JPH07272155A - Differential type heat sensor - Google Patents

Abstract

PURPOSE:To reduce power consumed by a microcomputer and reduce the memory capacity in a differential type heat sensor provided with a temperature detection part composed of the microcomputer and an A/D converter so as to obtain linear temperature data in a wide temperature measuring area. CONSTITUTION:A control means MC judges whether an outside air temperature belongs to the side of an area T1 lower than the middle area of the temperature measuring areas, to the side of an area T3 higher than it, or to the side of a middle area T2 by means of a resistance voltage dividing output obtained by closing a switching means SW2 in charge of almost a middle area among plural temperature measuring areas divided in advance. From this judged result, the control means MC reapeats an operation for obtaining a resistance voltage dividing output by closing the switching means SW2 in charge of almost the middle area of temperature measuring areas including the temperature measuring area to which the outside air temperature belongs to retrieve a divided temperature measuring area to which the outside air temperature belongs while successively narrowing the temperature measuring area which the outside air temperature belongs to, and finally, the control means MC A/D-converts a resistance voltage dividing output obtained by closing switching means SW1 to SW3 in charge of a divided temperature measuring area to which the outside air temperature belongs and thereafter, corrects the data to be linear to obtain temperature data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a differential thermal sensor, and more specifically, by using a microcomputer and an A / D converter, it is linearly corrected even in a wide temperature measurement range and continuously. The present invention relates to a differential heat sensor including a temperature detection unit that can obtain changing temperature data.

[0002]

2. Description of the Related Art In a differential type heat detector using a thermistor as a temperature detecting element, it is required that the relationship between the outside air temperature and the temperature data is linear in a wide temperature range (for example, -10 to 80 ° C.). However, in the conventional one, such a requirement is not sufficiently satisfied. Therefore, the present applicant has filed Japanese Patent Application No.
In No. 0177, using a microcomputer and an A / D converter, the measurement temperature region is divided into three regions of high, middle, and low in advance, and a resistance voltage divider circuit having a linear temperature characteristic output is provided in each divided region. A differential thermal sensor provided with a temperature detecting part formed by switching the switching means has been proposed.

That is, the temperature detector of this heat detector is
As shown in FIG. 6, for the constant voltage power supply VIN, one thermistor RTH and three resistance elements R1, R2, R having different resistance values prepared in advance for sharing the temperature measurement region.
3 can be selectively connected by switching means SW1, SW2, SW3 to form a resistance voltage dividing circuit, and the resistance voltage dividing output from the resistance voltage dividing circuit thus formed is converted into an A / D converter. After input to the CV and converted into a digital signal, temperature data linearly corrected by the microcomputer MC can be obtained.

However, in the temperature detecting section having such a configuration, it is necessary to A / D convert the resistance voltage division output obtained by the selective switching operation of the switching means SW1 to SW3, and this A / D is generally used. It consumes a lot of current for conversion. Further, in such a temperature detection unit, it is necessary to sequentially switch the switching means SW1, SW2, SW3 to A / D convert the resistance voltage division output, and then perform linear correction, but the procedure is as follows. ing.

[Procedure 1] First, only the switching means SW1 is closed,
The resistance voltage division output, which is the voltage division value of the resistance voltage division circuit formed by the thermistor RTH and the resistance R1, is A / in the microcomputer MC.
A / D conversion is performed by the D converter CV, and the A / D converted value is stored in the memory (RAM) in the microcomputer MC as temperature data Dx1 ′. [Procedure 2] Next, only the switching means SW2 is closed, and the resistance division output which is the division value of the resistance division circuit formed by the thermistor RTH and the resistance R2 is A / D by the A / D converter CV in the microcomputer MC. The D-converted and A / D-converted value is further stored in the memory (RAM) in the microcomputer MC as temperature data Dx2 ′. [Procedure 3] Further, only the switching means SW3 is closed,
The resistance voltage division output, which is the voltage division value of the resistance voltage division circuit formed by the thermistor RTH and the resistance RC, is A / in the microcomputer MC.
A / D conversion is performed by the D converter CV, and the A / D converted value is stored in the memory (RAM) in the microcomputer MC as temperature data Dx3 ′. [Procedure 4] As described above, the memory (R
AM) stored in three temperature data Dx1 ', Dx
The temperature data Dx2 ′ sharing the mid range of 2 ′ and Dx3 ′ is taken out, and the current temperature is referred to, and the current temperature is −10 to 20 ° C. (low range), 20 to 50 ° C. (medium range), 50.
Which temperature measurement region of -80 ° C (high range) is determined.

If Dx2 '<72, the criterion in this case is that the temperature measurement region is the low region T1, that is, -10 to 20.
If ℃ 72 ≦ Dx2 ′ <152, the temperature measurement area is the middle area T
2, that is, 20 to 50 ° C. 152 <Dx2, it is determined that the temperature measurement region is the high region T3, that is, 50 to 80 ° C. [Procedure 5] Three temperature data Dx1 ', Dx2', D obtained as described above
The temperature data Dx linearly corrected according to the following equation, that is, Dx1, Dx2, Dx3 is calculated according to the following equation, and stored in the RAM.

For example, in the temperature range of -10 to 20 ° C, Dx1 is calculated by the following equation. That is, Dx2 is calculated in the temperature range of Dx1 = Dx1′x3 / 4/7 10 to 50 ° C. That is, Dx3 is obtained in the temperature range of Dx2 = Dx2′x7 / 8 + 40 50 to 80 ° C.

That is, Dx3 = Dx3 '+ 97 Details of the above procedure are shown in steps 200 to 213 of FIG. However, in such a conventional method, the microcomputer M
It is necessary to perform A / D conversion 3 times in C.
The RAM capacity required to store the converted temperature data Dx1 ′, Dx2 ′ Dx3 ′ and the linearly corrected temperature data Dx, that is, Dx1, Dx2, Dx3, was 4 × 8 bits.

However, since a large current flows during A / D conversion in a microcomputer, it is preferable that the number of times A / D conversion is performed be as small as possible, and the RAM capacity of the microcomputer is also limited, so the RAM capacity used is as small as possible. Is desired.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a temperature detecting section for obtaining temperature data in a wide temperature range by using a microcomputer and A / D conversion. In the provided differential heat sensor, the current consumption is reduced and the memory capacity of the microcomputer used is reduced.

[0011]

SUMMARY OF THE INVENTION The present invention, which is proposed to achieve the above object, provides a differential sensor, in particular, a temperature detecting section and a method for processing temperature data detected by the temperature detecting section. It has features. That is, according to the present invention described in claim 1, in the constant voltage power supply, one thermistor is connected to a resistance element which divides a temperature measurement region divided in advance so as to be switchably selectable by the switching means, and the switching means. A differential thermal sensor for converting the resistance voltage divided output formed by switching the above into a digital signal by an A / D converter, and then linearly correcting it by control means including a CPU to obtain temperature data of the outside air. With regard to the above, particularly, the resistance element selectively connected to the thermistor by switching the switching means is selected in advance so that temperature data that linearly changes for each temperature measurement region to be shared is obtained. Is a resistance voltage division output obtained by closing the switching means that shares almost the middle region of the plurality of temperature measurement regions divided in advance. Therefore, to determine the outside air temperature is higher or side or side lower than the midrange of the temperature measurement area, or belonging to the middle band side. And
As a result of this determination, the operation for obtaining the resistance voltage-divided output is repeated by closing the switching means that shares almost the middle region of the temperature measurement region including the outside air temperature, and the temperature measurement region including the outside air temperature is gradually reduced. While retrieving, the temperature measurement region to which the outside air temperature belongs is searched, and finally, the resistance partial pressure output obtained by closing the switching means that shares the temperature measurement region to which the outside air temperature belongs is A / D converted and then linearly corrected. Then, temperature data is obtained.

The differential thermal sensor according to claim 2 is
The one thermistor is configured such that three types of resistance elements, which share temperature measurement regions of high band, middle band, and low band, are switchably connected by corresponding switching means. Each of the resistance elements is configured to form a resistance voltage dividing circuit that shares a temperature measurement region with a switching operation of switching means provided corresponding to one thermistor. The resistance element is connected in series to one thermistor in advance, and the output of the resistance voltage dividing circuit is additively changed by the switching operation of the corresponding switching means.

[0013]

EXAMPLE An example of the present invention will be described below. Figure 2
FIG. 2A is a diagram showing a temperature detection unit which is a main part of the differential heat sensor of the present invention, and FIG. 2B shows a procedure of switching the switching means SW1 to SW3 to perform A / D conversion. It is shown as a table (claims 2 and 3). As shown in the figure, for one thermistor RTH to which a constant voltage power supply VIN by a battery is applied, three types of resistance elements R
1, R2, R3 are switching means SW1, SW2, S
Connected switchably by W3, each resistor R1, R
The input terminals of 2, R3 are input to the A / D converter,
The other ends of the switching means SW1, SW2 and SW3 are connected to the negative terminal of the battery VIN.

Here, the resistance elements R1, R2 and R3 are the switching means SW1, SW2 provided corresponding to them.
By selectively closing SW3, a resistance voltage dividing circuit is formed, and this resistance voltage dividing circuit is pre-divided in the temperature measurement range (-10 to 80 ° C) that can be measured by the differential thermal sensor. Low temperature range T1 (-10 to 20
C), middle range T2 (20 to 50 C), high range T3 (50 to 8)
0 ° C.), and the resistance voltage division output from each resistance voltage division circuit is in the low range T1 (−10 to 20).
C), middle range T2 (20 to 50 C), high range T3 (50 to 8)
In the temperature range of 0 ° C., the outside air temperature and the temperature data are linearly corrected temperature data.

Next, a procedure for calculating temperature data according to the present invention will be described. According to the present invention, the outside air temperature is detected and A / D converted in the following procedure, and then the temperature data linearly corrected by the microcomputer is calculated. [Procedure 1] Only SW2 is closed, the divided voltage value of the thermistor RTH and the resistor R2 is A / D converted by the A / D converter CV in the microcomputer MC, and the A / D converted value is set as the temperature data Dx2 ′. It is stored in the RAM of the microcomputer MC. [Procedure 2] Temperature data Dx acquired by procedure 1
2'determines which temperature measurement area the current outside air temperature is from -10 to 20 ° C (low range), 20 to 50 ° C (medium range), and 50 to 80 ° C (high range). .

The determination criterion in this case is that if Dx2 '<72, the temperature measurement region is the low region T1, that is, -10 to 20.
If ℃ 72 ≦ Dx2 ′ <152, the temperature measurement area is the middle area T
2, that is, 20 to 50 ° C. 152 <Dx2, it is determined that the temperature measurement region is the high region T3, that is, 50 to 80 ° C. [Procedure 3] The following three methods are selected and executed according to the temperature measurement region determined by the temperature data Dx2 '. <Procedure 3-1> When the temperature measurement region is determined to be 20 to 50 ° C. by the temperature data Dx2 ′, the temperature data Dx2 ′ acquired in the procedure 1 is directly calculated to obtain the linearly corrected temperature data Dx2. Find, R of microcomputer MC
Store in AM (overwrite Dx2 ').

At this time, Dx2 is Dx2 = Dx2'x
Calculated as 7/8 + 40. <Procedure 3-2> If the temperature measurement region is determined to be −10 to 20 ° C. based on the temperature data Dx2 ′, only the switching means SW1 is closed and the partial pressure value between the thermistor RTH and the resistor R1 is A / of the microcomputer MC. A / with D converter CV
The D-converted and A / D-converted value is stored in the RAM of the microcomputer MC as the temperature data Dx1 ′ (overwritten on Dx2 ′).

Further, the temperature data Dx1 'is calculated to obtain the linearly corrected temperature data Dx1 and stored in the RAM of the microcomputer MC (overwriting Dx1').
At this time, Dx1 is Dx1 = Dx1′x3 / 4 / 4-17
Calculate as <Procedure 3-3> If the temperature measurement region is determined to be 50 to 80 ° C. by the temperature data Dx2 ′, only SW3 is closed and the partial pressure values of the thermistor RTH and the resistor R3 are converted into the A / D converter of the microcomputer MC. A / D conversion by CV, A / D
The converted value is used as the temperature data Dx3 ', and the microcomputer MC
Stored in the RAM (overwriting Dx2 ′).

Further, calculation is performed on the temperature data Dx3,
Microcomputer MC for obtaining linearly corrected temperature data Dx3
Stored in the RAM (overwriting Dx3 ′). At this time, Dx3 is calculated as Dx3 = Dx3 ′ + 97. The above procedure is shown in steps 100 to 113 of FIG. In the present invention, by performing the treatment in the above procedure, the A / D conversion in the temperature measurement region of 20 to 50 ° C. may be performed only once when obtaining Dx2 ′, and the temperature measurement region of −10 to 20.
A / D conversion is Dx2 ', Dx at 50 ℃ to 80 ℃
Two times are required when calculating 1 ′ and Dx3 ′.

In FIG. 3, five resistance elements R1 to R5 are connected to one thermistor and switching means SW1 to SW.
5 shows a temperature detecting section which is switchably connected by 5 to form five voltage dividing resistor circuits.
Shows a circuit diagram of the temperature detection unit, and FIG. 7B shows the order of switching connection of the five switching switches SW1 to SW5 when the present invention is applied (claims 1 and 3). The resistance voltage dividing circuit formed by the switching connection of the five switching switches SW1 to SW5 shares the temperature measurement region obtained by dividing the temperature measurement region that can be measured by the differential heat sensor into five in advance. , SW3 is formed by the resistance voltage divider circuit that shares the middle region of the measurable temperature measurement region and the higher temperature measurement region in the order of SW1, SW2, SW3, SW4, and SW5. There is.

In such a configuration, the switching means S
You can close W1-SW5 and perform A / D conversion up to 3 times. In FIG. 4, six resistance elements R1 to R6 are connected to the switching means S for one thermistor.
This figure shows a temperature detection part that is switched by W1 to SW6 to form six voltage dividing resistance circuits. FIG. 7A is a circuit diagram of the temperature detection part, and FIG. 6 switchings SW1 to SW6
The order of the switching connection is shown (claims 1 and 3).

SW3 or SW4 shares the middle region of the temperature measuring region that can be measured by the differential heat sensor, and the switching means SW1, SW2, SW3, SW4, SW.
5, the resistance voltage dividing circuit formed by switching SW6 is shared in order of the higher temperature measurement region. The temperature measurement area measured by the differential heat sensor is shared by the even number of six resistor voltage divider circuits.
SW3 and SW4 can be selected as the middle region of the temperature measurement region. In FIG. 4B, SW3 is first switched and connected to form a resistance voltage dividing circuit. Next, SW2 or SW5 is selected as the switching means to be switched and connected, and even with such a configuration, A / D conversion can be performed up to three times.

As described above, according to the present invention, the outside air temperature in the temperature measurement region is determined by the resistance partial pressure output obtained by closing the switching means for sharing the substantially middle region among the plurality of temperature measurement regions divided in advance. It is determined whether it is on the lower side, the higher side, or the middle range side than the range, and as a result of this determination, the switching means that shares almost the middle range of the temperature measurement area including the outside air temperature is closed and the resistance partial pressure output The operation of obtaining the temperature is repeated, the temperature measurement area including the outside air temperature is sequentially reduced, the temperature measurement area to which the outside air temperature belongs is searched, and finally, the switching means that shares the divided temperature measurement area to which the outside air temperature belongs is allocated. The resistance partial pressure output obtained by closing is
Since the method of obtaining temperature data by linearly correcting after D conversion is adopted, the number of times a large current flows during A / D conversion of the microcomputer MC can be reduced, and the current consumption of the heat sensor can be reduced. Can be reduced. In FIG. 5, the resistance elements RA to RC are connected in series to one thermistor RTH in advance, and switching means SW1, SW2 and SW3 are provided at the connection parts of the respective resistance elements RA, RB and RC to provide a temperature detection part. The switching means SW1,
The output of the resistance voltage dividing circuit is sequentially and additively changed by the switching operation of SW2 and SW3 (claim 4).

In such a configuration, the switching means S
When only W1 is closed, the thermistor RTH has a resistor R
When a resistance voltage dividing circuit to which A is connected is formed, the resistance voltage dividing output is input to the A / D converter CV, and only the switching means SW2 is closed, the resistance voltage dividing resistor RA and RB are connected to the thermistor RTH. A pressure circuit is formed,
The divided resistance output is input to the A / D converter CV,
When only the switching means SW3 is closed, a resistance voltage dividing circuit in which resistors RA, RB and RC are connected is formed in the thermistor RTH, and the resistance voltage dividing output is input to the A / D converter CV. Therefore, in this case, the relationship with FIG. 2A is R1 = RA R2 = RA + RB R3 = RA + RB + RC, and the resistance voltage dividing circuit formed by switching the switching means SW1, SW2, SW3 is a differential thermal sensing circuit. It suffices to share the low, middle and high regions of the temperature measurement region measured by the instrument.

Therefore, in such a method, the microcomputer M
The number of times a large current flows at the time of A / D conversion of C can be reduced, and the current consumption of the heat sensor can be reduced. Further, the RAM capacity to be used can be entirely overwritten, and the RAM capacity can be reduced as compared with the conventional method, and the RAM capacity can be sufficiently spared. In the present invention as described above, when a wide temperature measurement region (−10 to 80 ° C.) required for the differential thermal sensor is divided into a plurality of temperature measurement regions and the thermistor temperature characteristic is linearized, first, Since the A / D conversion is performed using the resistance voltage divider circuit that shares almost the middle region of the temperature measurement region, and the A / D conversion is performed after determining the outside air temperature, the number of A / D conversions is reduced. The RAM capacity used can also be reduced.

[0026]

As described above, according to the differential thermal sensor of the present invention proposed in claims 1 to 4, the number of A / D conversions can be reduced as compared with the conventional procedure. Therefore, it is possible to reduce the consumption capacity of the heat sensor associated with A / D conversion. Further, since the number of times of A / D conversion is reduced, the RAM capacity to be used can be reduced, so that the RAM capacity can have a margin, and the reduced RAM capacity used can be used for other purposes.

[Brief description of drawings]

FIG. 1 is a flowchart showing a basic operation procedure of temperature measurement in a differential heat sensor of the present invention.

FIG. 2 (a) is a block diagram showing a basic configuration of a heat detector (an example in which a temperature measurement region is divided into three parts) of a differential heat detector of the present invention, and FIG. 2 (b) is an A / D. It is explanatory drawing which shows the order of conversion.

FIG. 3 (a) is a block diagram showing a basic configuration of a heat detector (an example in which a temperature measurement region is divided into five parts) of a differential heat detector of the present invention, and FIG. 3 (b) is an A / D. It is explanatory drawing which shows the order of conversion.

FIG. 4A is a block diagram showing a basic configuration of a heat detector (an example in which a temperature measurement region is divided into six parts) of a differential heat detector of the present invention, and FIG. 4B is an A / D. It is explanatory drawing which shows the order of conversion.

FIG. 5 is a block diagram showing a basic configuration (Claim 4) of the heat detecting portion of the differential heat sensor of the present invention.

FIG. 6 is a block diagram showing a basic configuration of a heat detector of the differential heat detector.

FIG. 7 is a flowchart showing a conventional basic operation procedure of temperature measurement in the differential heat sensor.

[Explanation of symbols]

 VIN ・ ・ ・ Constant voltage source RTH ・ ・ ・ Thermistor R1, R2, R3, R4, R5, R6 ・ ・ ・ Resistor element MC ・ ・ ・ Microcomputer CV ・ ・ ・ A / D converter T1, T2, T3 ・ ・ ・ Split Temperature measurement area

[Procedure amendment]

[Submission date] August 30, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026]

As described above, according to the differential thermal sensor of the present invention proposed in claims 1 to 4, the number of A / D conversions can be reduced as compared with the conventional procedure. Therefore, it is possible to reduce the current consumption of the heat sensor due to A / D conversion. Further, since the number of times of A / D conversion is reduced, the RAM capacity to be used can be reduced, so that the RAM capacity can have a margin, and the reduced RAM capacity used can be used for other purposes.

Claims (4)

[Claims] 1. A constant voltage power supply, wherein a resistance element formed by switching the switching means is connected to one thermistor so as to be switchably selectable by a resistance element which divides a temperature measurement region divided in advance. After converting the pressure output into a digital signal with an A / D converter, C
In a differential thermal sensor in which temperature data of outside air is linearly corrected by control means including PU, the resistive element selectively connected to the thermistor is shared by switching the switching means. The temperature data that changes linearly for each temperature measurement region is selected in advance, and the control unit closes the switching unit that shares almost the middle region of the plurality of temperature measurement regions divided in advance. Based on the resistance partial pressure output obtained as a result, it is determined whether the outside air temperature is lower, higher, or belongs to the middle range of the temperature measurement area.As a result of this determination, the temperature that includes the outside air temperature is determined. The operation to obtain the resistance partial pressure output is repeated by closing the switching means that shares almost the middle region of the measurement area, and the temperature measurement area that includes the outside air temperature is gradually reduced while the outside air temperature is reduced. Of the temperature measurement region to which the outside air temperature belongs is searched, and finally, the resistance partial pressure output obtained by closing the switching means for sharing the divided temperature measurement region to which the outside air temperature belongs is A / D converted and then linearly corrected. A differential type heat sensor designed to obtain temperature data. 2. The differential thermal sensor according to claim 1, wherein the one thermistor corresponds to three types of resistance elements that share temperature measurement regions of a high band, a middle band and a low band. A differential heat sensor configured to be switchably connected by three switching means. 3. Each of the resistance elements is configured to form a resistance voltage dividing circuit that shares a temperature measurement region with one thermistor by switching operation of corresponding switching means. The differential thermal sensor described in. 4. A structure in which the resistance element is connected in series to one thermistor in advance, and the output of the resistance voltage dividing circuit is additively changed by switching operation of corresponding switching means. The differential thermal sensor according to claim 1 or 2.