JP3788990B2 - Temperature control device - Google Patents

Description

  The present invention relates to a temperature control device for a sample to be analyzed by a spectrophotometer, particularly, a spectrophotometer for biological science.

As a conventional example of this type, although it is a cooling device, there is a device that rapidly cools a sample in a thermostatic chamber without temperature unevenness by using two temperature adjusting mechanisms as in Patent Document 1, for example.
However, the temperature described in Patent Document 1 is specifically described as to what level of cooling is required and what level of accuracy is required.

Japanese Patent Laid-Open No. 2000-074741 (page 3-4, FIG. 1)

  Accordingly, an object of the present invention is to enable precise and stable temperature control of a sample used for a spectrophotometer.

  In order to solve such a problem, in the invention of claim 1, a first heat insulating member that has a window that transmits light and insulates a sample chamber in which a sample is placed, and the sample chamber and the first heat insulating member are provided. Further, a second heat insulating member for heat insulation, a first calculating means for taking a difference between a detected temperature of the first heat insulating member and a set temperature thereof, a detected temperature of the second heat insulating member and a set temperature thereof The second calculation means for taking the difference, the first driving means for heating the first heat insulating member, which receives the output from the first calculation means, and the outputs of the first and second calculation means Switch means for alternately switching, AD conversion means for converting the output of the switch means into a digital value, and the second drive means via the second drive means based on the digital value corresponding to the output from the second arithmetic means. The heat insulating member is heated and the switch And digital control means for the output of the stage of the switching control and the set temperature, and having a DA conversion means for converting the set temperature from the digital control means into an analog value.

In the first aspect of the present invention, the second heat insulating member can be a water tank (the second aspect of the present invention). In the first or second aspect of the present invention, the output from the AD converting means is the digital signal. Numerical display means for displaying a value obtained by adding the temperature set values output from the control means can be provided (invention of claim 3).
In any one of claims 1 to 3, the switch means may be a multiplexer (invention 4), and in any one of claims 1 to 4, the first drive The means is a constant value when the output from the first calculation means is larger than a predetermined value, and is a value proportional to the output when the output from the first calculation means is smaller than a predetermined value. Can be controlled (invention of claim 5), and in any of claims 1 to 5,
The second driving means can drive the second heat insulating member by a PWM method (invention of claim 6).

  According to the present invention, there is an advantage that highly accurate temperature control according to the resolution of a digital-analog converter (DAC) is possible. For example, when the resolution is 4 digits, it is possible to cope with a set temperature of 10 ° C. up to a level of 0.01 ° C.

  FIG. 1 is a schematic diagram showing an embodiment of the present invention. In the same figure, 1 is a numerical display unit, 2 is an analog-digital converter (ADC), 3 is a switch such as a multiplexer, 4 is a digital control unit (DCU), 5 is a digital-analog converter (DAC), 61, 62 is a differential circuit, 71 and 72 are temperature / voltage converters, 8 is a Peltier element driving circuit, 9 is a heater driving circuit, 10 is a sample chamber, 11 is a Peltier element, 12 is a water tank, 13 is a heater, Sa and Sb are temperatures It is a sensor. Although the heater 13 is provided outside the water tank 12 here, it may be provided inside the water tank. Although the sample chamber for calibration and the like are omitted, it is assumed that the analyzer is naturally included in the analyzer.

  The sample chamber 10 accommodates a spectroscopic analysis sample such as ribonucleic acid (DNA). In the sample chamber 10, a window 10 a is formed as shown in FIG. 2, for example, as shown in FIG. 2 so that light can be applied to such a sample. Surrounded by Depending on the case, the further outer side of the water tank 12 can also be covered with another heat insulation member. The reason why the outside is covered with the water tank 12 is to enable stable control by using water having a large specific heat as a control target.

  Temperature sensors Sa and Sb are attached to the Peltier element 11 and the water tank 12, respectively, and the respective temperatures are measured. The temperature measurement values are given to the temperature voltage converters 71 and 72, respectively, converted into voltages corresponding to the measurement values, and then input to the difference circuits 61 and 62, respectively. Since the difference circuits 61 and 62 are given temperature set values via the digital control unit (DCU) 4 and the digital-analog converter (DAC) 5, the difference circuits 61 and 62 receive the set values and the detected values. Difference signals a and b are output.

  The difference signals a and b from the difference circuits 61 and 62 are given to the analog-digital converter (ADC) 2 via the switch 3, and the difference signal a from the difference circuit 61 is also given to the Peltier element driving circuit 8. Thus, the temperature of the Peltier element 11 is controlled to be a desired set value. Further, since the difference signal b given to the ADC 2 from the difference circuit 62 via the switch 3 is converted into a digital value and then inputted to the DCU 4, the DCU 4 is heated via the heater drive circuit 9 based on the digital value of the difference signal b. By driving 13, the heater 13 is set to a desired set temperature value.

The driving of the heater 13 by the heater driving circuit 9 can be controlled relatively relaxed by, for example, a PWM (pulse width modulation) method. Since the difference circuits 61 and 62 are used, if the output of the DAC 5 is multiplied by a predetermined coefficient and introduced into the ADC 2, and the DAC 5 having, for example, a 4-digit resolution is used, the ADC 2 has a resolution lower than this. You can do it with an inexpensive one.
The number display unit 1 digitally displays a value obtained by adding the set temperature value to the digital equivalent value of the difference signal from the ADC 2 that is the output of the DCU 4. As the temperature display at this time, a detailed value is displayed in the vicinity of the set value, and an approximate value is displayed when the temperature is far from the set value.

The Peltier element driving circuit 8 drives the Peltier element 11 in accordance with the difference signal a from the difference circuit 61. To suppress the temperature oscillation of the sample chamber 10, for example, when the difference signal a exceeds a certain value a1. Is suppressed to a constant value, and temperature oscillation can be suppressed by controlling in proportion to the difference signal a in a region where the difference signal a is small. This state is shown in FIG. 3, where the constant value is limited by a clip or clamp circuit, and control proportional to the difference signal a can be realized by a non-linear circuit such as a diode.
3A shows the relationship between the temperature difference a and the power, FIG. 3B shows the time change of the power, and FIG. 3C shows the time change of the temperature difference.

Block diagram showing an embodiment of the present invention Structural diagram of the sample chamber Illustration of Peltier device control method example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Number display part, 2 ... Analog-digital converter (ADC), 3 ... Switch, 4 ... Digital control unit (DCU), 5 ... Digital-analog converter (DAC), 61, 62 ... Difference circuit, 71, 72 ... temperature-voltage converter, 8 ... Peltier element driving circuit, 9 ... heater driving circuit, 10 ... sample chamber, 10a ... window (window glass), 11 ... Peltier element, 12 ... water tank, 13 ... heater, Sa, Sb ... Temperature sensor.

Claims (6)

  A first heat insulating member that has a window that transmits light and insulates a sample chamber in which a sample is placed, a second heat insulating member that further insulates the sample chamber and the first heat insulating member, and the first heat insulating member First calculating means for taking a difference between the detected temperature of the second heat insulating member and the set temperature, second calculating means for taking the difference between the detected temperature of the second heat insulating member and the set temperature, and the first calculating means. The first drive means for heating the first heat insulation member, the switch means for alternately switching the outputs of the first and second calculation means, and the output of the switch means to a digital value The AD conversion means for converting, the second heat insulating member is heated via the second driving means based on the digital value corresponding to the output from the second calculating means, the switching control of the switch means, and the Output the set temperature And I digital control means, the temperature control apparatus characterized by having a DA conversion means for converting the set temperature from the digital control means into an analog value.   The temperature control apparatus according to claim 1, wherein the second heat insulating member is a water tank.   The temperature control apparatus according to claim 1 or 2, further comprising a number display means for displaying a value obtained by adding a temperature set value output from the digital control means to an output from the AD conversion means.   The temperature control apparatus according to claim 1, wherein the switch means is a multiplexer.   The first driving means is a constant value when the output from the first computing means is larger than a predetermined value, and is proportional to the output when the output from the first computing means is smaller than a predetermined value. The temperature control device according to any one of claims 1 to 4, wherein each of the temperature control devices is controlled by a value to be controlled. The temperature control apparatus according to claim 1, wherein the second driving unit drives the second heat insulating member by a PWM method.

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