Refrigeration – Storage of solidified or liquified gas – Including cryostat
Reexamination Certificate
1999-07-28
2002-04-09
Doerrler, William (Department: 3744)
Refrigeration
Storage of solidified or liquified gas
Including cryostat
C062S259200, C343S720000, C455S041300, C361S814000
Reexamination Certificate
active
06367266
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat insulation chamber which is made of heat insulating material and forms an inner chamber for storing an electronic part, and a thermostatic chamber and a cryostat to which the heat insulation chamber is applied.
2. Description of the Related Art
In recent years, many electronic equipments, which are required to have high performance and reliability, are mounted with a thermostatic chamber which accommodates an device applied in order to obtain a stable operating environment with high reliability, has a loose thermal coupling to the outside, and maintains the operating temperature of the device in a desired range.
Also, in recent years, telecommunication technology has progressed remarkably, and to the main part of communication equipment which configures the communication system, minimizing insertion losses and improving noise figures is severely required.
However, the minimization of insertion losses and the improvement of noise figures can be achieved by applying a superconductive filter and a low noise amplifier (LNA) operating at a cryogenic temperature. Therefore, many communication equipments are provided with cryostats for maintaining in a stable condition of an operating temperature of superconductive filters and low noise amplifiers. Such electronic parts are configured of, for example, HEMT or the like.
FIG. 16
is a diagram showing an exemplary configuration of a conventional cryostat.
In the drawing, a cold head
142
is attached to the bottom of a box-like cabinet
141
which is made of heat insulating material, and an electronic part
143
, which operates at a cryogenic temperature, is mounted on the top of the cold head
142
. Respective through holes
144
-
1
and
144
-
2
are formed among the side walls of the cabinet
141
, which faces the input and output terminals of the electronic part
143
. Respective ends of coaxial cables
145
-
1
and
145
-
2
are connected to these input and output terminals. These coaxial cables
145
-
1
and
145
-
2
are led to the outside of the cabinet
141
through the through holes
144
-
1
and
144
-
2
, which are then sealed with the interior of the cabinet
141
maintained under vacuum. The cold head
142
is connected to a refrigerating machine
147
through a pipe
146
.
In the cryostat configured as described above, the cold head
142
maintains the temperature of an inner chamber (hereinafter indicated with reference number “
141
A” allotted), which is sandwiched between the electronic part
143
and the interior walls of the cabinet
141
, at a cryogenic temperature that the electronic part
143
operates at, by liquid helium circulating through the pipe
146
as a heating medium between the cold head
142
and the refrigerating machine
147
.
The electronic part
143
receives input signals given from a circuit disposed outside of the cabinet
141
through the coaxial cable
145
-
1
, performs a predetermined operation (e.g., filtering as the superconductive filter and amplifying as the low noise amplifier as described above) to the input signals to generate output signals and feeds the output signals to a circuit connected through the coaxial cable
145
-
2
.
In other words, the operating temperature of the electronic part
143
is maintained at a desired cryogenic temperature under the temperature control by the refrigerating machine
147
, the pipe
146
, and the cold head
142
, so that the electronic part
143
exhibits predetermined characteristics and performance under the operating temperature and operates in cooperation with the circuit disposed outside of the cabinet
141
as described above.
In the conventional case described above, the coaxial cables
145
-
1
and
145
-
2
are not only conductors but also heat conductors. Therefore, the refrigerating machine
147
unnecessarily consumed a large quantity of electric power to keep the operating temperature of the electronic part
143
from rising by absorbing heat flowing from the outside of the cabinet
141
into the input and output terminals of the electronic part
143
through the coaxial cables
145
-
1
,
145
-
2
.
Technologies for decreasing heat quantity of heat flowing in from the outside as described above include, for example, a technology which uses a conductor with a low thermal conductivity for the inner conductor and outer conductor of the coaxial cables
145
-
1
and
145
-
2
and a technology which sets the cross section of the inner conductor and outer conductor to a small value. But, none of such technologies have actually been used because insertion losses of the coaxial cables
145
-
1
and
145
-
2
increased to an intolerable level.
And, when the quantity of heat flowing in from the outside through the coaxial cables
145
-
1
and
145
-
2
is large, either the operating temperature of the electronic part
143
is not secured, or it is necessary to use a refrigerating machine having higher performance as the refrigerating machine
147
.
Moreover, in connecting the coaxial cables
145
-
1
and
145
-
2
with the input and output terminals of the electronic part
143
, they are generally soldered directly, or, each plug previously fitted to the coaxial cables
145
-
1
and
145
-
2
is engaged to each receptacle which is previously soldered to the electronic part
143
.
However, the thermal expansion coefficients of the input and output terminals of the electronic part
143
and the receptacles or the coaxial cables
145
-
1
and
145
-
2
are generally considerably different.
Therefore, there has been a possibility of a disconnection or an unnecessary increase insertion losses between the coaxial cables
145
-
1
and
145
-
2
and the input and output terminals of the electronic part
143
during a large change in the temperature of the inner chamber
141
A such as at the moment of activating or stopping.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heat insulation chamber, a thermostatic chamber, and a cryostat which maintain the operating temperature efficiently and also maintain coupling with a circuit disposed outside in a stable condition.
It is also an object of the present invention to improve the performance and reliability of electronic appliances as well as to reduce their costs and dimentions.
The above-described objects are achieved by a heat insulation chamber, which comprises a cabinet which forms an inner chamber for accommodating an electronic part and is made of heat insulating material; and coupling means which is disposed in the inner chamber or the cabinet, connected to the electronic part, and forms a radio transmission path to an antenna disposed outside of the cabinet.
In this heat insulation chamber, the thermal conductivity of the radio transmission path is generally smaller than that of a conductor, so that heat flowing in and out between the outside and the inner chamber is suppressed more than in the prior art. Moreover, an antenna is not disposed in the inner chamber formed by the cabinet.
Therefore, the electronic part of which the operating temperature is maintained in a stable condition and is downsized, allowing the maintenance of high flexibility in arranging the cabinet's inner layout.
And, the above-described objects can be achieved by a heat insulation chamber, which comprises a cabinet which forms an inner chamber for accommodating an electronic part and is made of heat insulating material; an antenna which is disposed in the inner chamber or the cabinet; a feeder which leads the feeding point of the antenna to the outside of the cabinet;
and coupling means which is disposed in the inner chamber or the cabinet, connects the feeding point to the electronic part, and forms a radio transmission path to the antenna.
In this heat insulation chamber, the thermal conductivity of the radio transmission path is generally smaller than that of a conductor, so heat flowing in and out between the outside and the inner chamber is suppressed more than in the prior art. Besides, b
Abeno Ichiro
Akasegawa Akihiko
Kobayashi Fumihiko
Kobayashi Kazuhiko
Tozawa Yoshiharu
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