Thermal measuring and testing – Temperature measurement – In spaced noncontact relationship to specimen
Reexamination Certificate
2002-06-26
2004-02-24
Gutierrez, Diego (Department: 2859)
Thermal measuring and testing
Temperature measurement
In spaced noncontact relationship to specimen
C374S169000, C702S130000
Reexamination Certificate
active
06695471
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to temperature measurement method and apparatus capable of realizing accurate temperature measurement of a measurement target object whose temperature is difficult to measure directly as it is a movable object to which a temperature sensor cannot be fixed directly but there is a need to monitor its temperature constantly or frequently, even when there is a transient temperature change.
2. Description of the Related Art
The most popular and simple method for measuring temperature of an object to which a temperature sensor cannot be set in contact directly such as a movable object is a method as shown in
FIG. 10
, in which an atmospheric temperature in vicinity of a measurement target object
101
is measured by a thermometer
103
by using a temperature sensor
102
arranged in vicinity of the measurement target object,
101
and this temperature is regarded as the temperature of the measurement target object
101
. For the temperature sensor, a thermistor, a thermocouple, and a resistance temperature detector are often used. When a correspondence between the temperature sensor
102
and the temperature of the measurement target object
101
is calibrated in advance under a stable temperature condition such as that of a temperature controlled box, the temperature indicated by the thermometer
103
agrees with the actual temperature of the measurement target object
101
very well under a static environment.
Also, as a method for measuring temperature of a movable object including a transient temperature change, there is a method for measuring temperature indirectly by measuring another observation value which changes as the temperature changes. For example, when a radiation thermometer is used, the temperature can be measured according to infrared rays emitted from an object.
Also, when a measurement target object is an object through which lights can transmit, there is a method as shown in
FIG. 11
in which temperature is measured according to a transmission wavelength which varies as the temperature of the object changes.
FIG. 11
shows a method in which a white light from a white light source
202
is incident on a measurement target object
201
having a light transmitting characteristic, a transmission wavelength which varies as the temperature changes is observed by an optical spectrum analyzer
203
, and the temperature is measured from a conversion table
204
between transmission wavelengths and temperatures, which is calibrated in advance.
As described above, in order to measure temperature of a measurement target object whose temperature is difficult to measure directly as it is a movable object to which a temperature sensor cannot be fixed directly but there is a need to monitor its temperature constantly or frequently, the methods as shown in FIG.
10
and
FIG. 11
have been used conventionally. However, these conventional methods have drawbacks such as that the accurate temperature measurement cannot be realized when there is a transient temperature change, or that it is costly.
Namely, the method for measuring the temperature in vicinity of the measurement target object by using the temperature sensor and regarding this temperature as the temperature of the measurement target object has a drawback that, as shown in
FIG. 10
, there is a transient difference between the temperature characteristics
107
and
108
of the measurement target object
101
and the temperature sensor
102
due to a difference in the thermal capacity or the like, and there can be cases where this difference causes as a transient temperature error
109
.
Also, the method for indirectly measuring the temperature of the measurement target object by measuring another observation value which varies as the temperature changes in a non-contact manner has a drawback that method and apparatus for measuring these observation values are more complicated, larger, and more costly, compared with the method using the temperature sensor.
For example, a temperature meter using a combination of a thermistor and a thermometer will only costs about several thousand yen, whereas one using an optical spectrum analyzer as shown in
FIG. 11
will cost as much as several million yen. Consequently, from viewpoints of size and cost, it is not preferable to use a device such as the optical spectrum analyzer in the application that requires the constant or frequent temperature monitoring, although there can be cases where the optical spectrum analyzer is temporarily used in the application such as that for collecting temperature calibration data.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a temperature measurement method capable of eliminating a transient temperature error that can be caused by the conventional temperature sensor, and a temperature meter using this method which is capable of measuring temperature accurately by using the conventional temperature sensor even under a transient circumstance in which temperature changes are frequent.
According to one aspect of the present invention there is provided a temperature measurement method for measuring temperature of a measurement target object to which a temperature sensor cannot be fixed directly, comprising: obtaining an observed temperature from the temperature sensor arranged in a vicinity of the measurement target object and a temperature observation time from a timer; and calculating the temperature of the measurement target object T
obj
according to the observed temperature and the temperature observation time by a calculation processing based on a following equation (C):
T
obj
(
t
1
)=
G
in
·f
(&Dgr;
t
obs
)·&Dgr;
t
obs
+T
obj
(
t
0
) (C)
where t
1
is a current time at which the observed temperature is observed, t
0
is a time at which temperature was measured last time, G
in
is a time change rate of temperature applied to the measurement target object, f(&Dgr;t
obs
) is a polynomial regarding &Dgr;t
obs
, and &Dgr;t
obs
is a time interval by which temperature has been observed.
According to another aspect of the present invention there is provided a temperature meter for measuring temperature of a measurement target object to which a temperature sensor cannot be fixed directly, comprising: a temperature sensor configured to measure an observed temperature in a vicinity of the measurement target object; a timer configured to measure a temperature observation time; and a calculation processor configured to calculate the temperature of the measurement target object T
obj
according to the observed temperature and the temperature observation time by a calculation processing based on a following equation (C):
T
obj
(
t
1
)=
G
in
·f
(&Dgr;
t
obs
)·&Dgr;t
obs
+T
obj
(
t
0
) (C)
where t
1
is a current time at which the observed temperature is observed, t
0
is a time at which temperature was measured last time, G
in
is a time change rate of temperature applied to the measurement target object, f(&Dgr;t
obs
) is a polynomial regarding &Dgr;t
obs
, and &Dgr;t
obs
is a time interval by which temperature has been observed.
According to another aspect of the present invention there is provided a computer usable medium having computer readable program codes embodied therein for causing a computer to function as a temperature meter for measuring temperature of a measurement target object to which a temperature sensor cannot be fixed directly, the computer readable program codes include: a computer readable program code for causing said computer to calculate the temperature of the measurement target object T
obj
according to an observed temperature obtained from a temperature sensor arranged in a vicinity of the measurement target object and a temperature observation time obtained from a timer, by a calculation processing based on a following equation (C):
T
obj
(
t
1
)=
G
in
·f
(&Dgr;t
obs
)·&Dgr;t
obs
+T
obj
(
t
0
) (C)
where t
1
is a current time at w
Abe Tetsuo
Hashimoto Etsu
Katagiri Yoshitada
Suzuki Yoshio
Kilpatrick & Stockton LLP
Nippon Telegraph and Telephone Corporation
Pruchnic Jr. Stanley J.
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