Temperature regulator

A temperature regulator is provided which includes a temperature sensor, a temperature regulating unit, a cold junction temperature measuring device and a double-wall insulating partition. Temperatures measured by the temperature sensor are compensated with the temperatures measured by the cold junction temperature measuring device. Since the double-wall insulating partition insulates the cold junction measuring device from the heat generated inside the temperature regulating unit, the cold junction measuring device can correctly measure the temperature of the cold junction.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a temperature regulator, and more particularly, 
to a temperature regulator which employs a cold junction temperature 
measuring device. 
2. Discussion of the Related Art 
A type of temperature regulator, which employs connecting pins inserted 
into a socket to which a thermocouple is connected, is widely used. In 
such a temperature regulator, the temperature of a cold junction to which 
the thermocouple is connected, is measured to compensate temperatures 
sensed by the thermocouple. A cold junction temperature measuring device 
is used to measure the temperature of the cold junction. In such 
conventional temperature regulators, the temperature compensating device 
is incorporated in a boss of a connecting pin. 
However, since the boss is not thermally coupled to the cold junction, the 
temperature measuring device cannot correctly measure the temperature of 
the junction. Also, since the measuring device is not thermally insulated 
from the heat generated inside the regulator, the operation point of the 
regulator often fluctuates. Furthermore, the regulator requires a long 
time to begin to operate stably after its power supply is turned on. 
SUMMARY OF THE INVENTION 
It is, therefore, an object of this invention to provide a temperature 
regulator which allows the temperature measuring device to correctly 
measure the temperature of the cold junction. 
It is another object of this invention to provide a temperature regulator 
in which the temperature measuring device is thermally insulated from the 
heat generated inside the regulator. 
It is still another object of this invention to provide a temperature 
regulator which begins to operate stably in a short time after its power 
supply is turned on. 
According to this invention, there is provided a temperature regulator 
including a socket to which a temperature sensor is connected via a cold 
junction, and a temperature regulating unit which is connected to the 
socket. The temperature regulating unit includes (1) a cold junction 
temperature measuring means for measuring temperatures of the cold 
junction, (2) a first thermal insulating member for insulating the cold 
junction temperature measuring means from the heat generated inside the 
temperature regulating unit, and (3) compensating means for compensating 
the temperature measured by the temperature sensor with the temperatures 
measured by the cold junction temperature measuring means.

DETAILED DESCRIPTION OF THE INVENTION 
In FIGS. 1 to 3, a temperature regulating unit according to a preferred 
embodiment of this invention includes a front case 1 and a rear case 2. A 
terminal base 3 is provided on the rear side of rear case 2. Terminal base 
3 includes eight pin terminals 6a-6h which are oriented, e.g., in circular 
configuration and are inserted into a printed circuit board 5 and a socket 
4 in the orientation as shown in FIG. 2. Pin terminals 6a-6h are 
insert-molded into base 3. A boss 7 is disposed at the center of base 3. 
Also, base 3 includes a thermal insulating flat plate 8 having a pair of 
recesses 8a, and a cut-away portion 9. Either or both surfaces of plate 8 
can be corrugated as shown by side surface 8b. Circuit board 5 is disposed 
near insulating plate 8 in parallel with base 3. Circuit board 5 includes 
a pair of cut-away portions 5a and eight through-holes 5b. Two terminals 
of a cold junction temperature measuring device 10, which is a 
temperature-sensitive resistor made, e.g., of platinum and placed in 
cut-away portion 9, are mounted on cut-away portions 5a and 8a. Device 10 
changes its resistance as a function of temperature. Pin terminals 6a-6h 
are inserted into throughholes 5b. Thus, device 10 and terminals 6a-6h are 
connected to circuit patterns (not shown) provided on circuit board 5. 
As shown in FIG. 3, four through-holes 11a-11d are disposed on base 3 
through which atmospheric air is introduced in cut-away portion 9 in which 
device 10 is positioned. A thermocouple 22 (described below and which may 
be positioned remote from the temperature regulating unit) is exposed to 
the atmosphere and functions as a temperature sensor. Device 10 measures 
the temperature of the atmospheric air introduced into cut-away portion 9 
of base 3 to compensate the temperature measured by thermocouple 22. 
Terminal base 3 is fixed to the rear end of rear case 2 to complete the 
temperature regulating unit. 
In FIG. 4, a thermocouple 22 is shown connected to input terminals 20a and 
20b, which are provided as cold junctions, via lines 21. Lines 21 generate 
a thermoelectromotive force nearly equal to that produced by thermocouple 
22, i.e., there may be some resistance losses. Resistors R1-R3 and device 
10, which has a resistance which varies as a function of the temperature 
near terminals 20a and 20b, constitute a bridge circuit. An operational 
amplifier 23 amplifies the voltage difference between its two input 
terminals and outputs an electric signal, the level of which corresponds 
to the temperature measured by thermocouple 22. This output signal is sent 
to a controller (not shown) to contol a process so that its temperature 
can reach target values. Resistor R5 maintains a voltage input to 
amplifier 23 should thermo couple 22 and/or line 21 break. 
In this embodiment, device 10 is insulated from the heat generated inside 
the temperature regulating unit by circuit board 5 and thermal insulating 
plate 8 forming a double-wall insulating partition. Consequently, device 
10 is not adversely affected by this heat and can correctly detect the 
temperature near the cold junction. 
The above description and the accompanying drawings are merely illustrative 
of the application of the principles of the present invention and are not 
limiting. Numerous other arrangements which employ the principles of the 
invention and which fall within its spirit and scope may be readily 
devised by those skilled in the art. Accordingly, the invention is not 
limited by the foregoing description, but only limited by the scope of the 
appended claims.