JPH0477640A - Temperature sensor - Google Patents

Abstract

PURPOSE:To measure temperature in a fluctuating magnetic field with high accuracy by constituting a sensor of two kinds of temperature sensor in one set. and obtaining the difference between the two sensors. CONSTITUTION:A piece of thin wire such as platinum or the like whose electric resistance is changed with temperature is wound around a temperature sensitive part 1 at the about 0 pitch with respect to a diameter (d). The thin wire is wound around a temperature sensitive part 2 at a pitch (p) of pi/2d with respect to the diameter (d). A unitary body is formed with the temperature sensitive parts 1 and 2, and a sensor is formed. The resistances R5 and R3 which are balanced in a zero magnetic field at the lower limit humidity at the temperature used with this sensor are measured. The resistances R5 and R3 which are balanced in the maximum magnetic field in use are also measured. These two measurements impart the linear equalities of the resistances R5 and R3. The resistances R5 and R3 at the temperature can be determined by solving the two linear equalities as equations. The resistance R5 is fixed to this value. The resistance R3 is calibrated with respect to the temperature in the entire range of the temperature in use. Then, the resistance R3 does not depned on the magnetic field any more. The temperature sensor which is not dependent on the magnetic field as a whole is obtained. The temperature and the like of a superconductive magnet can be measured with high accuracy.

Description

[Detailed Description of the Invention] With the recent practical application of superconducting magnets, the use of high magnetic fields has increased in various fields, but temperature control of each part of the magnet is an important issue from the viewpoint of safety and energy saving. be. However, normally used thermometers are affected by magnetic fields and their readings vary. In principle, this deviation can be corrected by calibrating each thermometer under a magnetic field, and conventionally the temperature has been determined by knowing the value of the magnetic field and making necessary corrections.

However, with the development of superconducting technology, it has become possible to vary the value of the magnetic field of a superconducting magnet at a frequency of several Hz or several tens of Hz, and new fields of application have expanded, causing problems with the above technology. It's here. This is because the resistance value of the sensor is influenced by the fluctuating magnetic field and fluctuates at the same frequency as the fluctuating fm field, making it impossible to accurately measure or correct the value at all.

The temperature sensor manufactured based on the present invention is composed of two types of morning temperature sensors, and since each sensor is influenced differently by the magnetic field, by taking the difference,
It uses the fact that its output does not depend on the magnetic field at all. This sensor enables highly accurate temperature measurements under fluctuating magnetic fields.

The present invention is based on the fact that the electrical resistance R of a thin wire in a magnetic field H changes from the electrical resistance R in a zero magnetic field as follows.

The increase ratio of R=Rs (1+AH,,2+BH 2) can be changed.

For example, when a sensor is wound with 0 wires and a magnetic field is applied parallel to the winding axis, the resistance R9 becomes as follows.

n, = RD@ (1+AH2) On the other hand, the resistance R9 of a spirally wound product with a pitch p of π/2d for a diameter d does not depend on the direction of the magnetic field, and is as follows.

However, here, H~ and H are components of the magnetic field parallel and perpendicular to the direction of the thin wire, respectively, and A and B are constants that do not depend on the magnetic field. A and B are generally different, but A is larger than B. This causes anisotropy in that the amount of increase in resistance differs depending on the angle formed by the direction of current flow and the magnetic field.

By using this anisotropy, in the case of a thin wire, by changing the pitch, and in the case of a thin film, by changing the direction of the magnetic field of the film, the resistance B is generally very small compared to A. It can be carved and viewed through a blind. Now, assuming that the resistance when the magnetic field is 0 is R, = 2R1°RQ = 3Rz, the resistance difference R<=Ro-Re is as follows.

Rd=　Rq　−Rp =R, (3+2AH2)-R, (2+2AH2)=R.

As is clear from this, the electrical resistance difference Rm does not depend on the magnetic field, and is an easily measurable quantity, so that a sensor that does not depend on the il field can be easily constructed.

Therefore, once the electrical resistance difference of the target sensor is calibrated against temperature in a magnetic field, it can be used as is in the magnetic field without correction, and the reliability of temperature measurement under fluctuating magnetic fields is greatly increased. I can write.

[Example 1] A thin wire made of platinum or the like whose electrical resistance changes with temperature is wound with a diameter of d and a pitch of approximately 0, and a wire with a diameter of d and a pitch of π/2d. are integrated into a sensor as shown in FIG. In FIG. 1, the thin wire is wound so as to maintain the same pitch and unwind in order to prevent the induced voltage caused by the varying magnetic field from appearing between the terminals. The resistance difference measurement can be carried out as follows using, for example, a circuit as shown in FIG. 2 or 3.

FIG. 2 is a resistance difference measurement circuit diagram. First, R5 and R balanced in zero magnetic field at FB 4 degrees below the sensor operating temperature.
Measure 3. Also, R5 balances in the maximum magnetic field used.
and measure R3. These two measurements give linear equations for R5 and R3, respectively.

By solving these two -order equations as equations, R5 and R3 at that temperature can be determined. Fix R5 to this value and calibrate R3 against temperature over the entire operating temperature range. This R3 no longer depends on the magnetic field.

As a whole, a temperature sensor that does not depend on a magnetic field can be constructed.

FIG. 3 is a resistance difference measurement circuit diagram for a general-purpose AC Buri-Fuji circuit. The two temperature sensing parts are connected in series and connected to the current terminal IO of the bridge. The voltage across the temperature sensing section 20 is divided by the voltage divider 9 via the isolation transformer 8 and connected in series in the opposite direction to the voltage from the temperature sensing section 1, and is connected to the voltage terminal 11 of the bridge.
added to.

The method of use is to measure the resistance value of the bridge with respect to the voltage division ratio in zero magnetic field at the lower limit of the sensor's operating temperature. Also, measure the resistance of the bridge against the voltage division ratio in the same way even in the maximum magnetic field used. These two measurements give linear equations for the voltage divider ratio and bridge resistance, respectively. By solving these two -dimensional equations as equations, the voltage division ratio and resistance value at that temperature can be determined. Fix the voltage division ratio to this value and calibrate the bridge resistance against temperature over the entire operating temperature range. This bridge resistance is no longer dependent on the magnetic field, and a temperature sensor that is entirely independent of the magnetic field can be constructed.

[Example 2] The present sensor can also be constructed using a thin film. For example, if the chip shown in Figure 4 is configured as shown in Figure 5, the angle between the current and the magnetic field in chip 13 will be 90';
2, the angle formed is approximately 0°. As a result, the degree of increase in resistance to the magnetic field is greater in the former than in the latter.As in Example 1, the second rj! J or 31i
1 to measure the resistance difference, a temperature sensor can be constructed.

[Brief explanation of the drawing]

Figure 1 is a perspective view of a thin wire wound spirally, including unwinding.
Figure 2 is a resistance difference measurement circuit diagram, Figure 3 is a resistance difference measurement circuit diagram for a general-purpose AC bridge circuit, Figure 4 is a diagram of a temperature sensor chip composed of a thin film, and Figure 5 is a diagram of the sensor chip in Figure 4. It is a perspective view of double arrangement. 1 Temperature sensing part 1 2 Temperature sensing part 2 3 Resistor for bridge balance R3 4 Fixed resistor 5 Resistor for bridge balance R5 6I @ Output device 7 Current source 8 Isolation transformer 9 Voltage divider 10 Current terminal of AC bridge 11 Current terminal of AC bridge Voltage terminal 12 Temperature sensing chip 13 Temperature sensing chip Figure 4 iE2 Figure page 4

Claims (2)

[Claims] (1) The temperature-sensing part 1 is made by winding a thin wire whose electrical resistance changes with temperature changes at a certain pitch, and the temperature-sensing part 1 is brought into thermal contact with each other. A temperature sensor based on measuring the difference in resistance between the electrical resistance of the temperature sensing part 1 and a part or all of the electrical resistance of the temperature sensing part 2. (2) A sensor in which two metal films whose electrical resistance changes with changes in temperature are brought into thermal contact with each other so that the angle between the current-flowing surfaces is not 0.
Temperature sensor based on measuring the resistance difference with part or all of the electrical resistance of the first sheet.