JP2002076804A - Input circuit for temperature adjustment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input circuit for a temperature adjustment device especially employing an amplifier circuit whose amplification factor is variable with sufficiently improved resolution while suppressing the cost increase. SOLUTION: The input circuit has two modes, either of which is selected and which consist of a 1st mode where a 1st switch S11 in an amplification factor adjustment circuit 100 is closed and a 3rd switch S13 of a reference point shift circuit 200 is closed and of a 2nd mode where a 2nd switch S22 in the amplification factor adjustment circuit 100 is closed and a 4th switch S24 of the reference point shift circuit 200 is closed. In the 2nd mode, the amplification factor of an operational amplifier 40 is increased by using a 6th feedback resistor R6 for the 2nd mode, and a voltage from a high level side power terminal 10 is applied to a noninverting input terminal (+) of the operational amplifier 40 via a shift resistor RT so that the voltage is applied thereto at a lower level thereby shifting a reference point P2 in a characteristic curve B1 in the 2nd mode toward a high temperature side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input circuit of a temperature controller, and more particularly to a technique for improving resolution when a variable gain type is used.

[0002]

2. Description of the Related Art FIG. 15 shows the input of a conventional temperature controller.
FIG. 3 is a circuit diagram illustrating a configuration of a circuit. This conventional technology temperature
The input circuit of the regulator comprises a first switch S₁And the second sui
Switch S _TwoAnd resistor R₆(Sixth resistor)
A rate adjusting circuit 100 is provided. High voltage of the reference voltage Vref
Power supply terminal 10 and the ground-level low-potential power supply terminal
In order to connect the platinum resistance thermometer 30 between the
Resistor R₁In series with the positive terminal side of the platinum resistance thermometer 30
Insert the second resistor R_TwoIs the negative electrode of the platinum resistance thermometer 30
They are connected to the terminal side in a state of being inserted in series. Sand
The high-potential-side power supply terminal 10 and the first resistor R₁And platinum measurement
Temperature resistor 30 and second resistor R_TwoAnd low potential side power supply terminal 2
0 are connected in series in this order. Also, platinum temperature measurement
The negative terminal of the resistor 30 is connected to the high-potential-side power terminal 10.
Third resistor R_ThreeConnected via

The positive electrode terminal of the platinum resistance thermometer 30, that is, the first terminal
Resistor connection point a between R ₁ to be connected to the non-inverting input terminal of the operational amplifier 40 (+), are connected in a state of inserting the fourth resistor R ₄ in series.

The negative electrode terminal of the platinum resistance thermometer 30,
Inverting input terminal of the resistor operational amplifier 40 a connection point b between the R ₂ (-) to connect against, connected in a state of inserting the resistor R ₅ of the fifth to second switch S ₂ in series It is. The connection point f between the _third resistor R ₃ and the fifth resistor R ₅
Are connected in common.

A connection point g between the fifth resistor R ₅ and the second switch S ₂ and an output terminal j of the operational amplifier 40 are connected in series via a _sixth resistor R ₆ and a seventh resistor R _7. It is connected to the. Then, the sixth resistor R ₆ and the seventh resistor R
₇ , the second switch S ₂ and the operational amplifier 40
And a connection point i with the inverting input terminal (−) are connected in a bypass manner via a _first switch S ₁ .

The first switch S ₁ and the second switch S ₂
Is turned on / off reciprocally by the switching control signal Sc. That is, connecting the switch control signal input terminal 50 to a first control input terminal of the switch S _1, the switching control signal input terminal 50 inverter 60
Is connected to a second control input terminal of the switch S ₂ through.

A first switch S ₁ and a second switch S ₂
The loop circuit of the resistor R ₆ and the _sixth resistor R ₆ is an operational amplifier 10
Constitutes an amplification factor adjusting circuit 100 for adjusting the amplification factor.

In the input circuit of the prior art temperature controller, when performing temperature measurement over a wide temperature range from -200 ° C. to 500 ° C., for example, the first switch S ₁ is turned on, and the second switch S ₂ is turned on. Turn off and select the first mode, the characteristic curve A with a small gradient α ₀ shown in FIG.
Using the input circuit of the temperature controller under ₀ ,
Further, when performing temperature measurement in a narrow temperature range from -200 ° C. to 100 ° C., for example, the second switch S ₂ is turned on, the first switch S ₁ is turned off, and the second mode is selected. The input circuit of the temperature controller is used under the characteristic curve B ₀ of β ₀ .

FIG. 16 shows the voltage-temperature characteristics of the input circuit of this temperature controller. The first mode characteristic curve A ₀ is obtained when the switching control signal Sc is set to “H” level, the first switch S ₁ is turned on, and the second switch S ₂ is turned off via the inverter 60. Things. Contrary to the above, the second mode characteristic curve B ₀ sets the switching control signal Sc to the “L” level, turns on the second switch S ₂ via the inverter 60, and turns the first switch S _{1 on.} It is when turning off.

The characteristic curve A _{0 in} the first mode has a gentle gradient α ₀ , and the characteristic curve B _{0 in} the second mode has a steep gradient β ₀ . For the dynamic range DR ₀ in the A / D converter at the next stage of the input circuit of the temperature controller, the first
The characteristic curve A _{0 of the} mode can correspond to a wide temperature range from −200 ° C. to 500 ° C., and the characteristic curve B ₀ of the second mode corresponds to a narrow temperature range from −200 ° C. to 100 ° C. It is possible. The characteristic curve A ₀ and the characteristic curve B ₀ share a reference point P ₀ .

[0011]

The input circuit of the above-mentioned conventional temperature controller has the following problems.

[0012] When using the input circuit of the temperature regulator under the characteristic curve B ₀ of large gradient beta _0, although using a characteristic curve B ₀ at 300 ° C. ranging from -200 ° C. to 100 ° C. By further narrowing this range, for example, from 0 ° C. to 1
If the characteristic curve B ₀ having a large gradient β ₀ is to be used in the 100 ° C. range up to 00 ° C., the A / D conversion region DR ₁ is almost three-thirds of the dynamic range DR ₀ of the A / D converter. Only about 1 will be used.

Even if an attempt is made to obtain a high resolution in a measuring range from 0 ° C. to 100 ° C., in the input circuit of this prior art temperature controller, even if the gradient can be changed, the reference point P _{0 is obtained.} Cannot be shifted in the horizontal direction, which causes only about one-third of the above to be available.
That is, the ratio between the effective area and the invalid area is approximately 1: 2. However, such numerical values are merely examples, and it goes without saying that there may be various other numerical relationships.

For better understanding, the operational amplifier 1
The output voltage Vo of 0 is calculated.

(1) First Mode (Characteristic Curve A ₀ ) The first mode is set by setting the switching control signal Sc to the “H” level.
The mode is set. At this time, the amplification factor adjusting circuit 100
In the first switch S ₁ is turned on, the second switch S ₂ is turned off so contradictory manner. At this time, the seventh resistor R ₇ is selected as the feedback resistor of the operational amplifier 40. The sixth resistor R ₆ is connected to the operational amplifier 4 to reduce the gradient α ₀ of the characteristic curve A _{0 in} the first mode.
0 the inverting input terminal (-) and so as to present between the negative terminal of the platinum resistance thermometer 30, as a functional element, a fifth resistor R ₅ and not on the seventh resistor R ₇ side Connected to
It has the function of increasing the input resistance value.

The series circuit of the first resistor R ₁ and the platinum resistance temperature detector 30 forms a parallel circuit with the series circuit of the third resistor R ₃ . Assuming that the platinum resistance temperature detector 30 is expressed as a temperature sensor resistance R _Pt , when a composite resistance Rc of these resistance groups is calculated,

[0017]

(Equation 1) Becomes

The voltage at the negative terminal b of the platinum resistance thermometer 30, that is, the connection point f between the _third resistor R ₃ and the fifth resistor R _5.
When the voltage is V _2, the voltage V _2, the reference voltage Vre
f becomes the voltage across the second resistor R _{2 when} the voltage is divided by the combined resistor Rc and the second resistor R ₂ ,

[0019]

(Equation 2) Becomes

Next, the non-inverting input terminal of the operational amplifier 40
Voltage V applied to (+)₁With the above voltage V_Twouse
Ask for it. The reference voltage Vref of the high potential side power supply terminal 10
Is the first resistor R₁And the fourth resistor R_FourOp through
It is applied to the non-inverting input terminal (+) of the amplifier 40. this
Since current does not substantially flow in the path, the non-inverting input terminal
Voltage applied to (+)₁Results in a first resistor R
₁And the fourth resistor R_FourEqual to the voltage Va at the connection point a with
Become. First resistor R₁And temperature sensor resistance R_PtAnd by
Voltage drop is (Vref-V_Two). This voltage (V
ref -V_Two) To R ₁And R_PtAnd the voltage V
_Two, The voltage Va at the connection point a is obtained. And this
This is the voltage V applied to the non-inverting input terminal (+).₁It is. You
That is,

[0021]

(Equation 3) It is.

In the first mode in which the first switch S ₁ is turned on and the second switch S ₂ is turned off in the amplification factor adjusting circuit 100, the sixth resistor R ₆ and the seventh resistor R ₇ are turned on. inverting input terminal of the connection point h of the operational amplifier 10 by the first oN of the switch S ₁ and (-) are connected to the applied voltage of the voltage of the connection point i is the non-inverting input terminal (+) by an imaginary short equal to V _1. Feedback resistor of the operational amplifier 40 is only the resistor R ₇ of the seventh.

The current flowing from the output terminal j of the operational amplifier 10 to the lines of the seventh resistor R ₇ , the sixth resistor R ₆ , and the fifth resistor R ₅ is constant. Therefore, assuming that the output voltage of the operational amplifier 40 is Vo,

[0024]

(Equation 4) Becomes By transforming equation (4),

[0025]

(Equation 5) Becomes

By the way, if the voltage across the platinum resistance temperature detector 30 is Vpt,

[0027]

(Equation 6) It is. Therefore, in the case of the first mode showing the characteristic curve A ₀ having a small gradient α ₀ , the above equation (5) becomes:

[0028]

(Equation 7) Becomes When a is a constant and the temperature change Δt,

[0029]

(Equation 8) If you can determine

[0030]

(Equation 9) Becomes here,

[0031]

(Equation 10) After all,

[0032]

[Equation 11] Becomes

This means that it has linearity with respect to temperature changes.

(2) Second Mode (Characteristic Curve B ₀ ) The second mode is set by setting the switching control signal Sc to the “L” level.
The mode is set. At this time, the amplification factor adjusting circuit 100
In the second switch S ₂ is turned on, the first switch S ₁ is being turned off in contradictory manner. A series resistor including a _seventh resistor R ₇ and a sixth resistor R ₆ is selected as a feedback resistor of the operational amplifier 40. The sixth resistor R ₆ is connected to the inverting input terminal (−) of the operational amplifier 40 and the fifth resistor R ₆ in order to increase the gradient β ₀ of the characteristic curve B _{0 in} the second mode.
Disconnected from the connection line between the resistor R _5, as the functional element, a seventh resistor R rather than the fifth resistor R ₅ side
_It is connected to the ₇ side and has the function of increasing the feedback resistance value.

The point that a series circuit of the _first resistor R ₁ and the platinum resistance temperature detector 30 constitutes a parallel circuit with respect to the third resistor R ₃ is the same as in the first mode. , The combined resistance Rc of these resistance groups is the same as in the equation (1).

The voltage V at the negative electrode terminal b of the platinum resistance thermometer 30
₂ 'is the same as the equation (2), and is as follows.

[0037]

(Equation 12) Second switch S ₂ on the at gain adjustment circuit 100, in the second mode with a first turn off the switch S _1, the connection between the resistor R ₅ of the fifth resistor R ₆ of the sixth op point g is the second oN of the switch S ₂ 1
0 is connected to the inverting input terminal (-), and the voltage at the connection point g is non-inverting input terminal (+) due to an imaginary short.
To the applied voltage V ₁ ′. The feedback resistor of the operational amplifier 40 is a series resistor including the seventh resistor R ₇ and the sixth resistor R ₆ .

The current flowing from the output terminal of the operational amplifier 10 to the lines of the seventh resistor R ₇ , the sixth resistor R ₆ , and the fifth resistor R ₅ is constant. Therefore, the operational amplifier 4
Assuming that the output voltage of 0 is Vo ′,

[0039]

(Equation 13) Becomes By transforming equation (13),

[0040]

[Equation 14] Becomes

[0041]

(Equation 15)

[0042]

(Equation 16) In the case of the second mode showing the characteristic curve B ₀ having a large gradient β ₀ ,

[0043]

[Equation 17] Becomes here,

[0044]

(Equation 18) far. Since V ₁ ′ = V ₁ ,

[0045]

[Equation 19] Becomes This means that the characteristic curve has linearity with respect to temperature change.

Equations (11) and (19) have similar forms. Unlike a factor of the temperature variation and alpha ₀ beta ₀ and, (8) with respect to alpha ₀ with R ₇ to a molecule having the denominator (R ₅ + R ₆₎ as in Equation (15) as equation The _value of β ₀ whose denominator has R ₅ and (R ₆ + R ₇ ) in the numerator is larger. Therefore, the characteristic curve B ₀ has a larger slope than the characteristic curve A ₀ . However, the value of the output voltage Vo when the temperature change Δt is 0 is V ₁ which is the same in mode 1 and mode 2.

Reference V ₁ when there is no temperature change Δt
Is the same in the two modes, it means that the reference point P ₀
Is fixed.

That is, as long as the circuit configuration of the prior art shown in FIG. 15 is employed, no matter how the resistance value of each resistor is adjusted, the state of the characteristics shown in FIG. In temperature measurement in a narrower temperature range without any change, the dynamic range cannot be used effectively, and as a result, a sufficient improvement in resolution cannot be expected.

By the way, if comparison amplification is performed using an instrumentation amplifier, it is possible to change the gradient and the reference point.

However, there is a disadvantage that the instrumentation amplifier is very expensive as compared with the general-purpose operational amplifier.

The present invention has been made in order to solve the above-mentioned problems, and has as its object to provide an input circuit of a temperature controller capable of sufficiently improving resolution while suppressing an increase in cost. I have.

[0052]

The present invention for an input circuit of a temperature controller solves the above-mentioned problem by taking the following means.

The input circuit of the temperature controller according to the first aspect of the present invention is characterized in that the reference point of the characteristic curve is shifted according to the change of the amplification factor. That is, as a premise configuration,
First, a first resistor for voltage division, a temperature sensor having a temperature-resistance characteristic, and a second resistor are inserted in series between a high-potential-side power supply terminal and a low-potential-side power supply terminal in this order. A third resistor is connected to the series circuit of the first resistor and the temperature sensor.
Are connected in parallel, a connection point between the first resistor and the temperature sensor is connected to a non-inverting input terminal of an operational amplifier, and a connection point between the temperature sensor and the second resistor is a second connection point. 5 is connected to the inverting input terminal of the operational amplifier via a resistor of 5, and a gain adjustment circuit is inserted in a feedback loop between the output terminal and the inverting input terminal of the operational amplifier;
This amplification factor adjusting circuit is configured to switch between a first switch and a second switch which are on / off controlled reciprocally with each other, a state of a feedback resistor connected between these two switches, and a state connected to the fifth resistor. And a sixth resistor that can be switched. In the above, the temperature-resistance characteristic is
This is a characteristic in which the resistance value changes with a temperature change.

The input circuit of the temperature regulator having such a configuration is characterized by including the following elements. That is, a reference point shift circuit is interposed between the first resistor and the non-inverting input terminal of the temperature sensor and the operational amplifier.

The reference point shift circuit includes a shift resistor inserted between the first resistor and the temperature sensor, and a connection point between the first resistor and the shift resistor. A third switch interposed between the non-inverting input terminal of the operational amplifier and a fourth switch interposed between a connection point between the shift resistor and the temperature sensor and the non-inverting input terminal; And a switch.

When the first switch is turned on and the second switch is turned off so that the sixth resistor in the amplification factor adjusting circuit does not become a feedback resistor of the operational amplifier, the operational amplifier has The third point shift circuit in the reference point shift circuit is configured to apply a voltage between both ends of the temperature sensor and the shift resistor.
And the fourth switch is turned off. Further, when turning off the first switch and turning on the second switch so that the sixth resistor in the amplification factor adjustment circuit becomes a feedback resistor of the operational amplifier, The third switch in the reference point shift circuit is turned off and the fourth switch is turned on so that the shift resistor is disconnected and the voltage across the temperature sensor is applied.

A fourth resistor is inserted between the connection point of the third switch and the fourth switch and the non-inverting input terminal of the operational amplifier as necessary.

In the prior art, even if the amplification factor is varied, the reference point of the characteristic curve remains unchanged.
Even if the gradient of the characteristic curve is strengthened by switching to the measurement state in the narrower measurement range, since the reference point of the characteristic curve is the same, the output level range that can be effectively used in the narrower measurement range Is reduced compared to the available power level range over the original wider measurement range. That is, the change in the characteristic curve when the amplification factor is increased is a simple rotation around the reference point.

On the other hand, in the first invention,
The gain adjustment circuit changes the slope of the characteristic curve, and the reference point shift circuit shifts the reference point of the characteristic curve. That is, the horizontal shift of the reference point of the characteristic curve is assigned to the reference point shift circuit, and the change in the slope of the characteristic curve is assigned to the amplification factor adjustment circuit.

The slope of the characteristic curve is changed by changing the gain in the gain adjustment circuit inserted in the feedback loop of the operational amplifier. Increasing the feedback resistance changes the slope of the characteristic curve to a tighter one. Further, a reference point of the characteristic curve is shifted by a reference point shift circuit interposed between the sensor and the high potential side power supply terminal. This changes the voltage applied to the non-inverting input terminal of the operational amplifier. If the applied voltage is reduced, the reference point shifts to the higher side of the measurement range.

When the first switch is turned on and the second switch is turned off in the amplification factor adjusting circuit, the third switch is turned on and the fourth switch is turned off in the reference point shift circuit in conjunction with the turning on. By reducing the resistance value of the feedback loop, the slope of the characteristic curve is reduced and the reference point of the characteristic curve is shifted to a lower side.

On the contrary, when the second switch is turned on and the first switch is turned off in the amplification factor adjusting circuit, the reference point shift circuit interlocks with the fourth switch.
Is turned on, the third switch is turned off, and the resistance value of the feedback loop is increased to steep the slope of the characteristic curve and shift the reference point of the characteristic curve to a higher side.

As described above, when increasing the amplification factor, the reference point of the characteristic curve is shifted to the higher side of the measurement range in conjunction with the horizontal movement of the reference point of the characteristic curve and the rotation of the entire characteristic curve. As a result, the reference point can be brought close to or coincide with the lower limit of the narrower measurement range, and the output level range that can be used in the original wider measurement range can be effectively used as the output level range in the smaller measurement range. It is possible to secure a large output level range comparable to the output level range.

Therefore, when the amplification rate is increased, the reference point of the characteristic curve is shifted to the higher side of the measurement range in conjunction with the rotation of the entire characteristic curve while shifting the reference point to the higher side. In other words, since the characteristic curve changes as if horizontal movement and rotation are combined, it is possible to bring the reference point close to or coincide with the lower limit of the narrower measurement range. Thus, the output level range that can be effectively used in a narrower measurement range can be as large as the output level range that can be used in the original wider measurement range.

However, the reference point shift circuit is constructed by extremely simple circuit elements including two switches and a shift resistor.

According to a second aspect of the present invention, in the input circuit of the temperature controller according to the first aspect, the resistance value of the shift resistor of the reference point shift circuit is set to a lower limit value of a narrow measurement range by the temperature sensor. And the difference between the resistance value at the lower limit of the wide measurement range by the temperature sensor.

With this determination, it is possible to make the lower limit of the output level range of the characteristic curve coincide with the lower limit of the narrower measurement range for a narrower measurement range. Therefore, the output level range that can be effectively used in the narrower measurement range can be made substantially the same as the original output level range that can be used in the wider measurement range.

The input circuit of the temperature controller according to the third invention of the present application is the input circuit according to the first or second invention, wherein a connection point between the temperature sensor and the second resistor is connected to the third resistor. And an adjusting resistor whose resistance value is close to or equal to that of the shift resistor is inserted therebetween.

In applying the voltage between both ends of the temperature sensor having the temperature-resistance characteristic to the non-inverting input terminal and the inverting input terminal of the operational amplifier, the input line of the non-inverting input terminal, the inverting input terminal It is desirable that the current flowing in the input line of the first line is substantially zero. The operational amplifier is stable in operation when the applied voltage to the non-inverting input terminal is equal to the applied voltage to the inverting input terminal. This is generally called an imaginal short. According to the present invention, a shift resistor is inserted between the first resistor and the temperature sensor in the reference point shift circuit. In the third invention, however, an equivalent of both input applied voltages in the operational amplifier is used. In order to maintain the condition, an adjusting resistor having a resistance value close to or equal to that of the shift resistor is inserted as described above. Thus, despite the insertion of the shift resistor, the condition of the equivalent of both input applied voltages in the operational amplifier can be satisfied by the insertion of the adjustment resistor, and the operation of the operational amplifier can be further stabilized.

Here, the equivalent of both input applied voltages is
It means the case of taking an equal value and the case of taking a relatively close value, and the relatively close value is not particularly limited,
It may be arbitrarily determined according to the purpose and conditions. Here, it is assumed that the same applies to the case where the resistance values of the adjustment resistor and the shift resistor are equal or approximate.

An input circuit of a temperature controller according to a fourth aspect of the present invention is the input circuit according to the first to third aspects, wherein the temperature sensor is a platinum resistance temperature detector. Platinum resistance thermometers have temperature-resistance characteristics and excellent linearity, but have relatively low sensitivity (temperature change response). Therefore, when the resolution is increased as described above, the sensitivity can be substantially improved.

In the first to fourth inventions,
In place of the temperature sensor, it is also effective to configure the input circuit with a sensor for an arbitrary physical quantity having a temperature-resistance characteristic.

Further, it is desirable to use a general-purpose operational amplifier as the operational amplifier. This is because the configuration of the general-purpose operational amplifier is simpler than that of the instrumentation amplifier, and it is possible to suppress an increase in cost.

[0074]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an input circuit of a temperature controller according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing a configuration of an input circuit of a temperature controller according to an embodiment of the present invention. The input circuit of this temperature controller is configured as follows. Input circuit of the temperature regulator, with comprises a first switch S ₁₁ and the amplification factor adjustment circuit 100 consisting the second switch S ₂₂ and the resistor R ₆ (sixth resistor), third Switch S
₁₃ and a reference point shift circuit 200 consisting of the fourth switch S ₂₄ and the shift resistor R _T adjustable resistor R _T1 Prefecture.

The high potential side power supply terminal 10 of the reference voltage Vref
Platinum measurement between the ground-level low-potential-side power supply terminal 20
The first resistor R is connected to connect the temperature resistor 30.₁And shift
Resistor R_TTo the positive terminal side of the platinum resistance thermometer 30
The second resistor R _TwoOf the platinum resistance thermometer 30
It is connected to the negative terminal side in a state of being inserted in series. sand
That is, the high potential side power supply terminal 10 and the first resistor R₁And Schiff
Resistor R_T, Platinum resistance temperature detector 30 and second resistor R
_TwoAnd the low potential side power supply terminal 20 are connected in series in this order.
It is. Also, the negative terminal of the platinum resistance thermometer 30 is connected to a high potential.
A third resistor R is connected to the side power terminal 10._ThreeAnd adjustment resistor
Armor R_T1Connected via

A fourth switch S is used to connect the positive terminal of the platinum resistance temperature detector 30, that is, the connection point a with the shift resistor _RT to the non-inverting input terminal (+) of the operational amplifier 40.
With some connecting ₂₄ and a fourth resistor R ₄ in a state of inserting in series with the first resistor R ₁ and the connection point between the shift resistor R _T d and the fourth switch S ₂₄ a 4 between the connection point e of the resistor R ₄ is connected via a third switch S _13.

The third switch S ₁₃ and the fourth switch S ₂₄
Is turned on / off reciprocally by the switching control signal Sc. That is, connecting the switch control signal input terminal 50 to the control input terminal of the third switch S _13, the switching control signal input terminal 50 inverter 60
Is connected to the control input terminal of the fourth switch S ₂₄ through.

The negative electrode terminal of the platinum resistance temperature detector 30, that is, the second terminal
The inverting input terminal of the connection point b between the resistors R ₂ op 40 (-) to connect respect, the adjustment resistor R _T1 fifth
And resistor R ₅ a second switch S ₂₂ is connected in a state to be inserted in series. Third resistor R ₃ and adjustment resistor R _T1
If the resistor R ₅ of the fifth has a state of being connected to a common at a connection point f.

The connection point g between the fifth resistor R ₅ and the second switch S ₂₂ and the output terminal j of the operational amplifier 40 are connected in series via the sixth resistor R ₆ and the seventh resistor R _7. It is connected to the. Then, the sixth resistor R ₆ and the seventh resistor R
₇ and a connection point of h and a second switch S ₂₂ operational amplifier 40
The inverting input terminal (-) and between the connection point i is bypassed connected via a first switch S _11.

The first switch S ₁₁ and the second switch S ₂₂
Is turned on / off reciprocally by the switching control signal Sc. That is, connecting the switch control signal input terminal 50 to the control input terminal of the first switch S _11, the switching control signal input terminal 50 inverter 60
Via is connected to the control input terminal of the second switch S _22.

The first switch S ₁₁ and the second switch S ₂₂
The loop circuit of the resistor R ₆ and the _sixth resistor R ₆ is an operational amplifier 10
Constitutes an amplification factor adjusting circuit 100 for adjusting the amplification factor.

The third switch S ₁₃ and the fourth switch S ₂₄
The shift resistor _RT and the adjusting resistor _RT1 constitute a reference point shift circuit 200. The shift resistor R _T and the adjustment resistor R _T1 shall equal the resistance value from each other, but not necessarily need to be bound to it, the value approximating to the shift resistor R _T and the adjustment resistor R _T1 You only need to have

The input circuit of the temperature controller of the present embodiment
And a wide temperature range from -200 ° C to 500 ° C, for example.
When performing temperature measurement over the enclosure, the first switch
S₁₁And the third switch S₁₃On, second switch
S_{twenty two}And the fourth switch S _{twenty four}Turn off the first mode
And choose a small gradient α₁Characteristic curve A₁Temperature under
Use the input circuit of the regulator, for example from 0 ° C
When measuring temperature in a narrow temperature range up to 100 ° C
Is the second switch S_{twenty two}And the fourth switch S_{twenty four}The
, The first switch S₁₁And the third switch S₁₃The
To select the second mode,₁Characteristic song
Line B₁Use the input circuit of the temperature controller under
are doing.

The voltage-temperature characteristic of the input circuit of this temperature controller
The properties are shown in FIG. Characteristic curve A of the first mode₁Is the switching system
The control signal Sc is set to “H” level, and the first switch S
₁₁And the third switch S₁₃And turn on the inverter 6
0 through the second switch S _{twenty two}And the fourth switch S
_{twenty four}It is when turning off. 2nd mode characteristic song
Line B₁Changes the switching control signal Sc to the “L” level
As a bell, the second switch via the inverter 60
S_{twenty two}And the fourth switch S_{twenty four}Turn on the first switch.
Switch S₁₁And the third switch S₁₃When turned off
Things.

Characteristic curve A of the first mode₁Is the gradient α₁Is loose
Characteristic curve B of the second mode₁Is the gradient β₁Is sudden
It is. A / D conversion at the next stage of the input circuit of the temperature controller
Range DR in the heat exchanger₀For all areas of
And the characteristic curve A of the first mode ₁Is from -200 ° C to 50
It can be used in a wide temperature range up to 0 ° C.
And the characteristic curve B of the second mode₁Between 0 ° C and 100 ° C
In the narrow temperature range of A / D, the A / D
Transducer dynamic range DR₀For all regions of
It is available. Characteristic curve A of the first mode₁Output
Reference point P, which is the lower limit of the level range₁Is at -200 ° C
And the characteristic curve B of the second mode₁Lower limit of output level range
Reference point P which is a value_TwoIs 0 ° C. That is,
In the first mode due to the presence of the quasi-point shift circuit 200
Reference point P₁In the horizontal mode in the second mode.
It is designed to shift to the warm side.

(1) First mode (characteristic curve A₁) Switching system
The first mode is set by setting the control signal Sc to the “H” level.
Is set. At this time, the amplification factor adjustment circuit 100
And the first switch S₁₁And the third switch S₁₃But
And the second switch S_{twenty two}And the fourth
Switch S _{twenty four}Is turned off. Effective circuit configuration at this time
Is shown in FIG. Second switch S turned off_{twenty two}and
Fourth switch S_{twenty four}Is not shown. Operational amplifier 4
A seventh resistor R as a zero feedback resistor₇Is selected
You. And a sixth resistor R ₆Is the characteristic song of the first mode
Line A₁Gradient α₁In order to lower the
The inverting input terminal (-) and the negative terminal of the platinum resistance thermometer 30
As the functional element, the seventh resistor
Bowl R₇Fifth resistor R, not side_FiveConnected to the input
It has the function of increasing the resistance value.

A series circuit of the first resistor R ₁ , the shift resistor R _T, and the platinum resistance temperature detector 30 forms a third resistor R ₃
And an adjusting resistor _RT1 to form a series circuit and a parallel circuit. Assuming that the platinum resistance temperature detector 30 is expressed as a temperature sensor resistance R _Pt , when a composite resistance Rc of these resistance groups is calculated,

[0089]

(Equation 20) Becomes

[0090] When the voltage of the negative terminal b of the platinum resistance thermometer 30 and Vs, the voltage Vs is a reference voltage Vref of the combined resistance Rc and a second resistor R ₂ and obtained by dividing the second time was since the voltage across the resistor R _2,

[0091]

(Equation 21) Becomes

Next, the voltage V ₁ applied to the non-inverting input terminal (+) of the operational amplifier 40 is obtained by using the above voltage Vs. In reference point shift circuit 200, when the third switch S ₁₃ is on, the reference voltage Vref of the high potential side power supply terminal 10, a first resistor R ₁ and the third switch S
₁₃ to be applied to the non-inverting input terminal of the operational amplifier 40 (+) via a fourth resistor R _4. Since substantially no current flows through this path, the applied voltage V ₁ to the non-inverting input terminal (+) is equal to the voltage at the connection point e between the _fourth resistor R ₄ and the third switch S _13. It is equal, and consequently, equal to the voltage Vd at the connection point d between the _first resistor R ₁ and the shift resistor _RT . The first resistor R ₁ and a voltage drop due to a shift resistor R _T and the temperature sensor resistance R _Pt is, (Vref -V
s). This voltage is divided by R ₁ and (R _T + R _Pt ), and when the voltage Vs is added, the voltage Vd at the connection point d is obtained.
Becomes And, this is applied voltages V ₁ to the non-inverting input terminal (+). That is,

[0093]

(Equation 22) Becomes

Next, the third resistor R ₃ and the fifth resistor R
₅ and the voltage V _{2 at} the common connection point b between the adjustment resistor R _T1
Ask for. This voltage V ₂ is equal to the voltage drop (Vref
−Vs) is obtained by dividing the voltage by R ₃ and R _T1 and adding the voltage Vs. That is,

[0095]

(Equation 23) It is.

[0096] To turn on the first switch S ₁₁ in gain adjusting circuit 100, in the first mode to turn off the second switch S _22, a resistor R ₆ of the sixth seventh resistor R ₇ inverting input terminal of the connection point h of the operational amplifier 10 by the on of the first switch S ₁₁ and (-) are connected to the applied voltage of the voltage of the connection point i is the non-inverting input terminal (+) by an imaginary short equal to V _1. Feedback resistor of the operational amplifier 40 is only the resistor R ₇ of the seventh.

The current flowing from the output terminal j of the operational amplifier 10 to the lines of the seventh resistor R ₇ , the sixth resistor R ₆ , and the fifth resistor R ₅ is constant. Therefore, assuming that the output voltage of the operational amplifier 40 is Vo,

[0098]

(Equation 24) Becomes By transforming equation (24),

[0099]

(Equation 25) Becomes Further, substituting equations (22) and (23) into equation (25),

[0100]

(Equation 26) Is obtained.

(2) Second mode (characteristic curve B₁) By setting the switching control signal Sc to the “L” level, the second
The mode is set. At this time, the amplification factor adjusting circuit 100
At the second switch S_{twenty two}And the fourth switch S
_{twenty four}Is turned on, and on the contrary, the first switch S₁₁And the first
Switch S of 3 ₁₃Is turned off. Valid times at this time
The road configuration is shown in FIG. First switch S turned off₁₁
And the third switch S₁₃Is not shown. Opea
A seventh resistor R is used as a feedback resistor of the amplifier 40.₇And the sixth resistor
Armor R₆Is selected. And the second
6 resistors R₆Is the characteristic curve B of the second mode.₁Gradient β
₁Input terminal of the operational amplifier 40 to increase the
(-) And the fifth resistor R_FiveDisconnected from the connection line
As a functional element, the fifth resistor R_FiveThe side, not the side
7 resistor R₇Side to increase the feedback resistance.
I am carrying it.

A series circuit of the first resistor R ₁ , the shift resistor _RT, and the platinum resistance temperature detector 30 forms a third resistor R ₃
The point that a parallel circuit is formed with respect to the series circuit including the resistor R _T1 and the adjustment resistor R _T1 is the same as in the case of the first mode, and the combined resistance Rc of these resistor groups is the same as (A1).

The voltage V of the negative electrode terminal b of the platinum resistance thermometer 30
s' is the same as in equation (20), and is as follows.

[0104]

[Equation 27] Becomes

Next, a voltage V ₁ ′ applied to the non-inverting input terminal (+) of the operational amplifier 40 is obtained by using the above voltage Vs ′. In reference point shift circuit 200, when the fourth switch S ₂₄ is on, the high-potential-side power supply terminal 10
Reference voltage Vref is applied to the non-inverting input terminal of the first resistor R ₁ and an operational amplifier 40 shift resistor R _T and fourth switches S ₂₄ and via a fourth resistor R ₄ (+) Is done. Since substantially no current flows through this path, the applied voltage V ₁ ′ to the non-inverting input terminal (+) is consequently increased by the connection point a between the shift resistor _RT and the temperature sensor resistor _RPt. Voltage Va. The voltage drop due to the first resistor R ₁ , the shift resistor _RT and the temperature sensor resistor R _Pt is:
(Vref-Vs'). This voltage is referred to as (R ₁ +
If the voltage is divided by R _T ) and R _Pt , and the voltage Vs' is further applied, the voltage Va at the connection point a is obtained. This is the voltage V ₁ ′ applied to the non-inverting input terminal (+). That is,

[0106]

[Equation 28] Becomes

Next, the third resistor R ₃ and the fifth resistor R
The voltage V ₂ ′ at the common connection point f between ₅ and the adjustment resistor R _T1 is determined. The voltage V ₂ ′ can be obtained by dividing the above-mentioned voltage drop (Vref−Vs ′) by R ₃ and R _T1 and adding the voltage Vs ′. That is,

[0108]

(Equation 29) Becomes

[0109] The second switch S ₂₂ on the in gain adjusting circuit 100, in the second mode to turn off the first switch S _11, the resistor R ₆ and the resistor R ₅ of the fifth sixth inverting input terminal of the connection point g of the operational amplifier 10 by the on of the second switch S ₂₂ and (-) are connected to the applied voltage of the voltage of the connection point g of the non-inverting input terminal (+) by an imaginary short V ₁ '. The feedback resistor of the operational amplifier 40 is a series resistor including the seventh resistor R ₇ and the sixth resistor R ₆ .

The current flowing from the output terminal of the operational amplifier 10 to the lines of the seventh resistor R ₇ , the sixth resistor R ₆ , and the fifth resistor R ₅ is constant. Therefore, the operational amplifier 4
Assuming that the output voltage of 0 is Vo ′,

[0111]

[Equation 30] Becomes By transforming equation (30),

[0112]

(Equation 31) Becomes Furthermore, substituting equations (28) and (29) into equation (31),

[0113]

(Equation 32) Is obtained.

In equation (26) for the first mode,
The output voltage Vo of the operational amplifier 40 at −200 ° C. is V
o (-200) and the temperature sensor resistance of the platinum resistance thermometer 30
Anti-R _PtTo R_PtExpressed as (-200),

[0115]

[Equation 33] Becomes

In the equation (32) in the case of the second mode,
The output voltage Vo of the operational amplifier 40 at 0 ° C. is Vo ′
(0) and the temperature sensor resistance R of the platinum resistance temperature detector 30
_PtTo R _PtExpressed as (0),

[0117]

(Equation 34) Becomes

Expressions (33) and (34) are compared and weighed.

[0119]

(Equation 35) far. That is,

[0120]

[Equation 36] Set as Usually, Vs = Vs'. Therefore, when the expression (34) is further modified, by substituting the expression (35),

[0121]

(37) Becomes

Comparing the equations (33) and (37), the denominator in the former is [R ₁ + _RT + _RPt (−200)], while the denominator in the latter is [R ₁ + 2 · R _T + R _Pt (-200)]
This means that a difference has occurred. However, R _T is can be set sufficiently smaller than the R _1, for example, R _T = R _1/30 Toka R _T = R ₁ /
With a setting like 50, both denominators can be considered to be substantially equal. That is,

[0123]

(38) You can consider it.

By the way, [R _T = R _Pt (0)
−R _Pt (−200)], the resistance value R _Pt (0) at 0 ° C. is, for example, 100Ω, and the resistance value R _Pt (−200) at −200 ° C. is, for example, 18 as there is a platinum resistance thermometer 30 to be .5Omu, in this case, the resistance value of the shift resistor R _T, from 100-18.5 = 81.5, R
_T may be set to 81.5Ω. However, it is needless to say that such numerical values are merely examples and may be appropriately changed according to the specifications.

Although detailed calculations are omitted,

[0126]

[Equation 39] As, when determining the coefficients of Delta] t alpha ₁ when expressed as a function of Delta] t the Vo of equation (26),

[0127]

(Equation 40)In addition, Vo ′ in equation (37) is expressed by a function of Δt.
Coefficient β of Δt ₁And ask for

[0128]

[Equation 41]And β₁−α₁Is calculated, this is
Β₁> Α ₁It has become.

[0129] As a result of the above, the characteristic curve A ₁ when the first mode when the first switch S ₁₁ and the third switch S ₁₃ is turned on, the second switch S ₂₂ and the fourth switch the characteristic curve B ₁ at the time of the second mode with the S ₂₄ is turned on, as shown in FIG. That is, the reference point P ₂ of the characteristic curve B ₁ in the second mode is shifted to the high temperature side in the horizontal direction with respect to the reference point P ₁ of the characteristic curve A ₁ of the first mode.

That is, when the amplification factor is increased with reference to the characteristic curve A ₁ of the first mode, the characteristic curve B ₁ of the second mode shifts its reference point P ₂ to the higher side of the measurement range in conjunction therewith. Is done. In other words, the overall characteristic curve B _1, have launched rotated while shifting the reference point P ₂ on the high side. In other words, the characteristic change is such that horizontal movement and rotation are combined.

The reference point P ₁ corresponds to -200 ° C., and the reference point P ₂ corresponds to 0 ° C. Then, the characteristic curve B _{1 of} the second mode is compared with the gradient α ₁ of the characteristic curve A ₁ of the first mode.
Gradient β ₁ of is increased. Characteristic curve B ₁ in the second mode, the reference point P ₂ to the reference point P ₁ of the characteristic curve A ₁ of the first mode is shifted to the high temperature side as a base end, the slope of the characteristic curve A ₁ of the first mode α _Since it rises with a gradient β ₁ steeper than ₁ , the characteristic curve B ₁ of the second mode is 0 ° C.
And 100 ° C., intersects the characteristic curve A ₁ of the first mode. Incidentally, the crossing in the second mode of characteristic curve B ₁ a 100 ° C. at the upper limit of the dynamic range DR ₀ can be realized by determining the resistance values of the resistors appropriately.

Characteristic curve A of the first mode having a gentle gradient over a wide temperature range from -200 ° C. to 500 ° C.
₁ makes full use of the dynamic range DR ₀ in the A / D converter at the next stage of the input circuit of the temperature controller in the same manner as in the prior art.
The dynamic curve DR ₀ of the next-stage A / D converter is also fully used for the characteristic curve B ₁ of the second mode having a steep gradient over a narrow temperature range up to ° C. That is, in the second mode, temperature measurement with high resolution is possible.

[0133] Next, the empirical relationship between the resistance value of the shift resistor R _T and the resistance value of the adjusting resistor R _T1 at the reference point shift circuit 200 will be described with reference to FIGS. 5 to 14.

First, FIGS. 5 and 6 will be described.

Regarding the resistance value, the first to seventh resistors
Bowl R₁~ R₇And the temperature of the platinum resistance temperature detector 30
There is a resistance value of the degree-resistance characteristic. First to seventh resistance values
Can be arbitrarily determined, but
In the future, favorable numerical relationships are already required
You. Here, we base it. As a typical example
FIG. 5 (data chart). In addition, here
Then, as the first mode, similarly to the above case, −200
C. to 500.degree. About the second mode
Is different from the above case, and here, 0 ° C. to 200 ° C.
And The temperature-resistance characteristics of the platinum resistance thermometer 30
Resistance R_PtAbout JIS standard
ing. A / D conversion area required is 2.0 to 4.5.
[V]. The upper part of Fig. 5 shows the conventional circuit (old circuit)
1 and 2 show the first mode and the second mode.
The first mode and the second mode of the circuit (new circuit)
Is shown. In the conventional circuit, the shift resistor R_Tand
Adjustment resistor R_T1Because there is no _T= 0, R_T1= 0
ing. In the new circuit, R_T= R_T1= 82Ω.
Rc in the data chart of FIG. 5 is the combined resistance of equation (20).
Vs is the negative electrode of the platinum resistance thermometer 30 of the formula (21).
Is the voltage, and Vo is the equation (26) in the case of the first mode or
Is the operational amplifier output voltage of the equation (32) in the case of the second mode.
It is.

FIG. 6 is a graph showing the data of FIG. 6, the characteristic curve A ₀ indicated by ◆ symbols the case of the first mode of the old circuit (-200~500 ℃),
Characteristics indicated by × symbols curve B ₀ is the second mode of the old circuit (0
２００200 ° C.), and the characteristic curve A ₁ indicated by the symbol ■ indicates the first mode (−200 to 500
The case of ° C.), the characteristic curve B ₁ indicated by the symbol ▲ indicates the case of the second mode of the new circuit (0 to 200 ° C.), respectively. FIG. 6 corresponds to a combination of FIG. 16 and FIG.

In the case of the old circuit according to the prior art, -20
Since the amplification is performed around 0 ° C., the characteristic curve B₀Must
The required temperature range and dynamic range can be secured
Absent. On the other hand, in the case of the new circuit according to the present invention,
Adjustment resistor R_T1And R _T1= R_T(Or R_T1≒ R
_T), The voltage V shown in FIG.₁And voltage V_TwoWhen
Can be made as small as possible.
And the characteristic curve B in the second mode (0 to 200 ° C.)
₁Indicates the characteristics in the first mode (−200 to 500 ° C.)
Curve A₁As in the required temperature range
Amplification starts from the lower limit of the dynamic range.
Can be done. Of course, the characteristic song
Line B₁Is the characteristic curve A₁Of the measurement range from the reference point of
Horizontal shift to higher side.

Next, FIGS. 7 and 8 will be described. These look at the effect of the adjustment resistor R _{T1 in} the new circuit according to the invention. Although FIG. 7 shows a new circuit configuration, the upper two examples _assume that R _T1 = 0 for the adjustment resistor R _T1 . The A / D conversion area is the same as that of FIG.
To a 5 V, and adjusting the resistance value R ₇ of the second resistance value R ₂ and the seventh. The lower two examples are the same as the lower two examples in FIG.

FIG. 8 is a graph showing the data of FIG. 8, the first mode of the virtual circuit of the characteristic curve A ₁₁ indicated by ◆ symbols adjusting resistor R _T1 = 0 (-200
The case to 500 ° C.), the characteristic curve B ₁₁ indicated by × symbols second mode of the virtual circuit of the adjustable resistor R _T1 = 0 (0~20
0 ° C.). The characteristic curve B ₁ indicated by ▲ characteristic curves A ₁ and symbols shown in ■ the symbols are the same as in FIG.

Adjusting resistor R_T1= 0, that is, the adjustment resistor R
_T1Does not exist, the characteristic curve B ₁₁Is the required temperature
The area and dynamic range could not be secured. This result
From the result, the adjustment resistor R_T1You need to understand.

Next, FIGS. 9 and 10 will be described. These look at the effect of the adjustment resistor R _{T1 in} the new circuit according to the invention. FIG. 9 shows a new circuit configuration.
The upper two examples show the adjustment resistor R _T1 and the shift resistor R
Double _T that is virtually the _{R T1 = 2 · R T (} R T1
= 164Ω). The A / D conversion area is the same as that of FIG.
To a 0 to 4.5 [V], and adjusting the resistance value R ₇ of the second resistance value R ₂ and the seventh. The lower two examples are the same as the lower two examples in FIG.

FIG. 10 is a graph showing the data of FIG. In FIG. 10, a characteristic curve A indicated by a symbol ◆
₁₂ adjustable resistor R _T1 = 2 · R _T the case of the first mode of the virtual circuit (-200~500 ℃) of the characteristic curve B ₁₂ indicated by × symbols adjusting resistor R _T1 = 2 · R _T Of the virtual circuit of the second
Modes (0 to 200 ° C.) are shown. Characteristic curve A ₁ indicated by symbol お よ び and characteristic curve B indicated by symbol ▲
₁ is the same as in FIG.

Adjusting resistor R_T1To shift resistor R_T2
The characteristic curve B ₁₂Is the output voltage
Temperature level is too low and required temperature range and die
The natural range has not been secured. From this result,
Regulating resistor R_T1Is the shift resistor R_TToo big compared to
This is not desirable.

Next, FIGS. 11 and 12 will be described.
These are the adjustment resistors R in the new circuit according to the invention._T1Shadow of
It is to see the sound. FIG. 11 shows a new circuit configuration.
However, the upper two examples are adjustment resistors R_T1About shift resistor
Bowl R_T1/2 of R _T1= R_T/ 2 is virtual
(R_T1= 41Ω). The A / D conversion area is the same as that in FIG.
The second resistance value R is set to 2.0 to 4.5 [V].
_TwoAnd the seventh resistance value R₇Has been adjusted. The lower two examples are figures
5 are the same as the two lower examples.

FIG. 12 is a graph showing the data of FIG. 12, a case where characteristic curve A ₁₃ indicated by ◆ symbols first mode of the virtual circuit of the adjustable resistor R _T1 = R _T / 2 of (-200~500 ℃), the characteristic curve B shown by × symbols Reference numeral ₁₃ denotes the case of the second mode (0 to 200 ° C.) of the virtual circuit in which the adjustment resistor R _T1 = R _T / 2. The characteristic curve B ₁ indicated by ▲ characteristic curves A ₁ and symbols shown in ■ the symbols are the same as in FIG.

The adjustment resistor R _{T1 is connected} to the shift resistor R _T 2
For reduced amount 1 and the characteristic curve B ₁₃ is too high level of the output voltage, temperature range, requiring
The dynamic range has not been secured. From this result, it is understood that it is not preferable that the adjustment resistor _RT1 is too small as compared with the shift resistor _RT .

Next, FIGS. 13 and 14 will be described.
These look at the effect of the adjustment resistor R _{T1 in} the new circuit according to the invention. The left column in the upper part of FIG. 13 shows a conventional circuit. All others are new circuit configurations. In the upper right column,
Data at 100 ° C. and 200 ° C. In the lower right column, data at 0 ° C. and 100 ° C. are shown. In the upper right column, as the shift resistor _RT and the adjustment resistor _RT1 , 10
The value 13 of the resistance value R _Pt of the platinum resistance thermometer 30 at 0 ° C.
A value of 120Ω, which is the difference between 8.5Ω and a value of 18.49Ω at −200 ° C., is set. The fifth resistance value R ₅ and the sixth resistance value R ₆ are adjusted. The lower the value of the shift resistor R _T and the adjustment resistor R _T1, when the value 100Ω and -200 ° C. in the resistance value R _Pt when the 0 ℃ 18.49Ω
87 Ω, which is slightly larger than 81.5 Ω, which is the difference from the above, is set. The A / D conversion area is the same as that of FIG.
To a 0 to 4.5 V, it is adjusted with the resistance value R ₅ of the fifth resistance value R ₆ of the sixth.

FIG. 14 is a graph showing the data of FIG. 14, the case of the first mode of the conventional circuit characteristic curve A ₁₄ is indicated by ◆ symbol (-200~500 ℃), the characteristic curve B ₁₄ indicated by × symbols virtual circuits in the upper right column second Modes (100 to 200 ° C.) are shown. The characteristic curve A ₁ 'indicated by the symbol ■ and the symbol ▲
The characteristic curve B ₁ ′ indicated by corresponds to the case of FIG. Is enabled, even if the characteristic curve B _14.

[0149] From the above it, adjustable resistor R _T1, it is better provided than not provided, and the adjustment resistor R _T1
It can be seen that it is preferable that the resistance value of the shift resistor _RT be approximated or matched as much as possible.

[0150] Although one embodiment has been described above, the present invention can include the following configuration.

(1) The amplification factor adjusting circuit 100 does not need to be limited to the example shown in the figure, and may have any circuit configuration as long as it exhibits a predetermined function.

(2) The reference point shift circuit 200 does not need to be limited to the example shown in the figure, and may have any circuit configuration as long as it exhibits a predetermined function.

(3) The case where the temperature sensor is a platinum resistance temperature sensor has been exemplified, but it is not always necessary to be limited to this, and any temperature sensor such as a thermistor that converts a temperature change into a resistance change can be used. It may be of the form. A magnetoresistive element (MR element) is also effective.

(4) Although a temperature sensor has been described as a sensor, it is not necessary to be limited to the temperature sensor, and any type of sensor such as an optical sensor, a pressure sensor, a displacement sensor, and a speed sensor may be used.

(5) For any other items not directly related to the subject matter of the present invention, any known ones can be applied. It shall be applicable within the range not to be performed.

The above items (1) to (5) are independent of each other, and any number of these items may be appropriately combined.

[0157]

According to the present invention for the input circuit of the temperature controller, the reference point of the characteristic curve is shifted to the higher side of the measurement range in conjunction with the increase of the amplification factor, that is, horizontal movement and rotation. Since the characteristic curve is changed in a manner that combines the reference point with the lower limit of the narrower measurement range, the output level range that can be effectively used in the narrower measurement range is changed to the original wider measurement range. It can be secured as large as the output level range available in the range. Therefore, it is possible to sufficiently improve the resolution of the input circuit of the temperature controller while suppressing an increase in cost.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of an input circuit of a temperature controller according to an embodiment of the present invention.

FIG. 2 is a measured temperature-output voltage characteristic diagram of an input circuit of the temperature controller according to the embodiment of the present invention.

FIG. 3 is a circuit state diagram of the input circuit of the temperature controller according to the embodiment of the present invention in a first mode.

FIG. 4 is a circuit state diagram of the input circuit of the temperature controller according to the embodiment of the present invention in a second mode.

FIG. 5 is a data chart (part 1) for examining the influence of the adjustment resistor;

FIG. 6 is a measured temperature-output voltage characteristic diagram corresponding to the above data chart (part 1) for examining the influence of the adjustment resistor.

FIG. 7 is a data chart for examining the influence of the adjustment resistor (part 2).

FIG. 8 is a measured temperature-output voltage characteristic diagram corresponding to the above data chart (part 2) for examining the influence of the adjustment resistor.

FIG. 9 is a data chart (part 3) for examining the influence of the adjustment resistor;

FIG. 10 is a measured temperature-output voltage characteristic diagram corresponding to the above data chart (part 3) for examining the influence of the adjustment resistor.

FIG. 11 is a data chart (part 4) for examining the influence of the adjustment resistor;

FIG. 12 is a measured temperature-output voltage characteristic diagram corresponding to the above data chart (part 4) for examining the influence of the adjustment resistor.

FIG. 13 is a data chart for examining the influence of the adjustment resistor (part 5).

FIG. 14 is a measured temperature-output voltage characteristic diagram corresponding to the above data chart (part 5) for examining the influence of the adjustment resistor.

FIG. 15 is a circuit diagram showing a configuration of an input circuit of a conventional temperature controller.

FIG. 16 is a measured temperature-output voltage characteristic diagram of an input circuit of a conventional temperature controller.

[Explanation of symbols]

10 ... high-potential power supply terminal 20 ... low-potential power supply terminal 30 ... platinum resistance 40 ... operational amplifier 50 ... switching control signal input terminal 60 ... inverter 100 ... gain adjustment circuit 200 ... reference point shift circuit R ₁ to R ₇ ... No first seventh resistor R _Pt ... Temperature sensor resistance (platinum resistance thermometer) R _T ... Shift resistor R _T1 ... Adjusting resistor S ₁₁ ... First switch S ₁₃ . reference point a ₁ ... characteristics of the first mode when the switch S ₂₂ ... second switch S ₂₄ ... reference point P ₂ ... second mode when the fourth switch Sc ... switching control signal P ₁ ... first mode Curve B ₁ … Characteristic curve of the second mode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F056 PA03 2G025 BA00 BA08 5J100 AA03 AA04 AA16 BA01 BC07 CA00 CA05 CA11 DA09 EA02 FA00

Claims (5)

[Claims] 1. A first resistor for voltage division, a temperature sensor having a temperature-resistance characteristic, and a second resistor are inserted in series between a high potential side power supply terminal and a low potential side power supply terminal in this order. A third resistor is connected in parallel to the series circuit of the first resistor and the temperature sensor, and a connection point between the first resistor and the temperature sensor is connected to a non-inverting input terminal of an operational amplifier. And a connection point between the temperature sensor and the second resistor is connected to an inverting input terminal of the operational amplifier via a fifth resistor, and is connected between an output terminal and an inverting input terminal of the operational amplifier. An amplification factor adjustment circuit is interposed in the feedback loop. The amplification factor adjustment circuit includes first and second switches that are on / off controlled reciprocally, and a state of a feedback resistor connected between these two switches. And the state connected to the fifth resistor An input circuit of a temperature controller comprising: a sixth resistor that is switched between a first resistor and a non-inverting input terminal of the temperature sensor and the operational amplifier. The reference point shift circuit includes a shift resistor inserted between the first resistor and the temperature sensor, the first resistor and the shift resistor. A third switch inserted between a connection point of the operational amplifier and a non-inverting input terminal of the operational amplifier; and a third switch inserted between the connection point of the shift resistor and the temperature sensor and the non-inverting input terminal. And a fourth switch inserted therein, wherein the first switch is turned on and the second switch is turned on so that the sixth resistor in the amplification factor adjusting circuit does not become a feedback resistor of the operational amplifier. Turn off When,
While turning on the third switch and turning off the fourth switch in the reference point shift circuit so that a voltage between both ends of the temperature sensor and the shift resistor is applied to the operational amplifier, When the first switch is turned off and the second switch is turned on so that the sixth resistor in the amplification factor adjusting circuit becomes a feedback resistor of the operational amplifier, the shift resistor is shifted with respect to the operational amplifier. The third switch in the reference point shift circuit is turned off and the fourth switch is turned on so that a resistor is disconnected and a voltage across the temperature sensor is applied. The input circuit of the temperature controller. 2. A resistance value of a shift resistor of the reference point shift circuit, which is a difference between a resistance value at a lower limit value of a narrow measurement range by the temperature sensor and a resistance value at a lower limit value of a wide measurement range by the temperature sensor. The input circuit of the temperature controller according to claim 1, wherein: 3. An adjusting resistor between the connection point between the temperature sensor and the second resistor and the third resistor, the adjusting resistor having a resistance value close to or equal to the shift resistor. 3. The method according to claim 1, wherein said first and second parts are inserted.
An input circuit of the temperature controller according to 1. 4. The input circuit according to claim 1, wherein said temperature sensor is a platinum resistance temperature detector. 5. It has a configuration according to any one of claims 1 to 4, wherein the temperature sensor is used instead of the temperature sensor.
An input circuit comprising a sensor for an arbitrary physical quantity having a resistance characteristic.