output value of the operation time It is set as a value .

According to the pressure sensor of the second invention, the output value in the pressure state at the time when the setting means is operated can be set as the reference output value . Therefore, for example, when the pressure state is a vacuum state, not only when the output value is set to 0 as a reference output value, but also when the pressure state is a medium or low vacuum state that can be realized by the user's equipment In addition, an output value corresponding to this can be set as a reference output value . Thereby, adjustment of a detection value and an output value can be performed optimally according to a user's use state.

In the pressure sensor of the third invention, in the pressure sensor of the first or second invention, when there is an adjustment limit point as a range in which the output value with respect to the detected value can be adjusted, the current adjustment amount with respect to the adjustment limit point is It is characterized by comprising display means for performing different display depending on whether or not it is within a predetermined range .

According to the pressure sensor of the third invention, when there is adjustment limit points to adjust the range of the output value and the detected value, of whether the adjustment amount of current for the adjustment limit points on the display means it is approaching within a predetermined range Different displays are made accordingly. Therefore, the user can know whether or not the current adjustment amount has approached the adjustment limit point, and can be an index that keeps the adjustment between the detection value and the output value optimal.

  A pressure sensor according to a fourth aspect is the pressure sensor according to the third aspect, wherein the display means displays differently depending on whether the switching means is switched to the first mode or the second mode. It is characterized by performing.

  According to the pressure sensor of the fourth aspect of the invention, different displays are displayed on the display means when the first mode is selected by the user and when the second mode is selected. Therefore, the user can know the current operation state from the display, and can use it as an index that keeps the adjustment of the detection value and the output value optimal as described above.

  Hereinafter, a pressure sensor as one embodiment of the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of a pressure sensor, and FIG. 2 is a flowchart illustrating processing in the pressure sensor.

  The pressure sensor of this embodiment includes a diaphragm structure that detects a capacitance according to the pressure to be measured, and is particularly suitable for measuring a pressure close to a vacuum.

  As shown in FIG. 1, the pressure sensor of the present embodiment includes a pressure receiving unit 1 that detects pressure, a heater 2 as a heating unit that heats the pressure receiving unit 1, and a pressure receiving unit temperature sensor that detects the temperature of the pressure receiving unit 1. 3 (corresponding to the temperature detecting means of the present invention) and a heater control circuit 4 for controlling the heating amount of the heater 2 so that the temperature detected by the pressure receiving part temperature sensor 3 becomes a preset temperature (present invention) And a controller 5 that executes various arithmetic processes in the pressure sensor.

  The pressure receiving unit 1 includes a capacitance sensor 11 constituted by a capacitive sensor chip. The configuration of the capacitive sensor 11 is the same as the configuration described in, for example, Japanese Patent Application Laid-Open No. 2002-267559 and Japanese Patent Application Laid-Open No. 2006-3234 by the present applicant. The capacitance sensor 11 includes a sensor diaphragm that is distorted in response to application of pressure. The capacitance sensor 11 detects a change in the capacitance value of the capacitor due to a change in the distance between the fixed electrode and the movable electrode of the sensor chip. Output.

  A signal corresponding to the change in the capacitance value of the capacitor output from the capacitance sensor 11 is input to the capacitance detection circuit 21. The capacitance detection circuit 21 amplifies the input signal corresponding to the change in the capacitance value and converts it into a DC detection signal by the half-wave rectification or full-wave rectification circuit and the low-pass filter.

  The heater 2 is a heating wire that generates a heat generation amount corresponding to the energization amount, and is wound around the pressure receiving unit 1 to heat the entire pressure receiving unit 1. The heater 2 generates heat when supplied with electric power from an external power source 6 connected via a heater control circuit 4.

  The pressure receiving unit temperature sensor 3 is provided at a position adjacent to the capacitance sensor 11 of the pressure receiving unit 1, and outputs a signal corresponding to the temperature of the pressure receiving unit 1 to the pressure receiving unit temperature detection circuit 23. The pressure receiver temperature detection circuit 23 amplifies the signal corresponding to the input pressure receiver temperature, converts it into a DC detection signal, and outputs it.

  In addition, a circuit temperature detection circuit 24 that detects a reference temperature for correcting an influence due to a temperature difference between the pressure receiving unit 1 and the circuits 21 to 23 is provided at a position adjacent to each of the circuits 21 to 23. The circuit temperature detection circuit 24 includes a temperature sensor (not shown), detects the temperature of the circuits 21 to 23, amplifies a signal corresponding to the detected temperature of the circuit part, converts it into a DC detection signal, and outputs the signal. .

  Further, an external power supply 6 is connected to the power supply voltage detection circuit 26. The power supply voltage detection circuit 26 includes a voltage sensor that detects the output voltage of the external power supply 6, and amplifies the output signal from the voltage sensor to convert it into a DC detection signal and outputs it.

  The DC detection signals output from the circuits 21 to 24 and 26 are converted into digital signals via the analog-digital conversion circuit 30 and input to the controller 5.

  The controller 5 includes various hardware necessary for arithmetic processing including at least a CPU. The controller 5 performs various arithmetic processes on the signals from the circuits 21 to 24 and 26 input via the analog-digital conversion circuit 30 and outputs an output corresponding to the arithmetic process result.

  As main arithmetic processing by the controller 5, processing for correcting the detection value of the capacitance sensor 11 output from the capacitance detection circuit 21 using the detection value of the reference temperature output from the circuit temperature detection circuit 24 is executed. Then, the calculated detection value after correction is converted into an analog signal via the digital-analog conversion circuit 40, and a predetermined voltage (0 to 10 [V]) is output from the output terminal 50 connected to the digital-analog conversion circuit 40. ).

  The controller 5 includes a switching unit 5a and a setting unit 5b. The switching unit 5a and the setting unit 5b are configured by hardware common to the controller 5, and execute a predetermined process by reading a predetermined program from a data memory 56 described later.

  Specifically, the switching means 5a determines the output value output from the output terminal 50 when the pressure receiving unit 1 is placed in a predetermined pressure state according to a selection signal from the operation unit 55 as a predetermined reference output value. Between the first mode for executing the process of matching the output value and the second mode for allowing the user to manually adjust the output value from the output terminal 50 to the reference output value by operating the operation unit 55 described later.

  The setting unit 5b sets a reference output value in a predetermined pressure state by the operation of the operation unit 55 by the user.

  In addition to the output terminal 50, a loader communication port 51, an event output terminal 52, an event operation LED 53, a status LED 54, an operation unit 55, and a data memory 56 are connected to the controller 5.

  The loader communication port 51 is an input / output port that can be connected to an external device (computer or data logger). In addition to outputting data to the external device, the pressure sensor can be set and changed from the external device. It has become.

  The event output terminal 52 outputs a predetermined signal depending on whether or not the warm-up is completed, whether or not the measured pressure has reached a predetermined pressure set in advance, and whether or not an error detection described later is detected. In this case, one event output terminal 52 may be selectively used by setting, but a plurality of output terminals linked to each operation may be provided.

  The event operation LED 53 is a light emitting diode as a display element that is turned on / off in conjunction with the output state / shut-off state of the event output terminal 52. As described above, when the output signal of the event output terminal 52 is changed in accordance with a plurality of operation states, one event operation LED 53 is turned on corresponding to each operation state (flashing interval). Although the lighting color may be changed, a plurality of operation LEDs corresponding to each operation state may be provided.

  The status LED 54 is a light emitting diode as a display element that lights (flashes) / extinguishes in red, green, or orange in conjunction with an operation unit 55 described later.

  The operation unit 55 is a switch for adjusting the output value of the output terminal 50 with respect to the detection value of the pressure receiving unit 1, and includes an auto switch 55a, a down switch 55b, an up switch 55c, and a reference output value setting switch 55d. Has been.

  The auto switch 55a is switched to the first mode by the switching means 5a of the controller 5 by turning on the switch when the pressure receiving portion 1 is placed in a predetermined pressure state. Thereby, the controller 5 automatically calculates and sets the bias value (adjustment amount) of the following expression (1) so that the output value of the output terminal 50 matches the predetermined reference output value. Run. The pressure sensor is set so that the reference output value is set to 0 by placing the pressure receiving unit 1 in a vacuum state at the time of shipment, but is output in a predetermined pressure state by a reference output value setting switch 55d described later. The value can be set as a reference output value.

(Output value) = (Detection value) + (Bias value) (1)

On the other hand, when the down switch 55b or the up switch 55c is turned on, it is switched to the second mode by the switching means 5a of the controller 5. As a result, manual adjustment according to the operation of the down switch 55b or the up switch 55c by the user becomes possible. An operation signal of the down switch 55b or the up switch 55c is input to the controller 5, and a bias value (adjustment amount) corresponding to the operation signal is set by the controller 5. That is, every time the user turns on the down switch 55b once, the controller 5 sets a bias value for shifting the output of the output terminal 50 to the negative side, and every time the user turns on the up switch 55c, the output terminal 50 is turned on. Set a bias value that shifts the output of to the plus side.

  When the reference output value setting switch 55d is turned on, the setting means 5b of the controller 5 sets the output value output from the output terminal 50 at that time as the reference output value. In other words, the output value output from the output terminal 50 is related to the previous equation (1), and the pressure receiving unit 1 is placed in a known pressure state in advance so that the output value becomes the known pressure value. Adjust the bias value. In this state, when the user turns on the reference output value setting switch 55d, the setting unit 5b sets the output value as the reference output value. With this setting, when the user next turns on the auto switch 55a, the controller 5 automatically adjusts the bias value so that the output value becomes the set reference pressure value.

  For example, when the pressure state realized by the user's own equipment (reference device) is 1.33 k [Pa] (10 [torr]), the user places the pressure receiving unit 1 in the pressure state, and The output value output from the pressure sensor is monitored, and the down switch 55b and the up switch 55c are operated so that the output value becomes 1.33 k [Pa]. Then, by turning on the reference output value setting switch 55d with the output value adjusted to 1.33 k [Pa], the output value in the pressure state is set to 1.33 k [Pa] as the reference output value. The Thereafter, until the reference output value is changed, the user turns on the auto switch 55a in the pressure state of 1.33 k [Pa] realized by the reference device, thereby detecting the detected value and the output value. Calculate and set an optimal bias value that manipulates the error.

  The above is the overall configuration of the pressure sensor of the present embodiment.

  Next, the adjustment process of the output value output from the output terminal 50 will be described with reference to the flowchart of FIG.

  First, the controller 5 determines whether or not the operation mode is switched to the first mode by turning on the auto switch 55a of the operation unit 55 (STEP 1).

  If the switching unit 5a is switched to the first mode (YES in STEP 1), the controller 5 acquires a reference output value (STEP 2). Here, the reference output value is 0 in the initial state, and is a set value when a new reference output value is set by the reference output value setting switch 55d.

  Next, the controller 5 calculates a bias value that matches the output value of the output terminal 50 with respect to the detected value of the pressure receiving unit 1 with the reference output value acquired in STEP 2 (STEP 3). Thereby, the detected value of the pressure receiving unit 1 can be easily matched with the reference output value.

  At this time, the status LED 54 blinks to indicate that auto processing in the first mode is being performed (flashing that is repeatedly turned on and off three times per second), and the lighting color is in the bias variable range (adjustment). Display according to the current bias value (adjustment amount) with respect to the limit point). Specifically, the status LED 54 blinks in green when the bias variable range is ± 20% of full span and the current bias value is within ± 5% of full span. When it is larger than ± 5% and 20% or less, blinking is performed with an orange lighting color. Thereby, the user can know whether or not the current adjustment amount is close to the adjustment limit point, and can optimally maintain the adjustment between the detection value and the output value while predicting the replacement time of the pressure sensor. it can.

  Then, the controller 5 sets the bias value calculated in STEP 3 as the adjustment amount of the output value for the pressure receiving unit 1, and stores this in the data memory 56 (STEP 5). Thereby, it is possible to cancel the error between the detection value and the output value generated according to the secular change of the sensor itself, the use condition, etc., and to improve the detection accuracy of the pressure sensor.

  On the other hand, when the down switch 55b or the up switch 55c is operated and switched to the second mode by the switching means 5a (NO in STEP 1), the controller 5 operates the down switch 55b or the up switch 55c by the user. The bias value is changed according to (STEP 4).

  At this time, the status LED 54 performs flash blinking (flashing repeatedly lighting and extinguishing 9 times per second) indicating that the manual operation state is in the second mode, and the lighting color is within the bias variable range (adjustment limit). Display according to the current bias value (adjustment amount) with respect to (point). Specifically, the lighting color is the same as when the first mode is selected, when the bias variable range is ± 20% of the full span, and the current bias value is within the range of ± 5% of the full span. Blinks with a green lighting color, and blinks with an orange lighting color when it is greater than ± 5% and less than 20%. Thereby, even in the manual state in the second mode, the user can know whether or not the current adjustment amount is close to the adjustment limit point, and the detected value and output value can be calculated while predicting the replacement time of the pressure sensor. Can be optimally maintained.

  Then, the controller 5 sets the bias value as an adjustment amount of the output value for the pressure receiving unit 1, and stores this in the data memory 56 (STEP 5). As a result, the error between the detected value and the output value can be offset by the adjustment amount manually adjusted by the user, and the detection accuracy of the pressure sensor can be improved. The variable range of the bias value and the lighting method of the status LED 54 are not limited to the present embodiment.

  As described above, according to the pressure sensor of the present embodiment, the user can select the first mode and the second mode according to the use state of his / her own equipment, environment, and the like. Furthermore, by setting the reference output value in advance to a pressure state realized by the user's equipment (reference device), even if the vacuum state cannot be realized depending on the user's equipment, the detected value and the output value can be easily set. Can be adjusted. As described above, the detection value and the output value can be optimally adjusted according to the use state of the user.

The figure which shows the structure of the pressure sensor of this embodiment. The flowchart which shows the process in the pressure sensor of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Pressure receiving part, 2 ... Heater (heating means), 3 ... Pressure receiving part temperature sensor (temperature detection means), 4 ... Heater control circuit (control means), 5 ... Controller (switching means, setting means), 5a ... Switching means 5 ... Setting means, 6 ... External power supply, 11 ... Capacitance sensor, 21 ... Capacitance detection circuit, 23 ... Pressure receiver temperature detection circuit, 24 ... Circuit temperature detection circuit, 26 ... Power supply voltage detection circuit, 30 ... Analog-digital conversion Circuit: 40: Digital-analog conversion circuit, 50: Output terminal, 51: Loader communication port, 52: Event output terminal, 53: Event operation LED, 54: Status LED (display means), 55: Operation unit, 55a: Auto Switch, 55b ... Down switch, 55c ... Up switch, 55d ... Reference output value setting switch, 56 ... Data memory.

Claims (4)

A pressure sensor capable of adjusting a correspondence relationship between a detection value of a pressure receiving unit that detects pressure and an output value corresponding to the detection value;
A first mode for executing a process of matching the output value with a predetermined reference output value when the pressure receiving unit is placed in a predetermined pressure state, and adjusting the output value for the detected value by a user operation Switching means for switching between the second mode allowing
An operation unit that performs an operation for selecting a first mode and a second mode that are switched by the switching unit ;
The second mode switched by the switching unit allows the output value for the detected value to be adjusted by a user operation when the pressure receiving unit is placed in a pressure state different from the predetermined pressure state. A featured pressure sensor. The pressure sensor of claim 1 .
Comprising a setting means for setting a pre-Symbol reference output value, the pressure sensor by the operation of said setting means from a user, wherein the output value of the operation time is set as the reference output value. The pressure sensor according to claim 1 or 2,
When there is an adjustment limit point as a range in which the output value with respect to the detection value can be adjusted, display means for performing different display depending on whether or not the current adjustment amount with respect to the adjustment limit point approaches a predetermined range A pressure sensor characterized by that. The pressure sensor according to claim 3,
The pressure sensor according to claim 1, wherein the display means performs different display when the switching means is switched to the first mode and when the switching means is switched to the second mode.

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