JP3856071B2 - Differential scanning calorimeter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a differential scanning calorimeter, and more particularly, to a differential scanning calorimeter equipped with a cooling device for enabling measurement in a temperature region below room temperature.
[0002]
[Prior art]
In a differential scanning calorimeter, generally, a sample and a reference sample (reference material) are accommodated in a heating furnace, and the temperature of both is changed in a constant thermal environment, and is provided in the heating furnace. A DSC (Differential Scanning Calorimetry) sensor detects information related to the temperature difference between the sample and the reference sample, and measures thermal properties such as phase transition and melting of the sample.
[0003]
Also, in this type of apparatus, a device provided with a cooling means for directly or indirectly cooling the vicinity of the heating furnace has been put into practical use in order to perform measurement in a temperature region below room temperature. As such a cooling means, there are one using a refrigerant tank using liquid nitrogen as a refrigerant, and one using an electric cooler using a refrigerant other than liquid nitrogen and a compressor.
[0004]
Here, when the vicinity of the heating furnace is cooled by the cooling means as described above, the surroundings of the heating furnace are condensed. In order to prevent such dew condensation, conventionally, measures such as purging the entire apparatus in a nitrogen atmosphere or separating the apparatus and ambient air with a large amount of heat insulating material have been taken.
[0005]
[Problems to be solved by the invention]
By the way, the countermeasure for preventing condensation in the conventional differential scanning calorimeter as described above has a problem that the entire area of the apparatus is enlarged and a required area for installing the apparatus is increased. Also, the cooling means using liquid nitrogen and the cooling means using other electric coolers are greatly different in cooling capacity. Alternatively, it is necessary to adopt a heating furnace configuration that adopts anti-condensation measures adapted to the cooling means using liquid nitrogen, and in the former case, a configuration in which two types of measures can be selected is required, and the structure is complicated In the latter case, there is a problem that the cooling efficiency is deteriorated and the minimum temperature is raised, particularly when an electric cooler is used.
[0006]
The present invention has been made in view of such circumstances, and can easily cope with cooling means having different cooling capacities based on a compact apparatus configuration, and can be applied to a plurality of types of cooling means. On the other hand, an object of the present invention is to provide a differential scanning calorimeter that can surely prevent condensation around the heating furnace while minimizing the minimum temperature.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a differential scanning calorimeter of the present invention is provided with a heating furnace that contains a sample and a reference sample and heats them, and is placed in the heating furnace, and the temperature of the sample and the reference sample every moment In a differential scanning calorimeter having a sensor for detecting information related to the difference and a cooling means for cooling the vicinity of the heating furnace so as to enable measurement in a temperature region below room temperature, condensation is formed around the heating furnace. A temperature sensor for determining a selection status of the cooling means, provided with a prevention heater , and the cooling means having a plurality of selectable cooling means having different cooling capacities. And the voltage applied to the dew condensation prevention heater is characterized by being determined based on the selection status of the cooling means determined by the temperature sensor .
[0008]
The present invention raises only the surface temperature in the vicinity of the heating furnace by driving a heater provided around the heating furnace, thereby minimizing the minimum temperature in a compact configuration and in the vicinity of the heating furnace. It is intended to prevent condensation from forming around the heating furnace during cooling.
[0009]
The heater for preventing condensation in the present invention may be small because it only needs to raise the surface temperature in the vicinity of the heating furnace to such an extent that condensation does not occur. Different types of cooling means can be easily handled, and it is possible to reliably prevent condensation while achieving the lowest minimum temperature in common. In other words, the selection status of a plurality of types of cooling means having different cooling capacities is discriminated by the temperature sensor, and the magnitude of the voltage applied to the dew condensation prevention heater is determined according to the selection status. By automatically increasing the cooling means with a larger capacity, it is possible to reliably prevent condensation without adversely affecting the minimum temperature.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing an outline of a mechanical configuration and a block diagram showing an electrical configuration. The heating furnace 1 is heated as a whole by driving a heating heater 2 disposed below, and is in close contact with the heat transfer plate 3 disposed below. The heat transfer plate 3 is provided with a refrigerant tank 4 on the upper surface of the heat transfer plate 3 in the vicinity of the close contact portion with the heating furnace 1. Is bound to.
[0011]
The heating furnace 1 has a space for accommodating the sample S to be measured and the reference sample R in the same thermal environment, and a temperature sensor 5 for detecting the temperature in the furnace. A DSC sensor 6 for detecting temperature difference information between the sample S to be measured and the reference sample R is disposed. The furnace temperature detection signal from the temperature sensor 5 is taken into the temperature control circuit 11, and the temperature control circuit 11 uses the above-described heating temperature so that the detection result of the furnace temperature rises at a preset speed. The heater 2 is driven and controlled. The output of the DSC sensor 6 is output to the outside as a DSC signal via the measurement circuit 12.
[0012]
In this embodiment, in the measurement in the temperature region below room temperature, when it is necessary to lower the temperature to a low temperature region below a certain temperature, as shown in FIG. Liquid nitrogen LN is accommodated in the heating furnace 1 and the heating furnace 1 is cooled via the heat transfer plate 3. When it is not necessary to lower the temperature to the low temperature range as described above, instead of storing liquid nitrogen LN in the refrigerant tank 4, as shown in the schematic diagram of the main part in FIG. A vessel 7 is used. The electric cooler 7 has a cooler main body 71 mainly composed of a compressor using a normal refrigerant other than liquid nitrogen as a refrigerant, and a cold head 72 connected to the cooler main body 71 and cooled. By bringing the cold head 72 into close contact with the heat transfer plate 3 at the bottom surface position of the refrigerant tank 4, the heating furnace 1 can be cooled via the heat transfer plate 3.
[0013]
Now, along with anti-condensation heater 8 is disposed around the heating furnace 1, the lower surface portion of the heat transfer plate 3 directly under the coolant vessel 4 temperature sensor 9 for determining a cooling means is arranged . Anti-condensation heater 8 is intended to be activated when driving for the measurement in the following temperature range room temperature, i.e. either contains liquid nitrogen LN in the refrigerant tank 4, or an electric cooler 7, condensation The drive is controlled by a voltage signal supplied from the prevention control circuit 13. In anti-condensation control circuit 13, as described below, automatically determine the type of the cooling means based on the output signal of the temperature sensor 9 for determining the cooling means, based on the determination result, anti-condensation heater 7 The voltage signal to be supplied to is changed.
[0014]
That is, the dew condensation prevention control circuit 13 determines that the liquid nitrogen LN is accommodated in the refrigerant tank 4 when the temperature detection result by the temperature sensor 9 is equal to or lower than a certain temperature. 3 (a) constant DC voltage V so as to illustrate the time chart is applied. The magnitude of this DC voltage V, in a state where the heating furnace 1 houses a liquid nitrogen LN in the coolant vessel 4 and cooled, the surface in the vicinity of the heating furnace 1 by applying the DC voltage V in anti-condensation heater 8 Is heated to a minimum level that does not cause condensation on the surface in the vicinity of the heating furnace 1, and the specific voltage level is determined in advance by experiments or the like.
[0015]
On the other hand, when the temperature detection result by the temperature sensor 9 exceeds the fixed temperature, it is determined that the electric cooler 7 is used as the cooling means, and in that case, FIG. As shown in the time chart, a pulsed voltage obtained by turning ON / OFF the DC voltage V in a predetermined cycle is applied . The pulse duty of the pulse voltage is determined by applying the pulse voltage to the dew condensation prevention heater 8 in a state where the electric cooler 7 is driven under the maximum capacity and the heating furnace 1 is cooled. When the surface in the vicinity of is heated, the minimum duty that does not cause condensation on the surface in the vicinity of the heating furnace 1 is set, and the specific duty is determined in advance by experiments or the like as described above.
[0016]
According to the embodiment of the present invention described above, selecting one of the liquid nitrogen LN and electric cooler 7 as a cooling means, the type of cooling means is determined automatically, the anti-condensation heater 8 The applied voltage is automatically set to an optimum voltage corresponding to the cooling capacity of each cooling means. Then, by application of the anti-condensation heater 8 of the set voltage, in any case of using a case and an electric cooler 7 using liquid nitrogen LN as cooling means it is also the lowest of the heating furnace 1 which is based on each of the cooling capacity Condensation in the vicinity of the heating furnace 1 can be reliably prevented while lowering the ultimate temperature as much as possible.
[0017]
As the drive voltage of the anti-condensation heater 8 in the case of using a low electric cooler 7 with cooling capacity, without changing the absolute value of the DC voltage V supplied to the case of using the liquid nitrogen LN as described above In addition to a pulsed voltage chopped into pulses, a DC voltage with a lower absolute value may be used.
[0018]
【The invention's effect】
As described above, according to the present invention, by arranging the anti-condensation heater around the furnace, since the structure so as to heat the surface of the furnace near a differential in the following temperature range room temperature Even if the heating furnace is cooled by the cooling means in scanning calorimetry, it is possible to surely prevent condensation in the vicinity of the heating furnace, and which of the plural kinds of cooling means having different cooling capacities is selected. was determined by a temperature sensor, since changing the voltage applied to the anti-condensation heater in accordance with the determination result, and work to minimize its lowest temperature reached by using any of a plurality of types of cooling means having different cooling capacity Therefore, a high-performance differential scanning calorimeter can be obtained with a compact device configuration.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an embodiment of the present invention, and is a diagram illustrating a schematic diagram showing a mechanical configuration and a block diagram showing an electrical configuration.
FIG. 2 is a main part schematic diagram showing a state in which an electric cooler 7 is used as a cooling means in the embodiment of the present invention.
FIGS. 3A and 3B are time charts showing examples of voltage waveforms applied to the dew condensation prevention heater 8 according to the embodiment of the present invention. FIG. 3A shows the case where liquid nitrogen LN is used, and FIG. It is a figure which shows the case where it uses, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Heating heater 3 Heat transfer plate 4 Refrigerant tank 5 Temperature sensor (for detecting furnace temperature)
6 DSC sensor 7 electric cooler 8 anti-condensation heater 9 temperature sensor (cooling means determined)
11 Temperature Control Circuit 12 Measurement Circuit 13 Condensation Prevention Control Circuit LN Liquid Nitrogen S Sample to be Measured R Reference Sample

Claims (1)

A heating furnace that contains a sample and a reference sample and heats them, and a sensor that is disposed in the heating furnace and detects information related to the temperature difference between the sample and the reference sample, and a temperature region below room temperature In a differential scanning calorimeter equipped with cooling means for cooling the vicinity of the heating furnace in order to enable measurement at
A heater for preventing condensation is provided around the heating furnace , and the cooling means has a plurality of selectable cooling means having different cooling capacities, and the selection status of the cooling means. A differential scanning calorimeter , further comprising: a temperature sensor for determining whether or not the voltage applied to the dew condensation prevention heater is determined based on a selection state of the cooling means determined by the temperature sensor .

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