JP2990569B2 - Differential heat detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a differential heat sensor, and more particularly, to the use of a microcomputer and an A / D converter to correct linearly even in a wide temperature measurement region and to continuously correct it. The present invention relates to a differential type heat sensor having a temperature detecting unit capable of obtaining changing temperature data.

[0002]

2. Description of the Related Art A differential type heat sensor using a thermistor as a temperature detecting element is required to have a linear relationship between outside air temperature and temperature data in a wide temperature range (for example, -10 to 80 ° C.). However, in the conventional device, such a demand is not sufficiently satisfied. Therefore, the present applicant has filed Japanese Patent Application No. 4-32.
No. 0177, a microcomputer and an A / D converter are used to previously divide a measured temperature region into three regions of high, medium and low, and a resistance voltage dividing circuit having a linear temperature characteristic output in each of the divided regions. A differential heat sensor having a temperature detection unit formed by switching of switching means has been proposed.

[0003] 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, and R3 having different resistance values prepared in advance to share the temperature measurement region.
3 is selectively switched and connected by switching means SW1, SW2, and SW3 to form a resistance voltage dividing circuit. The resistance voltage dividing output output from the formed resistance voltage dividing circuit is converted to an A / D converter. After being input to the CV and converted into a digital signal, the microcomputer MC obtains linearly corrected temperature data.

However, in the temperature detecting section having such a configuration, it is necessary to A / D convert a resistance voltage divided output obtained by a selective switching operation of the switching means SW1 to SW3. Consumes a lot of current for conversion. Further, in such a temperature detecting section, it is necessary to sequentially switch the switching means SW1, SW2, and SW3 to A / D convert the resistance divided output, and then perform linear correction. ing.

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

[0006] In this case, if the criterion is Dx2 '<72, the temperature measurement region is in the low range T1, that is, -10 to -20.
If ℃ 72 ≦ Dx2 ′ <152, the temperature measurement region is the middle region T
2, that is, if 20 to 50 ° C. 152 <Dx2, the temperature measurement region is determined to be in the high range T3, that is, 50 to 80 ° C. [Procedure 5] The three temperature data Dx1 ′, Dx2 ′, D obtained as described above
An operation is performed on x3 'to calculate temperature data Dx that has been linearly corrected according to the following equation, that is, Dx1, Dx2, and Dx3, and store this in the RAM.

For example, in a temperature range of -10 to 20 ° C., Dx1 is obtained by the following equation. That is, Dx2 is obtained in a temperature range of 10 to 50 ° C. Dx1 = Dx1′x3 / 4-17. That is, Dx3 is obtained in the temperature range of Dx2 = Dx2'x7 / 8 + 40 50 to 80 ° C.

That is, Dx3 = Dx3 '+ 97 The details of the above procedure are shown in steps 200 to 213 of FIG. However, in such a conventional method, the microcomputer M
A / D conversion must be performed three times in C, and A / D conversion
In order to store the converted temperature data Dx1 ', Dx2' and Dx3 'and the linearly corrected temperature data Dx, that is, Dx1, Dx2 and Dx3, the capacity of the RAM required 4 × 8 bits.

However, in a microcomputer, a large current flows during A / D conversion, so that the number of times of A / D conversion is preferably as small as possible. Further, since the capacity of the RAM of the microcomputer is limited, the RAM capacity to be used is as small as possible. It is desired.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a temperature detecting unit for obtaining temperature data in a wide temperature range using a microcomputer and A / D conversion. Another object of the present invention is to reduce the current consumption and the memory capacity of a microcomputer to be used in the differential type heat sensor.

[0011]

SUMMARY OF THE INVENTION The present invention proposed to achieve the above object provides a differential sensor, in particular, a temperature detector, and a method for processing temperature data detected by the temperature detector. Has features. That is, according to the present invention, in a constant voltage power supply, a resistance element sharing a temperature measurement region divided in advance is connected to one thermistor by a switching means so as to be selectable by a switching means. A differential heat sensor that converts the resistance divided output formed by the switching of the above into a digital signal by an A / D converter, and then linearly corrects the temperature data of the outside air by control means including a CPU. In particular, in particular, by switching the switching means, the resistance element selectively connected to the thermistor is selected in advance so as to obtain temperature data that changes linearly for each temperature measurement area to be shared, and the control means Is a resistance divided voltage output obtained by closing a switching unit that substantially shares a middle region among a 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 discrimination, the operation of obtaining the resistance partial pressure output by closing the switching means, which substantially shares the middle region of the temperature measurement region including the outside air temperature, is repeated, and the temperature measurement region including the outside air temperature is sequentially reduced. While searching, the temperature measurement area to which the outside air temperature belongs is searched, and finally the resistance partial pressure output obtained by closing the switching means sharing the temperature measurement area to which the outside air temperature belongs is subjected to A / D conversion and then linearly corrected. Temperature data.

[0012] A differential heat sensor according to a second aspect of the present invention comprises:
The one thermistor has a configuration in which three types of resistance elements sharing the high, middle, and low temperature measurement regions are switchably connected by corresponding switching means. , Each of the resistance elements is configured to form a resistance voltage dividing circuit for sharing a temperature measurement region by switching operation of switching means provided corresponding to one thermistor. The resistance element is connected in series to one thermistor in advance, and has a configuration in which the output of the resistance voltage dividing circuit is additively changed by a switching operation of a correspondingly provided switching means.

[0013]

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

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

Next, a procedure for calculating temperature data according to the present invention will be described. According to the present invention, after the outside air temperature is detected and A / D converted by the following procedure, the microcomputer calculates temperature data that has been linearly corrected. [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 used as temperature data Dx2 '. It is stored in the RAM of the microcomputer MC. [Procedure 2] Temperature data Dx captured in Procedure 1
According to 2 ′, it is determined which of the temperature measurement areas of the current outside air temperature is −10 to 20 ° C. (low range), 20 to 50 ° C. (middle range), and 50 to 80 ° C. (high range). .

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

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

Further, an operation is performed on the temperature data Dx1 'to obtain the linearly corrected temperature data Dx1 and store it in the RAM of the microcomputer MC (overwrite Dx1').
At this time, Dx1 is Dx1 = Dx1'x3 / 4-17.
Is calculated as <Procedure 3-3> If the temperature measurement area is determined to be 50 to 80 ° C. based on the temperature data Dx2 ′, only the switch SW3 is closed, and the divided voltage between the thermistor RTH and the resistor R3 is converted into an A / D converter of the microcomputer MC. A / D conversion with CV, A / D
The converted value is used as the temperature data Dx3 'by the microcomputer MC.
(Overwrite Dx2 ').

Further, an operation is performed on the temperature data Dx3,
Calculates the linearly corrected temperature data Dx3 and calculates the microcomputer MC
(Overwrite Dx3 '). At this time, Dx3 is calculated as Dx3 = Dx3 '+ 97. The above procedure is shown in steps 100 to 113 in FIG. In the present invention, by performing the processing according to the above procedure, the A / D conversion needs to be performed only once when obtaining Dx2 ′ in the temperature measurement region 20 to 50 ° C., and the temperature measurement region −10 to 20
A / D conversion is Dx2 ', Dx
Only two times when calculating 1 ′ and Dx3 ′ are required.

FIG. 3 shows that five resistance elements R1 to R5 are connected to one thermistor by switching means SW1 to SW5.
5 shows a temperature detecting section which can be switched and connected to form five voltage-dividing resistor circuits.
FIG. 3B is a circuit diagram of the temperature detection unit, and FIG. 3B shows the order of switching connection of the five switching SW1 to SW5 when the present invention is applied. The resistance voltage dividing circuit formed by the switching connection of the five switching switches SW1 to SW5 is configured to share a temperature measurement region in which the temperature measurement region measurable by the differential heat sensor is divided into five in advance. , SW3 is closed, and the resistive voltage dividing circuit shares the middle region of the measurable temperature measurement region, and shares the higher temperature measurement region in the order of SW1, SW2, SW3, SW4, and SW5. I have.

In such a configuration, the switching means S
The maximum number of times of closing W1 to SW5 and performing A / D conversion can be three times. FIG. 4 shows that six resistance elements R1 to R6 are connected to one thermistor by switching means S.
FIG. 7A shows a temperature detecting unit which is switched by W1 to SW6 to form six voltage dividing resistor circuits, wherein FIG. 7A is a circuit diagram of the temperature detecting unit, and FIG. Switching SW1 to SW6 in the case of
(Claims 1 and 3).

SW3 or SW4 shares the middle area of the temperature measurement area that can be measured by the differential heat sensor, and switches SW1, SW2, SW3, SW4 and SW.
5, the resistance voltage dividing circuit formed by the switching of SW6 shares the higher temperature measurement region in order. Since the temperature measurement area measured by the differential heat sensor is shared by six even-numbered resistive voltage dividing 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 for switching connection. Even in 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 is reduced in the temperature measurement region by the resistance partial pressure output obtained by closing the switching means that substantially shares the middle region among the plurality of temperature measurement regions divided in advance. It is determined whether it belongs to the lower side, the higher side, or the middle side, and as a result of this determination, the switching means, which almost shares the middle range of the temperature measurement area including the outside air temperature, is closed and the resistance partial pressure output is obtained. Repeating the operation to obtain the temperature measurement area to which the outside air temperature belongs while searching for the temperature measurement area to which the outside air temperature belongs, and finally switching means for sharing the divided temperature measurement area to which the outside air temperature belongs The resistance divided output obtained by closing is represented by A /
Since a method of obtaining temperature data by linearly correcting after D-conversion is adopted, the number of times that a large current flows during A / D conversion of the microcomputer MC can be reduced, and the current consumption of the heat sensor is 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, SW3 are provided at the connection of each of the resistance elements RA, RB, RC to provide a temperature detection section. 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 resistance R
A resistor-divided circuit connected to A is formed. When the divided resistor output is input to the A / D converter CV and only the switching means SW2 is closed, the thermistor RTH connects the resistors RA and RB to each other. A pressure circuit is formed,
The resistance divided output is input to the A / D converter CV,
When only the switching means SW3 is closed, a resistance voltage dividing circuit in which the resistances RA, RB and RC are connected is formed in the thermistor RTH, and the resistance voltage divided output is inputted to the A / D converter CV. Therefore, in this case, the relationship with FIG. 2A is as follows: R1 = RA R2 = RA + RB R3 = RA + RB + RC, and the resistive voltage dividing circuit formed by switching of the switching means SW1, SW2, SW3 performs differential thermal sensing. The low, middle, and high ranges of the temperature measurement region measured by the instrument may be shared.

Therefore, in such a method, the microcomputer M
The number of times a large current flows during A / D conversion of C can be reduced, and the current consumption of the heat detector can be reduced. Further, the RAM capacity to be used can be completely overwritten, so that a smaller RAM capacity is required as compared with the conventional method, and the RAM capacity has a sufficient margin. According to the present invention, when a wide temperature measurement area (−10 to 80 ° C.) necessary for a differential heat sensor is divided into a plurality of temperature measurement areas and the thermistor temperature characteristics are linearized, first, A / D conversion is performed using a resistance voltage dividing circuit that shares almost the middle region of the temperature measurement area, and the A / D conversion is performed after determining the outside air temperature, so the number of A / D conversions is reduced. Also, the amount of RAM used can be reduced.

[0026]

According to the differential heat sensor of the present invention proposed in claims 1 to 4, as described above, the number of times of A / D conversion can be reduced as compared with the conventional procedure. Therefore, it is possible to reduce the current consumption of the heat detector due to the 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 can be used for other purposes.

[Brief description of the drawings]

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

FIG. 2A is a block diagram showing a basic configuration of a heat detection unit (an example in which a temperature measurement area is divided into three parts) of a differential heat sensor according to the present invention, and FIG. It is explanatory drawing which shows the order of conversion.

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

FIG. 4A is a block diagram showing a basic configuration of a heat detection unit (an example in which a temperature measurement area is divided into six parts) of a differential type heat sensor of the present invention, and FIG. It is explanatory drawing which shows the order of conversion.

FIG. 5 is a block diagram showing a basic configuration (claim 4) of a heat detecting section of the differential heat detector of the present invention.

FIG. 6 is a block diagram showing a basic configuration of a heat detection unit of the differential heat sensor.

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

[Explanation of symbols]

 VIN: constant voltage source RTH: thermistor R1, R2, R3, R4, R5, R6: resistance element MC: microcomputer CV: A / D converter T1, T2, T3: division Temperature measurement area

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G08B 17/06 G01L 7/24

Claims (4)

(57) [Claims] 1. A constant-voltage power supply, wherein one of the thermistors is connected in a selectable manner with a resistance element sharing a pre-divided temperature measurement region by switching means, and a resistance element formed by switching of the switching means is connected. After converting the pressure output to a digital signal with an A / D converter,
In a differential heat sensor in which temperature data of the outside air is obtained by performing linear correction by control means including a PU, a resistance element selectively connected to the thermistor by switching of the switching means is shared. The temperature data that linearly changes for each temperature measurement region to be obtained is selected in advance, and the control unit closes a switching unit that substantially shares a middle region among a plurality of temperature measurement regions divided in advance. It is determined whether the outside air temperature belongs to the lower side, the higher side, or the middle side of the temperature measurement area based on the resistance partial pressure output obtained as a result, and as a result of this determination, the temperature including the outside air temperature is determined. The operation of obtaining the resistance partial pressure output by closing the switching means sharing the substantially middle region of the measurement region is repeated, and while the temperature measurement region including the outside air temperature is sequentially reduced, the outside air temperature is reduced. A / D conversion is performed on the divided resistance measurement output obtained by closing the switching means for sharing the divided temperature measurement area to which the outside air temperature belongs. A differential heat sensor that obtains temperature data. 2. The differential heat sensor according to claim 1, wherein the one thermistor is provided with three types of resistance elements that share a high, middle, and low temperature measurement region. A differential heat sensor configured to be switchably connected by three switching means. 3. A resistance voltage dividing circuit for sharing a temperature measurement area by switching operation of switching means provided corresponding to one thermistor for each of said resistance elements. 4. A differential heat sensor according to claim 1. 4. A configuration in which the resistance element is connected in series to one thermistor in advance, and the output of the resistance voltage dividing circuit is added by a switching operation of a correspondingly provided switching means. The differential heat sensor according to claim 1 or 2, wherein