JP2832873B2 - Electronic measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an electronic measuring apparatus for measuring the concentration (amount) of a certain component in a gas or liquid, and more particularly to a consumer for converting a digital output of a measurement result into an analog output. The present invention relates to an electronic measuring device provided with a simple digital-analog converter having a very small current.

[0002]

2. Description of the Related Art Conventionally, moisture concentration in a gas phase such as humidity,
Alternatively, some electronic measuring devices for measuring the concentration in a liquid phase such as the amount of water in crude oil or lubricating oil output a measurement result as digital data such as a pulse output. For example,
An electronic measuring device using a moisture (gas) sensor having electric characteristics of a capacitance change type is configured as shown in FIG. 5, and a moisture (gas) sensor having electric characteristics of a resistance change type is provided. The electronic measuring device used is configured as shown in FIG.

[0003] In both measurement devices, two inverters 11 and 12 connected in series, such as a C-MOS type Schmitt inverter, a resistor R1 inserted in a feedback circuit of the inverter 11 in the preceding stage, and an inverter in the preceding stage as well. 5 uses a CR oscillation circuit 10 composed of an electrostatic capacitance element (capacitor) C1 connected to the input side of
In the measuring apparatus of the first embodiment, a capacitance change type sensor Ch whose capacitance changes according to a change in the concentration of an object to be measured such as moisture is used as a sensor. The CR oscillation circuit 10 is configured by being inserted in series between the input side and the capacitance element C1.

In the measuring apparatus shown in FIG. 5, the oscillation frequency of the CR oscillation circuit 10 is correspondingly changed by changing the capacitance of a sensor Ch, which is an oscillation frequency determining element, in accordance with a change in the concentration of an object to be measured. The oscillation output, that is, the frequency signal is sent to, for example, a microcomputer (not shown), and the microcomputer performs arithmetic processing to detect the oscillation frequency, and converts the detected frequency into a pulse signal corresponding to the concentration of the DUT. Output.

In the measuring apparatus shown in FIG. 6, a resistance change sensor Rh whose electric resistance changes in accordance with a change in the concentration of an object to be measured such as moisture is used as a sensor. In the circuit 10, a CR oscillation circuit 10 is configured by inserting this resistance change type sensor Rh as an oscillation frequency determining resistance element instead of the resistance R1 inserted in the feedback circuit of the inverter 11 in the preceding stage.
This measuring device also has a sensor R which is an oscillation frequency determining element.
The oscillation frequency of the CR oscillation circuit 10 is correspondingly changed by changing the electric resistance value of h in accordance with the change in the concentration of the device under test. From this oscillation output, that is, the frequency signal, the CR oscillation is performed as described above. It detects the oscillation frequency of the circuit 10 and provides a pulse output corresponding to that frequency.

Further, as shown in FIG. 7, a sensor GS having electric characteristics in which a capacitance component C and an electric resistance component R change according to a change in the concentration of an object to be measured such as moisture is used. The first, second and third switches X of the configuration,
When the sensor GS is used as a sensor of the capacitance change type by Y and Z, as shown in FIG. 5, the sensor GS is connected in series between the input side of the inverter 11 at the previous stage and the capacitor C1. Also, when used as a variable resistance type sensor, as shown in FIG. 6, this sensor GS is switched and connected so as to be inserted in place of the resistor R1 in the feedback circuit of the inverter 11 in the preceding stage. 5 and the CR oscillation circuit 10 shown in FIG. 6 have also been proposed.

The first, second and third switches X, Y,
Z has one movable contact XC, YC, ZC and two fixed contacts X0 and X1, Y0 and Y1, Z0 and Z1, respectively. The first switch X has a movable contact XC having a resistor R2 for removing a DC voltage. The first fixed contact X0 is not connected, and the second fixed contact X1 is connected to the input side of the inverter 11 in the preceding stage. The second switch Y has a movable contact YC connected to the other terminal of the sensor GS, and a first fixed contact Y0 connected to a connection point between the DC voltage removing resistor R2 and the capacitance element C1. , The second fixed contact Y1 is connected to the third switch Z
Is connected to the second fixed contact Z1. In addition, the third
Switch Z is the inverter 1 whose movable contact ZC is in the preceding stage.
1 and the first fixed contact Z0 is connected to the resistor R1
It is connected to the.

In the above configuration, three switches X,
When the movable contacts XC, YC, and ZC of Y and Z are connected to the first fixed contacts X0, Y0, and Z0 as shown, the resistor R1 is inserted into the feedback circuit of the inverter 11 in the preceding stage. A sensor GS is connected in series with the capacitive element C1 on the input side of the inverter 11 in the preceding stage, and the sensor G
5 has a capacitance measurement type circuit configuration in which a resistor R2 for removing a DC voltage is connected in parallel between both ends of S. The CR whose oscillation frequency changes in accordance with the capacitance value of the sensor GS same as that in FIG. The oscillator 10 is configured.

On the other hand, the movable contacts XC, YC, ZC of the three switches X, Y, Z are second fixed contacts X1, Y.
1, when connected to the Z1 side, the sensor GS is inserted in the feedback circuit of the inverter 11 in the preceding stage instead of the resistor R1, and the resistor R2 for removing the DC voltage on the input side of the inverter 11 in the preceding stage is Shorted by one switch X,
Since the capacitance element C1 is connected to the input side of the inverter 11 at the preceding stage through the first switch X, the CR oscillator 10 whose oscillation frequency changes in accordance with the electric resistance value of the sensor GS as in FIG. Is done.

The oscillation output from the CR oscillation circuit 10, that is, the frequency signal is sent to the microcomputer 20, where it is subjected to arithmetic processing to detect the oscillation frequency, and this detected frequency is converted into a pulse signal corresponding to the concentration of the measured object. Convert and output.

Usually, C-type inverters 11 and 12 are used.
A MOS Schmitt inverter is used, and a pulse signal whose frequency changes in response to a change in the capacitance value or a change in the electric resistance value of the sensor GS is output from the CR oscillation circuit 10 and sent to the microcomputer 20. . The microcomputer 20 is, in this example, the counter unit 21 for counting the number of pulses of the frequency signal F _C or F _R that is input
And a storage unit 22 including a ROM (Read Only Memory) storing an arithmetic processing program, and a storage unit 2 based on the number of pulses within a predetermined time counted by the counter unit 21.
2, an arithmetic processing unit 23 for detecting the frequency and converting the detected frequency to a pulse output corresponding to the concentration of the measured object, and transmitting control commands from the arithmetic processing unit 23 to the respective control lines LX, LY, LZ. And a control port 24 for supplying analog switches X, Y, and Z through the switch and controlling the connection of these switches.

The operation of the C-MOS type Schmitt inverters 11 and 12 will be briefly described.
Both Schmitt inverter has two threshold voltage of the high level of the threshold voltage V _TH and a low-level threshold voltage V _TL, when the input voltage is lower than the threshold voltage V _TH of the high levels generates an output voltage V _H of the high-level When the input voltage reaches the high-level threshold voltage V _TH , the output voltage switches from the high level V _H to the low level V _L , and keeps the low level until the input voltage drops to the low-level threshold voltage V _TL. and holding the output voltage V _L, the input voltage is an output voltage when the drop of the low-level threshold voltage V _TL operates to switches from the low level V _L to the high level V _H. Therefore, C
From the R oscillation circuit 10, a pulse voltage having a cycle corresponding to the charging and discharging of the capacitance of the capacitance element C1 or the series circuit of the capacitance element C1 and the sensor GS is output.

On the other hand, for example, lubricating oils used for various types of prime movers, engine oils of automobiles, etc., decrease in light transmittance as they become dirty or deteriorate. For this reason, a part of the lubricating oil is accommodated in a specific cell having light transmissivity or flows through the cell, and light is emitted from a light source such as an LED (light emitting diode), and the transmitted light is converted to a photodiode or the like. The light detection element receives light, detects the amount of transmitted light, and determines the contamination or degree of deterioration of the lubricating oil from the detection result (in other words, the concentration of degradation products or impurities in the lubricating oil). A target light amount measuring device has been proposed. Some of such electronic light quantity measuring devices output measurement results as digital data such as pulse output. For example, L as a light source
FIG. 8 shows an example of an electronic light quantity measuring device using an ED and a photodiode as a light detecting element.

This light quantity measuring device includes a photodiode PD as a light detecting element, a capacitor C as a capacitive load, a first Schmitt inverter 11 of a C-MOS type, and a feedback of the Schmitt inverter 11. A diode D which functions as a switch inserted in series with the resistor R in the circuit and whose frequency changes according to the illuminance (light amount) C
An R oscillating circuit 10 is formed. The diode D is connected in reverse polarity to the photodiode PD. The photodiode PD and the capacitor C are connected in series between a predetermined voltage source and the ground. Are connected to the input of the first Schmitt inverter 11.

An LED 13 is connected in series with a switching transistor 14 between a predetermined voltage source and the ground, and emits light when the transistor 14 is turned on to emit light when the transistor 14 is turned on. The object 16 to be measured such as oil is irradiated with light. The light transmitted through the object to be measured 16 is incident on the photodiode PD, therefore, proportional to the illuminance or amount of incident light current I _P photodiode P
Flow to D.

In the above configuration, the photodiode PD
In the initial state in which no current flows and no charge is stored in the capacitor C, the output voltage of the first Schmitt inverter 11 is at the high level _VH , so that the diode D is reversely biased and turned off. Performs the same function. Therefore, no current flows through the resistor R, and the capacitor C is in a chargeable state. Measurement of the amount of light is started and the measured light is incident on the photodiode PD, current I _P proportional to the illuminance or light quantity of the incident light flows through the photodiode PD. This current _IP is stored in the capacitor _C and converted to a voltage VC. When the charging voltage V _C of the capacitor C reaches a high level threshold voltage V _TH of the first Schmitt inverter 11, the output voltage is low level V from the high level V _H of the Schmitt inverter 11
Switch to _L. Since this by the diode D constitute the same function as the switch-on is forward biased, the output current I _P of the charging voltage V _C and the photodiode PD of the capacitor C flows through the resistor R and the diode D, capacitor C The charging voltage is discharged. When the charging voltage V _C of the capacitor C drops to the low level threshold voltage V _TL of the Schmitt inverter 11 by discharging, the output voltage of the Schmitt inverter 11 switches from the low level _VL to the high level V _H. As a result, the diode D is reverse-biased again and turned off, so that a charging current flows through the capacitor C. Hereinafter, as a result of the same operation being repeated, the output voltage of the first Schmitt inverter 11
That is, the output voltage V ₁ from the CR oscillation circuit 10 has a pulse waveform having a frequency corresponding to the charge / discharge cycle of the capacitor C.

The output voltage V ₁ of the first Schmitt inverter 11 is supplied to a second Schmitt inverter 12 of the same C-MOS type as the first Schmitt inverter 11 in this embodiment. This second Schmidt inverter 1
2 also has two threshold voltages, a high level threshold voltage V _TH and a low level threshold voltage V _TL , and operates similarly. That is, when a high-level voltage signal _VH is input from the first Schmitt inverter 11, a low-level voltage output _VL is generated, and when a low-level voltage signal _VL is input, a high-level voltage output _VL is generated. It generates an output V _H. Therefore, the second Schmitt inverter 12 generates an output voltage of the same frequency F ₀ in which the pulse waveform of the first Schmitt inverter 11 is inverted,
It is supplied to a microcomputer 20 which is an arithmetic measuring unit.

In the present embodiment, the microcomputer 20 comprises:
From the CR oscillation circuit 10 to the second Schmitt inverter 12
Counter 21 for counting the number of pulses of the frequency signal F ₀ input through the memory, and a storage unit 2 including a ROM (read only memory) storing an arithmetic processing program
2 and a calculation process of detecting a frequency from the number of pulses within a certain time counted by the counter unit 21 in accordance with a program in the storage unit 22 and converting the detected frequency into a pulse output corresponding to the amount of light incident on the photodiode PD. And a unit 23.

[0019]

The digital data output from each of the above-described electronic measuring devices is sent through an interface to, for example, a counter to display the concentration of the object to be measured such as a moisture value. It is sent to another computer or the like for processing. Further, in order to obtain an analog output required for various analog devices including a meter, a digital-analog converter is attached to the interface to convert the digital output to an analog output.

For this reason, there have been disadvantages in that the circuit configuration of the interface of each device is complicated, it takes time to design, the cost is increased, and miniaturization is difficult. Another drawback is that the current consumption is large.

Accordingly, an object of the present invention is to provide an electronic circuit having a simplified digital-analog converter which can simplify the circuit configuration of the interface, reduce the cost and size, and consume very little current. It is to provide a measuring device.

[0022]

The above object is achieved by an electronic measuring device according to the present invention. In summary, the present invention provides a C-type oscillator whose oscillation frequency changes according to the concentration of an object to be measured.
An R oscillation circuit, an arithmetic control means for detecting a frequency of an oscillation output of the oscillation circuit, converting the detected frequency into a pulse signal train corresponding to the concentration of the device under test, and outputting the pulse signal train at regular intervals; A means for applying a pulse signal train output from the arithmetic and control means to the capacitor for each of the predetermined periods to convert it into a charging voltage signal, and a means for amplifying the converted voltage signal and outputting it as an analog signal. An electronic measuring device, characterized in that:

[0023]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of an electronic measuring device according to the present invention.
0 and an independent simplified digital-to-analog converter 50
, An independent interface 60, and a connector 70 for connection to a host computer.

The measuring device 30 includes a CR oscillation circuit whose oscillation frequency changes according to the concentration of the device under test, as described above with reference to FIGS. 5 to 8, and outputs the measurement results as digital data. Any measuring device may be used as long as the measuring device performs the measurement. Therefore, in FIG. 1, the frequency of the CR oscillation circuit 31 and the frequency signal oscillated from the CR oscillation circuit 31 are detected, and the detected frequency is used as the concentration of the DUT. Only the microcomputer 32 that converts the digital signal into a digital signal corresponding to the above and outputs the digital signal is shown only as an example, and a specific configuration and detailed description are omitted. Incidentally, the microcomputer 32 is the counter part as usual in the present embodiment, the storage unit, an arithmetic processing unit such as, and digital data from a measurement result processing unit, i.e. the pulse signal P ₀ is parallel I A strobe signal STR output at a fixed cycle through a port (I / O port) and having the same cycle as that of the digital data is output in parallel I / O at the same time as the digital data.
It is configured to output from a port.

Next, a simplified digital-to-analog converter 50 used in the electronic measuring apparatus of the present embodiment will be described in detail with reference to FIG.

[0027] From the parallel I / O port of the microcomputer 32 of the measuring device 30 as described above pulse signal P ₀ corresponding to the concentration, etc. of the object to be measured is output every fixed period. This pulse signal P ₀ is stored in the capacitor C11 via the diode D11 and the resistor R11. That is,
Only during the period when the pulse output voltage is at a high level, the capacitor C11 is charged with the electric charge through the resistor R11. The diode D11 is a diode for preventing a reverse current for preventing the charge stored in the capacitor C11 from being discharged when the pulse output is at a low level.

On the other hand, the strobe signal STR is supplied to a first one-shot multivibrator MM1. Since the first one-shot multivibrator MM1 is activated when the strobe signal STR changes from a high level to a low level, that is, when it falls, the output of the first one-shot multivibrator MM1 is low when the strobe signal STR is supplied. Therefore, the same operation is performed (however, the operation is performed when the output of the first one-shot multivibrator MM1 changes from the high level to the low level). The output of the second one-shot multivibrator MM2 is also at the low level. Therefore, the first and second switches SW1 and SW
2 is in the off state as shown.

[0029] Now, the pulse width of the pulse signal P ₀ t1 (high level period), the voltage value at the high level V, 1
Assuming that the capacitor C11 is charged by the two pulses and its voltage becomes Vc, the following equation is established.

Vc = V (1−e− ^{t1 / C11 · R11} ) (1) ^{Assuming that} t1 << C11 · R11, the above equation (1) can be expressed as follows.

Vc = V (t1 / C11 · R11) (2) When N pulses are output in one cycle, assuming that Expression (2) is similarly satisfied, the voltage of the capacitor C11 is obtained. Vc1 can be expressed by the following equation.

Vc1 = V (Nt1 / C11 · R11) = N (Vt1 / C11 · R11) (3) Therefore, the voltage Vc1 proportional to the pulse number N is accumulated in the capacitor C11.

When N pulses are output, the strobe signal STR changes from a high level to a low level. The falling of the first one-shot multivibrator MM
1 is detected, and one pulse Vs1 having a pulse width of time constant t2 = R12 · C12 is output. Due to the output pulse Vs1 from the one-shot multivibrator MM1, the first switch SW1 is turned on for a time t2, and a part of the charge stored in the capacitor C11 is transferred to the capacitor C14. Assuming that the voltage of the capacitor C14 at that time is Vc2, the total charge Q is as follows: Q = C11 · Vc1 = (C11 + C14) · Vc2 (4), and if C11 >> C14, Vc2 = Vc1. This means that the charging voltage Vc1 of the capacitor C11 has been transferred to the capacitor C14 as it is.

Here, since the capacitance of the capacitor C14 is very small, the voltage of the capacitor C14 changes due to the influence of the leakage current of the first switch SW1, the capacitance between the contacts, the input impedance of the amplifier circuit AMP, and the bias current. Care must be taken in their selection. For example, it is necessary to select a switch having the smallest leakage current between the contacts and the smallest capacitance between the contacts.

Further, a one-shot multivibrator M
It is also necessary to take sufficient time such that the time during which the voltage of the capacitor C14 changes by minimizing the time of the pulse width t2 of M1. For example, assuming that the voltage Vc2 of the capacitor C14 in the previous cycle is Vc2 >> Vc1, when the first switch SW1 is in the ON state, the total charge Q 'of the capacitors C11 and C14 becomes the first charge.
C when the switch SW1 is turned on.
11, assuming that the voltage of C14 is Vc3, Q '= C11 · Vc1 + C14 · Vc2 = (C11 + C14) · Vc3 (5) In this case, too, in order to hold the voltage of the capacitor C11 by the capacitor C14, That is, Vc1
In order to satisfy = Vc3, it is necessary to use in a voltage range (Vc1 to Vc2) in which C11.Vc1 >> C14.Vc2 is satisfied.

However, since the density generally changes gradually, in such a case, it is not always necessary to satisfy the above equation (5), and only the condition of C11 >> C14 needs to be satisfied.

First one-shot multivibrator M
When the output pulse of M1 falls, the first switch SW
1 is turned off, and at the same time, the second one-shot multivibrator MM2 operates, and the time constant t3 = R13 · C
One pulse Vs2 having a pulse width of 13 is output. The output pulse Vs2 from the one-shot multivibrator MM2 turns on the second switch SW2 for the time t3, the electric charge charged in the capacitor C11 is rapidly discharged, and the voltage of the capacitor C11 becomes 0V. This is because the capacitor C1 is output by the pulse output of the next cycle.
Since 1 is recharged, the zero point is corrected. It should be noted that the first switch S
Since the second switch SW2 is turned on at the same time when W1 is turned off, there is a possibility that the charge of the instantaneous capacitor C14 is discharged by this operation. Therefore, it is preferable to insert, for example, a CR delay circuit in a stage preceding the control line for the second switch SW2. As with the first switch SW1, it is necessary to select the second switch SW2 that has the smallest leakage current between the contacts and the smallest capacitance between the contacts.

The above-mentioned signal STR, the waveform of P _0, the one-shot multivibrator MM1, MM2 of the output waveform V
FIG. 3 shows s1, Vs2 and voltage waveforms Vc1, Vc2 of the capacitors C11, C14.

The analog signal Vc2 thus converted by the simplified digital-analog converter 50 of the present embodiment is amplified to an appropriate size by the amplifier circuit AMP and supplied to, for example, a not-shown indicator, and the measurement result is obtained. Is displayed, or data is further processed by another analog device.

In order to easily convert the pulse output from the microcomputer 32 to the independent interface 60, as shown in FIG. 4, digital data consisting of N binary pulses output in one cycle is used. It is only necessary to put two pulses of a start bit and an end bit before and after. However, since these pulses of the start bit and the end bit are also charged in the capacitor C11,
Measurement accuracy decreases. To prevent this, diode D
In front of the 11 may be inserted AND circuit with the strobe signal STR and the pulse output P _0. However, if the number of parts is 1
If it is not desired to increase even the number of points, 74HC4066, 4053 are used as the first and second switches SW1 and SW2.
If a semiconductor switch such as that described above is used, there is a device that is not used and is vacant, and it can be used instead of the AND circuit. Therefore, the pulse of the start bit and the end bit is supplied to the capacitor C11 without increasing the number of components. Charging can be prevented.

As described above, in this embodiment, the digital data output is a binary pulse output at regular intervals, and this pulse data is directly converted into an analog output. The digital-to-analog converter 50 can be used, so that the cost can be reduced and the current consumption is extremely reduced. Incidentally, while the current consumption of the conventional digital-analog converter is several mA to several tens mA, the digital-analog converter 50 of this embodiment is less than 1 mA at the maximum. Further, the configuration of the measurement system including the electronic measurement device of the present embodiment can be simplified, and a measurement device having several different functions by combining the interfaces can be configured. Furthermore, since the circuit configuration of the interface of each device can be simplified,
Design becomes easy, and cost reduction and size reduction become possible.

In the above embodiment, the electronic measurement device according to the present invention is used to measure the concentration of water in the gas phase such as humidity, the concentration in the liquid phase such as the amount of water in crude oil or lubricating oil, or the use of an automobile. The case where dirt or deterioration of lubricating oil such as engine oil is measured has been described. However, when measuring the concentration of a certain component in various other gases or liquids, or when various types of light from a light source can be transmitted. Contamination or deterioration of liquid, gas, etc. (ie,
The measured amount is CR-oscillated both when measuring the concentration of contaminants or degradation products) and when measuring the illuminance (light amount) of the reflected light from the measurement object that reflects the light from the light source. The present invention is applicable as long as it converts a frequency signal using a circuit and outputs the measurement result as digital data.

The above embodiment is merely an example of the present invention, and the circuit configuration, elements used, and the like can be arbitrarily changed as necessary. For example, the CR oscillation circuit may be configured using an inverter other than the C-MOS type Schmitt inverter or another circuit element, or an arithmetic control element other than the microcomputer may be used. Also,
It goes without saying that a light source other than the LED may be used, or a photodetector other than the photodiode may be used. Further, the frequency output generated from the CR oscillation circuit may be a frequency output other than a pulse.

[0044]

As described above, according to the electronic measuring device of the present invention, digital data output from the measuring device is converted into pulse data output at regular intervals,
Since this pulse data is directly converted into an analog output, a simple digital circuit with an extremely simple circuit configuration is used.
An analog converter can be used, and as a result, cost can be reduced and current consumption is extremely reduced. In addition, the configuration of the measurement system can be simplified, and a measurement device having several different functions can be configured by combining the interfaces. further,
Since the circuit configuration of the interface of each device can be simplified, there are many remarkable effects such as easy design, downsizing, and cost reduction.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an electronic measuring device according to the present invention.

FIG. 2 is a circuit diagram showing a specific example of a simplified digital-to-analog converter used in the electronic measuring device of the present invention shown in FIG.

FIG. 3 is a waveform diagram showing voltage output at each part of the digital-analog converter of FIG. 2;

FIG. 4 is a waveform diagram showing another output form of digital data output from the electronic measuring device of FIG.

FIG. 5 is a circuit diagram showing an example of a conventional electronic measuring device. .

FIG. 6 is a circuit diagram showing another example of a conventional electronic measuring device.

FIG. 7 is a circuit configuration diagram showing still another example of a conventional electronic measuring device.

FIG. 8 is a circuit diagram showing an example of a conventional electronic light quantity measuring device.

[Explanation of symbols]

 Reference Signs List 10 CR oscillation circuit 11, 12 Schmitt inverter 13 LED (light emitting diode) 14 Switching transistor 15 Light transmissive cell 16 DUT 20 Microcomputer 21 Counter unit 22 Storage unit 23 Arithmetic processing unit 30 Measurement device 31 CR oscillation circuit 32 Microcomputer 40 counter 50 simple digital-analog converter 60 interface 70 computer AMP amplifier circuit MM1, MM2 one-shot multivibrator PD photodiode SW1, SW2 switch

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 27/00-27/24 G01J 1/00-1/60 G01N 21/00-21/61 G01R 23/00-23 / 20 G01R 27/00-27/32

Claims (3)

(57) [Claims] 1. A CR oscillation circuit whose oscillation frequency changes according to the concentration of an object to be measured, a frequency of an oscillation output of the oscillation circuit is detected, and a pulse corresponding to the concentration of the object to be measured is detected. into a signal sequence, an operation control means for outputting a predetermined cycle, charge and by a pulse signal train outputted from said arithmetic control means is applied to the capacitor over the respective predetermined period
Electronic measuring device comprising a hand stage that converts the electric voltage signal, amplifies the voltage signal said converted to and means for outputting an analog signal. 2. The CR oscillation circuit determines an oscillation frequency of a sensor having an electric characteristic in which a capacitance component or an electric resistance component or both components change according to a concentration of a certain component in a gas phase or a liquid phase. The electronic measuring device according to claim 1, wherein the electronic measuring device is included as an element for use. 3. The CR oscillation circuit includes a photodetector that receives transmitted light or reflected light from an object to be measured and changes an output current according to an amount of received light. 2. The electronic measuring apparatus according to claim 1, wherein a frequency signal corresponding to the illuminance (light amount) of light from the object is output.