JPH07270303A - Environment tester - Google Patents

Abstract

PURPOSE:To enhance the test efficiency by making the temperature almost at the center in a test chamber to be accurately controlled without disturbing the housing of test pieces while making the temperature reach a set temperature as early as possible at the start of a testing and at the altering of the set temperature. CONSTITUTION:A closed test chamber 3 to house test pieces is formed in a box body 4 of an apparatus body. Air in the test chamber 3 is circulated by the rotation of a fan 15 and sucked into an suction port 9 so that it passes through a heat exchange section 13 comprising a cooling coil 12 and a heater 11 to be blown into the test chamber 3 through a blowoff port 10. Then, platinum resistance thermometer elements 21 and 22 are arranged near the suction port 9 and near the blowoff port 10 as temperature sensors respectively and a controller controls the heat exchange section 13 so that a means of measured temperatures with the respective temperature sensors coincides with a target temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an environment used for investigating the characteristics and presence / absence of abnormalities under various environmental conditions such as temperature and humidity that can be assumed for various test products such as electronic parts and electronic devices. Regarding test equipment. This environmental test device includes a thermo-hygrostat, a high-low temperature thermostat, a weather resistance tester, a thermal shock test device, a thermal cycler, and the like.

[0002]

2. Description of the Related Art Products using various electronic parts and electric parts are artificially manufactured after completion in order to prevent any problems even if they are used under various environmental conditions. Assumed usage conditions (temperature, humidity, etc.)
Placed inside the product to check for abnormalities, measure the characteristics of the product in the development stage under various environmental conditions and use it as the technical data at the time of development, or the product after sale was returned to the manufacturer due to some defect. At times, in order to investigate the cause, it is performed to reproduce the environmental conditions under which it was used and investigate the cause of the failure.

To artificially create such environmental conditions, for example, a constant temperature and humidity chamber (high humidity is also possible), a high and low temperature constant temperature chamber, a weather resistance tester, a thermal shock test device, a thermal cycle device (temperature cycle test). Environment test equipment such as a container) is used. Such an environmental test device is a case that forms a sealed test chamber for storing a test product to be subjected to an environmental test, and a heating unit (heater or the like) for keeping the test chamber at a required temperature. And a heat exchanging unit including both or one of a cooling unit (freezing coil and the like) and a control unit (controller) for the heat exchanging unit.

Further, a suction port and an air outlet are opened at positions such as upper and lower portions of the test chamber, air in the test chamber is sucked from the air inlet, and blown into the test chamber from the air outlet through the heat exchange section. An air blower (a blower fan or the like) is provided, and the temperature is controlled so as to maintain the set target temperature while circulating the air in the test chamber.

Therefore, in the conventional environmental test apparatus, a temperature sensor is generally arranged near the outlet, and the temperature of the warm air or the cold air blown into the test chamber is measured by the blowing means, and the temperature is set as the target. To match the temperature,
The controller was controlling the heater etc. of the heat exchange part. Alternatively, a temperature sensor may be arranged near the suction port to measure the temperature of the air recirculated from the test chamber, and the temperature may be controlled to match the target temperature.

The temperature within the test chamber that can be controlled by such an environmental test apparatus is generally -20.
℃ ~ +100 ℃, but some can be cooled to -70 ℃, +2 in thermal shock test equipment
It is possible to heat above 00 ° C. Further, the environmental conditions (temperature, etc.) in the test chamber can be set to a program that changes the environmental conditions every predetermined time, in addition to always maintaining constant conditions.

[0007]

However, in such an environmental test apparatus, although the air in the test chamber is circulated, it is not uniform in the entire room, and the position where the temperature is measured by the temperature sensor and the actual test product are measured. Since there is a temperature difference between the mounting position (usually the central portion is large), the test product cannot be accurately maintained at the set temperature.

Further, when a new test product is stored in the test chamber to start the test, or when the test is performed by changing the set temperature arbitrarily or in a predetermined cycle, the set temperature and the test product are compared with each other. Since the temperature difference becomes large, heat absorption or heat dissipation occurs due to the heat capacity of the test product, and the temperature difference between the vicinity of the blowout port and the vicinity of the test product or the suction port becomes large, and the above-mentioned problem becomes remarkable.

Therefore, if an environmental test cannot be performed under strict temperature conditions, or if a temperature sensor is installed near the air outlet, the room temperature will be measured high during heating and low during cooling. There is a problem that cooling is suppressed and it takes time to reach the set temperature, and the test time also takes a long time.If a temperature sensor is installed near the suction port, the room temperature should be low when heating and low when cooling. Since the measurement is performed at a high level, heating or cooling may be excessive, which is not preferable in terms of safety.

In order to solve such a problem, it is possible to install a temperature sensor in the center of the test chamber.
This will hinder the storage of test products of various shapes and sizes, and if the temperature sensor comes into contact with the test products, it will not be possible to accurately measure the room temperature.

The present invention has been made in order to solve these various problems, and it is possible to accurately control the temperature in the substantially central portion of the test chamber without hindering the storage of test products. At the same time, it is an object of the present invention to safely and quickly reach the set temperature at the start of the test and when the set temperature is changed so that the test efficiency can be improved.

[0012]

In order to achieve the above-mentioned object in the above-mentioned environmental test apparatus, the present invention provides temperature sensors in the vicinity of the inlet and the outlet of the test chamber, The control means is configured to control the heat exchange section (heating section or cooling section) so that the average value of the temperatures measured by the respective temperature sensors coincides with the target temperature (set value). In the heat exchange part including a heating part and a cooling part, the control means may be configured to control only the heating part so that the average value of the temperatures measured by the temperature sensors coincides with the target temperature. Good.

A platinum resistance temperature detector may be used as each of the temperature sensors. In that case, two platinum resistance temperature detectors, which are respectively arranged near the suction port and near the blowout port, are connected in series to flow a constant current, and both ends of the series circuit of the two platinum resistance temperature detectors are connected. The temperature measuring circuit can be configured so that the potential difference generated between them is input to the control means as information corresponding to the average value of the temperature measured by each temperature sensor.

[0014]

The environmental test apparatus thus constructed targets the average value of the intake air temperature and the blown air temperature from the test chamber, which are measured by the temperature sensors respectively arranged near the inlet and the outlet of the test chamber. Since the heating section or the cooling section of the heat exchange section is controlled so as to match the temperature (set value), the temperature of the substantially central portion where the test article is placed can be set to the set value. Moreover, the measured temperature never rises or falls when the temperature rises or falls, heating or cooling is suppressed and the time until the set temperature is reached is extended, and conversely heating or cooling is excessive. There is no loss of safety.

In the case where the heat exchanging section is composed of a heating section and a cooling section, a general refrigerator operating the cooling section cannot finely adjust the cooling output, so that it is always operated during the test and heated. The temperature of the central part of the test chamber can be set to the set temperature and maintained by the control of only the part.

If a platinum resistance temperature detector is used as the temperature sensors arranged near the suction port and near the air outlet, respectively, the temperature can be controlled with high stability and high accuracy. In addition, the two platinum resistance thermometers are connected in series, and a constant current (a current that is 1/2 that of a single platinum resistance temperature detector) is applied to the two platinum resistance thermometers. The potential difference between both ends of the series circuit of the resistance temperature detector, that is, the value corresponding to the measured temperature, becomes a value corresponding to the average value of the temperature measured by each platinum resistance temperature sensor, and the value is measured by the control means (controller). If the input is made as information, the conventional control means can be used almost as it is.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 2 is a front view of an environmental test apparatus showing an embodiment of the present invention, and FIG. 1 is a schematic sectional view taken along the line AA.

This environmental testing device can be used as a high and low temperature incubator, a cooling and heating cycle device, and the like. As shown in FIG. 2, a sealed test chamber 3 for accommodating a test product to be environmentally tested is provided. An apparatus main body 1 mainly including a casing 4 to be formed, and a control panel unit 2 standing upright along the side surface thereof.
It is composed of and.

As shown in FIG. 1, the portion of the housing 4 forming the test chamber 3 of the apparatus main body 1 is formed of a metal plate on the inner and outer surfaces, and a heat insulating wall having a sandwich structure in which a sufficient heat insulating material is sandwiched therebetween. The test chamber 3 is surrounded by 4a, and a door 5 having a similar heat insulation structure is provided on the front side.
Is hinged so that it can be opened and closed. An observation window 6 is provided at the center of the door 5, and a fog prevention glass 6a with a double-sided heater is provided.
Is fitted. Reference numeral 7 is a door opening / closing and locking lever.

As shown in FIG. 1, the rear part of the test chamber 3 is partitioned by a partition plate 8, a suction port 9 is provided in the lower part of the test chamber 3, and a blow-out port 10 is provided in the upper part thereof. A heat exchange section 13 including a heater 11 which is a section and a cooling coil 12 which is a cooling section, and a fan 15 which is a blowing unit rotated by a fan motor 14 are provided. Louvers or nets are provided at the suction port 9 and the air outlet 10.

Then, the fan 1 by the fan motor 14
By the rotation of 5, the air in the test chamber 3 is sucked in through the suction port 9 and passed through the heat exchange section 13, and the air after the heat exchange is blown out from the blowout port 10 into the test chamber 3 and the air in the test chamber 3 is discharged. Is circulated as indicated by the arrow in FIG. 1 to adjust the temperature. A refrigerator 16 for cooling the cooling coil 12 is housed in the lower part of the device body 1, and a louver 17 for circulating outside air for heat radiation from the refrigerator 16 is provided on the front surface thereof as shown in FIG. Has been. In FIG. 1, piping between the refrigerator 16 and the cooling coil 12 is omitted. An indoor lamp 18 is provided on the ceiling of the test room 3, and a two-stage shelf 19 for mounting a test product is provided in the room.

Two rod-shaped platinum resistance temperature detectors 21 and 22 are inserted as temperature sensors so as to penetrate the side wall of the housing 4 and project into the test chamber 3 as shown by a broken line in FIG. As shown in FIG. 1, each of the platinum temperature measuring resistors 21 and 22 having a built-in resistance element at the tip of each of the resistance temperature detectors 21 and 22 is attached near the suction port 9 (rear side) and near the air outlet 10 ( It is located on the front side).

On the other hand, the control panel unit 2 displays a keyboard 23 consisting of a large number of keys used for various inputs on the front upper part thereof, input information such as test conditions and temperature information in the test chamber 3. CRT display 24, instrumentation section 25 including a light pen (not shown), and hybrid recorder 2 for printing out accumulated data
6, and a power switch 27 is arranged at the bottom.

Further, in the control panel unit 2, 2
The heat exchange unit 13 is arranged so that the average value of the temperatures measured by the platinum resistance temperature detectors 21 and 22 matches the set target temperature.
The controller is a controller having a function of controlling the heater 11 in this embodiment.

FIG. 3 is a block diagram showing a configuration example of the controller. This controller 30 is a CPU, R
From a microcomputer (hereinafter abbreviated as "microcomputer") 31 configured by OM, RAM, etc., an A / D converter 32, a D / A converter 33, and a solid state relay (hereinafter abbreviated as "SSR") 34 Become.

Further, the resistance elements of the two platinum resistance temperature detectors 21 and 22 are connected in series, and the constant current source circuit 35 causes a constant current Is to flow therethrough to form a temperature measuring circuit.
The potential difference Vi generated between both ends of the series circuit of the platinum resistance temperature detectors 21 and 22 is input to the A / D converter 32 of the controller 30, converted into digital data, and converted into the microcomputer 3.
I am trying to read it in 1.

Here, the resistance values which change according to the temperature of the resistance elements of the platinum resistance temperature detectors 21 and 22 are R ₁ and R ₂ , respectively.
Let R ₂ be the resistance values R ₁ and R _{2 and} the potential differences generated thereby are V ₁ and V ₂ , respectively, and the potential differences correspond to the temperatures measured by the platinum resistance temperature detectors 21 and 22, respectively. Since the potential difference Vi at both ends of is a sum thereof, the potential difference Vi obtained when the constant current Is is passed is obtained by the following equation. Vi = V ₁ + V ₂ = (R ₁ + R ₂ ) Is

When one platinum resistance temperature detector is arranged near the air outlet or suction port to measure temperature as in the conventional case, the current value flowing through the platinum resistance temperature detector is I ₀ , When the resistance value of the resistance element of the platinum resistance thermometer is R ₀ and the potential difference generated across the resistance element is V ₀ , V ₀ = R ₀ · I ₀ . Therefore, by the Is = I _0/2, Vi
= (R ₁ + R ₂ ) Is = (R ₁ + R ₂ ) I _0/2 .

In this formula, the numerator on the right side, R ₁ · I ₀ and R ₂
I ₀ is a potential difference corresponding to the measured temperature when a current having the same current value I ₀ as that in the conventional case is applied to each of the platinum resistance temperature detectors 21 and 22, and Vi is an average obtained by halving the sum. Clearly the value. Therefore, by inputting this potential difference Vi into the controller 30, the temperature in the vicinity of the air outlet 10 (before heat is used) and the vicinity of the air inlet 9 in the test chamber 3 (without using a special arithmetic circuit) ( Information corresponding to the average value of the temperature (after using heat) can be input as the detected temperature Ti.

The microcomputer 31 of the controller 30 reads the data obtained by A / D conversion of the data, and sets the temperature (Ts) which is set by the instrumentation section 25 or preprogrammed for a specified test condition. ), And outputs control data according to the difference to the D / A converter 33. The D / A converter 33 converts it into a duty control signal to control the ON duty of the SSR 34 (the ratio of the time during which the heater 11 is energized with respect to the cycle of the rectangular wave AC) to adjust the heat generation amount of the heater 11, Detection temperature Ti
The temperature of the circulated air is controlled to match the temperature Ts with the set temperature Ts.

In this embodiment, since the refrigerator 16 cannot finely control the temperature of the cooling coil 12, the drive circuit of the refrigerator 16 is not shown in FIG. 3, but the power switch 27 of FIG. 2 is turned on. In this case, the refrigerator 16 is always operated and the temperature is controlled only by controlling the energization of the heater.

FIG. 4 is an explanatory diagram of heater control when the temperature rises,
FIG. 5 shows the controller 30 of FIG. 3 (mainly the microcomputer 3
It is a processing flow figure of temperature control by 1). The controller 30 starts the process shown in FIG. 5 by turning on the power switch 27, and turns on the refrigerator 16 in step 1.

Next, in step 2, the set temperature Ts is read, and in step 3, the above-mentioned detected temperature Ti is read.
Then, in step 4, it is judged whether or not Ti ≧ Ts−ΔT1, and if NO (Ti <Ts−ΔT1), step 5
Then, the heater 11 is turned on with a duty of 100%. If YES in step 4, step 6
Go to and determine if Ti> Ts + ΔT2.

If NO (Ti≤Ts + ΔT2), the routine proceeds to step 7, where the duty corresponding to the value of Ti-Ts is calculated, and at step 8, the heater 11 is turned on with the calculated duty. Yes in the judgment of step 6
If it is S, it means that the heater 11 is off because it is in an overheated state. At this time, a warning process such as turning on a warning lamp or sounding a buzzer may be performed. Here, .DELTA.T1 and .DELTA.T2 are temperature ranges in which the heaters above and below the set temperature Ts are duty-controlled as shown in FIG.

Next, in step 10, it is judged whether or not there is a stop instruction, and if not, in step 11, the set temperature T is set.
It is determined whether or not s has been changed, and if it has not been changed, the process returns to step 3 and the process from reading the detected temperature is repeated. If the set temperature has been changed, the process returns to step 2 to read a new set temperature Ts, and then the process from step 3 is repeated. If the stop instruction is given in step 10, the heater 11 is turned off in step 12.
Then, in step 13, the refrigerator 15 is turned off, and this temperature adjustment process is completed.

Therefore, when the temperature control described above is started from a state where the temperature in the test chamber 3 is considerably lower than the set temperature Ts, the detected temperature Ti is Ts-Δ, as shown in FIG.
Until T1 is reached, the heater 11 is turned on with a duty of 100% to rapidly raise the temperature and Ti becomes Ts-ΔT1.
After that, Ts-Ti with heater 11 turned on
By PID (proportional / integral / derivative) control according to the value of
The ON duty is gradually decreased so that the detected temperature Ti matches the set temperature Ts as soon as possible.

Even if Ti = Ts, in order to compensate for the slight heat dissipation from the housing 4 during cooling and circulation by the cooling coil 12 to the outside air, the heat absorption by the test article in the test chamber 3, and the like. The heater 11 is turned on at a certain duty. However, when Ti> Ts, Ts-Ti becomes negative, so
When the duty is further reduced and Ti exceeds Ts + ΔT2, it is judged that the heater 11 is overheated.
Is turned off (duty: 0%).

Contrary to the above case, the heater 11 is turned off and the cooling coil 12 cools the temperature of the test chamber 3 rapidly to lower the detected temperature Ti from a state considerably higher than the set temperature Ts. , Ti is Ts
When it decreases to + ΔT2, the heater 11 is turned on and Ts
-The duty control according to the value of Ti is started, and the detected temperature Ti is controlled to approach the target temperature Ts as soon as possible. Such duty control can also be performed by phase control of an AC waveform using a thyristor or the like, but in this embodiment, the SSR 34 is used for a fixed time (for example, 4 Se).
The heater 11 is energized for each cycle corresponding to the duty every c: 200 cycles of 50 cycles of alternating current.

Although such temperature control is carried out in the conventional environment test apparatus, the detected temperature Ti is usually a temperature sensor such as a platinum resistance temperature detector arranged near the outlet of the test chamber. Since the temperature of the blown air is measured by, the detected temperature Ti is measured higher than the central portion of the test chamber, so that heating of the heater is suppressed early. Therefore, after the duty control of the heater is started, the detected temperature T
The time required for i to reach the set temperature Ts (the time at the curve of the detected temperature Ti in FIG. 4) was long, and the temperature at the center of the test chamber could not be accurately maintained at the set temperature.

On the other hand, according to this embodiment, the detected temperature Ti is measured by the two platinum resistance temperature detectors 21 and 22 arranged in the vicinity of the inlet 9 and the outlet 10 of the test chamber 3, respectively. Since it is the average value of the temperature of the sucked air and the temperature of the blown air, the time required to reach the set temperature Ts after starting the duty control of the heater 11 is shortened, and moreover, the temperature of the central portion of the test chamber is reduced. The set temperature can be accurately maintained.

This action / effect can be clearly understood by comparing FIG. 6 and FIG. FIG. 6 is a curve diagram showing temperature control test results according to the embodiment of the present invention, and FIG. 7 is a temperature control test result by a conventional environmental test device (a platinum resistance temperature detector is installed only near the outlet). Is.

In these figures, the vertical axis indicates temperature (C
°), and the horizontal axis is the elapsed time (hour). In each case, the set temperature Ts is 25, 70, 50, 25, 10, -15,-
A change in temperature actually measured by 30 temperature sensors (platinum resistance thermometers), which are sequentially changed to 30 (C °) and dispersed throughout the test chamber 3, is shown by a curve.
The part where these curves are doubled shows the highest temperature (upper curve) and the lowest temperature (lower curve) among the measured values of the 30 temperature sensors, and the one-dot chain line shows the test room. It shows the temperature measured by the temperature sensor arranged in the central part.

From these figures, the time required for the detected temperature to stabilize at the set temperature after the set temperature is changed is shown by the test results (for example, times t ₁ and t) according to the embodiment of the present invention shown in FIG. ₂ , t ₃ , t ₄ ) and the test results (time t ₁ , t ₂ ,
Times t ₁ ′, t ₂ ′, which correspond to t ₃ and t ₄ , respectively.
Comparing t ₃ ′ and t ₄ ′), the former is clearly shorter.

That is, in this embodiment, the curve in which the temperature linearly rises or falls and shifts to the horizontal state of the set temperature is steep, and the temperature is quickly stabilized at the set temperature. Moreover, the temperature of the central portion of the test chamber can be accurately maintained at the set temperature. Therefore, it is possible to quickly start the environmental test at the accurate set temperature, and it is possible to efficiently perform the entire environmental test performed by changing the set temperature in a plurality of steps in a shorter time than before.

As a result, even when a large number of products are subjected to environmental testing within a limited time, the number of environmental testing devices to be used can be small, so that equipment cost can be reduced and power consumption can be reduced. It consumes less.

In this embodiment, the heat exchanging part is provided with the heating part and the cooling part, and only the heater of the heating part is controlled to adjust the temperature. However, the electronic part using the semiconductor thermoelectric element in the cooling part is used. When a refrigerator or the like that can be finely controlled is used, it may also be controlled to adjust the temperature.
Further, in the case of the high temperature incubator, only the heating section may be provided, and in the case of the low temperature incubator, only the cooling section may be provided as the controllable heat exchange section.

Furthermore, a humidifier and a humidity controller can be combined. Currently, platinum resistance thermometers are preferable as the temperature sensor because of their good measurement accuracy and stability, but the present invention is not limited to this, and depending on the application, various temperatures such as thermistors, thermocouples, crystal temperature sensors, IC temperature sensors, etc. Sensors can also be used. Further, the present invention can be applied to an air conditioner, an air conditioner that controls the temperature of a substantially sealed room, and the like.

[0048]

As described above, the environmental test apparatus according to the present invention can accurately control the temperature in the substantially central portion of the test chamber without hindering the storage of the test product. At the start of the test and when the set temperature is changed, the set temperature can be reached safely and quickly and accurately and becomes stable, so that the test efficiency can be improved. As a result, it is possible to reduce equipment costs and power consumption.

Further, two platinum resistance temperature detectors are used as a temperature sensor, and they are connected in series to flow a constant current of 1/2 of the conventional one, and the potential difference generated between both ends of the series circuit is detected. By using this information, the information corresponding to the average value of the temperature measured by both temperature sensors can be obtained without using a special arithmetic circuit, and the conventional control unit can be used almost as it is.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view taken along the line AA of FIG.

FIG. 2 is a front view of an environment test apparatus showing an embodiment of the present invention.

3 is a block diagram showing a configuration example of a controller in the control panel unit 2 of FIG.

FIG. 4 is an explanatory diagram of heater control at the time of temperature rise by the controller of FIG.

FIG. 5 is also a controller 30 (mainly the microcomputer 3
It is a processing flow figure of temperature control by 1).

FIG. 6 is a curve diagram showing a temperature control test result according to an example of the present invention.

FIG. 7 is a curve diagram showing a temperature control test result by a conventional environment test device (a platinum resistance temperature detector is installed only in the vicinity of an outlet).

[Explanation of symbols]

 1: Device main body 2: Control panel unit 3: Test chamber 4: Case 5: Door 6: Observation window 8: Partition plate 9: Suction port 10: Air outlet 11: Heater (heating unit) 12: Cooling coil (cooling unit) ) 13: Heat exchange part 14: Fan motor 15: Fan (blower means) 16: Refrigerator 21, 22: Platinum resistance thermometer (temperature sensor) 23: Keyboard 24: CRT display 25: Instrumentation part 26: Hybrid recorder 27: Power switch 30: Controller (control means) 31: Microcomputer (microcomputer) 32: A / D converter 33: D / A converter 34: Solid state relay (SSR) 35: Constant current circuit

Claims (4)

[Claims] 1. A housing comprising a sealed test chamber for storing a test product to be subjected to an environmental test, and a heating unit and / or a cooling unit for bringing the test chamber to a required temperature. The heat exchange section and its control means, a suction port and a blowout port which are opened at positions distant from the test chamber, the air in the test chamber is sucked from the suction port, and the test is performed from the blowout port through the heat exchange section. In an environmental testing device having a blowing means for blowing into the room, temperature sensors are arranged in the vicinity of the suction port and in the vicinity of the blowing port, and the control means targets the average value of the temperature measured by each temperature sensor. An environment test apparatus characterized in that the heat exchange section is controlled so as to match the temperature. 2. A housing for forming a sealed test chamber for storing a test product to be subjected to an environmental test, a heat exchange unit including a heating unit and a cooling unit for keeping the test chamber at a required temperature, and Control means for the heating unit, a suction port and a blowout port that are opened at positions distant from the test chamber, air in the test chamber is sucked from the suction port, and the test chamber is blown from the blowout port through the heat exchange unit. In an environmental testing device having a blowing means for blowing out to, a temperature sensor is arranged in the vicinity of the inlet and the vicinity of the outlet, the control means the average value of the temperature measured by each temperature sensor target temperature An environment test apparatus characterized in that the heating unit is controlled so as to match with the above. 3. The environmental test apparatus according to claim 1, wherein each of the temperature sensors is a platinum resistance temperature detector. 4. The environment test apparatus according to claim 3,
Two platinum resistance temperature detectors respectively arranged near the suction port and near the blowout port are connected in series to flow a constant current, and the control means connects the two platinum resistance temperature resistors in series. An environment test apparatus, wherein a temperature measuring circuit is configured so that a potential difference generated between both ends of the circuit is input as information corresponding to an average value of temperature measured by each of the temperature sensors.